AprilJune 2015 Perspective 1 MG Steve Jones The Role of Strength and Power During Performance of High Intensity 3 Military Tasks Under Heavy Load Carriage Jesse Mala, MS; Tunde K. Szivak, MA; Shawn D. Flanagan, MA; Brett A. Comstock, PhD; et al Performance Differences Between Male and Female Marines on Standardized 12 Physical Fitness Tests and Combat Proxy Tasks: Identifying the Gap James Jameson, PhD; Leon Pappa; Brian McGuire; Karen R. Kelly, PhD Musculoskeletal, Biomechanical, and Physiological Gender 22 Differences in the US Military Katelyn F. Allison, PhD; Karen A Keenan, PhD, ATC; Timothy C. Sell, PhD, PT; et al The Effects of Cross-Training on Fitness and Injury in Women 33 Tyson Grier, MS; Michelle Canham-Chervak, PhD; Morgan K. Anderson, MPH, CPH; et al Physical Training, Smoking, and Injury During Deployment: 42 A Comparison of Men and Women in the US Army Morgan K. Anderson, MPH, CPH; Tyson Grier, MS; Michelle Canham-Chervak, PhD; et al Physical Fitness and Injury Reporting Among Active Duty and National Guard/ 49 Reserve Women: Associations with Risk and Lifestyle Factors Josh B. Kazman, MS; Sarah de la Motte, PhD, MPH, ATC; Elizabeth M. S. Bramhall, MPH; et al Josh B. Kazman, MS; Diana L. Purvis, PhD; Yuval Heled, PhD; Peter Lisman, PhD; et al Effects of Basic Combat Training on Iron Status in Male and Female Soldiers: 67 A Comparative Study MAJ Ran Yanovich, ISDF; J. Philip Karl, PhD, RD; Einat Yanovich, PhD; et al Female Combat Amputees Have Higher Rates of Posttraumatic 74 Stress Disorder Disability MAJ Jessica C. Rivera; CPT (P) Chad A. Krueger; LTC (P) Anthony E. Johnson in Iraq and Afghanistan CPT Christina Hylden; LTC (P) Anthony E. Johnson; MAJ Jessica C. Rivera Lt Col Candy Wilson USAF; COL Lori Trego; CAPT Jacqueline Rychnovsky, USN; et al ALSO IN THIS ISSUE Complex d-TGA Status Post Rastelli Repair Presenting with Palpitations: 91 Cardiac CTA Imaging Findings and Discussion of Long Term Outcomes Capt Ross Pinson, USAF; MAJ Dustin Thomas; Maj S. Jared Bentley, USAF US Army Psychiatry in the Vietnam War A New Offering from the Borden Institute History Series 97 Reviewed by LTC Daniel E. Banks and COL (Ret) Hershell L. Moody J OURNAL THE UNITED STATES ARMY MEDICAL DEPARTMENT PHYSIOLOGICAL FACTORS OF EXP ANDED ROLES FOR MILITARY WOMEN Article Retracted By Authors May 6, 2015
J OURNAL A Prof essional Publication of the AMEDD Community THE UNITED STATES ARMY MEDICAL DEPARTMENT Online issues of the AMEDD Journal are available at http://www.cs.amedd.army.mil/amedd_journal.aspx AprilJune 2015 US Army Medical Department Center & School PB 8-15-4/5/6 The Army Medical Department Journal [ISSN 1524 0436 ] is published quarterly 3630 Stanley RD STE B 0204 78234 6100 The Army Medical Department Journal are listed and Journal s CORRESPONDENCE: (210) 221-6301, DSN 471-6301 DISCLAIMER: The AMEDD Journal in the AMEDD Journal AMEDD Journal CONTENT: AMEDD Journal OFFICIAL DISTRIBUTION: By Order of the Secretary of the Army: GERALD B. OKEEFE Secretary of the Army Raymond T. Odierno 1503606 COL Denise Hopkins-Chadwick, AN Claude W. Bowman, PhD Richard Burton LTG Patricia D Horoho MG Steve Jones EDITORIAL REVIEW BOARD COL Jeanne Tofferi, MC, Chairman COL (Ret) Mustapha Debboun, MS COL Noreen Murphy, VC COL Steven L. Eikenberg, DC COL Judith A. Bock, AN Coleen P. Baird, MD, MPH COL Stephen C. Craig, MC
April June 2015 1 Perspective COMMANDERS INTRODUCTION MG Steve Jones Women have been part of the Army since 1775, serving with skill, determination, and valor. In Army Medicine they have played a critical role maintaining the health readiness of the force and caring for the injured and ill. The Army began expanding the role of women 40 men as members of the profession of arms. During the campaigns in Afghanistan and Iraq they have done their women Marines were killed when their convoy was at Marines wounded in that attack, 11 were women. This incident represented the largest loss of women in uni Ann Hester of Nashville, Tennessee was awarded the and into their position where she assaulted a trench line and one was captured. routine security patrol along in Afghanistan s Paktika province when insurgents attacked her convoy in April II. 4 pied by enemy insurgents. During the assault, the enemy triggered multiple suicide and improvised explosive de explosive devices to render aid to the casualties and as sist with evacuation. While moving toward a wounded soldier, she triggered a device and was killed in action. humously for her valor. 5 Throughout our history, women have proven there are few limits to the contributions they are capable of mak Army is working to remove as many barriers as pos liberate, service-wide effort to staff its units with the ing forces by preserving unit readiness, cohesion, and morale; validate both physical and mental occupational performance standards for all military occupational or women, have an opportunity to succeed as their tal mand began the process by studying attitudes of women in combat units. They found that most men who had worked and fought beside women expected them to perform well in combat roles; it is those with little or no experience serving beside women who require more convincing that women will perform well. There was agreement across the force that we not lower the stan dards for service in combat roles, and that women, based on their wartime performance, have earned the oppor tunity to stand in any of our formations for which they tional specialties and over 55,000 positions across all WOMEN IN COMBAT 1
2 http://www.cs.amedd.army.mil/amedd_journal.aspx Army components. Among the newly opened positions physical standards and conducting a gender integra tion study to inform decisions on opening the remain ing 14 military occupational specialties currently closed process. Upon completion of the study, the Army will cohesion, discipline, and morale. Having served shoulder to shoulder with women dur their new roles while strengthening the force. REFERENCES 1. azine women. valor in Iraq. [seri 4. [serial 5. no, an Army nurse killed in Afghanistan. PERSPECTIVE
April June 2015 3 Throughout history, load carriage has been shown to be an essential aspect of soldiering during military opera are required to carry various loads on their person or in a pack while engaging in demanding activities, ranging from long distance marching to short explosive sprints. The speed with which the soldier is able to maneuver on an objective carrying these loads, while performing strenuous activities, is critical to the completion of mis sions and survivability of personnel. Knapik et al 1 characterized the various loads that were carried by different Soldiers throughout history, from the Greek Hoplites to the US infantryman in Afghani stan during Operation Enduring Freedom, showing an increase in loads carried into battle. Load carriage has been shown to increase physiological strain, leading to excessive fatigue and attenuating combat effectiveness. 2-4 Much of the increase in load can be attributed to tech nological advances in weaponry and armor, which aim to improve the combat effectiveness and survivability of the Soldier, but have negative implications on mobil ity and endurance due to the increase in weight. 3,4 the increase in weight resulting in a greater performance decrement, several studies have investigated approaches to optimal training programs designed to improve the 5-7 The majority of the current research on military load carriage has examined the physiological determinants, the effects of various loads, and the training required to improve the speed of load carriage over medium to long distances, ranging from 2.5 km to 25 km. 8-10 medium to long distance marching with various loads is merely a single component of the multifaceted occu tactics of past wars where Soldiers would march long distances, over several days, carrying their supplies into battle. However, combat operations have evolved from marching into battle to primarily conducting direct The Role of Strength and Power During Performance of High Intensity Military Tasks Under Heavy Load Carriage Jesse Mala, MS Justin Z. Laferrier, PhD Tunde K. Szivak, MA Carl M. Maresh, PhD Brett A. Comstock, PhD ABSTR A CT Objective: Previous research has investigated the physiological determinants of heavy load carriage while per forming medium to long distance road marching, yet research examining the physiological underpinnings of high-intensity combat tasks under heavy load carriage. Methods: Eighteen recreationally trained men (meanSD: age, 212 years; height, 1726 cm; weight, 8013 kg) participated in this study and performed an anaerobic combat course under 2 randomized experimental conditions; unloaded and loaded. Subjects performed 3 trials under each condition on separate days, with a 5-minute rest between each trial. In the unloaded trial, subjects wore a uniform with boots weighing approxi mately 3.2 kg. During the loaded trial, in addition to the uniform and boots, subjects wore Interceptor body armor (6.94 kg-9.10 kg) and a MOLLE rucksack weighing 30 kg. The course consisted of 3 consecutive tasks, which began from the prone position, led into a 30 m sprint, followed by a 27 m zigzag run, and ended with a 10 m casualty drag weighing approximately 79.4 kg. Results: .05) strong correlations between lower body strength (r= 0.63, 0.62), lower body power (r= 0.67, 0.67) and upper body strength (r= 0.60, 0.62) and overall per formance times in the unloaded and loaded condition, respectively. Conclusion: Strength and power are strongly related to high-intensity military tasks with and without heavy load carriage.
4 http://www.cs.amedd.army.mil/amedd_journal.aspx action raids. During raids, troops are transported near or directly onto an objective and must quickly traverse the objective, perform ing anaerobic tasks such as sprint ing, lifting, pulling, crawling, and climbing, while still carrying sig aerobic, more studies examining the demands of this anaerobic 11 are necessary, so that Soldiers can train optimally to meet these demands. There is limited re search investigating the physiologi cal underpinnings and effects of heavy load carriage during the per formance of short duration, highintensity anaerobic tasks, which 4 examined the overall effect of a combat load (21.8 kg) as having a strong relationship with unloaded and loaded sprint time (r= 0.80, .01), however no strength mea sures were examined in this investigation. Pandorf et al 12 examined the correlates of load carriage during the per formance of a military obstacle course, yet no upper or lower body strength and power variables were assessed. Therefore the purpose of this investigation was to clarify the relationship between upper and lower body strength and lower body power and short duration, high-intensity military relevant tasks, while carrying heavy loads. METHODS Experimental Approach to the Problem To examine the role of strength and power in high-in tensity military tasks under heavy load carriage, lower body and upper body strength were measured using a one repetition maximum (1RM) squat and bench press protocol, and lower body power was assessed using countermovement jumps as measured by a force plate, using previously described methods. 13 Three military relevant tasks (30 m sprint, 27 m zigzag run, 10 m ca sualty drag) were used to simulate explosive offensive and defensive maneuvers routinely encountered on the 4,12 During the performance of the tasks, sub jects wore an Army combat uniform, boots, Interceptor body armor (IBA), and a Modular Lightweight Loadcarrying Equipment (MOLLE) rucksack, resulting in a total weight of approximately 42 kg (body size depen dent), which is representative of the typical load carried by US Army Soldiers during recent combat operations. 14 Subjects Eighteen recreationally active men (age: 21.82.4 years, height: 172.96.4 cm, weight: 80.713 kg) participated in this study. The phys ical characteristics of the subjects are presented in Table 1. To reduce variance caused by differences in age, and to be able to generalize population, subjects recruited for this study were men between the ages of 18 and 35. Also, since most active combat units physically train at least 3 times a week to maintain ness, 15 subjects in this study were recreationally trained men who exercised at least 3 times a week for 60 minutes each day. Twelve Corps (ROTC) unit from the university population, and 6 subjects were civilian students from the university population. Subjects were required to complete a medi cal questionnaire and were screened by a physician for any orthopedic, cardiovascular, or other medical prob lems that may have prevented a subject from safely com pleting the study or may have confounded the results of this investigation. Participants were briefed on the risks pleted a written informed consent form to participate in the study. This investigation was approved by the local university Institutional Review Board for use of human subjects. Procedures To minimize learning effects related to the unfamiliarity of the different protocols in the study, participants un derwent a familiarization session prior to any data col lection, which exposed the subjects to the experimen tal conditions of the performance testing protocol, the Army Physical Fitness Test (APFT) protocol, and the military course protocol. In addition, anthropometric measurements were collected, and subjects were famil iarized with a standardized dynamic warmup protocol that would be used before all experimental visits. The standardized warmup consisted of 5 minutes on a cycle ergometer at a resistance level of 5, with a speed main tained under 60 rpm, followed by dynamic stretches, including forward and lateral lunges, knee hugs, quad riceps stretches, straight leg marches, and body weight THE ROLE OF STRENGTH AND POWER DURING PERFORMANCE OF HIGH INTENSITY MILITARY TASKS UNDER HEAVY LOAD CARRIAGE Table 1 Overall Subject Characteristics. Subject Number Height (cm) Weight (kg) Age (yr) 1 178 86.1 22 2 168 81.1 21 3 173.5 58.9 21 4 162 61.4 22 5 173 78 19 6 165 66.6 21 7 179.5 80 22 8 169.5 98.8 21 9 176.2 104.9 30 10 173.5 84.7 24 11 162 69.7 20 12 187 103.6 23 13 173.5 88.6 22 14 177 72.1 21 15 177 74.9 20 16 175 78.3 20 17 167 77.9 21 18 176 86.4 22 MeanSD 172.96.4 80.713 21.82.4
April June 2015 5 squats. 16 Furthermore, to reduce any discomfort related MOLLE rucksack and also were instructed on proper wear technique. Performance Testing Protocol Following the familiarization session, participants com pleted a countermovement jump protocol, a 1 repeti tion maximum (1RM) squat protocol and a 1RM bench press protocol in the same visit. After performing the standardized warmup, countermovement vertical jump power was assessed using a force plate (Fitness Technol ogy, Skye, South Australia) and Ballistic Measurement System software (http://ballistic-measurement-system. software.informer.com/2.0/). Lower body power and 1RM strength were assessed using previously described methods. 13 For the countermovement jump, subjects were asked to perform 3 consecutive maximal jumps with their hands on their hips. Participants performed 2 sets of the countermovement jumps, with at least 2 minutes of rest between sets. Peak power for each set was recorded. Subsequently, after the countermovement jump testing and a 5 minute rest, lower body strength was assessed by a 1RM squat protocol using a Smith machine, and upper body strength was assessed with the use of a 1RM free-weight (barbell) bench press pro tocol. For each 1RM test, subjects performed 8-10 rep etitions at approximately 50% of estimated 1RM, fol lowed by another set of 3-5 repetitions at 85% of 1RM. Up to 4 maximal trials separated by 2-3 minutes of rest were used to determine individual 1RMs for the squat and bench press exercise. 13 Army Physical Fitness Testing Following the performance testing protocol, civilian subjects were given at least 24 hours of rest before per forming the APFT. After completing the standardized warmup, subjects performed the APFT, which consists of 2 minutes of maximal push-ups, 2 minutes of maxi mal sit-ups, and a timed 2-mile run, following guide lines outlined in Army Field Manual 7-22 15 A rest of 5-10 minutes was allotted between each test. The ROTC cadets in this study performed the APFT with the ROTC cadre one week prior to participation in this study, fol lowing the same testing guidelines. The APFT scores were used from this testing session and were deemed re experienced Army personnel familiar with the testing procedures outlined in Field Manual 7-22 15 Military Course Protocol To control for any extraneous variables in the partici pants diet and activity, subjects were asked to record formance of the military course. Participants were en couraged to continue their normal exercise routines, but were asked to refrain from strenuous exercise during the dom order, which was performed in either the unloaded (combat uniform and boots [approximately 3.2 kg]) or loaded condition (combat uniform, boots, IBA [6.9 kg, 8.1 kg, or 9.1 kg depending on body size], and MOLLE rucksack [30 kg]; total weight of approximately 42 kg). rest, with subjects replicating their diet and activity logs the military course, ensuring that subjects would be in a similar physiological state during both visits. For each visit, after performing a standardized warmup, subjects were reminded of the test protocols for the military course. The military course, illustrated in Fig ure 1, consisted of 3 consecutive military relevant tasks and began from the prone position, leading into a 30 m sprint, followed by a 27 m zigzag run, and concluding Figure 1 Military course design. Time check points are represented by T 1 T 2 T 3 and T 4 Start 5 m Finish Task 3: 10 m Casualty Drag T1 T3 T4 T2 Task 2: 27 m Zigzag Run Task 1: Sprint 30 m from prone position
6 http://www.cs.amedd.army.mil/amedd_journal.aspx with a 10 m, 79.5 kg casualty drag, which is the approxi mate weight of a US infantryman with a combat load. 14 of the casualty drag apparatus passed the 10 m mark. Times were hand-recorded by the same timer using a Three trials were performed to increase the reliability of recorded performance times, 12 and a 5-minute rest between each trial ensured adequate recovery. Subjects also performed both of the military course visits during hormone variations. All of the military task visits were conducted in the evening, since the majority of direct action raids and combat operations take place during this time. Lastly, to reduce tester induced variability, the same tester recorded the timing of the military course for each subject for both visits. Statistical Analysis It was determined that a sample size of 18 would be suf a Cohen probability of 0.80 or more for each dependent variable (nQuery Advisor software, Statistical Solutions, Saugus, MA). Subjects were separated into 2 different groups, shown in Table 2, based on their primary mo dality of training for the past year (resistance-trained [RT] and traditional Army-trained [AT]). A 2 (tradition al Army-trained vs strength-trained) by 2 (loaded trial vs unloaded trial) by 5 (total time, 5m time, 30 m time, agility time, casualty drag time) mixed methods analy mean differences (SPSS Version 21, IBM Corp, Armonk, was used to make pairwise comparisons. A Pearson product moment correlation was used to determine the relationship between potential anthropometric and per also used independent t -tests to compare mean values for these potential predictors in the 2 groups. All values are presented as means and standard deviations, and sig .05. RESULTS Differences Between Unloaded and Loaded Times The means and standard deviations of the unloaded mil itary course time and the loaded military course time for the RT and AT groups are depicted in Figure 2. tween the unloaded (28.72.5 sec) and loaded (38.74.8 sec) conditions, with the loaded condition eliciting a compared to the unloaded time (10.03.4 sec, .05). group between the unloaded (25.41.8 sec) and loaded (32.73.6 sec) conditions, with the loaded condition time when compared to the unloaded time (7.32.1 sec, plete the military course under load when compared to the RT group (RT: 7.32.1 sec, 29% increase vs AT: 10.03.4 sec, 35% increase, .05). Overall Loaded Course Time and Times for Each Course Component Average time to complete the total course and each com ponent within the course in the loaded condition are de picted in Figure 3. THE ROLE OF STRENGTH AND POWER DURING PERFORMANCE OF HIGH INTENSITY MILITARY TASKS UNDER HEAVY LOAD CARRIAGE Table 2. Subject Characteristics for RT and AT Groups. RT AT Age (yr) Height (cm) Weight (kg) Age (yr) Height (cm) Weight (kg) 22 178 86.1 21 168 81.1 22 179.5 80 21 173.5 58.9 21 169.5 98.8 22 162 61.4 30 176.25 104.9 21 165 66.6 24 173.5 84.7 20 162 69.7 23 187 103.6 20 177 74.9 22 173.5 88.6 20 175 78.3 21 167 77.9 21 177 72.1 22 176 86.4 19 173 78 22.62.9 175.3.6 *88.910.1 20.80.7 169.96.5 *70.47.8 NOTE: Bottom row presents mean SD( Indicates significant difference). RT indicates resistance-trained. AT indicates Army-trained. 45 40 35 30 25 20 LD UNLD * AT RT Time (sec) Figure 2 Means and standard deviations of unloaded (UNLD) and loaded (LD) total course time for RT (resistancetrained) and AT (Army-trained) groups. RT: UNLD 25.41.8 sec; LD 32.73.6 sec. AT: UNLD 28.752.5 sec; LD 38.74.8 sec.
April June 2015 7 In the loaded condition, the RT group per faster ( faster when rising from the prone position to drag ( .05). Group-specific Differences in Strength and Power Variables The means and standard deviations of peak pow er for the RT and AT groups are shown in Fig the RT group averaging 44% greater peak pow er (watts) than the AT group (RT=4806.7936.3 and standard deviations for the RT and AT ferences were found between the RT (155.554 kg) and AT groups (84.716.9 kg), with the RT group averaging 83% greater lower body strength. The means and standard deviations of bench press 1RM are listed in Figure 6 for the RT and AT groups. Sig .05) were found between the RT (121.629.9 kg) and AT groups (75.610.9 kg), with the RT group averaging 61% greater bench press 1RM than the AT group. APFT components between the RT and AT groups. The means and standard deviations of performance out comes for each APFT component for the two groups are provided in Table 3. Relating Performance Test Variables to Loaded Military Course Performance The correlation of all the performance testing variables with the loaded military course time and its 3 compo nents is shown in Table 4. There was a strong negative correlation between total loaded time and peak power (watts) (r= 0.67, .05), total loaded time and squat 1RM (kg) (r= 0.62, .05), and total loaded time and bench press 1RM (kg) (r= 0.62, .05). Strong correla tions were also observed between the strength and pow er measures and the majority of the components within relation between a component of the APFT (number of push-ups) and performance on the loaded military course (total time). CO MM ENT The purpose of this study was to determine the role of strength and power in short duration, high-intensity military tasks incorporating heavy load carriage. Most studies that have examined strength and power in mili assessed strength and power in conjunction with perfor loads. This investigation used only 3 military relevant tasks (prone position into 30 m sprint, 27 m zigzag run, 10 m casualty drag) vs the multistation (8-19) obstacle courses frequently used in other investigations, since direct action raids mostly involve short distance sprint 5 meters of the 30 m sprint began from the prone po sition, because it was here that Treloar et al 4 observed the greatest decrement in 30 m loaded sprint times. This is also the starting position for basic offensive and de fensive maneuvers. A short distance casualty drag was Figure 3 Mean times for each component of the military course for RT (resistance-trained) and AT (Army-trained) groups. 3.54 3.1 * 11.4 12.9 8.5 13.5 9.2 15.4 40 20 10 0 30 50 RT AT 5 m 30 m Zigzag Casualty Drag Time (sec) Power (watts) RT AT 7000 6000 5000 4000 3000 2000 1000 Figure 4 Mean differences between RT (resistance-trained) and AT (Army-trained) groups in peak power. RT: 4806.7963.3 W AT: 3333.6449.5 W
8 http://www.cs.amedd.army.mil/amedd_journal.aspx dier would quickly transfer the casualty behind a point used in this investigation (approximately 42 kg) is typi cal of loads carried by US infantrymen during modern combat operations. 14 There were strong negative correlations between upper body strength, lower body strength, lower body power, and overall loaded military course time, highlighting the role of strength and power during high-intensity, combat-relevant tasks. It is important to mention that the negative correlations indicate that greater strength and power were associated with shorter course comple al, 17 Bishop et al, 18 and Treloar et al, 4 cant correlations between strength and power and mili tary obstacle course performance. Strength and power being highly correlated to high-intensity military tasks 19 who found that lower body power could predict simu a 30 m run and a 27 m zigzag run with an 18 kg combat load. In the present study, lower body strength was the only variable that had a consistently strong correlation with overall loaded course time, as well as with every individual component of the course (prone position to 5 m, 30 m sprint, 27 m zigzag run, 10 m casualty drag). relationship between push-ups, sit-ups, and 2-mile run time with respect to overall time on the loaded military dorf et al 20 who observed that APFT scores did not cor relate with performance on a loaded military obstacle APFT component and military course time was the asso ciation between the number of push-ups performed and 5 m sprint of the course. This coincides with previous 4,19 The lack of correlation between push-ups, sit-ups, and 2-mile run time with respect to high-intensity combat tasks is highly relevant; as the majority of the military continues to use calisthenics and aerobic training as the primary methods of preparation for combat deployment. Yet, the physical demands of deployment more closely mirror the conditions of the loaded military course used in the present investigation. Given the observed strength of correlations between strength/power and perfor mance on the high-intensity combat task, it is likely that a strength and conditioning program that focuses on the development of strength and power will better prepare 5,7,11 To further illustrate differences between resistance training and traditional Army training in terms of the performance on high-intensity combat tasks, groups were dichotomized based on training history over the previous year, resulting in placement into a RT or tra groups were found for lower body power, squat 1RM, bench press 1RM, and most importantly, performance on the loaded military course. It is important to note that while the RT group outperformed the AT group on the overall loaded military course by on average 5.99 THE ROLE OF STRENGTH AND POWER DURING PERFORMANCE OF HIGH INTENSITY MILITARY TASKS UNDER HEAVY LOAD CARRIAGE 180 160 140 120 100 80 60 40 20 RT AT Kilograms Figure 6 Mean differences between RT (resistance trained) and AT (Army trained) groups in bench press RT: 121.629.9 kg AT: 75.610.9 kg * RT AT 240 190 140 90 40 Kilograms Figure 5 Mean differences between RT (resistance-trained) and AT (Army-trained) groups in 1 repetition maximum squat test. RT: 155.554 kg AT: 84.716.9 kg
April June 2015 9 seconds ( .05), 4.95 seconds (82%) of that time difference was attributed to performance of the casualty drag component. This is not surprising, as the casualty drag was the most heavily loaded component of the course, and was therefore likely to be most sensi tive to differences in upper and lower body strength. As measured by the squat 1RM, the RT group had substantially greater lower body strength when com pared to the AT group (RT: 155.554 kg. AT: 84.616.9 kg, bench press 1RM (RT: 121.629.9 kg. AT: 75.510.9 kg, .05). In view of these differences, it is no surprise casualty drag, since this task involves the same muscle groups in the upper and lower body as the squat and bench press exercises. The 2 groups also differed on the time to complete the prone position to sprint 30 m. On average, this segment accounted for 10% of the difference in total course time (0.5 seconds), with RT outperforming AT. The action of rising from the prone position with a load into a sprint which is also reinforced by the strong correlations of the bench press 1RM and the squat 1RM with the prone to 5 m task (r=-0.65, r= 0.70, respectively, .05). There and the AT group for the loaded 30 m sprint time, and the loaded 27 m zigzag run time, which coincides with Harman et al, 21 between 8 weeks of Army training and weight training The observed effect of loading on military course per formance was expected and corresponds with previous research. Overall, performance on the military course decreased 31% when loaded (26.82.7 seconds vs 35.35.0 seconds, ings of Treloar et al 4 who observed a 29% increase in time when a 21.6 kg load was added to 30 m sprints. The larger performance decrements observed in this study may be explained by the use of a heavier loading scheme. The increase of the weight of body armor has intensity military tasks, with time to completion being 10% slower during armored trials. 3 An examination of overall performance decrements during loaded trials in the RT and AT groups showed that the AT group had a 35% increase in course time versus the RT group, for which a 29% increase in course cant difference in performance between the RT and AT groups difference ( .05) in group aver age body mass (RT 88.910.1 kg; line with previous investigations, which have shown that larger, more muscular individuals per form better and are less affected by heavier loads than smaller, less muscular individuals. 20,22 the AT group in the loaded 30 m sprint time and the 27 m zigzag run time may be due to the familiarity of the AT group with military loads and equipment. Even though each subject was familiarized with the course and the load, the AT group may have had an advantage due to prior training exposure. The AT group consisted of ROTC cadets, while the RT group was mainly com prised of civilians who had no prior experience carrying military loads. Thus even larger differences might have been evident if both groups had similar overall exposure to military load carriage. observed between the RT and the AT groups (88.910 kg vs 70.47.8 kg, .05), which may help explain the lack of difference in the 30 m and 27 m zigzag run time. Individuals with more body weight carry their own weight, in addition to the external load, with the heavier subjects carrying a greater overall load, which may place the heavier subject at a disadvantage in the cant differences in weight, 30 m sprint time (RT 8.50.9 seconds vs AT 9.31.1 sec) and 27 m zigzag run times (RT 12.81.1 seconds vs AT 13.70.9 seconds) were not statistically different between the RT and AT groups. This may be explained by the RT group possessing a Table 4. Correlation of Performance Testing Variables with the Military Course and Individual Components. Total Loaded Loaded 5 m Loaded 30 m Loaded Zigzag Loaded Casualty Drag Peak power -0.67 -0.66 -0.60 -0.39 -0.64 Squat 1 RM -0.62 -0.70 -0.58 -0.48 -0.57 Bench press 1 RM -0.62 -0.65 -0.54 -0.44 -0.59 Push-ups -0.38 -0.507 -0.428 -0.254 -0.34 Sit-ups 0.113 0.104 -0.069 0.095 0.138 2 Mile run time -0.374 -0.112 -0.285 0.043 0.036 Indicates significant difference ( P ). Indicates significant difference ( P ). 1 RM indicates one repition maximum. Table 3. Raw scores for each component (max push-ups in 2 minutes, max sit-ups in 2 min utes, and 2 mile run) of the Army Physical Fit ness Test (APFT) for the RT and AT groups. APFT Components RT (meanSD) AT (meanSD) Push-ups (repetitions) 7217 6610 Sit-ups (repetitions) 6417 715 2 Mile run (seconds) 954133 89151 RT indicates resistance-trained. AT indicates Army-trained.
10 http://www.cs.amedd.army.mil/amedd_journal.aspx setting the detrimental effects of extra weight, reinforc ing the importance of lower body power. Subjects were also placed in the RT and AT groups on the basis of their training history (exercise at least 3 times per week for the past year in one modality) with programs (power, hypertrophy, strength, intensity, etc). Greater differences may be observed if strictly poweror strength-trained subjects are compared with tradi tional Army-trained subjects. There is a need for further investigation concerning the effects of different training programs (strength, power, hypertrophy, calisthenics, etc) on the performance of short duration, high-intensity military load carriage tasks. RELEV A NCE TO THE PERFOR MA NCE TRI A D This investigation examined the role of upper and lower body strength and power in the performance of short duration, high-intensity, combat relevant tasks, under task length examined in the current investigation was distinctly different from previous work (3 tasks vs 8-19 observations of previous studies. The physiological un scored the overriding importance of strength and power 11 this investigation can be used by military leadership and strength coaches working with the military popu lation in providing a basis to develop optimal training regimens that include strength, power, and hypertro phy training. For modern combat occupations, training approaches which emphasize strength, power, and hy pertrophy would likely improve combat effectiveness the mission with decreased injury risk, contributing to the overall resilience of the Soldier. ACKNOWLEDGE M ENTS The authors thank LTC James Zopelis, MSG Matthew of the cadets of the Army ROTC unit at the University of Connecticut for their participation in and support of this study. The authors also thank Dr Bradley Nindl and the US Army Public Health Command for their support of this study. Also, many thanks to the graduate assistants and undergraduate students for their hard work and dedi cation during data collection and manuscript preparation. This study was funded by internal laboratory funds and was not formally endorsed by the Department of Defense. REFERENCES 1. Knapik JJ, Reynolds KL, Harman E. Soldier load carriage: historical, physiological, biomechanical, and medical aspects. Mil Med 2004;169(1):45-56. 2. Dubik JM, Fullerton TD. Soldier overloading in Grenada. Mil Rev 1987;67:38-47. 3. Martin PE, Nelson RC. The effect of carried loads on the combative movement performance of men and women. Mil Med 1985;150(7):357-362. 4. Treloar AK, Billing DC. Effect of load carriage on performance of an explosive, anaerobic military task. Mil Med 2011;176(9):1027-1031. 5. Hendrickson NR, Sharp MA, Alemany JA, et al. Combined resistance and endurance training improves physical capacity and performance on tactical occupational tasks. Eur J Appl Physiol 2010;109(6):1197-1208. 6. of resistance training on womens strength/power and occupational performances. Med Sci Sports Exerc 2001;33(6):1011-1025. 7. concurrent resistance and aerobic training on loadtest. Mil Med 2004;169(12):994-999. 8. Dziados JE, Damokosh AI, Mello RP, Vogel JA, Farmer KL. Physiological Determinants of Load Bearing Capacity Natick, MA: US Army Re search Institute of Environmental Medicine; June 1987. Report No. T19-87. Available at: http://oai. 20, 2015. 9. Knapik J, Staab J, Bahrke M, et al. Relationship of Soldier Load Carriage to Physiological Factors, Military Experience and Mood States Natick, MA: US Army Research Institute of Environmental Medicine; May 1990. Report No. T17-90. Available at: http://oai.dtic.mil/oai/oai?verb=getRecord&m cessed February 20, 2015. 10. Vogel JA. The Physiological Determinants of Load Bearing Performance at Different March Distanc es Natick, MA: US Army Research Institute of Environmental Medicine; April 1988. Report No. T15-88. Available at: http://oai.dtic.mil/oai/oai?ve ADA197733. Accessed February 20, 2015. 11. J Strength Cond Res 2012;26(suppl 2):S107-S118. 12. Pandorf CE, Nindl BC, Montain SJ, et al. Reli ability assessment of two militarily relevant oc cupational physical performance tests. Can J Appl Physiol 2003;28(1):27-37. THE ROLE OF STRENGTH AND POWER DURING PERFORMANCE OF HIGH INTENSITY MILITARY TASKS UNDER HEAVY LOAD CARRIAGE
April June 2015 11 13. of amino acids supplement on physiological adap tations to resistance training. Med Sci Sports Exerc 2009;41(5):1111-1121. 14. Dean CE. The Modern Warriors Combat Load. Dismounted Operations in Afghanistan, April-May 2003 Fort Leavenworth, KS: US Army Center for Lessons Learned; 2004. Available at: http://thedon ovan.com/archives/modernwarriorload/Modern ary 20, 2015. 15. Field Manual 7-22: Army Physical Readiness Train ing 16. Hooper DR, Szivak TK, Distefano LJ, et al. Effects of resistance training fatigue on joint biomechanics. J Strength Cond Res 2013;27(1):146-153. 17. Jette M, Kimick A, Sidney K. Evaluation of an indoor standardized obstacle course for Canadian infantry personnel. Can J Sport Sci 1990;15:59-64. 18. Bishop PA, Fielitz LR, Crowder TA, Anderson CL, Smith JH, Derrick KR. Physiological determinants of performance on an indoor military obstacle course test. Mil Med 1999;164(12):891-896. 19. Harman E, Gutekunst DJ, Frykman PN, et al. Mil Med 2008;173(1):36-41. 20. Pandorf CE, Harman EA, Frykman PN, Patton JF, Mello RP, Nindl BC. Correlates of load carriage and obstacle course performance among women. Work 2002;18(2):179-189. 21. Harman EA, Gutekunst DJ, Frykman PN, et al. Ef fects of two different eight-week training programs on military physical performance. J Strength Cond Res 2008;22(2):524-534. 22. Koerhuis CL, Veenstra BJ, van Dijk JJ, Delle man NJ. Predicting marching capacity while carrying extremely heavy loads. Mil Med 2009;174(12):1300-1307. AUTHORS Mr Mala is A Doctoral Fellow in the Department of Educational Leadership at the University of Connecti cut. He deployed to Afghanistan in 2002 and 2004, and Iraq in 2003 with the 3rd Ranger Battalion, 75th Ranger Regiment. Ms Szivak is a Doctoral Fellow in the Department of Hu man Sciences at The Ohio State University. A former US member of the 101st Airborne Division. Mr Flanagan is a Doctoral Fellow in the Department of Human Sciences at The Ohio State University. Dr Comstock is an Assistant Professor in the Department of Kinesiology and Sport Science at the University of South Dakota. Dr Laferrier is an Assistant Professor in the Department of Physical Therapy at the University of Connecticut. charge of physical therapy for the Department of Defense Extremity Trauma and Amputation Center for Excellence. Dr Maresh is a Professor and Department Chair for the Department of Human Sciences at The Ohio State University. Dr Kraemer is a Professor in the Department of Human US Army Research Institute of Environmental Medicine from 1984 to 1987.
12 http://www.cs.amedd.army.mil/amedd_journal.aspx For decades women have been restricted from direct assignment to certain military occupational specialties (MOSs), such as infantry. These restrictions can limit the advancement of women through the ranks of military leadership, and could also potentially deprive the mili tary of a rich pool of talented applicants. Since World War II, there has been a gradual push to open closed oc cupations (primarily combat roles) to women. Eventually this trend became policy when Section 535 of the Nation al Defense Authorization Act for Fiscal Year 2011 (Pub The Secretary of Defense, in coordination with the Sec retaries of the military departments, shall conduct a review of laws, policies, and regulations, including the collocation policy, that may restrict the service of female members of the Armed Forces to determine whether changes in such laws, policies, and regulations are need ed to ensure that female members have an equitable op portunity to compete and excel in the Armed Forces. tant questions must be answered, each pointing to a physical requirements of combat that could potentially prevent women from assignment to closed positions? (2) Can readiness for combat be assessed in a fair way, one that captures the actual physical requirements of those combat situations, and would not unfairly exclude women? This initial effort, as part of a larger physical Performance Differences Between Male and Female Marines on Standardized Physical Fitness Tests and Combat Proxy Tasks: Identifying the Gap Jason Jameson, PhD Leon Pappa Brian McGuire Karen R. Kelly, PhD ABSTR A CT Objectives: For decades women have been restricted from direct assignment to certain military occupational specialties such as infantry. These restrictions can limit the advancement of women through the ranks of military leadership. Thus, the purpose of this effort was to identify those physical requirements most likely to serve as barriers for women wanting to enter closed combat arms positions, and to evaluate the quality of existing Methods: Data were collected from 3 different sites within the US Marine Corps Training and Education Command. All participants (409 male, 379 female) were active-duty Marines who recently completed the Results: cases, with performance on combat-related proxy tasks (Spearmans typically ranged from 0.60 to 0.80). Estimates of fat-free mass and VO 2 max were also strongly related to an overall measure of combat readiness (Spearmans =0.77 and =0.56, respectively). Conclusions: The primary physical obstacle for women is upper body strength. However, some women could successfully complete all of the proxy tasks and thus are physically capable of meeting the demands of closed combat occupations. The fact that some female Marines could complete the most challenging upper body THIS ARTICLE RETRACTED BY AUTHORS MAY 6, 2015
April June 2015 13 standards validation effort, was aimed at answering these questions. The general approaches in addressing the 2 questions Question 1 ( a ) Identify or develop tasks that could reasonably serve as proxies for important combat-related tasks. ( b ) Identify and describe the physical capabilities required to meet the corresponding occupational demand. ( c ) Compare the performance of women to the per formance of men. The performance of active duty male Marines can serve as standard against which to evaluate the readiness of women for combat assignment. Question 2 ( a extent to which those tests can accurately iden tify combat-ready Marines. ( b ) Evaluate candidate static measures (like esti mated fat-free mass and VO 2 max ) as predictors Currently, all Marines, irrespective of sex, are required the Physical Fitness Test (PFT) and the Combat Fit ness Test (CFT). The PFT assesses the collective level unit/MOS capability. 1 The CFT extends the PFT by incorporating physical activities that directly mirror Commandant of the Marine Corps initiated the devel opment of the CFT as a training and assessment tool in response to increased casualties that were related to common combat maneuvers. The CFT was developed in functional movements that a Marine may face on a daily basis during training and/or combat. 2 predictors of performance on ground combat element face during integration into previously closed combat arms positions. Second to these primary aims, the rela tionship between estimated aerobic capacity, body com position, and performance was also investigated. METHODS Subjects Active-duty male and female Marines were recruited rine Corps Recruit Depot, Parris Island, South Caroli all participants, and informed consent was provided by those who volunteered. The combat-related tasks were designated as the physical training for the day, which is a mandatory requirement for active duty Marines. The The testing protocol was reviewed and approved by the Marine Corps Combat Development Command Institu tional Review Board. Data Collection All participants in the study were required to have com cial PFT and CFT composite scores, as well as individu al component scores, were acquired for each participant from their respective command so as not to rely on in dividual recall. All combat proxy tasks were performed on the same day to reduce between-day variability, and participants were asked to refrain from physical training on the day of participation. Combat Fitness Test Following observations of increased casualties related to common combat maneuvers, the Commandant of the Marine Corps initiated the development of a training and assessment tool that goes beyond those factors mea sured by the existing PFT. The CFT consists of basic aerobic (880 yd run), strength testing (ammunition can lift of 97 repetitions or to exhaustion in 2 minutes), and ness and technical skill in carrying out the maneuvers effectively. The events within the MANUF are representative of the types of movements that Marines routinely make in training and in combat. A sprint-to-J-hook turn is a proxy for a quick momentum and directional change as ering a distance and then transitioning to a faster high crawl to maneuver between 2 points for safety. A casu alty evacuation is a lifesaving technique that requires danger to a safer location as quickly as possible. The MANUF also incorporates an ammunition can carry THIS ARTICLE RETRACTED BY AUTHORS MAY 6, 2015
14 http://www.cs.amedd.army.mil/amedd_journal.aspx and run, as well as a grenade toss, all of which are com mon combat skills. These individual MANUF tasks are combined into a single timed event, which enables assessment of a Marines combat capability and physi and aerobic. The CFT score is a composite of scores from the 3 com ponents. The maximum achievable score is 300 points. Combat Proxy Tasks All participants completed a dynamic warm-up prior to testing on the combat proxy tasks. The warm-up con sisted of a 50-m jog, 50-m backward run, 25-m walking weight squats, 10 push-ups, and 10 burpees. Following the warm-up period, participants completed 6 combat ups, dead-lift, clean and press, 120-mm tank round lift and load, 155-mm artillery round lift and carry, and ne pants were asked to execute as many full pull-ups (no kipping) as possible. The dead-lift drill required partici pants to complete one repetition of a set of progressively 135 lb. Similarly, the clean and press was performed in progression from 6 lifts of 65 lb to single lifts of 70 lb, 80 lb, 95 lb, and 115 lb. If a participant could not lift a weight with proper technique and/or lock out the weight above their head, the lower weight was considered their maximal lift. The 120-mm (replica) tank round lift and tiles (replica rounds weighing 55 lb) in 35 seconds. The 155-mm (replica) artillery round lift and carry consisted of picking up and carrying a 155-mm projectile (replica round weighing 95 lb) a distance of 50 m in 2 minutes. cle course wall using a lower level entry (a 20-in assist with Small Arms Protective Insert plates). One important note is in order regarding the use of pullups as a combat proxy task, despite its prominent use ups have been included as part of the combat proxy test set, the task has been treated in this article as akin to a component of the PFT, to facilitate direct comparison between men and women. Anthropometrics and Aerobic Capacity Height and weight were measured and body mass in dex (BMI) calculated as a function of height and weight. From this information, percent body fat was calculated using the Gallagher equation. 3 Fat-free mass was then calculated for each individual. From these data, esti mates of volume of oxygen consumption (VO 2 max) were made for both men and women (AR, for activity code was set to 7, which is the code for estimated physical activity. On a coarse ordinal scale, 7 indicates Run over 10 miles per week or spend over 3 hours per week in comparable physical activity) 3-5 For women, VO 2 max (ml/kg/min)= 45.628 ( 0.265 age) ( 0.309 %fat) + ( 2.175 AR ) ( 0.044 %fat AR ) For men, VO 2 max (ml/kg/min)= 47.820 ( 0.259 age) ( 0.216 %fat) + ( 3.275 AR ) ( 0.082 %fat AR ) Statistical Analysis Descriptive statistics and results are presented as means and standard deviations. Performance scores (on the PFT and CFT) between Marines who passed the com bat proxy tasks and those who failed were compared using t tests. In addition, the results in this study were also corroborated by the nonparametric equivalents of these tests (eg, Mann-Whitney U ), when concerns were raised about satisfaction of required parametric assump tions (eg, normality). The conclusions of the study are the same, regardless of the test type used. As an index of overall combat readiness, the proportion of all combat proxy tasks that were successfully com proxy tasks were included in this overall measure, not the pull-ups task, which was treated as a predictor, not outcome variable). Bivariate correlation analyses (non ) were used to measure statistical dependence between variables. Spearmans is useful for describing mono tonic trends between 2 variables when it is not appropri ate to assume that the relationship is linear, which was the case with the measured variables in this study (eg, of tasks successfully completed). Interpretation of mag nitudes is similar to that of the Pearson product-moment correlation. To facilitate comparison between sexes, overlapping density plots (ie, estimates of the underlying prob ability density function, using a Gaussian kernel) were constructed separately for men and women. 6 Density plots represent the distribution of a variable and can be interpreted in way similar to histograms, however, the smoothed patterns of density plots better reveal the differences in performance between males and PERFORMANCE DIFFERENCES BETWEEN MALE AND FEMALE MARINES ON STANDARDIZED PHYSICAL FITNESS TESTS AND COMBAT PROXY TASKS: IDENTIFYING THE GAP THIS ARTICLE RETRACTED BY AUTHORS MAY 6, 2015
April June 2015 15 females. All analyses were performed with SPSS 19.0 web/packages/dplyr/index.html), gg plot2, 7 ect.org/package=scales) were employed for data preprocessing, visualization, and variable rescaling, respectively. The code used to generate the results is available upon request. Statistical sig P <.05. RESULTS Subjects The sample comprised 788 Marines (409 male, 379 female). Summaries of key demographic variables (eg, age, height, weight) as well as body composition estimates (eg, BMI, percentage fat, and VO 2 max ) are presented in Table 1. Note that overall means for the body compo sition variables were not included, as the calculation of percentage fat and VO 2 max values were sex-dependent. Fitness Tests Descriptive statistics for the break down of the PFT and CFT, by overall score and by component task, are provided in Tables 2A and 2B. Overall, men outperformed women on all represented in Figures 1 and 2. Note that the pull-ups from the combat proxy testing were used as the basis of comparison, since both males and females completed the task. The component tasks of the PFT that do not admit direct comparison between males and females (ie, Collectively, these data illustrate 2 key pat male scores, and men generally outperform women on the physical tasks. To illustrate this pattern more clearly, the measures associated pull-ups, and the component CFT tasks) were the rescaled test scores was then adopted as the measure of overall performance (scores for the timed events were reversed, before range rescaling, so that shorter duration times were translated into higher performance scores). The derived scale represents relative performance, anchored by the worst performer in the sample as a whole (a score of 0) and the best performer ter performance. The resulting density is provided in Figure 3. Combat Proxy Tasks Performance differences between men and women across all combat proxy tasks are shown in Figure 4A. Over all, there was a high rate of successful completion on the combat proxy tasks a breakdown of the clean and press task was conducted separately (Figure 4B). Correlations As expected, there were strong relation ships between components of the PFT and CFT and the overall measure of combat readiness (Table 3A). The CFT tasks, in general, exhibited stronger relationships to combat readiness, as expected. Relationships between physi cal characteristics (eg, BMI, VO 2 max fat-free mass) and the other physical tests, including the composite measure of overall mission readiness, were also relatively high, with fat-free mass performing particularly well as a pre dictor (Table 3B). All correlations were statistically sig P <.01. CO MM ENT In general, men outperformed women on physical ability tasks and combat proxy tasks. However, this difference cant upper body strength component (ie, clean and press, Table 1 Demographic Character istics of Study Participants. Mean SD Min Max Age (years) Men 22 4.3 17 42 Women 22 4.6 17 39 All 22 4.4 17 42 Height (cm) Men 175 6.8 147 196 Women 163 6.9 152 183 All 170 9.4 147 196 Weight (kg) Men 76 12 51 108 Women 60 7.0 43 81 All 68 12 43 108 BMI (kg/cm 2 ) Men 24 3.0 17 33 Women 23 1.9 17 32 Body Fat (%) Men 16 4.5 5.6 30 Women 25 2.8 17 40 VO 2 max (ml/kg/min) Men 52 4.1 39 61 Women 39 2.3 30 45 N=788 (men, n=409; women, n=379) Table 2A Physical Fitness Test Com ponent Tasks. Mean SD Min Max Crunches (repetitions) Men 99 5 45 100 Women 94 11 48 100 All 96 8.85 45 100 3-Mile Run (seconds) Men 1,282 115 994 1,729 Women 1,470 131 1,088 1,857 All 1,372 155 994 1,857 Pull-Ups (repetitions) Men 16 6 2 33 Women 4 4 0 23 All 10 8 0 33 N=788 (men, n=409; women, n=379) Table 2B Combat Fitness Test Component Tasks. Mean SD Min Max Movement to Contact (seconds) Men 173 15 132 233 Women 211 22 126 292 All 192 27 126 292 Maneuver Under Fire (seconds) Men 145 18 108 235 Women 200 26 138 308 All 172 36 108 308 Ammo Can Lift (repetitions) Men 97 10 55 125 Women 57 15 16 117 All 78 23 16 125 N=788 (men, n=409; women, n=379) THIS ARTICLE RETRACTED BY AUTHORS MAY 6, 2015
16 http://www.cs.amedd.army.mil/amedd_journal.aspx Figure 1 Comparison between men and women on the Physi cal Fitness Test (PFT) events: Crunches (A), 3-Mile Run (B), and Pull-ups (C). Data are presented as density plots, which are normalized representations of each distribution that facilitate comparison between samples differing in size. The dashed line in each plot represents the median performance of that group. Note that the Pull-ups event was tested along with the other combat proxy tasks and was not taken from the PFT proper, as it is the only version of pull-ups that enables direct comparison of men and women. Density PFT Pull-ups (repetitions) 0 10 20 30 0.05 0.10 0.15 0.00 Men Women C Density 1000 1250 1500 1750 0.001 0.002 0.003 0.000 Men Women B Time (seconds) PFT 3-Mile Run Density PFT Crunches (repetitions) 25 0 50 75 100 0.1 0.2 0.0 Men Women A per body strength is a potential barrier to full integration of women into previously closed combat arms positions. it were an insurmountable barrier, we would expect few if any women to be capable of surpassing men in upper body strength. On the contrary, some women were able to perform well, or at least better, than many men. For example, 66 women outperformed the worst perform ing, lowest decile of male performers (subsample of 44 men). The best performing female Marine completed 23 tested. In addition, as expected, there were strong relationships between performance on upper body tasks as well as between estimated body fat percentage and estimated VO 2 max and various performance metrics. Indeed, the relative strength of the relationships between the de rived measures of fat-free mass, VO 2 max and the physi cal tasks is striking and in line with previous research in the military which suggests that aerobic performance is related to body fat. 8,9 Additionally, increased body fat has been associated with poor performance in female Army Soldiers. Therefore, based on this current and past efforts, it can be suggested that body composition standards should be established in parallel with physical standards for individuals seek ing a direct combat MOS. The fact that this study used previously established regression equations and gleaned such valuable information with so little effort suggests that they may serve as useful replacements when labora tory measures such as DEXA scan or VO 2 max testing are not available or practical. body strength when it comes to lifting heavy objects. PERFORMANCE DIFFERENCES BETWEEN MALE AND FEMALE MARINES ON STANDARDIZED PHYSICAL FITNESS TESTS AND COMBAT PROXY TASKS: IDENTIFYING THE GAP THIS ARTICLE RETRACTED BY AUTHORS MAY 6, 2015
April June 2015 17 Figure 2. Comparison between men and women on the Combat Fitness Test (CFT) events: Movement to Contact (A), Maneuver Under Fire (B), and Ammo Can Lift (C). Data are presented as density plots, which are normalized representations of each distribution that facilitate comparison between samples differ ing in size. The dashed line in each plot represents the median performance of that group. Density Time (seconds) CFT Movement to Contact Men Women 150 200 250 300 0.01 0.02 0.00 A Time (seconds) CFT Maneuver Under Fire Density 100 200 250 150 300 0.005 0.010 0.015 0.020 0.025 0.000 Women Men B Density Ammo Can Lift (repetitions) 25 50 75 100 125 0.05 0.10 0.00 C Men Women 0 25 50 75 100 Density Performance Men Women 0.00 0.02 0.04 Figure 3. Comparison between men and women on a de rived measure of overall performance. The raw scores for crunches, run, pull-ups, and the component CFT tasks, were rescaled into a range from 0 to 100 ; the mean of the rescaled test scores was then adopted as the measure of overall performance (scores for the timed events were reversed, before range rescaling, so that shorter duration times were translated into higher performance scores). The derived scale represents relative performance, anchored by the worst performer in the sample as a whole (a score of 0 ) and the best performer (a score of 100 ), with greater mag each plot represents the median performance of that group. THIS ARTICLE RETRACTED BY AUTHORS MAY 6, 2015
18 http://www.cs.amedd.army.mil/amedd_journal.aspx It is important to note, however, that female Marines likely not properly conditioned to perform these types of physical tasks. Thus, while the majority of women could be considered successful on most of the combat proxy tasks, the discrepancy in upper body strength may point to lack of conditioning, which could poten tially be overcome with training. 10,11 Previous studies have shown that women who are strength trained and/ or endurance trained can increase their performance on combat-related tasks. 10-12 has been shown to be effective at increasing the number of pull-ups completed by women, as well as improving overall upper body muscle endurance. This may trans late to other upper body exercises, such as push-ups. In a separate Marine Corps study, a 12-week training program increased the number of women who could 15 In addition, the authors of the study concluded that pull-ups were a good indicator of upper body strength and that pull-up train ing may be the best way to increase upper body strength for female Marines. While women in this study were less successful than men in upper body strength tasks, existing literature suggests that, with proper training, women could increase their upper body strength and re duce the size of this gap. In addition, an important question to address is whether PFT and CFT performances translate to performance on required to complete both the PFT and CFT semiannu ally, and the results from those tests serve as markers these tests useful for achieving these aims? That is, do the PFT and CFT successfully distinguish those who are likely to perform well (physically) during combat? This consideration touches on the validity of the PFT and CFTthe extent to which the interpretations drawn from those tests are valid 16 (ie, does successful PFT and CFT performance predict better combat performance?). A thorough investigation of test validity is a challenging the scope of the present study and is currently being ad dressed in a separate physical standards validation ef fort. Performance on the physical tasks in this study was limited to plausible occupational constraints (eg, particu lar weights, limited repetitions) and did not account for measuring maximum physical capacity. Thus, the result ing restricted range may underestimate the true validity of the PFT and CFT for predicting performance during combat. With this caveat in mind, one of the aims of this effort was to determine whether the PFT and CFT could be used as predictors of performance on combat proxy tasks. To what extent does the performance on one test indicate more successful performance on the other? In relation to the existing dataset, does better performance on the PFT and CFT translate to a more successful per formance on the combat proxy tasks? Statistically, this question was addressed by separating women who were successful on the combat proxy tasks from those who were unsuccessful, and then examining their respective PFT and CFT scores as shown in Table 4. As expected, women who performed well on their semiannual physi tasks. Also, a difference of 2 pull-ups separated success ful from unsuccessful performers, with the exception of Figure 4. Comparison between men and women on Combat Proxy Tasks (A) and Clean and Press (B). Combat Proxy Tasks Proportion Successful Completion Men Women 0.25 0.50 0.75 1.00 0.00 Clean & Press 115 lb O-Course Wall Dead Lift 155mm Round 120mm Round A Clean and Press 65 lb, 6 reps 70 lb, 1 rep 80 lb, 1 rep 95 lb, 1 rep 115 lb, 1 rep Proportion Successful Completion 0.25 0.50 0.75 1.00 0.00 B Men Women PERFORMANCE DIFFERENCES BETWEEN MALE AND FEMALE MARINES ON STANDARDIZED PHYSICAL FITNESS TESTS AND COMBAT PROXY TASKS: IDENTIFYING THE GAP THIS ARTICLE RETRACTED BY AUTHORS MAY 6, 2015
April June 2015 19 the clean and press in which 5 pull-ups separated suc cessful from unsuccessful performers. Further, a 20-sec ond difference on the MANUF, which is a short burst aerobic activity, separated successful from unsuccess ful performers. Not surprisingly, 3-mile run time was strongly related to performance on the MANUF. Addi cated by a nearly 30 second difference in MANUF times) and were more successful on the most challenging clean studies demonstrating a strong relationship between fatfree mass, aerobic capacity, and overhead lifting. 14,15 The results also provide evidence for a strong relationship between the PFT and CFT components tasks and overall mission readiness (Table 3A). In all, these results suggest that the PFT and CFT could serve as reliable indicators of performance on ground combat elements. While the results provided in the study support reason ably strong conclusions, there are limitations that must be addressed. The primary limitation derived from necessary restrictions on allowable performance, con straints that were required due to the large population range restriction on performance scores likely under However, the goal of the study was simply to establish that the physical tests were good predictors of perfor mance on combat-related tasks, which was amply dem onstrated by the uncorrected correlations. Another limitation concerned the high suc cess rates of performance on most of the combat proxy tasks. Once a participant successfully completed a task, the test was terminated rather than allowing someone to reach their true maximum, as in the deadlift. In that task, there were no weights available above 135 lb, nor were the partici pants asked to complete as many repetitions as possible. Those weights were chosen mands, and not to be unnecessarily taxing. If a more accurate picture of the maximum capabilities of Marines is required, additional, nonre stricted testing would be required. Similarly, at the time of this study, women did not perform pull-ups in the PFT (except for infrequent exceptions), and thus the pull-ups task tested during the combat proxy task was used as a replace ment test to enable compari son between men and women. However, this decision means that the correlations computed in the study were measuring something closer to concurrent validity than predictive validity. In our opinion, these nuances are un likely to matter as far as the practical decision to include pull-ups as an assessment instrument is concerned. In conclusion, the key limiting factor for females is upper body strength and greater emphasis should be placed on developing this capability in female Marines if they intend to serve in closed combat arms positions. The results also suggest that the PFT and CFT serve as useful indicators of combat readiness. However, further study on unrestricted performance will likely shed light on the validity of the PFT and CFT as predictors of per formance on combat-relevant tasks. ACKNOWLEDGE M ENT This study was supported by the US Marine Corps Train ing and Education Command, under work unit N1235. The research was conducted in compliance with all ap plicable federal regulations governing the protection of human subjects in research REFERENCES 1. Marine Corps Order 6100.13: Marine Corps Physi cal Fitness Test and Body Composition Program Manual Table 3A Spearman Correlations Among the PFT and CFT Tasks, and Overall Mission Readiness. Spearman's Crunches 3-Mile Run MTC AL MANUF Overall Mission Readiness Pull-ups 0.46 -0.66 -0.76 0.74 -0.76 0.75 Crunches -0.37 -0.43 0.43 -0.41 0.38 3-mile run 0.80 -0.63 0.74 -0.61 CFT MTC -0.75 0.83 -0.71 CFT AL -0.78 0.76 CFT MANUF -0.77 PFT indicates physical fitness test. CFT indicates combat fitness test. MTC indicates movement to contact. AL indicates ammunition can lift. MANUF indicates maneuver under fire. Table 3B Spearman Correlations Among Physical Characteristics and Physical Tasks. Spearmans Pull-ups Crunches 3-Mile Run MTC AL MANUF Overall Mission Readiness Height 0.53 0.29 -0.53 -0.62 0.68 -0.67 0.67 Weight 0.46 0.26 -0.44 -0.53 0.64 -0.61 0.68 BMI 0.20 0.10 -0.16 -0.20 0.34 -0.29 0.39 Body Fat % -0.63 -0.28 0.52 0.61 -0.59 0.61 -0.50 FFM 0.62 0.32 -0.57 -0.67 0.78 -0.75 0.77 VO 2 max 0.64 0.27 -0.55 -0.62 0.64 -0.64 0.56 MTC indicates movement to contact. AL indicates ammunition can lift. MANUF indicates maneuver under fire. FFM indicates fat-free mass. THIS ARTICLE RETRACTED BY AUTHORS MAY 6, 2015
20 http://www.cs.amedd.army.mil/amedd_journal.aspx 2. United States Marine Corps. A Concept for Func tional Fitness. library/USMCFunctionalFitnessConcept.pdf. Ac cessed October 20, 2014. 3. Gallagher D, Visser M, Sepulveda D, Pierson mass index for comparison of body fatness across age, sex and ethnic groups?. Am J Epidemiol Combat Proxy Task PFT/CFT Event Results Outcome n Mean SD sig ( P ) Clean & Press, 115 lb PFT Crunches Pass 33 96 9 .19 Fail 346 93 11 PFT 3-mile Run (sec) Pass 33 1,400 137 <.01 Fail 346 1,477 128 PFT Pull-ups Pass 33 8 6 <.01 Fail 346 3 4 CFT Movement to Contact (sec) Pass 33 194 19 <.01 Fail 345 213 21 CFT Ammunition Can Lift Pass 33 68 16 <.01 Fail 345 56 14 CFT Maneuver Under Fire (sec) Pass 33 174 23 <.01 Fail 345 203 25 120 -mm Tank Round Lift and Carry PFT Crunches Pass 309 94 11 .25 Fail 70 92 13 PFT 3-mile Run (sec) Pass 309 1,457 130 <.01 Fail 70 1,526 119 PFT Pull-ups Pass 309 4 4 <.01 Fail 70 2 3 CFT Movement to Contact (sec) Pass 308 209 22 <.01 Fail 70 222 18 CFT Ammunition Can Lift Pass 308 58 15 <.01 Fail 70 51 14 CFT Maneuver Under Fire (sec) Pass 308 197 25 <.01 Fail 70 215 25 Combat Proxy Task PFT/CFT Event Results Outcome n Mean SD sig ( P ) 155 -mm Artillery Round Lift and Carry PFT Crunches Pass 271 95 9 <.01 Fail 108 89 13 PFT 3-mile Run (sec) Pass 271 1,446 133 <.01 Fail 108 1,531 102 PFT Pull-ups Pass 271 4 5 <.01 Fail 108 2 2 CFT Movement to Contact (sec) Pass 270 206 21 <.01 Fail 108 224 18 CFT Ammunition Can Lift Pass 270 60 14 <.01 Fail 108 48 13 CFT Maneuver Under Fire (sec) Pass 270 194 26 <.01 Fail 108 216 22 Obstacle Course Wall PFT Crunches Pass 298 94 10 <.05 Fail 81 91 13 PFT 3-mile Run (sec) Pass 298 1,455 129 <.01 Fail 81 1,525 120 PFT Pull-ups Pass 298 4 4 <.01 Fail 81 2 2 CFT Movement to Contact (sec) Pass 297 209 21 <.01 Fail 81 221 20 CFT Ammunition Can Lift Pass 297 58 15 <.01 Fail 81 53 14 CFT Maneuver Under Fire (sec) Pass 297 197 26 <.01 Fail 81 214 24 Table 4 Successes and Failures of Female Marines on Combat Proxy Tasks in Relation to Physical Fitness Test (PFT) and Combat Fitness Test (CFT) Scores (continued on next page). PERFORMANCE DIFFERENCES BETWEEN MALE AND FEMALE MARINES ON STANDARDIZED PHYSICAL FITNESS TESTS AND COMBAT PROXY TASKS: IDENTIFYING THE GAP THIS ARTICLE RETRACTED BY AUTHORS MAY 6, 2015
April June 2015 21 4. Jackson AS, Blair SN, Mahar MT, Wier LT, Ross RM, Stuteville JE. Prediction of functional aerobic capacity without exercise testing. Med Sci Sports Exerc 5. Jackson AS, Beard EF, Wier LT, Ross RM, Stute ville JE, Blair SN. Changes in aerobic power in men, ages 25-70 yr. Med Sci Sports Exerc 6. Jackson AS, Wier LT, Ayers GW, Beard EF, Stute ville JE, Blair SN. Changes in aerobic power in women, ages 20-64 yr. Med Sci Sports Exerc 7. Wickham H. ggplot2: Elegant Graphics for Data Analysis (Use R!) 8. Mikkola I, Keinnen-Kiukaanniemi S, Jokelainen J, Peitso A, Hrknen P, Timonen M, Ikheimo T. Aerobic performance and body composition chang es during military service. Scand J Prim Health Care 9. Anderson MK, Grier T, Canham-Chervak M, Bushman TT, Jones BH. Risk factors associated with higher body fat in US Army female soldiers. US Army Med Dep J 10. Hendrickson NR, Sharp MA, Alemany JA, et al. Combined resistance and endurance training improves physical capacity and performance on tactical occupational tasks. Eur J Appl Physiol. 11. Kraemer WJ, Mazzetti SA, Nindl BC, et al. Effect of resistance training on womens strength/power and occupational performances. Med Sci Sports Exerc 12. Szivak TK, Kraemer WJ, Nindl BC, et al. Relation ships of physical performance tests to military-rel evant tasks in women. US Army Med Dep J April13. McGuire B, Vickers RR, Reynolds JH, Curry A, Bockelman T, Massimo R. Examination of Pullups and Push-ups as Possible Alternatives to the Flexed Arm Hang on the Marine Corps Physi cal Fitness Test getRecord&metadataPrefix=html&identifier=A DA554498. Accessed March 2, 2015. 14. Jackson AS, Borg G, Zhang JJ, Laughery KR, Chen J. Role of physical work capacity and load weight on psychophysical lift ratings. Int J Ind Er gon 15. Friedl KE. Body composition and military perfor mancemany things to many people. J Strength Cond Res 16. Kane MT. Validating the interpretations and uses of test scores. J Educ Meas. AUTHORS formance Department of Operational Readiness, Naval Health Research Center, San Diego, California. Mr Pappa and Mr McGuire are with the US Marine Corps Training and Education Command, Marine Corps Base, Quantico, Virginia. Table 4 (continued) Successes and Failures of Female Marines on Combat Proxy Tasks in Relation to Physi cal Fitness Test (PFT) and Combat Fitness Test (CFT) Scores (continuation from previous page). Combat Proxy Task PFT/CFT Event Results Outcome n Mean SD sig ( P ) Deadlift 135 lb PFT Crunches Pass 368 94 11 .95 Fail 11 93 13 PFT 3-mile Run (sec) Pass 368 1,467 130 <.01 Fail 11 1,586 103 PFT Pull-ups Pass 368 4 4 <.01 Fail 11 2 2 CFT Movement to Contact (sec) Pass 367 211 21 <.01 Fail 11 233 20 CFT Ammunition Can Lift Pass 367 57 15 .20 Fail 11 52 12 CFT Maneuver Under Fire (sec) Pass 367 200 26 <.01 Fail 11 221 21 THIS ARTICLE RETRACTED BY AUTHORS MAY 6, 2015
12 http://www.cs.amedd.army.mil/amedd_journal.aspx Women have historically played an important role in the US military despite facing restrictions on unit assign ment. 1 Since the repeal of the Direct Ground Combat and Assignment Rule, the US armed forces renewed fo cus on evaluation of women performing in previouslyrestricted military occupational specialties (MOSs) by assessing sex-neutral performance standards and train ing capabilities. Previous research demonstrated male and female athletes and military personnel possess dif ferent musculoskeletal, biomechanical, and physiologi 2-4 and suffer musculoskeletal injuries at dif fering rates and severity. 5 Physical, physiological, and personnel are important to determine the potential for women to safely and successfully occupy newly-opened training programs. Epidemiological research has explored injury rates, types, and causes in military personnel. 5-9 Studies inves tigating nonbattle injuries sustained during deployment cidence of injury than male Soldiers. 10,11 Other research indicated female Soldiers sustain a greater proportion of lower extremity and overuse injuries. 6-8 Researchers Musculoskeletal, Biomechanical, and Physiological Gender Differences in the US Military Katelyn F. Allison, PhD Takashi Nagai, PhD, ATC Karen A. Keenan, PhD, ATC Jennifer Deluzio, MS Timothy C. Sell, PhD, PT COL Mark McGrail, MC, USA John P. Abt, PhD, ATC Scott M. Lephart, PhD ABSTR A CT The repeal of the Direct Ground Combat Assignment Rule has renewed focus on examining performance capabilities of female military personnel and their ability to occupy previously restricted military occupational specialties. Previous research has revealed female Soldiers suffer a greater proportion of musculoskeletal injuries Potential differences may also exist in musculoskeletal, biomechanical, and physiological characteristics injury risk and enhance performance. Purpose: To examine differences in musculoskeletal, biomechanical, and physiological characteristics in male and female Soldiers. Methods: A total of 406 101st Airborne Division (Air Assault) Soldiers (348 male; 58 female) participated. balance, lower body biomechanics during a stop jump and drop landing, body composition, anaerobic power/ capacity, and aerobic capacity. Independent t tests assessed between-group comparisons. Results: P <.01P <.001) and better balance ( P P ml/kg/min, P P P P <.001). Women demonstrated P <.05P <.001). Conclusions: Gender differences exist in biomechanical, musculoskeletal, and physiological characteristics. decrease the injury risk during gender-neutral training, and decreasing between-sex variability in performance patterns and characteristics should facilitate adjustments in training in order for both sexes to meet the genderneutral occupational demands for physically demanding military occupational specialties.
April June 2015 13 more injury, including stress fractures, by the end of injury in female Soldiers may be because female and the same training. 12 Although the reason(s) for sex dif ferences in injury rates, types, and causes are unclear, they may result from sex differences in physical, physi ological, and musculoskeletal characteristics and differ ences in training intensity during basic combat training, daily physical training, and deployment. Previous research evaluating requirements for physi cally-demanding jobs, like lifting, carrying, pushing/ ful completion of these tasks, including strength, power, 13,14 It is well known that female Soldiers, on average, possess less absolute strength and force generating capacity, less endurance and higher fatigability during repetitive tasks, and less aerobic capacity than male Soldiers. 14 Studies inves tigating movement patterns of military personnel also landing techniques that may contribute to ACL injury risk, 15,16 which is important in airborne units. Sex dis parities in physical, physiological, and musculoskeletal characteristics should be examined further in contem porary military populations to determine the capability of women to safely and successfully perform strenuous occupational tasks and to reduce performance gaps be tween sexes. The purpose of this study was to investigate potential sex differences across a comprehensive set of physi cal, physiological, musculoskeletal, and biomechanical characteristics within a modern military population. It was hypothesized that male and female Soldiers would readiness and resiliency, especially as women are inte grated into previously restricted MOSs. MA TERI A LS A ND METHODS Subjects A total of 406 Soldiers (348 male, 58 female) of the 101st Airborne Division (Air Assault) at Fort Camp bell, Kentucky, participated in this study. Demo graphic information is presented in Table 1. Subjects are a subset of subjects enrolled in the Human Perfor mance and Injury Prevention Initiative (Eagle Tacti cal Athlete Program) 6-step model derived from the public health model of injury prevention and control. All subjects met the following criteria: 18 to 45 years of age and no current medical or musculoskeletal condi tions that prevented full active duty. Human protection for the current study was approved by the appropriate civilian and military institutional review boards. Writ ten informed consent was obtained from each subject prior to participation in this study. Procedures Testing occurred over 2 days (approximately one week apart) at the University of Pittsburgh Human Perfor mance Research Center (Fort Campbell). Each session lasted 2 hours. Testing was performed bilaterally where applicable; only right-sided data is presented, as no be tween side differences were noted. A standard goniometer or digital inclinometer was used to measure passive range of motion of the shoul of the knee (extension) and ankle. 18 Reliability of these measurements has been previously established. 19,20 Hip tion, and internal and external rotation were assessed in the supine position. Shoulder extension was assessed in the prone position. Posterior shoulder tightness was also assessed passively in the supine position. Active range knee with the active knee extension test and to assess ley, NY) measured active torso range of motion, with the subject seated and actively rotating in the right and left directions. internal/external rotation, shoulder abduction/adduction, The reliability of isokinetic strength testing has been previously established for peak torque/body weight 21 For shoulder, knee, and torso strength testing, subjects Table 1 Subject Demographics Men Women P Value n Mean SD n Mean SD Age (years) 348 28.06 6.63 58 26.72 5.48 .147 Height (m) a 348 1.77 0.07 58 1.65 0.06 <.001 Weight (kg) a 348 83.48 12.57 58 64.93 9.90 <.001 a Statistically significant difference between men and women ( P <.05)
14 http://www.cs.amedd.army.mil/amedd_journal.aspx of 60 seconds, 5 repetitions of reciprocal concentric iso kinetic testing were performed at 60 per second. Hip abduction/adduction was assessed isometrically in a sidelying, neutral hip position. Subjects performed 3 sets of 5-second isometric contractions, alternating between with the knee and hip at 90. Subjects performed 3 sets of 5-second isometric contractions, alternating between A hand held dynamometer (Lafayette Instrument Com pany, Lafayette, IN) assessed ankle inversion and ever sion strength. Strength measured via hand held dyna mometry has been demonstrated to be reliable for ankle 0.85, respectively) 22,23 and is a valid measurement of an kle strength. 22-24 Ankle inversion and eversion strength was tested with the subject long-sitting with the foot and ankle off the end of the table. A single force plate (Kistler 9286A, Amherst, NY), with a sampling frequency of 100 Hz, measured balance. Three, 10 second trials of single-leg standing balance were performed with subjects barefooted with their hands on their hips, with eyes opened and eyes closed conditions based on Goldie et al. 25,26 This protocol was previously demonstrated valid and reliable. Tri als were discarded and recollected if the subjects nonstance leg hit the stance limb or the ground outside of down on the force plate with their non-stance leg and immediately lift the leg back into test position. A portable metabolic system (OxyCon Mobile, Viasys, Yorba Linda, CA) and lactate analyzer (Arkray, Inc, Kyoto, Japan) captured maximal oxygen consumption (VO 2 max ) and lactate threshold during an incremental ramp protocol. The OxyCon Mobile has been demon difference compared to simulated VO 2 during a maxi mal cardiopulmonary exercise test. 28 Following a 5-min ute warm-up, the test was performed in 3-minute stages, each subjects 2-mile run time during the Army Physi cal Fitness Test and remained constant throughout the ing the last minute of each stage prior to an increase in incline in order to assess blood lactate levels. Heart rate (Polar USA, Lake Success, NY) and VO 2 were collected and monitored continuously throughout the test. Rela tive VO 2 max maximum heart rate, VO 2 at lactate thresh old, percent of VO 2 max at lactate threshold, heart rate at lactate threshold, and percentage of maximum heart rate at lactate threshold were reported. An electromagnetic cycle ergometer (RacerMate, Inc, Seattle, WA) measured anaerobic power and capac ity during a Wingate protocol, 29 which has been previ ously demonstrated as a highly valid and reliable test of these variables. 30 Following a warm-up at a self-selected cadence at 125 watts, the 50-second protocol was per formed: 15 seconds maintaining 100 RPM at 125 W with minimal resistance; 5 seconds sprinting to generate maximum speed prior to initiation of normalized resis tance; and 30 seconds attempting to sprint and main tain maximal speed against the normalized resistance. weight for men and women, respectively. ment Instruments, Concord, CA) assessed body com position, which has previously demonstrated reliability 21 and validity. 31 Men wore spandex shorts and a swim cap while women wore span dex shorts, a sports bra, and swim cap. Once 2 consis tent body volume measurements were obtained, percent body fat was calculated using predicted lung volume and the appropriate body densitometry equation; body Six high-speed cameras (Vicon, Centennial, CO) with 200 Hz sampling frequency captured biomechanical data during an athletic task (stop jump task) and func tional landing task (drop landing task). Following Vi rior superior iliac spines lateral thigh, lateral femoral condyle, lateral lower leg, lateral malleous, posterior calcaneus, and head of the second metatarsal. Appropri ate anthropometrics were measured with an anthropom eter (Lafayette Instrument, Lafayette, IN). A static trial in an anatomical neutral position captured a baseline for joint angle calculations. The accuracy and validity of the Plug-in Gait model have been previously estab lished. 32-34 The stop jump task was a standing broad the subjects height, followed immediately (after landing on the force plates) by a maximal effort vertical jump. The drop landing was initiated by subjects leaning for ward while standing on a standardized, 0.51 meter high platform, allowing gravity to drive the drop movement, followed by landing with one foot on each of the force plates (1200 Hz). MUSCULOSKELETAL, BIOMECHANICAL, AND PHYSIOLOGICAL GENDER DIFFERENCES IN THE US MILITARY
April June 2015 15 Data Processing and Reduction Flexibility/range of motion and handheld dynamom eter strength measures were averaged across 3 trials. reported as the peak average torque across 5 trials nor malized to each subjects individual body mass. For VO 2 max data, a 15-second moving window was used breath-by-breath data points. Maximal oxygen uptake was calculated as the highest consecutive oxygen up take levels over one minute of data collection relative one mmol/L or more between stages. Anaerobic pow while anaerobic capacity was calculated as the mean power output over the 30 seconds of the test following resistance initiation nor malized to body mass. For both balance and biomechanical data, force plate data were passed through an am Digital Translation, Marlboro, MA) and stored on a personal computer. A custom Natick, MA) script processed ground reac tion force data. For eyes opened and eyes closed balance conditions, the standard devi ation for the ground reaction forces for each direction (anterior-posterior, medial-lateral, vertical) was calculated and then averaged across all 3 trials. Prior to calculation of joint kinematics, the Vicon Nexus software reconstructed 3-dimensional hip, knee, and ankle joint centers were estimated based on marker locations and anthropometric parameters ac cording to Vicons Plug-in Gait model. Joint kinemat ics including the following variables were calculated for gus/varus angles at initial contact, and maximum knee across the 3 trials prior to analysis. Statistical Analysis All variables were assessed for normality and frequency distribution. The mean and standard deviation were cal culated for each of the variables included in the study. All variables were analyzed with independent t tests to examine potential sex differences. An alpha level of 0.05 comparisons. Statistical analyses were performed with NY). RESULTS greater shoulder extension, abduction, and external ro posterior shoulder tightness test, indicating less poste rior shoulder tightness than male Soldiers. Strength data are presented in Table 3. Female Soldiers external rotation and shoulder abduction and adduction. Shoulder internal/external rotation strength ratio was Soldiers. medial/lateral, and vertical scores bilaterally, under both eyes open and eyes closed conditions. Higher scores represent poor balance. Physiology data are presented in Table 5. Female Sol anaerobic power, anaerobic capacity, VO 2 max and VO 2 at lactate threshold. Table 2 Range of Motion and Flexibility (in degrees) Men Women P Value n Mean SD n Mean SD Shoulder Flexion 160 187.2 7.3 35 188.0 14.7 .636 Shoulder Extension a 338 70.8 13.3 56 83.6 9.8 <.001 Shoulder Abduction a 159 206.1 9.5 34 211.8 8.8 .002 Shoulder External Rotation a 340 109.9 13.2 57 120.3 16.8 <.001 Shoulder Internal Rotation 340 58.5 10.6 57 59.9 11.6 .399 Posterior Shoulder Tightness a 299 102.4 9.7 52 108.7 7.5 <.001 Knee Flexion a 156 143.1 6.6 33 148.5 5.9 <.001 Active Knee Extension a 340 18.8 9.4 57 11.4 7.9 <.001 Hip Flexion 170 133.1 7.1 35 135.8 16.9 .126 Hip Extension a 340 29.3 8.0 56 33.9 7.3 <.001 Calf Flexibility 340 15.9 6.8 57 15.1 5.4 .399 Torso Rotation 341 70.4 11.0 57 72.7 11.5 .147 a Statistically significant difference between men and women ( P <.05).
16 http://www.cs.amedd.army.mil/amedd_journal.aspx sented in Table 6 for the stopjump task and vertical drop landing. Female Soldiers dem and greater knee valgus at initial contact during both the stop jump and drop landing tasks. Female Soldiers dem during the drop landing task. CO MM ENT The elimination of the Direct Ground Combat and Assign ment Rule and the potential for an increased number of female service members in combat arms warrants ex amination of potential sex differences that may result in decreased performance and increased injury risk de pending on occupational task requirements. The purpose of this study was to assess musculoskeletal, biomechani cal, and physiological differences between sexes in sex differences were found in Soldiers of the 101st Airborne Division (Air Assault) in range of motion and biomechanics. However, within-sex variability quirements should be considered when determining injury risk. tremities compared to female Soldiers. Previous re ibility increase risk of acute and overuse musculoskel etal injuries, 35-39 also been demonstrated to increase the risk of musculo skeletal injury. active knee extension were almost 3 times more likely However, both men and women in the current study were, on average, well below this threshold. 40 Men with with the sit-and-reach test were at more than 2 times the risk to sustain a time-loss injury during basic combat training than those in the middle tertile. No such rela tionship was seen in women in basic combat training. ceps muscle injury, patellofemoral pain syndrome, and patellar tendinitis. Similarly, subjects with shoulder shoulder range of motion. 41 However, due to method ological differences in testing positions and the use of Table 4 Single-leg Balance: Variability (SD) in Ground Reaction Forces (N ) Men Women P Value n Mean SD n Mean SD Eyes Open Anterior/Posterior a 267 2.78 0.86 51 2.02 0.55 <.001 Medial/Lateral a 266 3.44 1.16 51 2.43 0.96 <.001 Vertical a 267 4.65 2.19 51 3.18 1.34 <.001 Eyes Closed Anterior/Posterior a 267 6.44 2.66 51 4.43 1.77 <.001 Medial/Lateral a 266 10.11 4.57 51 6.15 2.39 <.001 Vertical a 267 14.53 12.22 51 8.61 5.52 .001 a Statistically significant difference between men and women ( P <.05). Table 3. Strength Men Women P Value n Mean SD n Mean SD Shoulder Strength Internal Rotation (%BW) a 334 59.6 15.5 57 36.3 8.5 <.001 External Rotation (%BW) a 334 42.1 8.8 57 29.9 5.1 <.001 Internal/External Strength Ratio a 334 0.73 0.14 57 0.85 0.20 <.001 Abduction (%BW) a 169 78.1 15.2 24 55.3 6.7 <.001 Adduction (%BW) a 169 83.1 25.5 24 55.7 16.2 <.001 Abduction/Addubction Strength Ratio 169 1.00 0.30 24 1.16 0.87 .077 Knee Strength Flexion (%BW) a 334 114.8 27.1 57 93.0 21.1 <.001 Extension (%BW) a 334 236.1 48.0 57 191.3 37.2 <.001 Flexion/Extension Strength Ratio 334 0.49 0.09 57 0.49 0.06 1.000 Hip Strength Abduction (%BW) 169 167.3 34.2 24 158.8 32.9 .254 Adduction (%BW) 169 148.1 35.8 24 139.5 30.4 .264 Abduction/Adduction Strength Ratio 169 0.89 0.18 24 0.89 0.19 1.000 Ankle Strength Plantar Flexion (%BW) 150 133.6 45.9 22 120.9 44.9 .226 Dorsiflexion (%BW) a 150 45.4 10.2 22 37.40 8.1 .001 Plantar Flexion/Dorsiflexion Strength Ratio 150 3.06 1.20 22 3.44 1.59 .186 Inversion Strength (kg) a 335 34.4 7.2 57 24.9 6.7 <.001 Eversion Strength (kg) a 335 30.5 6.7 57 22.2 5.9 <.001 Inversion/Eversion Strength Ratio 335 1.15 0.19 57 1.13 0.21 .470 Torso Strength Rotation (%BW) a 340 145.1 33.1 57 110.5 32.9 <.001 a Statistically significant difference between men and women ( P <.05). BW indicates body weight. MUSCULOSKELETAL, BIOMECHANICAL, AND PHYSIOLOGICAL GENDER DIFFERENCES IN THE US MILITARY
April June 2015 17 pathological populations in these studies, comparisons cannot be made between the results from these studies and those in the current study. Further, no threshold for increased injury risk was reported in any of these stud exercises into training to decrease injury risk. Future research should investigate if such thresholds exist (and rent study, which are representative of typical goniomet ric measures obtained in clinical settings. pared to men even after normalization to body mass. Yet, in the US Army, male and female Soldiers may be called upon to perform the same occupational tasks. Strength differences may put female Soldiers at increased risk of unintentional musculoskeletal injury while performing the duties required of their positions. Additionally, since women gener ally use a greater percentage of their absolute strength than males during high intensity repetitive tasks, they are more likely to fatigue earlier, 14 and may be at higher injury risk due to compensated technique. Previous research revealed targeted resistance training programs result in increased tasks and reduce gender disparity in strength and occupational lifting/car rying tasks, 42,43 indicating these pro grams and subsequent adaptations are successfully perform physically demanding jobs. creased injury risk. Weak hamstrings have been demon strated to increase the risk of hamstring strain. 44 Lower hamstring to quadriceps ratios, falling below the opti mal range of 0.60 to 0.90, increases the risk of hamstring strain and injury to the lower leg. 44,45 Although there was hamstring to quadriceps ratio, both demonstrated ratios (0.49 to 0.50) well below the ratios recommended for de creased injury risk. This may indicate training for both men and women should be adjusted to increase ham string strength while maintaining quadriceps strength in order to achieve more favorable ratios. Female Soldiers strength than male Soldiers. Individuals with less an kle strength may be at increased risk for ankle sprains, chronic ankle instability, and other lower leg injuries, 46-49 so targeted programs may be less ankle strength in order to reduce injury risk. Female Soldiers demonstrated and torso musculature than in Soldiers with physicallydemanding MOSs (lifting/low ering, carrying/load bearing, pulling) each rely heavily on upper body and core strength. Individuals with shoulder in stability and shoulder impinge in shoulder strength. 41 Studies Table 6 Biomechanical Analysis Men Women P Value n Mean SD n Mean SD Stop-Jump Task Hip Flexion at Initial Contact ( ) a 259 42.37 11.26 49 45.87 11.74 .048 Hip Abduction at Initial Contact ( ) 259 -3.70 4.07 49 -2.58 3.48 .072 Knee Flexion at Initial Contact ( ) 259 25.79 8.02 49 26.82 7.73 .408 Knee Varus/Valgus at Initial Contact ( ) a,b 259 4.58 6.25 49 -1.36 5.58 <.001 Maximum Knee Flexion ( ) 259 91.98 13.97 49 89.41 13.40 .236 Maximal Vertical GRF (%BW) 258 205.28 56.32 49 201.64 63.88 .685 Vertical Drop Landing Hip Flexion at Initial Contact ( ) a 237 19.4 7.3 50 23.6 6.7 <.001 Hip Abduction at Initial Contact ( ) 237 -3.7 3.4 50 -2.7 4.0 .068 Knee Flexion at Initial Contact ( ) a 237 17.9 6.1 50 20.1 6.4 .022 Knee Varus/Valgus at Initial Contact ( ) a,b 237 2.8 5.0 50 -0.5 4.4 <.001 Maximum Knee Flexion ( ) 237 86.7 18.9 50 90.5 14.0 .264 Maximal Vertical GRF (%BW) 236 365.3 98.4 50 359.2 92.3 .688 a Statistically significant difference between men and women ( P <.05). b Negative value indicates valgus. Table 5 Physiology Men Women P Value n Mean SD n Mean SD Body Mass Index (kg/m 2 ) a 347 23.0 2.9 58 24.0 3.1 .017 Body Fat (%) a 338 20.1 7.5 57 26.7 5.7 <.001 Anaerobic Power (watts/kg) a 326 13.3 2.1 56 9.5 1.7 <.001 Anaerobic Capacity (watts/kg) a 326 7.8 1.0 55 6.1 0.8 <.001 VO 2 Max (mL/kg/min) a 322 47.5 7.6 54 40.3 5.4 <.001 VO 2 at Lactate Threshold (mL/kg/min) a 320 39.0 7.0 54 33.5 5.5 <.001 VO 2 % at Lactate Threshold 320 81.8 10.3 54 82.2 14.0 .803 HR Max (bpm) 322 188.6 14.2 53 188.9 9.6 .882 HR at Lactate Threshold (bpm) 319 169.4 15.3 53 171.4 12.1 .366 HR% at Lactate Threshold 319 89.6 7.2 53 91.0 5.2 .176 a Statistically significant difference between men and women ( P <.05).
18 http://www.cs.amedd.army.mil/amedd_journal.aspx in civilians and in the workplace have associated low torso rotation strength with low back pain. 50,51 Soldiers upper body and torso strength in an attempt to decrease injury risk and increase performance capabilities. Previous research demonstrated female Soldiers pos sess less absolute strength than males. However, data revealed some women are stronger than some men, and strength overlap is increased when strength is normal ized for body mass and fat-free body mass. 14 This evi dence suggests the ability to produce a muscle force is similar between sexes, but differences in quantity of muscle mass between males and females limits the abso lute amount of force able to be generated. 14 In the current study, while female Soldiers, on average, possess less strength than male Soldiers, examination of individual variability among strength characteristics revealed the top performing women possess similar or better strength characteristics than the bottom performing men, indi cally, when assessed by percentiles, the top 25th percen tile of women demonstrated greater shoulder strength than the bottom 10th percentile of men and better knee and torso strength than the bottom 25th percentile of men. The top 25th percentile of women demonstrated onstrated greater ankle inversion and eversion strength ability should be considered when assessing capabilities of male and female Soldiers to safely and successfully perform tactical activities. Strength overlaps should be interpreted with caution, as strength in the current study is normalized to body weight, and absolute strength sex overlaps are likely more conservative. Male Soldiers demonstrated worse static balance than athletic and tactical tasks by providing a stable base of support and enhancing overall joint stability, espe cially with unstable surfaces or unexpected perturba tions. Prospective studies demonstrated athletes with increased postural sway in the anterior/posterior and medial/lateral directions have increased risk of sustain ing an ankle injury. 52-54 Female Soldiers may possess better balance, because, on average, the center of grav ity/center of mass is lower than in male Soldiers. How ever, previous research revealed men tend to have better like during tasks involving dynamic postural stability. 55 Further research is warranted to investigate sex differ ences in postural control during more challenging tacti cal tasks and maneuvers. tive of the ability to perform quick burst activity and to ticipating in training targeting anaerobic components of maintain a higher intensity longer. A limitation of the current study is the braking torque applied during the Wingate test differed for male and female Soldiers, so results must be interpreted with caution, and may differ compared to what would have been demonstrated with uniform braking torque. Male Soldiers also had higher VO 2 max and VO 2 at lac tate threshold in the current study. Previous research postulated women may have reduced aerobic capacity because they carry less fat-free mass and a greater per centage of nonmetabolic (fat) tissue, have a lower oxy gen carrying capacity, and possess a decreased cardiac output compared to males. 14,56 While VO 2 max is largely based these factors, in addition to genetics and age, it can be positively affected by training. Perhaps more im portantly, the point at which lactate threshold occurs is occurs at a higher percentage of maximal oxygen con sumption, then an individual will be able to train at a higher intensity for a longer period of time. Individu als who train to enhance lactate threshold may be able to perform physical activity longer and at a higher in tensity, thereby potentially improving performance and maximizing operational readiness. Overall, increasing a role in mitigating onset of fatigue and reducing risk of unintentional, musculoskeletal injuries. When anaerobic and aerobic data was assessed by per centiles to investigate variance within sex, an overlap of capabilities was revealed. While considering the limita tion of different braking torques, the top 25th percentile of women demonstrated better anaerobic power and ca pacity than the bottom 10th percentile of men. The top 25th percentile of women demonstrated better aerobic capacity than the bottom 25th percentile of men. The 2 max ) than the bottom 25th percentile of men. Therefore, physiological capabilities must be assessed injury risk and performance capabilities. and body fat percentage than male Soldiers, similar less muscle mass than their male counterparts. Since MUSCULOSKELETAL, BIOMECHANICAL, AND PHYSIOLOGICAL GENDER DIFFERENCES IN THE US MILITARY
April June 2015 19 fat-free mass is positively correlated with maximum muscular strength, and body fat is negatively correlated with aerobic capacity, body composition plays an important role in force generating capacity and perfor mance capability. Previous retrospective research found including plantar fasciitis and ankle sprain. 59,60 Higher factors of injury to the low back and lower extremity in a military population. 61 kg/m 2 2 ) had higher rates of medical and all-cause discharges compared to 24.9 kg/m 2 ing Soldiers with a normal/average body composition are least likely to sustain an injury. 62 Soldiers with body fat percentages considered to be too high or too low may designed to optimize body composition to reduce injury risk, enhance performance, and augment health/longev ity, but an appropriate range of body fat for male and female Soldiers should be assessed separately. and female Soldiers during both the stop-jump and the vertical drop landing. Women tended to land with ing both tasks. During the drop landing, women landed previous research in the athletic population revealing sex differences in cutting, stopping, and jumping ma neuvers. Prospective research found individuals who land with greater knee valgus are at increased risk of anterior cruciate ligament injury. 66 Subjects with inju ry to the anterior cruciate ligament land with increased been noted in fatigued subjects. lar strength and endurance may play a role in the in female Soldiers. Poor landing mechanics may be a func proper landing mechanics. Previous research demon strated training programs that address both strength and landing mechanics are able to improve landing biome chanics and reduce the injury risk. A limitation of the current study is the uneven distribu tion of male and female Soldiers available for analysis. However, the percentage of female Soldiers in the cur 13 Another in the current study. Future research should assess the those unique to ground combat units. CONCLUSION The current study demonstrated female Soldiers are sig of physical, physiological, and musculoskeletal charac and female Soldiers possess the capability to perform physically-demanding job requirements, on average, fe male Soldiers possessed lower strength, power, endur ance, and worse body composition and biomechanics than male Soldiers. Therefore, progressive, periodized programs designed to enhance these characteristics in female Soldiers may increase the proportion of women capable of safely and successfully performing job tasks and reduce the sex disparity evidenced in the current study. At the same time, within-sex variability of char acteristics demonstrating the highest performing wom en possess comparable or better strength, anaerobic, and aerobic characteristics than the lowest performing men suggests military personnel should be evaluated on an individual (gender neutral) basis to determine perfor mance capabilities, injury risk, and targeted program adaptations may be critical to improving overall forcepecially as female Soldiers are integrated into ground combat positions. ACKNOWLEDGE M ENT This work was supported by the US Army Medical Re search and Materiel Command under Award No. W81X REFERENCES 1. performance of women in the US Army. Work 1994;4(2):80-92. 2. Fu FH. Gender differences in strength and lower extremity kinematics during landing. Clin Orthop Relat Res 2002(401):162-169. 3. Ford KR, Myer GD, Hewett TE. Valgus knee mo tion during landing in high school female and male basketball players. Med Sci Sports Exerc 4. improves physical characteristics, swing mechan ics, and golf performance in recreational golfers. J Strength Cond Res
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22 http://www.cs.amedd.army.mil/amedd_journal.aspx 55. Gender and limb differences in dynamic pos tural stability during landing. Clin J Sport Med 2006;16(4):311-315. 56. Wells CL. Women, Sport, & Performance: A Physi ological Perspective 2nd ed. Champaign, IL: Hu Fitzgerald PI, Vogel JA, Daniels WL, et al. The Body Composition Project: A Summary Report and Natick, MA: US Army Research Institute of Environmental Medicine; December March 10, 2015. 58. Teves MA, Vogel JA, Carlson DE, Schnakenberg Aspects of the 1985 CFFS Test. Natick, MA: US Army Research Institute of Environmental Medi cine; April 1986. Report No. T12/86. Available at: March 10, 2015. 59. Riddle DL, Pulisic M, Pidcoe P, Johnson RE. Risk factors for Plantar fasciitis: A matched case-control study. J Bone Joint Surg Am 60. McHugh MP, Tyler TF, Tetro DT, Mullaney MJ, Nicholas SJ. Risk factors for noncontact ankle sprains in high school athletes: the role of hip strength and balance ability. Am J Sports Med 61. Williams J, Hodges T. A comparison of injuries, limited-duty days, and injury risk factors in infan try, artillery, construction engineers, and special forces soldiers. Mil Med 62. Am J Clin Nutr 2011;93(3):608-614. 63. ters lower extremity kinematics during a single-leg stop-jump task. Knee Surg Sports Traumatol Ar throsc 64. Rozzi SL, Lephart SM, Gear WS, Fu FH. Knee joint laxity and neuromuscular characteristics of male and female soccer and basketball players. Am J Sports Med 65. Sell TC, Ferris CM, Abt JP, et al. The effect of direction and reaction on the neuromuscular and biomechanical characteristics of the knee during tasks that simulate the noncontact anterior cruci ate ligament injury mechanism. Am J Sports Med 2006;34(1):43-54. 66. cal measures of neuromuscular control and valgus loading of the knee predict anterior cruciate liga ment injury risk in female athletes: a prospective study. Am J Sports Med 2005;33(4):492-501. eo analysis of anterior cruciate ligament injury: abnormalities in hip and ankle kinematics. Am J Sports Med 68. Jacobs CA, Uhl TL, Mattacola CG, Shapiro R, Rayens WS. Hip abductor function and lower ex tremity landing kinematics: sex differences. J Athl Train 69. Kernozek TW, Torry MR, Iwasaki M. Gender dif ferences in lower extremity landing mechanics caused by neuromuscular fatigue. Am J Sports Med 2008;36(3):554-565. Lephart SM, Abt JP, Ferris CM, et al. Neu romuscular and biomechanical characteristic changes in high school athletes: a plyometric ver sus basic resistance program. Br J Sports Med 2005;39(12):932-938. AUTHORS Dr Allison, Dr Keenan, Dr Sell, Dr Abt, Dr Nagai, and Ms Deluzio are with the Neuromuscular Research Labo ratory of the Department of Sports Medicine and Nutri tion, University of Pittsburgh, Pittsburgh, Pennsylvania. Hospital, Fort Campbell, Kentucky. Dr Lephart is with the College of Health Sciences, Uni versity of Kentucky, Lexington, Kentucky. MUSCULOSKELETAL, BIOMECHANICAL, AND PHYSIOLOGICAL GENDER DIFFERENCES IN THE US MILITARY
April June 2015 23 As combat arms occupations become available to women, adequate muscular strength and aerobic endurance will be essential for the completion of physically demanding, job-related tasks. The Army Physical Readiness Train ing Manual ( Field Manual 7-22 ) 1 provides guidance on developing strength, endurance, and mobility among Soldiers. However, the Physical Readiness Training sys tem is performed in groups and may not always meet the or objectives. Therefore, in addition to Army Physical Readiness Training, Soldiers will often engage in their The ultimate goal of physical training is to improve oc cupational or physical performance. In an attempt to op timize training goals, the frequency, intensity, and dura tion of workouts can be manipulated over time. However, performing too much of one activity, exercising too long, and improper technique can result in both overuse and traumatic injury. Therefore in an attempt to minimize The Effects of Cross-Training on Fitness and Injury in Women Tyson Grier, MS Michelle Canham-Chervak, PhD Morgan K. Anderson, MPH, CPH Timothy T. Bushman, MS Bruce H. Jones, MD, MPH ABSTR A CT Background: As combat arms occupations become available to women, adequate muscular strength and aerobic endurance will be essential for the completion of physically demanding job-related tasks. Therefore, in addition to programs. Purpose: Methods: ministered to female Soldiers in an infantry division. Women were categorized into the following 4 groups based on 2 Results: Average age and body mass index was 26.25.8 years and 24.53.3 kg/m 2 respectively with no differences between a 12-month period. All injury rates and lower extremity injury rates among women with a cross-training personal 2.6 and 2.1 times more likely to experience a running related injury when compared to those in the weight training likely to experience a lifting/moving heavy objects related injury when compared to the weight training only group. Conclusions:
24 http://www.cs.amedd.army.mil/amedd_journal.aspx injuries and improve or maintain performance, some athletes have tried cross-training. 2-6 Cross-training is Previous studies investigating cross-training type pro grams have found that performance remains similar or improves with the addition of a different training compo nent. 2-5 As part of a study investigating female distance 2 max and concluded that aerobic performance was adequately maintained in the running/cycling group when com pared to the running only group. 3 In an investigation of competitive swimmers, the intervention group (perform ing both strength and endurance training) improved their land strength, tethered swimming force and 400 meter freestyle performance when compared to the control group (endurance training only). 2 It has also been shown that 60 minutes of cross-training (combined aerobic and resistance training) results in improved state anxiety or mental health 10 minutes after exercising, 8 whereas acute bouts of resistance training have resulted in no reduc tions 9 or delayed reductions occurring at 180 minutes. 10 Single mode training such as aerobic or resistance train ness performance. 11-16 The purpose of this investigation participating in personal cross-training programs (more than one mode of training) compared to women per ness program. METHODS Population The population consisted of 620 female Soldiers within 3 light infantry brigades. Each brigade consisted of 6 battalions/regiments including a special troops battalion, a cavalry regiment, an armor regiment, an infantry regi ment (1 brigade had 2 infantry regiments and no brigade support battalion. Rosters of unit mem bers were requested and obtained through the sex, rank and battalion. Survey Surveys were administered between 2010 and 2011. The surveys were used to collect informa tion from the Soldiers about personal character istics, physical training, performance on their and injuries occurring within the last 12 months. Wom en who indicated that they performed strength training, distance running or sprinting/interval training once or program were considered as having participated in these they performed personal strength training, distance run ning or sprinting/interval training less than once a week or not at all were considered as not participating in these grams, the women were then categorized into a crosstraining group, running only group, weight training only Army Physical Fitness Test obtained from the survey. High correlations have been scores. maximal effort push-up event, a 2 minute maximal ef fort sit-up event, and a 2-mile run for time. Events were performed in accordance with instructions contained in Field Manual 7-22 1 2 max was estimated 2 max (2mile run time )). 18 Data Analysis percent distribution were calculated for categorical vari ables such as age groups, military occupational special ty, body mass index (BMI) level, etc, as shown in Table 2. Means and SD were calculated for continuous vari ables such as age in years, weight, height, miles run per week, 2-mile run times in minutes, number of push-ups, etc, shown in Table 3. The BMI (weight in kilograms divided by height in meters squared (kg/m)) was cat egorized according to the Centers for Disease Control overweight, and obese. 19 THE EFFECTS OF CROSS-TRAINING ON FITNESS AND INJURY IN WOMEN Table 1 Personal Fitness Training Program WT, RUN, ST WT, RUN WT, ST RUN, ST RUN WT NPF Cross-Training Running Only Weight Training Only No Personal Fitness Program 1 mile or more) as part of a personal physical
April June 2015 25 A 2 programs. Injury rates were calculated for all (overall) injuries, lower extremity injuries, and upper extremity An independent t test was used to determine any differ RESULTS The average age of the female Soldiers was 26.25.8 years with an average BMI of 24.53.3 kg/m 2 A major ity of the Soldiers were of ranks E4 and E5, in a combat services support role, and had a normal BMI. A ma jority of the Soldiers reported participating in personal and unit distance running, personal strength training, and unit sprint/interval training one or more times per week. Less than half of the Soldiers reported partici pating in unit resistance training, agility training, and personal sprint/interval training one or more times Age, height, weight, and BMI were similar among par cross-training group was different from the running group in that they ran more miles per week during per compared to the other 3 groups. The cross-training group had better performance and higher estimated 2 max over a 12-month period. Table 4 displays injury rates and lower extremity injury rates among women with a a lower risk of upper extremity injury when compared to the weight training only program. The running only injury rates than the weight training only group for both all injuries and upper extremity injuries. Table 5 displays the activities associated with injuries for women participating in the cross-training and run cant differences in injury risk by activity between the 2 groups. Table 6 displays the activities associated with injuries for women participating in a cross-training and weight training only programs. The comparison of injury in cross-training were more likely to experience a run ning related injury when compared to women perform ing weight training only. However, women performing weight training only were more likely to experience a lifting/moving heavy objects related injury in compari son to women performing cross-training. Table 2 Personal Characteristics, Physical Fitness Activities, 620 ). Variable Subcategory of Variable n % N 18-22 178 29% 23-27 255 41% 184 30% <18.5 / m 2 15 3% 18.5-24.9 / m 2 332 54% 25-29 / m 2 237 39% 30+ / m 2 28 5% E 1E 3 138 23% E 4E 5 357 58% E 6E 9 55 9% Officer / Warrant Officer 64 10% Specialty Combat Support 176 30% Combat Services Support 429 70% 196 32% 253 41% 171 28% Unit Distance Running None 178 30% 423 70% Unit Strength Training None /<1 417 69% 186 31% Training None /<1 198 33% 407 67% Unit Agility Training None /<1 392 65% 208 35% Personal Distance Running None /<1 298 48% 322 52% Personal Strength Training None /<1 274 44% 346 56% Training None /<1 390 63% 174 37% Fitness Training Group Cross Training 260 42% Running Only 93 15% Weight Training Only 86 14% No Personal Fitness Training 181 29%
26 http://www.cs.amedd.army.mil/amedd_journal.aspx for women participating in a cross-training program showed women performing cross-training were more likely to experience a running related injury when com to experience a walking, hiking, or marching with no load injury in comparison to the cross-training group. CO MM ENT women with personal cross-training programs com pared to women performing only one mode of personal a cross-training program had greater muscular endurance as measured by up tests compared to women with oth Women who participated in cross-train 2 max formance compared to women with no no differences for all injuries and lower body injuries between cross-training and the other programs. However, the cross-training group had a lower risk of upper body in jury when compared to the weight training only group. An examination of activities associated with injury showed women with a cross-training program were more than twice as likely to experience a running related program focused on weight training only and women were twice as likely to experience a walking, hiking, or marching with no load injury, and were almost 3 times as likely to experience a lifting/moving heavy objects re lated injury when compared to the cross-training group. Higher muscular and aerobic endurance have been dem onstrated in other studies of cross-training programs. THE EFFECTS OF CROSS-TRAINING ON FITNESS AND INJURY IN WOMEN Table 3 Program. Variables Cross-Training Running Only Weight Training Only No Personal Fitness Program ANOVA ANOVA With Tukey 25.85.5 (n=259) 26.66.4 (n=93) 27.36.1 (n=85) 26.25.9 (n=180) 0.20 164.38.1 (n=256) 163.07.6 (n=92) 165.07.1 (n=86) 163.67.0 (n=181) 0.24 65.79.6 (n=255) 66.29.2 (n=90) 68.39.2 (n=86) 65.710.2 (n=181) 0.09 2 ) 24.33.3 (n=234) 24.93.3 (n=90) 25.03.1 (n=86) 24.33.2 (n=181) 0.10 7.76.5 (n=234) 6.15.2 (n=78) 0.03 APFT Push-Up 41.812.2 (n=243) 37.713.8 (n=85) 35.410.9 (n=80) 36.311.3 (n=160) <0.01 Cross-Training Running Program P=. 04 Cross-Training Weight Training P <. 01 Cross-Training No Program P <. 01 APFT Sit-up 67.813.5 (n=244) 63.415.1 (n=86) 61.710.9 (n=76) 61.811.3 (n=156) <0.01 Cross-Training Running Program P=. 04 Cross-Training Weight Training P <. 01 Cross-Training No Program P <. 01 APFT 2-mile Run 17.42.1 (n=230) 18.02.1 (n=76) 17.81.6 (n=49) 18.52.3 (n=136) <0.01 Cross-Training No Program P <. 01 VO 2 max 42.13.7 41.03.8 41.52.9 40.24.1 <0.01 Cross-Training No Program P <. 01 t test Table 4 Injury Type Cross-Training Running Only Weight Training Only No Personal Fitness Program P Value All Injuries 55% (n=260) 40% (n=93) 65% (n=86) 49% (n=181) <.01 Extremity Injuries 24% (n=235) 20% (n=91) 23% (n=78) 24% (n=174) .47 Upper Extremity Injuries 23% (n=235) 19% (n=91) 39% (n=78) 24% (n=174) .02
April June 2015 27 Studies examining the addition of a resistance training program to an already established endurance training program found improve ment in both strength and aerobic performance. 20-24 are also supported by a recent me ta-analysis of concurrent resistance and endurance training, where in vestigators found larger effects on 1.84)), when compared to endurance 1.19)). 25 Previous studies investigat ing resistance training and running performance found increased run ning economy and improved running performance when resis tance training was incorporated into their training program. In another study investigating mod erately trained runners participat ing in a running, sprinting, and weight training program (RSW) compared to program showed improvements in run ning performance and dynamic strength 29 As suggested by this analysis, these studies indicate that ness program with one mode of training. program were not different from injury rates among women with other training programs. In previous military studies investigating the implementation of new exercise programs (incorporating addi tional cross-training components), inju ry rates neither increased nor decreased with implementation of a cross-traininglike program. 6,30,31 Women who performed weight training only were more likely to experience an upper body injury compared to the cross-training group as well as the other programs. Women performing weight training only as part of their injury when compared to women with a program based gram. In a study comparing women who participated in a resistance training program to a control group, the 32 The investigators went on to say that strength training provided favorable changes in lean mass and strength, while injury rates were lower than previously reported population-based survey rates. Even though injury rates were higher for the weight only group when compared to Table 6 Cause of Injury Cross-training Weight Training Only Risk Ratio P Value Running 33% (44) 13% (7) 2.55 (1.23-5.31) <.01 Other Exercise 15% (20) 13% (7) 1.16 (0.52-2.58) .71 11% (15) 11% (6) 1.02 (0.42-2.48) .97 Heavy Objects 10% (13) 28% (15) 0.35 (0.18-0.69) <.01 Sports 9% (12) 4% (2) 2.44 (0.56-10.52) .35 Stepping, Climbing 5% (6) 0% (0) 4% (5) 4% (2) 1.02 (0.20-5.07) .99 3% (4) 4% (2) 0.81 (0.15-4.30) .99 Equipment 0 (0%) 4% (2) Other 11% (14) 20% (11) 0.52 (0.25-1.07) .07 Table 5 Cause of Injury Cross-Training Running Only Risk Ratio Chi square P Value Running 33% (44) 19% (7) 1.75 (0.86-3.56) .10 Other Exercise 15% (20) 19% (7) 0.79 (0.36-1.73) .57 11% (15) 8% (3) 1.39 (0.43-4.55) .84 Heavy Objects 10% (13) 14% (5) 0.72 (0.28-1.90) .51 Sports 9% (12) 5% (2) 1.67 (0.39-7.13) .75 Stepping, Climbing 5% (6) 11% (4) 0.42 (0.12-1.40) .30 4% (5) 8% (3) 0.46 (0.12-1.85) .48 3% (4) 8% (3) 0.37 (0.09-1.58) .35 Equipment 0% (0) 0% (0) ------Other 11% (14) 8% (3) 1.30 (0.39-4.28) .94 *
28 http://www.cs.amedd.army.mil/amedd_journal.aspx previous studies have shown that resistance training im proves physical and occupational task performance. 12-16 However, it is more effective to use 2 modes of training rather than one, as shown by improved muscular endur ance in the cross-training group when compared to the weight training only group tective against injury. 33 When looking at sex differ ences in resistance training, women were found to have compared to men. 34 It may be that women have less ex perience with weight training, poor exercise technique, or lack of coaching education when compared to men, placing them at a greater risk of injury and possibly an even higher risk of upper body injury. It is likely that muscular strength would also have improved had it been cular strength after the addition of a resistance training program. 15,35 In a 6-week study of untrained (regarding resistance training) college women, absolute one repeti tion maximum (1RM) leg press strength was improved ditional strength training program. In another resistance and aerobic training study, women who participated in a 12 week aerobic and resistance training program im changes were found. 35 Strength training programs would likely show similar outcomes in Army populations. In this investigation, women perform ing cross-training were more than twice as likely to experience a run ning related injury when compared to the weight training and no personnel very minimal (less that once a week) or no additional running per week beyond unit PT. The greater expo sure to running in the cross-training group placed them at a higher risk of injury. Prior studies have shown increased risk of injury with miles run per week. 36-38 In another crosstraining study consisting of running, sprinting, weight training, backpack ing, and lift and carry drills, weight lifting accounted for about one third of the injuries and clinic visits, while running injuries accounted for about visits. 5 These results are different from the current study in that those participating in cross-training were more likely to experience a running related injury. It may be that the participants in the current investigation ran more miles per week, whereas the other study had a more di verse training program with quite a few more strength training activities. Women who performed weight training only were at al most 3 times the risk of injury for moving/lifting heavy objects when compared to the cross-training group. It may be that women in the weight training group spent more time per week weight training or had advanced to lifting heavier weights, possibly increasing their risk for strains and sprains when compared to the cross-training their weight training program would be required to de termine why their risk of injury was higher. risk of injury for walking, hiking, and marching with out a load when compared to the cross-training group. lower estimated aerobic capacities when compared to the cross-training group. Soldiers with lower aerobic capacities will likely experience greater amounts of physiological stress and/or fatigue during tasks such as running, marching and hiking due to exercising at a higher percentage of their maximum aerobic capac levels. The greater physiological stress and/or fatigue THE EFFECTS OF CROSS-TRAINING ON FITNESS AND INJURY IN WOMEN Table 7 Cause of Injury Cross-training No Personal Fitness Program Risk Ratio P Value Running 33% (44) 16% (13) 2.14 (1.23-3.72) <.01 Other Exercise 15% (20) 13% (11) 1.15 (0.58-2.27) .69 11% (15) 23% (19) 0.50 (0.27-0.93) .03 Heavy Objects 10% (13) 14% (12) 0.68 (0.33-1.43) .31 Sports 9% (12) 6% (5) 1.52 (0.55-4.15) .41 Stepping, Climbing 5% (6) 6% (5) 0.76 (0.24-2.41) .64 4% (5) 5% (4) 0.79 (0.22-2.86) .97 3% (4) 1% (1) 2.53 (0.29-22.22) .71 Equipment 0 (0%) 0 (0%) Other 11% (14) 17% (14) 0.63 (0.32-1.26) .19
April June 2015 29 experienced may lead to a higher risk of injury. Studies on fatigue have demonstrated decrements in propriocep tive ability, 39 a decrease in joint stability, 40 alterations in muscle activity, 39 changes in gait, 41-45 balance, low frequency fatigue, 48 neuromuscular function, 49 and liga ment laxity. 50 CONCLUSION had higher muscular endurance compared to women 2 max when compared to the no personal and lower body injuries between cross-training and oth were more than twice as likely to experience a running related injury when compared to weight training and no REFERENCES 1. Field Manual 7-22: Army Physical Readiness Train ing 2. Aspenes S, Kjendlie P, Hoff J, Helgerud J. Combined strength and endurance training in competitive swimmers. J Strength Cond Re 3. M. Effectiveness of cycle cross-training between competitive seasons in female distance runners. J Strength Cond Re 4. Heng M. Effect of run vs combined cycle/run train 2 max and running performance. Med Sci Sports Exerc 5. Reynolds K, Harman E, Worsham R, Sykes M, ed with a periodized strength training and running program J Strength Cond Re 6. Lyons W. Adaptations to a New Physical Training Program in the Combat Controller Training Pipe line Wilmore JH, Costill DL. Physiology of Sports and Exercise 1994. 8. Hale B, Koch K, Raglin J. State anxiety responses to 60 minutes of cross training. Br J Sports Med 9. Exercise and Sports Science Reviews 10. of different intensities on state anxiety and blood pressure. Med Sci Sports Exerc 11. Zhang JJ, Jackson AS. The function of maximal oxygen consumption, job intensity, smoking, and gender on work-related injuries 199. Med Sci Sports Exerc 12. resistance training on womens strength/power and occupational peformances. Med Sci Sports Exerc 13. Rosenblum K, Shankar A. A study of the effects of isokinetic pre-employment physical capability screening in the reduction of musculoskeletal dis orders in a labor intensive work environment. Work 14. Knapik JJ, Gerber J. Training on the Manual Material Handling Capa bility and Road Marching Performance of Female Soldiers Research and Engineering Directorate, US Army 2015. 15. Rana SR, Chleboun GS, Gilders RM, et al. Com parison of early phase adaptations for traditional strength and endurance, and low velocity resis tance training programs in college-aged women. J Strength Cond Res 16. bined resistance and endurance training im proves physical capactiy and performance on tactical occupational tasks. Eur J Appl Physiol Jones SB, Knapik JJ, Sharp M, Darakjy S, Jones scores. Mil Med 18. Relationship Be tween a Two Mile Run for Time and Maximal Oxy gen Uptake 19. Centers for Disease Control and Prevention. About assessing/bmi/adult_bmi/index.html. Accessed March 5, 2015.
30 http://www.cs.amedd.army.mil/amedd_journal.aspx 20. Aagaard P, Andersen J. Effects of strength training on endurance capacity in top-level endurance ath letes. Scand J Med Sci Sports 21. mal strength training improves running econo my in distance runners. Med Sci Sports Exerc 22. Hickson R, Dvorak B, Gorostiaga E, Kurowski training to amplify endurance performance. J Appl Physiol 23. Sedano S, Marin P, Cuadrado G, Redondo J. Con of strength versus muscular endurance training on performance outcomes. J Strength Cond Res 24. Effects of resistance training on running economy and cross-country performance. Med Sci Sports Exerc 25. Wilson J, Marin P, Rhea M, Wilson S, Loenneke J, examining interference of aerobic and resistance exercises. J Strength Cond Res 26. pact on running economy. J Strength Cond Res mela A, Rusko H. Explosive strength training improves 5-km running time by improving run ning economy and muscle power. J Appl Physiol 28. strength training on three-kilometer performance in recreational women endurance runners. J Strength Cond Res 29. Skovgaard C, Christensen P, Larsen S, Andersen T, Thomassen M, Bangsbo J. Concurrent speed endur ance and resistance training improves performance, trained runners. J Appl Physiol 30. ation of the advanced tactical athlete conditioning and extreme conditioning programs in the 25th United States Army Insitute of Public Health; 2010. 31. Darakjy S. United States Army physical readi physical training doctrine. J Strength Cond Res 32. Warren M, Schmitz K. Safety of strength training from a two year randomized trial. Am J Health Pro mot 33. treme conditioning programs and injury risk in a US Army brigade combat team. US Army Med Dep J 34. Quatman C, Myer G, Khoury J, Wall E, Hewett T. Sex differences in weightlifting injuries present ed to United States emergency rooms. J Strength Cond Res 35. tance training combined with bench-step aerobics Med Sci Sports Exerc 36. Koplan JP, Powell KE, Sikes RK, Shirley RW, Campbell CC. An epidemiologic study of the bene JAMA the epidemiology of running injuries. The 1984 Bern Grand-Prix study. Am J Sports Med 38. Samet JM, Chick TW, Howard CA. Running-relat Ann Sports Med Res 39. tigue on knee joint laxity and neuromuscular char acteristics of male and female athletes. J Athl Train 40. Melnyk M, Gollhofer A. Submaximal fatigue of and knee stability. Knee Surg Sports Traumatol Ar throsc 41. Candau R, Belli A, Millet GY, George D, Barbier B, Rouillon JD. Energy cost and running mechanics during a treadmill run to voluntary exhaustion in humans. Eur J Appl Physiol 42. ML. Relationship of fatigued run and rapid stop to ground reaction forces, lower extremity kinematics, and muscle activation. J Orthop Sports Phys Ther 43. Gerlach K, White S, Burton H, Dorn J, Leddy J, Horvath P. Kinetic changes with fatigue and re lationship to injury in female runners. Med Sci Sports Exerc 44. mard L, Barrey E. Effect of fatigue on stride pat tern continuously measured by an accelerometric gait recorder in middle distance runners. J Sports Med Phys Fitness THE EFFECTS OF CROSS-TRAINING ON FITNESS AND INJURY IN WOMEN
April June 2015 31 45. Yoshino K, Motoshige T, Araki T, Matsuoka K. Effect of prolonged free-walking fatigue on gait and physiological rhythm. J Biomech 46. Johnston R, Howard M, Cawley P, Losse G. Ef fect of lower extremity muscular fatigue on mo tor control performance. Med Sci Sports Exerc Dickin D, Doan J. Postural stability in altered and unaltered sensory environments following fatigu ing exercise of lower extremity joints. Scand J Med Sci Sports 48. Low-frequency fatigue at maximal and submaxi mal muscle contractions. Braz J Med Biol Res 49. Wojtys E, Wylie B, Huston L. The effects of muscle fatigue on neuromuscular function and anterior tib ial translation in healthy knees. Am J Sports Med 50. Sakai H, Tanaka S, Kurosawa H, Masujima A. The effect of exercise on anterior knee lax ity in female basketball players. Int J Sports Med AUTHORS Mr Grier is a Kinesiologist for the Injury Prevention Program of the Epidemiology and Disease Surveillance Portfolio, US Army Public Health Command, Aberdeen Proving Ground, Maryland. Dr Canham-Chervak is a Senior Epidemiologist for the Injury Prevention Program of the Epidemiology and Disease Surveillance Portfolio, US Army Public Health Command, Aberdeen Proving Ground, Maryland. Mrs Anderson is an Epidemiologist for the Injury Pre vention Program of the Epidemiology and Disease Sur veillance Portfolio, US Army Public Health Command, Aberdeen Proving Ground, Maryland. Mr Bushman is an Exercise Physiologist for the Injury Prevention Program of the Epidemiology and Disease Surveillance Portfolio, US Army Public Health Com mand, Aberdeen Proving Ground, Maryland. Dr Jones is a Program Manager for the Injury Prevention Program of the US Army Public Health Command, Ab erdeen Proving Ground, Maryland. Announcing The 2015 Spurgeon Neel Annual Award Competition The Army Medical Department Museum Foundation is pleased to announce the 2015 Spurgeon tory, legacy, and traditions of the Army Medical Department. all federal employees, military and civilian, as well as nongovernmental civilian authors. More The AMEDD Museum Foundation will present a special medallion award and a $500 monetary prize to the winner at a Foundation-sponsored event early in 2016. The winning submission will be published in the AMEDD Journal during 2016. any other periodical. It must conform to the Writing and Submission Guidance of the AMEDD Journal ment. Manuscripts will be reviewed and evaluated by a six-member board with representatives AMEDD Journal. The winning manuscript will be selected and announced in December 2015. Submit manuscripts to Additional details concerning the Spurgeon Neel Annual Award may be obtained by contacting Mrs Sue McMasters at the AMEDD Museum Foundation, 210-226-0265.
32 http://www.cs.amedd.army.mil/amedd_journal.aspx Soldiers physical and/or mental well-being due to al tered schedules, environmental conditions, and avail able resources during deployments. Physical training ployed Soldiers. varying physical demands during deployments. It is important that all Soldiers have the aerobic endurance maintain a physical training program requires appropri ate space, equipment, and time, which varies by loca 1-3 It is essential to continue physical training, either with the unit, during personal time, or both. men. 4 This announcement raised questions about the tering these positions, and highlighted a need to better understand current physical training practices, both be 5 Physical Training, Smoking, and Injury During Deployment: A Comparison of Men and Women in the US Army Morgan K. Anderson, MPH, CPH Tyson Grier, MS Timothy T. Bushman, MS ABSTR A CT Purpose: Methods: Results improved by 50 seconds ( P=. P<. 01), while muscular endurance in creased by 0.6 repetitions ( P<. P P=. P<. Conclusion: between men and women should be addressed, with suggestions regarding where improvements can be made,
April June 2015 33 deployed Soldiers, and none that have included women. during a 13-month deployment showed upper and lower body strength improved, upper body power improved, sports during deployment. 6 Another investigation which es in aerobic capacity, upper body power, and body com 7 8 METHODS Data Collected A volunteer-based survey was administered to Soldiers dex (BMI), and tobacco use during the 6 months prior to resistance, sprint, cross-training, and running. Health Review Board. 2 days prior to the survey administration date. Data Analysis demographics were calculated. Means and standard incidence. P P values between 0.06 and 0.10 RESULTS Descriptive Statistics P<. 01) and decreased P =.02) (Table 1). Prior to deployment, av 2 2 P <.01), Personal and Unit Physical Training Table 1 Injury Rates Differences Before and During Deployment for Men and Women. Before deployment injury rate (per 1,000 Soldiers per month) Deployment injury rate (per 1,000 Soldiers per month) P value, before deployment vs deployment Male Soldiers (n=727) 36.2 19.0 <.01 Female Soldiers (n=43) 42.6 14.0 .02 P value, male vs female <.01 <.01 P is calculated using 2 person-time rates z-score
34 http://www.cs.amedd.army.mil/amedd_journal.aspx Table 2 Demographic, Physical Fitness, and Physical Training Differences Before and During Deployment for Men and Women. Men (n=727) Women (n=43) % Difference Between Sexes: Predeployment % Difference Between Sexes: Deployed Predeploy (meanSD) Deployed (meanSD) P % Change Predeploy (meanSD) Deployed (meanSD) P % Change Age (years) 24.75.1 25.85.1 <.01 +4% 25.24.7 26.34.7 .28 +4% 4% 2% BMI (kg/m 2 ) 25.83.3 26.03.2 .24 +<1% 24.42.8 24.52.5 .86 +<1% 6% 6% Smokers (%) 47% 56% <.01 +19% 40% 38% .90 -5% 7% 18% APFT 2 mile run (minutes) 14.341.33 14.82 1.40 <.01 +3% 17.83 2.14 16.99 1.78 .06 -5% 24% 15% Sit-ups (repetitions) 69.810.7 69.59.9 .37 -<1% 66.813.4 69.114.2 .45 +3% 4% 1% Push-ups (repetitions) 65.912.6 66.512.3 <.01 +1% 43.417.2 44.211.3 .80 +2% 52% 50% Personal PT Resistance Training (n) 723 720 43 43 None 31% 8% <.01 -74% 51% 21% <.01 -59% +20% +13% 36% 20% -44% 44% 40% -11% +8% +20% 33% 72% +119% 5% 40% +750% -28% -32% Sprinting (n) 722 723 43 43 None 50% 33% <.01 -34% 70% 35% <.01 -50% +20% +2% 42% 57% +37% 26% 61% +136% -16% +4% 8% 10% +20% 5% 5% 0% -3% -5% Running Mileage (n) 697 700 41 43 None 33% 12% <.01 -64% 44% 14% <.01 -67% +10% +2% <5 miles per week 42% 29% -30% 49% 28% -40% +7% -1% 25% 59% +134% 7% 58% +733% -18% -1% Unit PT Resistance Training (n) 708 723 41 43 None 11% 47% <.01 +333% 20% 51% .01 +175% +9% +4% 53% 16% -69% 56% 28% -48% +3% +12% 36% 37% +7% 24% 21% -10% -12% -16% Sprinting (n) 709 725 42 43 None 10% 59% <.01 +484% 17% 56% <.01 +243% +7% -3% 72% 36% -49% 67% 44% -32% -5% +8% 18% 6% -68% 17% 0% -100% -1% -6% Cross-Training (n) 704 722 38 43 None 21% 56% <.01 +174% 37% 61% .10 +86% +3% -4% 42% 35% -15% 45% 26% -35% +1% -4% 37% 7% -80% 19% 14% -14% -5% +8% Running Mileage (n) 699 710 41 40 None 4% 54% <.01 +117% 7% 50% <.01 +578% +16% +5% <5 miles per week 28% 17% -39% 29% 13% -75% +3% -9% 68% 30% -56% 63% 38% -42% -18% +7% P <. 10 is considered significant ANOVA Chi-square PHYSICAL TRAINING, SMOKING, AND INJURY DURING DEPLOYMENT: A COMPARISON OF MEN AND WOMEN IN THE US ARMY
April June 2015 35 ployment. Participation in unit cross-training drills 3 or ployment (Table 2), personal resistance training showed women prior to deployment was seen in unit sprinting ble 2), personal resistance training showed the largest ing deployment was seen in personal running mileage Physical Fitness 2-mile) ( P=. 06). Cardiorespiratory endurance de 2-mile) ( P<. 01) but their muscular strength improved by P<. 01) during deploy ment (Table 2). CO MM ENT physical training, decreases in unit physical training, While deployed women saw a 50 second improvement 31% 36% 33% 72% 36% 53% 11% 47% 16% 37% 50% 57% 42% 33% 8% 10% 42% 42% 68% 37% 25% 28% 33% 4% 59% 56% 59% 17% 29% 30% 36% 35% 12% 54% 21% 18% 72% 10% 20% 8% 6% 7% Personal Resistance Training Personal Sprinting Personal Running Mileage Unit Resistance Training Unit Sprinting Unit Running Mileage Cross Training (Unit) Predeployment Predeployment Predeployment Predeployment Predeployment Predeployment Predeployment During Deployment During Deployment During Deployment During Deployment During Deployment During Deployment During Deployment 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 100% Figure 1 Mens physical training participation before and during deployment. None 3 days per week < 5 miles per week 1-2 days per week 5 miles per week
36 http://www.cs.amedd.army.mil/amedd_journal.aspx 6 and Sharpe et al 7 also showed cardiorespiratory endurance among men sonal running mileage among both men and women dur A study 11 The increase in cardiorespi ratory endurance in women could be due to increased quency during deployment. Past studies have reported motes increases in muscular and aerobic endurance. 14,15 This improvement could be due to the increase in the deployment. Although women also increased the rates could indicate that women desire to improve their mus sistance training exercises. Resistance training instruc tion and equipment geared towards women might help healthy weight and improved circulation, balance, coor dination, and bone/ligament strength. 16,17 The American group to improve strength and power. 18 women, similarities were seen in running mileage with tween men and women were seen in personal resistance Both running and resistance training are crucial com ponents to improving and maintaining Soldiers cardio vascular and muscular endurance. Resistance training during personal time and with the unit should be highly 44% 51% 28% 35% 70% 26% 67% 21% 40% 24% 60% 51% 56% 44% 40% 20% 44% 60% 37% 45% 28% 26% 5% 5% 5% 49% 58% 56% 18% 60% 37% 45% 14% 14% 14% 26% 18% 17% 17% 21% 7% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% 100% Predeployment During Deployment Personal Resistance Training Personal Sprinting Personal Running Mileage Unit Resistance Training Unit Sprinting Unit Running Mileage Cross Training (Unit) Predeployment Predeployment Predeployment Predeployment Predeployment Predeployment During Deployment During Deployment During Deployment During Deployment During Deployment During Deployment None 3 days per week < 5 miles per week 1-2 days per week 5 miles per week Figure 2 Womens physical training participation before and during deployment. PHYSICAL TRAINING, SMOKING, AND INJURY DURING DEPLOYMENT: A COMPARISON OF MEN AND WOMEN IN THE US ARMY
April June 2015 37 participated in endurance and strength/power training. training, and showed individuals who participated in 14 rison compared to men. Encouraging similar physical training regimen between men and women might be combat and other physically demanding military occu and women. Even though unit level PT decreased and own pace and intensity level, which may explain why in 20 observed Soldiers that participated in et al 21 deployments, multiple deployments, and combat expo 22 STRENGTHS A ND LI M IT A TIONS 23 CONCLUSION and women. Personal PT played a larger role in physical training compared to unit PT participation during de ployment, which may have contributed to the decrease men and women, while there was an increase in the physical training activities and health behavior among that increased resistance training could be recommend rison and during deployment. Given the potentially im Addressing physical training gaps between men and women in garrison, suggest where improvements can be combat positions with high physical demands. REFERENCES 1. Health, Performance, and Nutritional Status of U.S. Army Women during Basic Combat Training 2. in basic combat training. Med Sci Sports Exerc 3. Mil Med 4. combat roles to women. USA Today [internet]. Jan uary 24, 2013. Available at: http://www.usatoday. com/story/news/nation/2013/01/24/women-com 2, 2015. 5. New York Times wanted=all&_r=3&
38 http://www.cs.amedd.army.mil/amedd_journal.aspx 6. Mil Med 2010;175(6):417-423. 7. Med Sci Sports Exerc 2015. 8. deployments. ArmyTimes [internet]. August 5, 2011. Available at: http://www.armytimes.com/arti 2, 2015. Prev Med 10. Mil Med 2007;172(5):527-532. 11. Macera CA, Arali HJ, MacGregor AJ, Rauh among male navy personnel. Nicotine Tob Res 12. soldiers. Am J Prev Med 13. cal readiness test. Mil Med 14. Combined resistance and endurance training physi Eur J Appl Physiol 15. Wilson JM, Marin PJ, Rhea MR, Wilson SMC, bic and resistance exercise. J Strength Cond Res 16. and adiposity in premenopausal women: strong, healthy, and empowered study. Am J Clin Nutr 2007;86:566-572. 17. at: http://www.womensheart.org/content/exercise 18. Med Sci Sports Exerc resistance training on womens strength/power and Med Sci Sports Exerc 2001;33(6):1011-1025. 20. Mil Med 21. Am J Prev Med 22. deployment. J R Soc Med 23. test scores. Military Medicine, 2007;172(2):115-120. AUTHORS Aberdeen Proving Ground, Maryland. Proving Ground, Maryland. Command, Aberdeen Proving Ground, Maryland. mand, Aberdeen Proving Ground, Maryland. erdeen Proving Ground, Maryland.
April June 2015 39 As combat roles become open to women serving in the military, questions about their ability to maintain the physical demands and stay injury-free in these roles have been raised. 1,2 Musculoskeletal injuries (MSK-I) and oth er noncombat illnesses are a leading cause of lost-duty time and morbidity among training and deployed mili tary populations, particularly among women. 3-8 Today, women comprise approximately 13% of the US armed forces 9 ; however, they are more likely than men to suffer from MSK-I 3,5-7,10-12 and be medically discharged from service due to their training-related injuries. 13 Other risk factors for MSK-I and physical activity-related condi tions (eg, heat stroke, exertional rhabdomyolysis) in women include older age, lower body mass/bone den dex (BMI) and previous MSK-I history. 6,10,14,15 High-risk psychological and behavioral factors, which may be in 16 also differ by sex. 17,18 Women, for example, report higher rates of disordered sleep, 18 which may contribute to their increased risk for MSK-I. 19 In contrast, men report higher rates of alcohol and tobacco use, 16 which contributes to their MSK-I. 7 Physical Fitness and Injury Reporting Among Active Duty and National Guard/Reserve Women: Associations with Risk and Lifestyle Factors Josh B. Kazman, MS Sarah de la Motte, PhD, MPH, ATC Elizabeth M. S. Bramhall, MPH Dianna L. Purvis, PhD Patricia A. Deuster, PhD, MPH ABSTR A CT Objective: As more women enter the military, it is important to understand how different risks and lifestyle physical training than men. They also use more medical care during deployment than men. Using data from lifestyle and behavioral risk factors were analyzed in nondeployed Army personnel, with the goals of examin ing (1) service-component differences across traditional risk and lifestyle factors, and (2) correlates of physical performance and physical activity-related injury. Methods: and alcohol use), self-reported health metrics (height, weight, Army Physical Fitness Test (APFT) scores), and Results: Across all service components, predictive factors for APFT failure included high body mass index (BMI), fair/ poor health, and unhealthy diet. Predictive factors for physical injury included high BMI, fair/poor health, and binge drinking. Conclusion which is accompanied by a greater prevalence of physical activity-related injuries. As womens roles expand into combat military occupation specialties, a thorough understanding of service component differences will be critical to inform training programs, mitigate physical injury, and enhance force health protection and readiness.
40 http://www.cs.amedd.army.mil/amedd_journal.aspx Service component differences further complicate MSK-I concerns in military women. During Operation Iraqi Freedom and Operation Enduring Freedom, over force. 20 deployment, 21 and suffered from more MSK-I during deployment than AD women. 11 And even though women serving in the tivity are likely different. For example, AD Soldiers typ ically spend 1-1.5 hours, 4 days per week participating 22 However, little is known about how these service components differ in terms of of deployment. 11,23,24 The Comprehensive Soldier and Family Fitness (CSF2) line survey of physical, emotional, social, family, and 25 The signed to build and improve psychological resilience 26 Army service components, so it provides a unique op portunity to assess a variety of risk factors among Army study were to examine how traditional risk and lifestyle factors related to physical performance and to physi cal injury among female Soldiers across service com ponents. Identifying key risk factors related to physical diers would be critical for revising training programs and implementing injury mitigation strategies. METHODS As a key component of the Armys CSF2 program, non deployed Army soldiers are required to complete the families and DoD civilians). 25 online survey that assesses 5 components of strength: ness. 27 In 2012, 57 pilot questions were added to the original 105 questions in order to more accurately assess female Soldiers (n=2,335) who completed the updated pants were excluded due to missing health behavior data, which allowed for a total sample size of 2,305 Army AD women. Participants were on average 26.48.1 (17 to 58) additional participant characteristics divided by service Health and Behavioral Risk Factors iors (sleep, diet, heavy alcohol use and tobacco use) and general health questions. Measures were dichotomized, as described below, based on available standards or pre vious research where available. Body Mass Index. Self-reported height and weight were used to compute body mass index (BMI, weight (kg)height (m) -2 ), which was then dichotomized at the cut point 27.5 kg/m 2 based on Army Regulation 600-9 28 Although low BMI has previously been reported to be a risk factor for MSK-I among women, 6 only 1% of par ticipants in our sample were underweight (BMI<18.5), and these women were included in the normal weight category. Nutrition Behavior using a 5-question Healthy Eating Score (HES-5). 29 This measure was derived from the more comprehensive US Department of Agricultures Healthy Eating Index, 30 but with only 5 food category components: the frequency answered by using a 6-point Likert-type scale (rang ing from 0, rarely or never, to 5, 3 or more times per day). The HES-5 was extensively analyzed in the larger 29 and has adequate internal con previous analyses, 29 the HES-5 was dichotomized, such that participants with a sum score in the lowest quartile were coded as unhealthy eaters. Sleep. Sleep was assessed with the 2-item 31 version of the 32 which was sample. 18 The 2 items ask about sleep over the past 7 days with a focus on how much a person was bothered by lack of energy due to poor sleep and perception of overall sleep satisfaction, each answered along separate 4-point Likert-type scales. The items were developed using 31 with an overall cutoff score that was used to dichotomize Additional Health Behaviors. Additional health behav iors included tobacco and alcohol use. Tobacco was as sessed by asking participants about their use of tobacco PHYSICAL FITNESS AND INJURY REPORTING AMONG ACTIVE DUTY AND NATIONAL GUARD/RESERVE WOMEN: ASSOCIATIONS WITH RISK AND LIFESTYLE FACTORS
April June 2015 41 products (cigarettes, cigars, smokeless tobacco, chew, dipping, pinching) in the last year, with responses di chotomized based on regular ( 4 times per week) use versus minimal (<4 times per week, no use, or quit in past year) use of tobacco products. Since only 1.4% of females reported use of smokeless tobacco, it was not feasible to distinguish between types of tobacco use. Heavy alcohol use was assessed with the question Have you exceeded 5 alcoholic drinks on any single occasion of binge drinking 33 and has been used in previous mili tary survey research. 16 General Health single item, How do you consider your general health?, which was answered along a 4-point Likert-type scale (excellent, good, fair, and poor), to include dont know. Using a single question to measure overall health has of both physical and mental health, or measure of glob al health. 34 Although general health is broader than the other predictors above, and is often assessed as a health outcome, it has strong predictive power for injury risk 35-37 and is a practical screening measure in general. 34,38 As with previous research in this sample, 18,29 responses to this question were dichotomized, with participants re porting fair and poor health categorized as at risk. Outcome Variables physical activity-related injury in the previous 6 months, and medical care seeking for any physical activity-relat ed injury. Physical Fitness. Participants reported raw data scores from their most recent Army Physical Fitness Test (APFT, number of push-ups, number of sit-ups, and run time in minutes and seconds), which were converted to a 22 Physical Injury Reporting and Medical Care Seeking Be haviors Participants indicated whether they had experi enced a physical activity-related injury over the past 6 months. Examples of physical activity-related injuries included joint sprains, muscle or tendon strains, con cussion, broken bone, shin splints, heat stroke, and/or exertional rhyabdomyolysis. Participants reporting a physical activity-related injury were then asked whether or not they sought medical care for the reported injury. Statistical Analyses were compared using Pearson 2 analyses. Pearson 2 analyses were also used to test univariate relations be tween health/behavioral risk factor categories, includ ing service component, and outcome measures. Among those participants who sustained a physical activityrelated injury, 2 analyses were conducted to determine service-component differences in seeking medical care for that injury (eg, do injured AD seek medical care for analyses, measures of effect size include Cramrs v (suit able for ordinal or dichotomous variable analyses, 39 such that a small effect=0.1, moderate=0.3, and large 0.5) or Cohens d (for continuous variables, notably age, such that small effect=0.2, moderate=0.5, and large 0.8). 40 Multivariate logistic regression analyses with back wards-stepwise methodology were used to determine predictive health and behavioral risk factors for the fol lowing outcomes: (1) APFT pass/fail, (2) physical injury, and (3) seeking medical care for a physical injury. First, demographic variables (age, service component, and risk factors were individually selected using backwards stepwise entry, with a P value for the likelihood ratio set at 0.1. Interactions between Army service component gression analysis were tested. All analyses were conduct RESULTS Table 1 presents descriptive statistics for all participants by service component. Pearson 2 analyses revealed sev ables. Active duty participants had higher rates of most health and behavioral risk factors. Active duty partici pants were 1.3 (95% CI, 1.05-1.55; P<. 05) times more (95% CI, 1.04-1.72, P<. 05) and 1.4 (95% CI, 1.09-1.83; P<. P<. 05) P<. 001) and 1.5 (95% CI, 1.13-1.99; P<. 01) times more likely to 2 =87.7, v =0.25, P<. pants being 4.3 (95% CI, 3.04, 6.14; P<. participants 4.0 (95% CI, 2.81-5.71; P<. 001) times more likely to fail APFT compared to AD women. Active duty women also reported higher physical injury rates 2 =84.0, v =0.19, P<. 001), such that AD women were 2.6 (95% CI, 2.04-3.28; P<.
42 http://www.cs.amedd.army.mil/amedd_journal.aspx 2.1 (95% CI, 1.70-2.69; P<. 001) times more likely than months. Among those with reported physical activityrelated injuries (n=624), 80% of AD sought medical 2 =8.4, v =0.12, P<. 05); the difference between AD Outcome Variables: Univariate and Multivariate Analyses APFT Failure. Table 2 presents univariate and multivariate anal yses with APFT pass/fail as the outcome variable. On the left of Table 2, participant characteris tics are presented for those who passed versus those who failed their APFT; multivariate regres sion results are depicted on the right. Univariate analyses re ations between predictor and out come variables, the majority of which were retained in the mul Soldiers who were younger, en poor diet, and self-reported fair/ poor overall health were more likely to fail the APFT. Physical Injury Table 3 presents univariate and multivariate anal yses with physical injury as the outcome variable. On the left of Table 3, participant characteris tics are presented for those who reported a physical injury versus those who did not report a physi cal injury. Women with high BMI and self-reported fair/poor overall health and binge drinking were more likely to report expe riencing a physical injury in the previous 6 months. Medical Care Seeking Behavior for Physical Injury Table 4 pres ents univariate and multivariate analyses with seeking medical care for a physical injury as the outcome variable. On the left of Table 4, participant characteris tics are presented for those who sought medical care for a physical injury versus those sults similar to physical injury were noted, with the ex ception that BMI was not retained in the medical care model. havioral risk factors and multivariate outcomes were noted. PHYSICAL FITNESS AND INJURY REPORTING AMONG ACTIVE DUTY AND NATIONAL GUARD/RESERVE WOMEN: ASSOCIATIONS WITH RISK AND LIFESTYLE FACTORS Table 1 Participant Characteristics and Service Group Differences. All Women ( N= 2,305 ) Active Duty (n= 1,014 ) National Guard (n= 645 ) Reserve (n= 646 ) Effect Size Age (years) 26.48.13 26.77.64 a 25.27.65 a,b 27.39.16 b 0.01 Height (m) 1.630.08 1.630.08 1.630.08 1.620.09 Weight (kg) 66.410.63 66.29.84 66.511.10 66.811.41 BMI (kg/m 2 ) (n= 1,758 ) High ( >27.5 ) 22% 20% (30.73.4) 24% (30.73.2) 23% (31.43.6) 0.05 Normal ( 18.5-27.5 ) 78% 80% (23.62.1) 76% (23.32.3) 77% (23.62.3) Value 25.23.9 25.03.7 25.04.1 25.34.3 Military Status Officer 15% 19% a 9% a 13% a 0.12 Enlisted 85% 81% 91% 87% Health Fair/Poor 21% 24% a 19% a 20% 0.06 Good/Excellent 79% 76% 81% 80% Sleep (n= 2,058 ) Poor sleep 15% 18% a,b 13% a 13% b 0.07 Good sleep 85% 82% 87% 87% Diet Unhealthy 27% 29% a 23% a 27% 0.05 Healthy 73% 71% 77% 73% Tobacco Use Smoker 16% 16% 18% 15% 0.03 Nonsmoker 84% 84% 82% 85% Alcohol Use Binged 12% 10% a 16% a,b 11% b 0.08 Did not binge 88% 90% 84% 89% APFT (n= 1,431 ) Fail 18% 8% a,b 27% a 28% b 0.25 Pass 82% 92% 73% 72% Physical Injury (n= 2,219 ) Injured 28% 38% a,b 19% a 22% b 0.19 Not injured 72% 62% 81% 78% Care for Injury (n= 2,076 ) Sought care 25% 34% a,b 17% a 18% b 0.19 Did not seek care 75% 66% 83% 82% NOTE: For pairwise comparisons, values within a row sharing a common superscript (a or b) are significantly different from each other at P <.05. Omnibus effect size with 2 was used for continuous variables, while Cramers v was used for all other ordinal variables. P <.05 P <.001
April June 2015 43 CO MM ENT Female service members comprise approximately 13% of the US Armed Forces, 9 but are much more likely than men to suffer from MSK-I, even when exercising under the same conditions. 3-7,10-12 Previous studies have identi physical injury in female service members, 3,6,12,41 but few female Soldiers. As combat roles across service compo is of prime concern. 1,2 One study comparing ployment found that they had similar levels 21 Soldiers appeared to seek more medical care and suffer from MSK-I more than AD. 11 studies had previously examined these dif ferences outside of the deployment cycle. Our results demonstrate differences in physical across service components among women. high BMI, poor diet, and overall poor health ure. However, despite these lower levels of were less likely to suffer from physical injury in the previous 6 months than AD females. tial factors related to self-reported perceived health and physical injury. 23 A study by Warr et al 23 ness (VO 2 max perceived health changes over the deploy ness. It is important to note that our results indicate that female Soldiers with high BMI and poor health were more likely to fail their required to train with their unit once a month, but outside of this, they are expected to main Whereas Army guidelines related to physical Field Manual 7-22 to use this manual when daily physical train ing is not commonplace. For other health and behavioral risk factors, AD females were more likely to report fair/poor health, poor sleep, females. Having healthy food patterns should improve overall health and wellness, and be one approach for physical injury prevention. 1 in AD females is worrisome, as healthy dietary patterns can counteract glycogen depletion, restore energy bal ance, mitigate fatigue, and minimize muscle damage. 1 In the present study, AD females were more likely to Table 2. Univariate and Multivariate Predictors of APFT Failure. Univariate ( N= 1,431 ) Backwards Stepwise a ( N= 1,174 ) Failed APFT (n= 259 ) Passed APFT (n= 1,172 ) Effect Size b Adjusted OR (95% CI) Age (years) 22.95.50 26.87.86 0.20 c 0.9 (0.89, 0.94) c Army Status Active Duty 8% 92% 0.25 c National Guard 27% 73% 3.7 (2.50, 5.57) c Reserve 28% 72% 4.9 (3.27, 7.43) c Military Status Officer 6% 94% 0.14 c 1.8 (0.95, 3.29) Enlisted 20% 80% BMI (kg/m 2 ) (n= 1,174 ) High ( >27.5 ) 26% 74% 0.12 c 2.2 (1.53, 3.21) c Normal ( 18.5-27.5 ) 15% 85% Health Fair/Poor 24% 76% 0.08 d 1.6 (1.12, 2.40) d Good/Excellent 17% 83% Sleep (n= 1,267 ) Poor sleep 20% 80% 0.01 Good sleep 18% 82% Diet Unhealthy 22% 78% 0.06 d 1.6 (1.10, 2.25) d Healthy 17% 83% Tobacco Use Smoker 23% 77% 0.06 d Nonsmoker 17% 83% Alcohol Use Binged 20% 80% 0.02 Did not binge 18% 82% Physical Injury (n= 1,387 ) Injured 15% 85% 0.04 Not injured 19% 81% Care for Injury (n= 1,296 ) Sought care 17% 83% 0.02 Did not seek care 18% 82% a Multiple backwards stepwise regression conducted, with demographic variables (age, Army status, military status) force-entered and significant health risks then entered stepwise. b For effect size, Cohens d was used for continuous variables (age), while Cramers v was used for all other ordinal variables. c P <. 001 d P <. 05
44 http://www.cs.amedd.army.mil/amedd_journal.aspx months, and unhealthy diet, along with poor sleep and overall health, may be contributing factors. In addition to AD status, predictive factors for physical injury in our study included high BMI, poor overall health, and binge drinking behav iors, which correspond to previously established risk factors in similar populations. 3,10,42 Previ ous research has linked low BMI to MSK-I risk among women. 6 In the present study, the number of women with low BMI was too small to deter mine its effect on any of study outcomes. Smok ing behavior, which has previously been strongly linked to physical injury, 7,43 had a weak effect on sis. However, female Soldiers tend to use tobacco products less than male Soldiers, which may ac 16 Of the 624 females who reported a physical in jury in the previous six months, AD were slight ly more likely to seek medical care (80%) than medical care, or both. The lower rate of seeking deployment appear to be a particularly strong risk factor for noncombat physical injury. In were twice as likely to use medical resources for noncombat physical injuries than those who ex 23 Our study has several limitations. First, selfreport data are not always consistent with mea sured values, although the data are mixed. 44,45 patterns, health, and wellness, all of which have been previously validated. Second, the military occupation al specialties (MOSs) of women in this cohort are not known. Particular MOSs may vary greatly in their phys ical and mental demands, and therefore exhibit diverse health and behavioral outcomes. Third, it is unclear as to whether these women had deployed in the previous 6 months, and thus we cannot ascertain how deployment may have affected the service component differences for physical injuries, both of which could provide more each service component. Despite these limitations, the tential risk factors in a large population of female Sol diers. This is important for targeting risk factors. members. In particular, we simultaneously examined ness, and health and behavioral risk factors using the PHYSICAL FITNESS AND INJURY REPORTING AMONG ACTIVE DUTY AND NATIONAL GUARD/RESERVE WOMEN: ASSOCIATIONS WITH RISK AND LIFESTYLE FACTORS Table 3. Univariate and Multivariate Predictors of Reported Physical Injury. Univariate ( N= 2,219 ) Backwards Stepwise a ( N= 1,174 ) Sought Care (n= 624 ) Did Not Seek Care (n= 1,595 ) Effect Size b Adjusted OR (95% CI) Age (years) 27.1.20 26.3.13 0.05 c 1.0 (0.99, 1.02) Army Status Active Duty (ref) 22% 78% 0.19 d National Guard 18% 81% 0.3 (0.26, 0.46) d Reserve 22% 78% 0.5 (0.35, 0.61) d Military Status Officer 26% 74% 0.02 1.3 (0.95, 1.88) Enlisted 29% 71% BMI (kg/m 2 ) (n= 1,699 ) High ( >27.5 ) 37% 63% 0.09 d 1.4 (1.10, 1.90) d Normal ( 18.5-27.5 ) 27% 73% Health Fair/Poor 43% 57% 0.18 d 2.4 (1.83, 3.09) d Good/Excellent 24% 76% Sleep (n= 1,980 ) Poor sleep 44% 56% 0.13 d Good sleep 27% 73% Diet Unhealthy 32% 68% 0.05 c Healthy 27% 73% Tobacco Use Smoker 33% 67% 0.05 c Nonsmoker 27% 73% Alcohol Use Binged 39% 61% 0.09 d 1.6 (1.14, 2.17) d Did not binge 27% 73% APFT (n= 1,387 ) Fail 26% 74% 0.04 Pass 31% 69% a Multiple backwards stepwise regression conducted, with demographic variables (age, Army status, military status) force-entered and significant health risks then entered stepwise. b For effect size, Cohens d was used for continuous variables (age), while Cramers v was used for all other ordinal variables. c P <. 05 d P <. 001
April June 2015 45 assess the overall health of service members. As wom their performance during combat training may be de termined by various risk factors. Our results show that service component is a key factor to consider as women (APFT pass rates), while women with high BMI and self-reported poor health are at greater risk for physical injury. These data lend credence towards the develop mization strategies for women as their roles in the mili tary expand. REFERENCES 1. Physiological employment standards IV: inte gration of women in combat units physiological and medical considerations. Eur J Appl Physiol 2013;113(11):2673-2690. 2. performance of females as light infantry sol diers. BioMed Res Int 2014;Epub August 18, 2014. 3. and exercise-related injuries among young men and women. Am J Prev Med 2000;18(suppl 3):96-102. 4. Bijur PE, Horodyski M, Egerton W, Kurzon M, Lifrak S, Friedman S. Comparison of injury during cadet basic training by gender. Arch Pe diatr Adolesc Med 1997;151(5):456-461. 5. Injuries and illnesses among armor brigade soldiers during operational training. Mil Med 2006;171(11):1051-1056. 6. Ely M, Jones BH. Stress fracture risk factors in basic combat training. Int J Sports Med 2012;33(11):940-946. 7. Knapik JJ, Sharp MA, Canham-Chervak M, training-related injuries among men and wom en in basic combat training. Med Sci Sports Ex erc 2001;33(6):946-954. 8. juries in infantry soldiers. Am J Prev Med 1994;10(3):145-150. 9. Women in Ground Close Combat Roles: The Experiences of other Nations and a Review of the Academic Lit erature. Porton Down, Salisbury, Wiltshire, UK: Defence Science and Technology Laboratory; 2009. 10. reported training-related injury before arrival at the US Army Ordnance School. Public Health 2010;124(7):417-423. 11. soldiers at a forward deployed medical facility in Iraq. Mil Med 2009;174(11):1167-1171. Table 4. Univariate and Multivariate Predictors of Seeking Medical Care. Univariate ( N= 2,076 ) Backwards Stepwise a ( N= 1,174 ) Sought Care (n= 509 ) Did Not Seek Care (n= 1,567 ) Effect Size b Adjusted OR (95% CI) Age (years) 26.98.27 26.48.20 0.03 1.0 (1.00, 1.02) Army Status Active Duty 34% 66% 0.19 c National Guard 17% 87% 0.4 (0.26, 0.51) c Reserve 18% 82% 0.4 (0.31, 0.54) c Military Status Officer 20% 80% 0.04 d 1.3 (0.95, 1.88) Enlisted 25% 75% BMI (kg/m 2 ) (n= 1,591 ) High ( >27.5 ) 34% 66% 0.11 c Normal ( 18.5-27.5 ) 22% 78% Health Fair/Poor 36% 64% 0.14 c 1.8 (1.41, 2.29) c Good/Excellent 21% 79% Sleep (n= 1,864 ) Poor sleep 35% 65% 0.10 c Good sleep 23% 77% Diet Unhealthy 27% 73% 0.03 Healthy 24% 76% Tobacco Use Smoker 29% 71% 0.04 d Nonsmoker 24% 76% Alcohol Use Binged 32% 68% 0.07 c 1.6 (1.18, 2.16) c Did not binge 23% 77% APFT (n= 1,296 ) Fail 24% 76% 0.02 Pass 26% 74% a Multiple backwards stepwise regression conducted, with demographic variables (age, Army status, military status) force-entered and significant health risks then entered stepwise. b For effect size, Cohens d was used for continuous variables (age), while Cramers v was used for all other ordinal variables. c P <. 001 d P <. 05
46 http://www.cs.amedd.army.mil/amedd_journal.aspx 12. tors among men and women in US Army Combat Medic Advanced individual training. Mil Med 2000;165(9):647-652. 13. Musculoskeletal Inju ries in Military Women. Fort Sam Houston, TX: The Borden Institute; 2011. Available at: http:// www.cs.amedd.army.mil/borden/FileDownload public.aspx?docid=b42d1acd-0b32-4d26-8e224a518be998f7. Accessed February 11, 2015. 14. vak M, Canada S. Musculoskeletal injuries descrip tion of an under-recognized injury problem among military personnel. Am J Prev Med 2010;38(suppl 1):S61-S70. 15. Jones BH, Knapik JJ. Physical training and exer cise-related injuries. Surveillance, research and injury prevention in military populations. Sports Med 1999;27(2):111-125. 16. 2008 Department of Defense Survey of Health Related Behaviors Among Active Duty Military Person nel tional; 2009. Available at: http://www.tricare.mil/ tma/2008healthbehaviors.pdf. Accessed February 11, 2015. 17. building, energy, and weight-loss supplements are associated with deployment and physical ac tivity in US military personnel. Ann Epidemiol. 2012;22(5):318-330. 18. Lentino CV, Purvis DL, Murphy KJ, Deuster PA. Sleep as a component of the performance triad: the importance of sleep in a military population. US Army Med Dep J October-December 2013:98-108. 19. Finestone A, Milgrom C. How stress fracture in cidence was lowered in the Israeli army: a 25-yr struggle. Med Sci Sports Exerc 2008;40(suppl 11):S623-S629. 20. States. At a glance. National Guard Magazine. 2012;66(4):52-82. 21. Warr BJ, Alvar BA, Dodd DJ, et al. How do they J Strength Cond Res 2011;25(11):2955-2962. 22. Field Manual 7-22: Army Physical Readiness Training. Washington, DC: US Department of the Army; 2012. 23. Warr BJ, Heumann KJ, Dodd DJ, Swan PD, Alvar Mil Med 2012;177(10):1136-1142. 24. soldiers. J Strength Cond Res 2013;27(2):315-322. 25. the U.S. Army Comprehensive Soldier Fitness pro Am Psychol 2011;66(1):10-18. 26. a challenging institutional context. Am Psychol 2011;66(1):4-9. 27. Seligman ME. Building resilience. Harv Bus Rev 2011;89(4):100-106. 28. Army Regulation 600-9: The Army Body Compo sition Program .Washington, DC: US Dept of the Army; 2013. 29. Purvis DL, Lentino CV, Jackson TK, Murphy performance triad: how healthy eating behaviors contribute to soldier performance and military readiness. US Army Med Dep J October-December 2013:66-78. 30. ment of the Healthy Eating Index-2005 J Am Diet Assoc 2008;108(11):1896-1901. 31. Moul DE, Mai E, Shablesky M, et al. The 2-item and 20-item versions of the Pittsburgh Insomnia modeling. Paper presented at: Annual Meeting of the World Psychiatric Association; 2009; Mel bourne, Australia. 32. Moul DE, Pilkonis PA, Miewald JM, Carey TJ, Buysse DJ. Preliminary study of the test-retest reliability and concurrent validities of the Pitts Sleep 2002;25:A246-A247. 33. Canagasaby A, Vinson DC. Screening for haz ardous or harmful drinking using one or two quantity-frequency questions. Alcohol Alcohol. 2005;40(3):208-213. 34. Cella D. Development of physical and mental health summary scores from the patient-reported out IS) global items. Qual Life Res 2009;18(7):873-880. 35. Does health status matter for the risk of injury? N Z Med J 2010;123(1327):35-46. 36. Mattila VM, Jormanainen V, Sahi T, Pihlajam ki H. An association between socioeconomic, health and health behavioural indicators and fractures in young adult males. Osteoporos Int 2007;18(12):1609-1615. PHYSICAL FITNESS AND INJURY REPORTING AMONG ACTIVE DUTY AND NATIONAL GUARD/RESERVE WOMEN: ASSOCIATIONS WITH RISK AND LIFESTYLE FACTORS
April June 2015 47 37. health status of students in-processing into mili tary medical advanced individual training. Work 2009;34(4):387-400. 38. P. Mortality prediction with a single general selfrated health question. A meta-analysis. J Gen In tern Med 2006;21(3):267-275. 39. McHugh ML. The chi-square test of independence. Biochem Med 2013;23(2):143-149. 40. Cohen J. Statistical Power Analysis for the Behav ioral Sciences Erlbaum Associates; 1988. 41. Army personnel. Mil Med 2005;170(12):1005-1011. 42. use injuries in female athletes. Croat Med J 2007;48(6):767-778. 43. duction effectiveness of selecting running shoes based on plantar shape. J Strength Cond Res 2009;23(3):685-697. 44. white race, gender, and health literacy subgroups. Am J Health Promot 2014 [March 26 Epub ahead of print]. 45. Lassale C, Peneau S, Touvier M, et al. Validity of web-based self-reported weight and height: results J Med Internet Res 2013;15(8):e152. AUTHORS Mr Kazman, Dr de la Motte, Ms Bramhall, Dr Purvis, and Dr Deuster are with the Consortium for Health and Military Performance, Department of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland.
48 http://www.cs.amedd.army.mil/amedd_journal.aspx As women enter into previously closed military occupa tional specialties, 1 they are likely to be exposed more to challenging and extreme conditions. For example, exer cise in extreme environments could increase their risk for exertional heat illness (EHI) 2 and exertional heat stroke (EHS), the most extreme type of EHI and a fa 3-6 athletes, 7-9 and others who engage in physically demanding jobs. 10 EHS occurs dur ing physical exertion, typically in a hot and humid en vironment, and is characterized by a rise in core body temperature (usually 40C or more), accompanied by central nervous system dysfunction (eg, delirium, con vulsions, coma) and sometimes multiple organ system failure. 11 erational resources, 3,5 in most cases it is preventable, given our understanding of predisposing risk factors and proper implementation of safeguards. 5,12-15 Key risk factors include dehydration, lack of acclimatization, re cent illness, 16,17 certain classes of medication, 18 and prior Women and Exertional Heat Illness: Identification of Gender Specific Risk Factors Josh B. Kazman, MS Danit Atias, PhD Dianna L. Purvis, PhD Stephanie Van Arsdale, MS Yuval Heled, PhD Patricia A. Deuster, PhD, MPH Peter Lisman, PhD ABSTR A CT Objective: With the expanding role of women into previously closed combat military occupational specialties, women will likely be exposed more to challenging and extreme conditions. Physical work or exercise in ex treme environments could increase the risk for exertional heat illness (EHI) and exertional heat stroke (EHS), the most severe type of EHI. Although men have higher rates of EHS than women, women have slightly higher rates of other EHI. Women may respond differently to exertion in the heat than men, as they typically have higher percentage of body fat (BF%) and lower aerobic power. Further, published pilot-data using the Israeli and sex. Methods: ties to participate in a standardized HTT. Subjects underwent measures to calculate anthropometric variables (BF%, body surface area, and waist circumference), a maximal oxygen uptake test to assess aerobic power (VO 2 max ), and a standardized HTT, which consisted of treadmill walking at 5 km/h at a 2% grade for 120 min greater than 150 bpm or a core body temperature (T c ) more than 38.5C. Separate hierarchical regressions were conducted using categorical (heat tolerant/intolerant) and continuous (physiological strain index, maximum c Results: Women were 3.7 (95% CI, 1.21-11.24) times more likely to be heat intolerant than men ( 2 =6.85, P <.01). VO 2 max All heat intolerant participants had lower VO 2 max heat tolerant. When VO 2 max and BF% were entered into regression equations to predict HTT outcomes, sex be 2 max Conclusion: are largely explained by VO 2 max The higher rates of heat intolerance among women likely correlate with higher EHI risk, and underscore the need to understand the physiological and thermoregulatory differences between men and women. As lower aerobic power is a major risk factor for EHI, maximizing the aerobic power of women will be critical to force health protection and readiness as they integrate into combat military oc cupational specialties.
April June 2015 49 EHS. 3,13,14,16,17,19 Additionally, poor aerobic power and high percentage of body fat, two of the strongest risk factors for EHI in the military, 20-22 may be of particular concern for women. Since men in combat military training typically engage in more physically demanding activities under many en vironmental conditions than women, the prevalence of EHS is higher in men than women. 3,4,23,24 In 2013, 324 cases of EHS and 1,701 additional EHI were reported in the US armed forces, which represented a decline in EHI over the previous few years. 3 The incidence rate of EHS was higher among men (0.24 per 1,000 personyears) than women (0.15). However, for all other EHI, women had a higher rate (1.30) than men (1.19). Thus, when baseline rates are corrected for gender participa tion, women have a slightly higher incidence of EHI (not EHS) than men, both in the military 3,4,25 and in the gen eral population. 23,24 Although men and women thermoregulate internal tem perature in a similar manner, key sex differences exist in how they respond to heat. 26,27 Most notably, women have a higher baseline core temperature, 28,29 especially during the luteal phase of the menstrual cycle. 30,31 Thus, women begin to sweat at a higher core temperature than men. 32 Women typically have a lower body surface area, but a higher body surface area-to-mass ratio than men, tion in certain environments (eg, very humid weather). 33 Taken together, these differences may place women at a slight advantage in hot and humid climates, and a slight disadvantage in hot and dry climates, relative to men. 32,33 However, the net effect of these sex differences on EHI risk is generally considered to be negligible, es pecially in comparison to larger differences in aerobic power and anthropometrics, particularly percentage of body fat. 26,30,31 One approach to assessing the capacity to thermoregu late is to expose individuals to a designated heat chal lenge during exercise, and the Israeli heat tolerance test (HTT) is one valuable tool for use in the laboratory. The HTT, designed over decades of iterative studies, is used as a clinical test to guide return to duty decisions for suffered an EHS event. 5,34 Between 2008 and 2010, 26% of men and 67% of women in the IDF who had been di agnosed with EHS (or EHS was suspected) were classi 35 which suggests sex differences. Importantly, the HTT was originally developed using our military, and particularly as women enter combat military occupational specialties, it will be necessary to know how they respond to the HTT, with and without a prior EHI. Additionally, the IDF did not have data on either aerobic power or body composition, 35 which could be key in assessing risk of EHI. 20-22,36 Thus, the purposes of the present study were to examine the responses of men and women to the HTT and to compare their clas power and body composition to help explain any sex dif ferences observed with the HTT. METHODS Subjects ed from military and university communities to partici pate in a standardized HTT. Inclusion criteria included: and (9) not presently being treated for any mental health disorder. Participants included those with and without a history of EHI. Participants who had a previous clini cally documented EHS (n=20, of which 19 were male) were tested 6 weeks or more after their EHS. Each par ticipant underwent a thorough telephone health screen and on-site medical examination to ensure that inclu sion criteria were met. All participants were informed of written consent prior to participation. Approval was ob tained from the Uniformed Services University Institu a subset of a larger study. Baseline Screening and Anthropometric Testing Participants underwent a medical examination, several anthropometric evaluations (body mass, height, waist circumference, and percentage of body fat), and a maxi mal aerobic graded exercise test to assess aerobic power. After completion of a medical history and other ques WI) and electrocardiographic activity (Philips Stress Vue Testing System with Trackmaster Full Vision Inc. Treadmill, Waltham, MA) were obtained at rest. Partici pant body mass was measured with a calibrated metric scale to the nearest 0.1 kg, and height was measured to the nearest 0.1 cm while the participant was wear ing light clothing and no shoes. Body mass index was calculated from height and mass, and waist circumfer ence was determined with a tape measure by standard
50 http://www.cs.amedd.army.mil/amedd_journal.aspx techniques. 37 Body surface area and surface-to-mass ra tio were calculated by standard methods. 38 Percentage of body fat was determined using 2 tech niques: skinfold measurements and bioelectrical imped ance analysis (BIA). Skinfolds were used to allow com parison with previous analyses from the present study 36 and similar research. 39,40 The BIA was used due to con cern about reliability/validity of skinfold measurements, especially for sex comparisons. Skinfold thickness was Industries Inc, Cambridge, MD) at 4 sites (biceps, tri ceps, subscapular, and suprailiac) on the right side of the body and BF% was computed by using the Durnin and Womersley calculation. 41 In order to combine data from a previous pilot study, 36 3 skinfold sites were used for 36% of participants based on ACSM guidelines, 37 using chest, triceps, and subscapular for men, and tri ceps, abdomen, and suprailiac for women. The BIA was ton Township, Michigan), with participants lying down, arms at a 30 angle from body, and legs not touching. Based on recent research comparing BIA equations to estimate BF% among a military sample, 42 equations published by Segal et al 43 were selected (using the equa tions generalized across body fat levels). The correlation between the skinfold and BIA-derived BF% values was 0.76 ( P <.001). During the second visit, subjects underwent a standard ized HTT, which consisted of walking on a treadmill for 2 hours in an environmental chamber as described below. Determination of VO 2 max The VO 2 max was determined by a maximal aerobic graded exercise test on a motorized treadmill through indirect calorimetry. Expired respiratory gases were collected continuously and analyzed by open-circuit spirometry (Oxycon Mobile portable system, Viasys Healthcare Inc, Yorba Linda, CA). The test used in this study, adapted from a protocol previously described by our laboratory, 44 consisted of a 5-minute warm-up (5.0 km/h and a 2.0% grade) followed by a running por achieved during warm-up), with incline starting at 0% and increasing 2.5% every 2 minutes, until the subject could no longer continue or VO 2 plateaued with an in crease in workload. Heat Tolerance Testing All HTTs were conducted in the morning with partici shirt, but women wore a sports bra. The HTT consisted of walking on a treadmill at 5.0 km/hr at a 2% grade for 2 hours at 40C and 40% relative humidity. Wom en were tested between days 3 and 9 of their follicu lar phase. To ensure adequate hydration before testing, or more, the participant was provided water to hydrate until it was less than 1.02. Participants were instruct ed to void their bladder, and then nude body mass was measured. From this point on, all urine was collected in a 3.0 L polypropylene collection container. During the HTT, participants were permitted to hydrate with water ad libitum (up to one L/hr). Core temperature (T c ) was measured by using a rectal thermometer inserted 10 cm sured with skin sensors placed at 4 different sites (shoul der, chest, thigh, and calf). The T c was measured using either a thermistor-based system (64% of participants) (MEAS Temperature Probes (Measurement Special ties Inc, Dayton, OH) with Sensor Interface Box Model thermocouple system for more recent participants (Type T Thermocouples with Thermes WiFi, Physitemp, Clif (Polar Team 2 Pro, Polar USA Inc, Lake Success, NY). c and skin temperatures were continuously c as suggested by Moran et al. 45 Physiological strain index values range from 0-10, and (3-4), moderate (5-6), high (7-8), and very high (9-10) strain. Sweat rate was estimated based on the difference in nude body mass before and after the test corrected ducted in the summer (49%), followed by the fall (24%), spring (20%), and winter (7%). Baseline and maximum c did not differ by season. The HTT was discontinued if any participant met one of the following criteria: (1) T c c above 150 bpm, or failure to plateau, 5,34 with the latter c of greater than 0.45C during the second hour of the HTT. 46 Data Analyses Sample characteristics are provided for men and wom en in Table 1, with independent-samples t tests used to identify differences between men and women, and heat d is used WOMEN AND EXERTIONAL HEAT ILLNESS: IDENTIFICATION OF GENDER SPECIFIC RISK FACTORS
April June 2015 51 Logistic regression models were developed to predict HTT performance. For the regression models, sex was entered into a second one. The primary HTT outcome c a more granular assessment of heat tolerance, logistic regressions were also conducted to predict elevated T c Linear regression models were developed to predict con tinuous HTT outcomes. These additional models, even though similar to those above, were run because cutoffs for heat tolerance are being debated 47 and dichotomi zation reduces statistical power, especially with small sample sizes. Continuous HTT outcomes included max c RESULTS Demographic, anthropometric, and aerobic power char acteristics are presented in Table 1. As expected, women had lower VO 2 max body surface area, waist circumfer ence, and body mass index and higher body surface area-to-mass ratio and BF% compared to men. Women 2 =6.85, P <.01, d= 0.63), such that 45% of women (9 out of 20) were in tolerant, compared to 18% of men (10 out of 55). Sex dif ferences in other HTT outcomes are presented in Table 2 and graphically in Figures 1 and 2. During the HTT, ( t 73 =2.27, P <.01, d= between maximum T c cance ( t 73 =0.71, P Heat intolerant participants (34% of sample) had lower VO 2 max ( t 73 =2.28, P <.05, d =0.60) and higher BF% than heat tolerant ones, shown in Table 3. However, group dif fold BF% ( t 73 =2.30, P <.05, d =0.57), but not for BIA BF% ( t 73 =1.51, P=. 15). Because VO 2 max and BF% were strongly correlated (skinfold: r r= P <.001), they were assessed in separate regression mod els to predict HTT outcomes. For each regression, sex ther VO 2 max (Block 2A), skinfold BF% (Block 2B), or BIA BF% (Block 2C). In the logistic regression models (Table 4, column 1), sex initially predicted heat tolerance, however its effect 2 max and BF% were en tered into the model. In the linear regression models, sex for VO 2 max max (assessed dichoto mously and continuously) and maximal physiological VO 2 max =-0.48 vs sex=0.14 and physiological strain in dex: VO 2 max =-0.34 vs sex=0.03). On the other hand, skinfold BF% only exceeded sex in relation to maxi did not hold for BIA BF% (sex=0.15 vs BIA BF%=0.03). CO MM ENT as heat intolerant to a greater extent than men, VO 2 max appears to account for most, if not all, of this sex dif ference. When heat tolerance was broken down into 2 c c Thus, cardiovascular strain is far more important than thermal strain. This Table 2 Physiological Measurements (meanSD) During HTT by Sex. Variable Women Men All (n= 20 ) (n= 55 ) (n= 75 ) Core Temperature, T c ( C) Baseline T c 37.10.4 36.90.4 37.00.4 Max T c 38.10.4 38.10.4 38.10.4 c (over min 60-120 ) 0.260.19 0.280.11 0.270.18 Heart rate, HR (bpm) Baseline HR 7615.0 6812.1 7013.3 Max HR 13720.1 12220.2 12621.1 (over min 60-120 ) 7.57.2 4.68.2 5.38.0 Physiological strain index 5.21.4 4.71.3 5.38.0 Sweat rate (L/h) 0.810.28 1.100.31 1.030.33 P <. 05 P <. 01 Table 1 Participant Characteristics (meanSD) by Sex. Variable Women Men All (n=20) (n=55) (n=75) Age (yrs) 28.65.2 28.76.3 28.76.0 Height (cm) 163.85.5 178.36.6* 174.49.0 Weight (kg) 63.87.5 84.311.2* 78.813.8 BMI (kg/m 2 ) 23.82.5 26.53.0* 25.83.1 Body surface area (m 2 ) 1.690.11 2.020.16* 1.930.21 Body surface/mass (m 2 kg 1 10 2 ) 2.670.16 2.410.18* 2.480.21 Skinfold BF% 28.45.1 18.75.1* 21.36.7 BIA BF% 30.121.6 21.65.1* 23.86.2 Waist circumference (cm) 72.44.8 84.67.0* 81.48.5 VO 2 max (ml kg 1 min 1 ) 45.36.8 52.37.4* 50.57.8 BIA=bioelectrical impedance analysis P <.05
52 http://www.cs.amedd.army.mil/amedd_journal.aspx military setting by participating in an HTT. 5 As women are integrated into combat military oc al and physical injuries must be determined to quirements, 2 as combat exposures will be gen der neutral. The present study results suggest that when standard risk factors are controlled for, particularly aerobic power, women do not appear to be at greater risk for EHI than men. Aerobic power and BF% serve key roles in ther moregulation, 48 risk for EHI, 14,19-21 and military performance. 49 Importantly, poor aerobic pow er and high BF% are the 2 most studied risk factors for EHI. 20-22 Even though aerobic power and body fat are strongly negatively correlated, they may both directly relate to EHI risk. 21,22 Individuals with poor aerobic power need to work at a higher relative intensity for a given workload than individuals with high aerobic power. This increases their relative physiologi cal strain, which, in turn, decreases peripheral creases heat absorption. 14,50 Higher body fat also increases metabolic heat and hinders heat dissipation. 7,14 Since aerobic power and BF% also differ by sex, it is important to clarify their independent contributions to thermoregulation, into combat roles. In fact, proposed algorithms to stratify EHI risk typically include aerobic power and percentage of body fat. 22,51 These algorithms are useful screening tools for warf ighters and athletes. But a full HTT is often warranted among EHS patients, 5 particularly when gradual return to physical activity may be problematic. 19,52 Laboratory exercise studies have consistently demon strated that sex differences in thermoregulation in the heat become minimal after controlling for aerobic power and body fat. 32,39,40,53,54 Other demographic differences in heat thermoregulation, such as age, may be explained by these factors as well. 55,56 Nevertheless, previous studies have used relatively small sample sizes and varied proto in exercise type (eg, walking, cycling), acclimatization procedures, and test conditions, depending on the par that women are not at a thermoregulatory disadvantage compared to men when matched for body composition and when performing tasks appropriate for their aerobic sition standards are often relative to sex, and in some military occupational specialties, physically demanding tainly in the deployed setting, task assignment cannot be based on gender. 2 is an indi tasks and be able to accomplish all aspects of a combat mission, while staying healthy and uninjured. Combat Core Temperature (C) Time (minutes) 120 100 80 60 40 20 0 38.0 38.5 39.0 37.0 37.5 36.0 36.5 Women (n= 20 ) Men (n= 55 ) Figure 1 Mean core body temperature response to the heat tolerance test displayed by sex. Women (n= 20 ) Men (n= 55 ) Time (minutes) Heart Rate (BPM) 120 130 140 100 110 80 90 120 100 80 60 40 20 0 Figure 2 Mean heart rate response to the heat tolerance test displayed by sex. WOMEN AND EXERTIONAL HEAT ILLNESS: IDENTIFICATION OF GENDER SPECIFIC RISK FACTORS
April June 2015 53 (cardiovascular endurance, muscular strength, and eye coordination, agility, speed, and power) and partially address these questions, each service and operational specialty is reevaluating occupational the same time maximizing successful outcomes, regardless of whether the service member is male or female. Thermoregulatory differences between men and women can likely be attributed to physical char acteristics rather than other inherent metabolic/ regulatory differences. 2 Given that women are at higher risk for EHI, efforts should focus on improving intrinsic matched for age, men have greater lean body mass and less fat mass compared to women. 57 A smaller body mass and higher BF% will increase T c 58 Additionally, when compared to men, women have lower relative and absolute aerobic power, which may contribute to earlier fatigue compared to men. 2 Clearly, sex differences in performance variables, such as muscle mass and VO 2 max tance training programs for women can improve physi cal performance through increases in strength, power, and endurance. 59 The challenge of operating in hot environments is compounded by the use of protective gear and body armor, which inhibit sweat evaporation and heat dissipation, and increase thermoregulatory and cardiovascular strain. Although performance require ment criteria may become gender-neutral for certain combat military occupational specialties, new training sex differences. Limitations to the present study include the sample size and debate regarding the IDF HTT. The number of women in the present study was larger than some previ ous studies, 32,33,35,39,40,53,54 but still somewhat limited. Fu ture studies should include a greater number of female subjects to allow for more robust sex comparisons and the use of other statistical techniques such as propensity score matching/adjustment. 60 In addition, there is con troversy with regard to the construct of heat tolerance in general 61 and the standardized use of the HTT in partic ular. 62 Alternatives to the IDF HTT include measuring heat tolerance over the course of a multiday acclimation protocol, 62 the individual being tested. 63 Since many of the EHI pa tients in the study visited the laboratory from other loca tions and were on temporary physical activity restric tions, it was not feasible to assess and control for heat acclimation status. More advanced techniques to mea concerns about validity and reliability of skinfolds and to a lesser degree BIA, which often vary across sex. 42 losses, may be important to consider. 64 The IDF HTT remains the most widely used and clinically useful test to assess Warf ighter return to duty following EHS, 5,52 as it simulates the conditions of many military EHI scenarios. 65 Importantly, it correlates with risk factors for EHS in the military, 36 for men and women. As women are inte grated into combat military occupational specialties, their risk for EHS will increase, and physicians will have to decide whether to return them to duty following such an event. The IDF HTT can help, but research on how women perform has been lacking. Based on the present study and previous work by Druyan et al, 35 women demonstrate a much higher failure rate on the test. As Table 4 Adjusted Odds Ratios (95% CI) from Hierarchical Logistic Regres sion Predicting Dichotomous HTT Outcomes. Independent Variable HTT Outcome Heat Tolerant Core > 38.5 C HR > 150 BPM Block 1 Gender 3.7 (1.21-11.24) 2.0 (0.56-6.90) 3.5 (0.98-12.56) Block 2A Gender 2.5 (0.75-8.54) 1.7 (0.43-6.86) 1.5 (0.35-6.47) VO 2 max (ml kg 1 min 1 ) 0.9 (0.87-1.02) 0.9 (0.90-1.07) 0.9 (0.76-0.96) Block 2B Gender 2.2 (0.49-9.87) 1.1 (0.18-6.63) 1.8 (0.33-10.16) Skinfold BF% 1.1 (0.95-1.18) 1.1 (0.98-1.31) 1.0 (0.89-1.13) Block 2C Gender 3.5 (0.82-15.09) 2.0 (0.39-10.54) 1.6 (0.30-8.19) BIA BF% 1.0 (0.90-1.12) 1.0 (0.88-1.13) 1.1 (0.96-1.27) BIA indicates bioelectrical impedance analysis. P <. 05 P <. 01 Table 3 Characteristics (meanSD) of Heat Tolerant versus Heat Intolerant Participants. Independent Variable HTT Outcome Heat Tolerant (n= 56 ) Heat Intolerant (n= 19 ) t VO 2 max (ml kg 1 min 1 ) 51.67.5 47.07.9 2.28 Skinfold BF% 20.36.1 24.37.6 2.30 BIA BF% 23.25.4 25.78.2 1.51 BMI (kg/m 2 ) 25.93.0 25.23.4 0.89 Body surface area (m 2 ) 1.960.21 1.850.19 1.93 Body surface/mass (m 2 kg 1 10 2 ) 2.460.21 2.540.22 1.55 Waist circumference (cm) 82.48.4 78.27.9 1.92 BIA indicates bioelectrical impedance analysis. P <. 05
54 http://www.cs.amedd.army.mil/amedd_journal.aspx with any high stake test, it is important to determine whether group differences are due to underlying dif ferences in the latent variable. 66 Since the sex differ ences appear mostly attributable to aerobic power and to those familiar with human thermoregulation research, as they are consistent with a long line of previous re search. 26-29,32,33,39,40 In the present context, however, these results will be crucial for physicians tasked with inter preting IDF HTT scores for men and women, and may inform broader military policy. REFERENCES 1. Dempsey ME, Panetta LE. Memorandum: Elimi ary 24, 2013. Available at: http://www.defense.gov/ 2015. 2. ological employment standards IV: integra tion of women in combat units physiological and medical considerations. Eur J Appl Physiol 3. Armed Forces Health Surveillance Center. Heat in juries, active component, U.S. Armed Forces, 2013. MSMR 4. Epidemiology of hospitalizations and deaths from heat illness in soldiers. Med Sci Sports Exerc 5. Epstein Y, Druyan A, Heled Y. Heat injury preven tion-a military perspective J Strength Cond Res 6. ertional heat stroke: a case series Am J Med Sci 7. Casa DJ, Guskiewicz KM, Anderson SA, et al. Na ment: preventing sudden death in sports. J Athl Train 8. ness in athletes: the dangerous combination of heat, humidity and exercise. Sports Med 9. port for the National Center for Catastrophic Sports 2012. 10. Xiang J, Bi P, Pisaniello D, et al. Health impacts of workplace heat exposure: an epidemiological re view. Ind Health 11. Bouchama A, Knochel JP. Heat stroke. N Engl J Med 12. velopments. J R Army Med Corps 13. Casa DJ, Armstrong LE, Kenny GP, et al. Exer tional heat stroke: new concepts regarding cause and care. Curr Sports Med Rep 14. Cleary M. Predisposing risk factors on suscep tibility to exertional heat illness: clinical deci sion-making considerations. J Sport Rehabil 15. Epstein Y, Shani Y, Moran DS, et al. Exertional heat J Basic Clin Physiol Pharmacol 16. report of idiosyncratic hyperthermia and review of U.S. Army heat stroke hospitalizations. J Sport Re habil 17. Epstein Y. Heat intolerance: predisposing fac tor or residual injury?. Med Sci Sports Exerc 18. ergogenic aids on exercise heat tolerance and hydra tion status. Curr Sports Med Rep 19. Armstrong LE, Casa DJ, Millard-Stafford M, et al. American College of Sports Medicine position stand. Exertional heat illness during training and compe tition. Med Sci Sports Exerc. 20. Bedno SA, Li Y, Han W, et al. Exertional heat illness among overweight U.S. Army recruits in basic training. Aviat Space Environ Med 21. tors predicting exertional heat illness in male Marine Corps recruits. Med Sci Sports Exerc 22. tors for recruit exertional heat illness by gender and training period. Aviat Space Environ Med 23. Kerr ZY, Casa DJ, Marshall SW, et al. Epidemi ology of exertional heat illness among U.S. high school athletes. Am J Prev Med 24. ertional heat-related injuries treated in emergency departments in the U.S., 1997-2006 Am J Prev Med 25. of heat-related injury to disaster relief workers in J Occup Environ Med WOMEN AND EXERTIONAL HEAT ILLNESS: IDENTIFICATION OF GENDER SPECIFIC RISK FACTORS
April June 2015 55 26. Kenney WL. A review of comparative responses of men and women to heat stress. Environ Res 27. Stephenson LA, Kolka MA. Thermoregulation in women. Exerc Sport Sci Rev 28. Heikens MJ, Gorbach AM, Eden HS, et al. Core body temperature in obesity. Am J Clin Nutr. 29. core temperature in obese and lean men and wom en. Obesity (Silver Spring) 30. Compr Physiol 31. Marsh SA, Jenkins DG. Physiological responses to the menstrual cycle: implications for the develop ment of heat illness in female athletes. Sports Med 32. Shapiro Y, Pandolf KB, Avellini BA, et al. Physi ological responses of men and women to humid and dry heat. J Appl Physiol Respir Environ Exerc Physiol 33. Shapiro Y, Pandolf KB, Avellini BA, et al. Heat balance and transfer in men and women exercising Ergonomics 34. Moran DS, Erlich T, Epstein Y. The heat toler ating susceptibility to heat. J Sport Rehabil 35. Druyan A, Makranz C, Moran D, et al. Heat tol Aviat Space Environ Med 36. tolerance testing: association between heat intoler Mil Med 37. American College of Sports Medicine. ACSMs Guidelines for Exercise Testing and Prescrip tion 9th ed. Baltimore, MD: American College of 38. Dubois D. Clinical calorimetry: a formula to estimate the appropriate surface area if height and weight be known. Arch Intern Med 39. Havenith G, Luttikholt VG, Vrijkotte TG. The rela stress response. Eur J Appl Physiol Occup Physiol 40. thropometric measures and gender on individual reactions to heat stress. Eur J Appl Physiol Occup Physiol. 41. Durnin J, Womersley J. Body fat assessed from total body density and its esimation from skinfold thick ness: measurements on 481 men and women aged from 16 to 72 years. Br J Nutr 42. ity and reliability of bioelectrical impedance analy sis and skinfold thickness in predicting body fat in military personnel. Mil Med 43. body mass estimation by bioelectrical impedance analysis: a four-site cross-validation study. Am J Clin Nutr 44. Kyle SB, Smoak BL, Douglass LW, et al. Vari ability of responses across training levels to maximal treadmill exercise. J Appl Physiol 45. Moran DS. Stress evaluation by the physiological strain index (PSI). J Basic Clin Physiol Pharmacol 46. tion between heat tolerant and heat intolerant indi viduals during a heat tolerance test. J Therm Biol 47. conference proceedings. Curr Sports Med Rep 48. way. Scand J Med Sci Sports 49. Nindl BC, Castellani JW, Warr BJ, et al. Physi ological Employment Standards III: physiological challenges and consequences encountered during international military deployments. Eur J Appl Physiol 50. to exercise and thermal stress. Physiol Rev 51. Eberman LE, Cleary MA. Development of a heatillness screening instrument using the Delphi panel technique. J Athl Train 52. Kazman JB, Heled Y, Lisman PJ, et al. Exertional heat illness: the role of heat tolerance testing. Curr Sports Med Rep 53. Gagnon D, Dorman LE, Jay O, et al. Core tempera ture differences between males and females during intermittent exercise: physical considerations. Eur J Appl Physiol 54. Hypohydration and exercise: effects of heat accli mation, gender, and environment. J Appl Physiol Respir Environ Exerc Physiol
56 http://www.cs.amedd.army.mil/amedd_journal.aspx 55. Best S, Caillaud C, Thompson M. The effect of to high-intensity exercise. Scand J Med Sci Sports 56. Tankersley CG, Smolander J, Kenney WL, et al. fects of age and maximal oxygen uptake. J Appl Physiol 57. Friedl KE. Body composition and military perfor J Strength Cond Res. 58. thermoregulation during exercise in the heat. Ex erc Sport Sci Rev 59. Kraemer WJ, Mazzetti SA, Nindl BC, et al. Effect and occupational performances. Med Sci Sports Exerc 60. Beal SJ, Kupzyk KA. An introduction to propen sity scores: what, when, and how. J Early Adolesc 61. Armstrong LE, Maresh CM. The induction and decay of heat acclimatisation in trained athletes. Sports Med 62. return from exertional heat stroke. Curr Sports Med Rep 63. Jones DM, Green MS, Heaney JH, et al. Heat and hypoxia cause additive increases in heat shock protein 72 during submaximal exercise. Med Sci Sports Exerc 64. Hori S. Index for the assessment of heat tolerance. J Hum Ergol (Tokyo) 65. Epstein Y, Moran DS, Shapiro Y, et al. Exertional heat stroke: a case series. Med Sci Sports Exerc 66. ous interpretations of test bias. Cultur Divers Ethnic Minor Psychol. AUTHORS Mr Kazman, Dr Purvis, Dr Lisman, Ms Van Arsdale, and Dr Deuster are with the Department of Military and Emergency Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland. Dr Heled and Dr Atias are with the Institute of Military Medical Center, Tel HaShomer, Israel. WOMEN AND EXERTIONAL HEAT ILLNESS: IDENTIFICATION OF GENDER SPECIFIC RISK FACTORS
April June 2015 57 Iron, a nutrient found in food sources of both vegetable (nonheme) and animal (heme) origin, is an essential min eral that confers function in a number of biological pro cesses, to include physical and cognitive performance, 1 immunity, 2 and energy metabolism. 3 duced iron stores coupled with diminished hemoglobin) are a worldwide public health concern, affecting billions of individuals. 4 associated with decreased physiological and cognitive performance in both civilian and military populations. 5,6 Recent data from the United States and the United respectively, among premenopausal women, 7-9 and ap 9 engage in strenuous physical activity, are known to be at increased risk for decrements in iron status. Such declines may be caused by several contributing factors including hemolysis and iron sequestration due to the 10,11 may reduce both physical work capacity and cognitive tributed in hemoglobin and developing erythroid cells, 3 poor iron status impairs physiological performance as iron is required for oxygen transport to peripheral tis sues. 10 ties such as military training may cause declines in iron status 12-15 Effects of Basic Combat Training on Iron Status in Male and Female Soldiers: A Comparative Study ABSTR A CT Objective: Iron is an essential micronutrient known to affect physical and cognitive performance. Studies although the comparative effects of military training on iron status between male and female Soldiers have not Methods: transferrin saturation (TS). Results: ( P <.05) and sTfR levels were lower ( P P P ( P Conclusions: These data indicate that although dietary iron intake improves, iron status declines in both male should aim to determine the mechanism by which iron status declines during military training, with a focus on functional outcomes affecting Soldier health and performance.
58 http://www.cs.amedd.army.mil/amedd_journal.aspx Iron status has been reported to decline during military training in recent studies among female Soldiers, 16,17 however, reports investigating changes in iron status limited. sex differences in dietary iron intake, iron status, and es in iron levels are similar between the sexes, and to quantify the relative contribution of dietary iron intake to iron homeostasis during military training. METHODS This study was approved by the Human Use Review study after providing their free and informed volun tary consent. The study was conducted in compliance with Army Regulation 70-25 19 and US Army Medical Research and Materiel Command Regulation 70-25 20 on the use of volunteers in research. The data presented in this manuscript were collected in association with a larger study investigating the effects of military training on cardiometabolic risk. 21 Volunteers Baseline data (time-point 1) were collected within one al data collections as follows: weeks 3, 6, and 9 (timesuch as road marching with weighted packs, obstacle courses, distance running, and sprinting. Energy costs 22 (BMI), and body fat percentage) characteristics were de termined at baseline and week 9. Weight was recorded lated by dividing the individuals weight by the square of -2 21 skin fold thickness was assessed at the chest, triceps, and sub scapular sites for men, and at the triceps, suprailiac, and calculated from body density using 3-site skinfold equa tions. 23-25 Body composition was assessed under similar experimental conditions (fasted, similar attire) by the same trained technician. and during the 10-week training course. Mean daily iron Blood samples were collected at each time-point after an overnight fast. Samples were obtained through an tecubital venepuncture into tubes containing the appro was determined in whole blood using a hematology ana was measured using an automated immunoassay in determined using a commercially available immunoas determined by dividing serum iron by total iron bind were measured with a multiplex assay with a lower de mated immunoassay instrument with a lower detectable anthropometric measures and dietary iron intake were made using Students t -tests. Two-factor repeated mea main effects of sex and time and biomarker by time in EFFECTS OF BASIC COMBAT TRAINING ON IRON STATUS IN MALE AND FEMALE SOLDIERS: A COMPARATIVE STUDY
April June 2015 59 in dietary iron intake and indicators of iron status were percentage changes in iron status between groups were set at P <.05. RESULTS ferences in age, anthropometrics, or any of the baseline biomarkers between those who completed the study and to men, women were shorter, weighed less, had a lower BMI, and had a greater body fat percentage ( P <.05). BMI whereas women did not, although both men and women experienced reduced ( P <.05) body fat. were observed between sexes. In comparison to females, males had greater levels of hemoglobin ( P ( P <.05), coupled with reduced sTfR levels ( P <.05). changes in many of the biochemical indicators of iron status in both male and female Soldiers, shown in Ta P <.05). P <.05), sTfR levels P ( P and sTfR increased at week 3 ( P <.05), although TS was cantly affected ( P <.05) in both male and female Sol diers by week 6. iron status (with the exception of hemoglobin in female male Soldiers as compared to baseline. The magnitude P <.05) in fe male Soldiers in comparison with male Soldiers as re P >.05). Dietary Iron Intake P <.05) P <.05) over the course of ( P <.05) in male Soldiers as compared to female Soldiers 26 Table 1 Volunteer demographics and an thropometrics (meanSD): males, n= 89 ; females, n= 65 Week 0 Week 9 Effect Age (years) Males 23.15.4 Females 23.16.0 Height (cm) Males 176.17.0 Females 162.85.8 Weight (kg) Males 83.515.9 79.811.9 T X G Females 66.28.5 66.37.5 -2 ) Males 26.94.6 25.73.3 T X G Females 25.02.8 25.02.3 Body fat (%) Males 14.24.9 12.33.5 T X G Females 26.65.7 22.65.0 ( P <. 05 ). P <. 05 ). T X G indicates time X group interaction ( P <. 05 ). Table 2 Longitudinal changes (meanSD) in iron status indicators during BCT among male and female Soldiers: hemoglobin (Hgb), serum ferritin (SF), soluble transferrin receptor (sTfR), and transferrin saturation (TS). Week 0 Week 3 Week 6 Week 9 Effect Hgb (g/dL) Males (n=77) 14.70.8 14.10.8 13.90.8 14.00.9 T X G Females (n=56) 12.70.9 12.41.0 12.31.0 12.41.2 SF (ng/mL) Males (n=84) 129.579.8 121.581.3 105.768.6 101.966.3 T X G Females (n=65) 35.627.1 23.416.1 20.213.4 18.914.2 sTfR (nmol/L) Males (n=82) 16.83.6 19.74.8 19.74.6 19.64.7 T X G Females (n=65) 18.97.2 23.98.4 24.68.6 24.68.5 TS (%) Males (n=89) 31.611.7 31.411.6 25.39.7 24.110.5 T X G Females (n=65) 28.513.8 18.09.1 15.87.9 13.26.3 P <. 05 ). P <. 05 ). T X G indicates time X group interaction ( P <. 05 ).
60 http://www.cs.amedd.army.mil/amedd_journal.aspx in dietary iron intake and indicators of iron status in tion ( P< .05) between changes in dietary iron intake and CO MM ENT study was that iron status declined in both sexes during military training, regardless of improvements in dietary iron status among military recruits on induction day, and throughout military training courses, this is the tween the sexes in iron intake and metabolism during tivities associated with military training may contribute were meeting dietary requirements for iron. Improved previous studies have not assessed micronutrient intake tribution of particular food items to iron intake was not assessed, previous work indicates that dietary patterns especially among individuals who enter military service with the least favorable eating habits. 30 among physically active populations. 31 with an increase in sTfR were evident in both male and female Soldiers, although the decrement experienced in female Soldiers was nearly double that experienced by their male counterparts. These differences between the integrated military platoons or professional athletes, al though limited data are available with regards to iron status in males. 32,33 These studies indicated a greater training periods among females exposed to the same absolute physical demands as males. 31,34,35 It is possible that female Soldiers experience a relatively higher phys iological strain in comparison to their male counterparts when exposed to similar absolute strains, which may contribute to the declines in iron status. 36 increased expression of several cytokines, including EFFECTS OF BASIC COMBAT TRAINING ON IRON STATUS IN MALE AND FEMALE SOLDIERS: A COMPARATIVE STUDY 35 30 25 20 15 10 5 0 40 Female Male Week 0 Week 9 RDA Iron Intake (mg/day) Figure 2 0 ) 9 ) of BCT among males (n= 89 ) and females (n= 65 (for males and females aged 19-30 fects of time and group ( P <. 05). * * 20 0 -20 -40 -120 -100 -80 80 -60 60 40 Percentage Female Male Hgb SF TS sTfR Figure 1 0 9 ) in iron status indicators during BCT in male and female Soldiers: hemoglobin (Hgb), serum ferritin (SF), soluble transferrin receptor (sTfR), and transferrin saturation (TS). Note: P <. 05).
April June 2015 61 related with the intensity of the activity. 37 Hepcidin, a key regulator of iron homeostasis, increases in response in the sequestering of iron in enterocytes and macro phages, preventing iron from becoming available for physical performance and energy metabolism. 11 cent study conducted on 12 physically active women (aged 19 to 32 years) found that hepcidin was increased 3 hours after either a 60-minute or 120-minute run at 2 max levels increased immediately after the end of the exer cise bout. Soldiers, although increases were not statistically or may have been expected in female Soldiers given the greater decrement in iron status markers. However, the short half-life of acute phase proteins and cytokines especially following an overnight fast. 11 Recent studies have demonstrated the acute effects of military training during intense operational exercises, 15 although future studies should more carefully investigate the nature of both male and female Soldiers. in iron status in this study population regardless of di etary iron intake, the functional consequences of poor iron status and effective countermeasures to prevent declines in iron status remain unclear. It appears that the decline in iron status is of much greater concern for female Soldiers, as male Soldiers began the training course with more robust iron stores, and experienced an attenuated decline in iron status as compared to female tionship between iron status and physical or cognitive performance, previous studies have demonstrated a re lationship between declines in iron status and running performance and mood in female Soldiers. 14,16 on physical performance have been noted in civilian populations. 6 military training, especially in female Soldiers, as the in sTfR could approach values known to affect perfor mance. The relationship between declining iron sta tus and performance in male Soldiers during military training has not been studied and may warrant further exploration. ing declines in iron status during military training as both iron supplements 14 39 for attenu ating the decline in iron status in female Soldiers during mechanism by which iron status declines in response to military training, which may drive the development of effective nutritional or pharmacologic methods for pre venting the negative consequences of poor iron status in dress limitations of the current study, to include further exploration of the mechanism responsible for the decline in iron status including the incorporation of a more de of activities the day prior to blood collection, and greater future studies should assess iron status in both male and as advanced individual training, including associations with physical and cognitive performance, with a focus on female Soldiers that may begin these activities with degraded iron status. ACKNOWLEDGE M ENTS no role in study design, collection, analysis, and inter submit the report for publication. We thank the Soldier volunteers that participated in the REFERENCES 1. Am J Clin Nutr 2. J Neural Transm 3. tabolism. Biochem J 4. J Nutr
62 http://www.cs.amedd.army.mil/amedd_journal.aspx 5. Lancet 6. premenopausal women: effects of poor iron status on physical and neuropsychological performance. Annu Rev Nutr 7. United States. JAMA tions of changes in the modern diet: iron intake, ab sorption, and status. Best Pract Res Clin Haematol 9. MMWR Morb Mortal Wkly Rep 10. Sports Med 11. and diminished iron status: mechanisms and func tional outcomes. Curr Opin Clin Nutr Metab Care 12. by 7 weeks of intensive physical exercise. Eur J Appl Physiol Occup Physiol 13. M. Iron status in cyclists during high-intensity interval training and recovery. Int J Sports Med 14. ble-blind, placebo-controlled trial of iron supple mentation in female Soldiers during military train ing: effects on iron status, physical performance, and mood. Am J Clin Nutr 15. tory biomarkers, serum hepcidin, and iron status. Nutr J 16. ments in iron status during military training in fe male Soldiers. Br J Nutr 17. fractures in female combatants during 16 months. J Strength Cond Res stress fractures among elite male combat recruits. J Int Soc Sports Nutr 19. Army Regulation 70-25: Use of Volunteers as Sub jects of Research 20. US Army Medical Research and Development Com mand Regulation 70-25: Use of Human Subjects in Research, Development, Testing and Evaluation 2003]. 21. basic combat training. PloS One 22. US Army Med Dep J 23. Heyward VH. Evaluation of body composition. Sports Med. 24. for predicting body density of men. Br J Nutr. 25. equations for predicting body density of women. Med Sci Sports Exerc. 26. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadi um, and Zinc 27. ously trained adolescents. J Adolesc Health the role of nutrition among female military recruits. Med Sci Sports Exerc 29. adolescents: results of a longitudinal follow-up study. J Adolesc Health 30. dietary intake using the healthy eating index dur ing military training. US Army Med Dep J. 31. Am J Clin Nutr 32. ciency with and without anemia in recreation ally active men and women. J Am Diet Assoc EFFECTS OF BASIC COMBAT TRAINING ON IRON STATUS IN MALE AND FEMALE SOLDIERS: A COMPARATIVE STUDY
April June 2015 63 33. factors and stress fractures among female mili tary recruits. Med Sci Sports Exerc 11):S691-S697. 34. sex-integrated army basic training. Med Sci Sports Exerc 35. J Strength Cond Res 36. gration of women in combat units physiological and medical considerations. Eur J Appl Physiol 37. Immunol Cell Biol exercise bouts on hepcidin in women. Int J Sport Nutr Exerc Metab 39. product in female Soldiers during military train ing: relations between iron status, serum hepcidin, Am J Clin Nutr AUTHORS Hashomer, Israel. Wingate Institute, Israel. stitute of Environmental Medicine administered by the stitute of Environmental Medicine administered by the Articles published in the Army Medical Department Journal are indexed in MEDLINE, the National Library of Medicines (NLMs) bibliographic database of life sciences and biomedical information. Inclusion in the MEDLINE database ensures that citations to AMEDD Journal content will
64 http://www.cs.amedd.army.mil/amedd_journal.aspx Women currently comprise 15% of the total active duty population and 10% of brigade units. 1 The number of expected to rise accordingly. 2 While the study of the fe male veterans as a distinct population lags behind the study of the overall veteran population, there is evidence that the female veteran reacts to combat trauma differ ently than males. 3 This is consistent with several reports in the literature describing sexual dimorphism in out comes in the civilian trauma population. 4,5 Evidence from prior wars suggests that female veterans have higher incidence of reproductive health issues compared to females who never served in the military. 6,7 Outside of the physical toll of trauma, mental health outcomes also differ between men and women in the civilian trauma literature. Posttraumatic stress disorder (PTSD) rates are higher for women in civilian accidents and for women who witness death or injury versus men. 8,9 Some studies support that female veterans experience similar rates of PTSD compared to male veterans. 10,11 Howev er, the most common cause of evacuation of deployed women service members from both recent wars in Iraq and Afghanistan was and is mental health condition. 12,13 A recent publication on disability following combat in juries highlights the importance and frequent nature of orthopaedic related disability. 14 This is certainly so for service members with combat related amputations and the ensuing disability related to the amputation. The dis ability outcomes for female veterans, including females been determined. We aim to determine what differ who sustained a combat related amputation versus male veterans with amputations. Because mental health dis orders such as PTSD are known to adversely affect out comes following trauma and because the PTSD rates for female veterans may be higher than for male veterans, both physical and mental health conditions may exist. 15 Based on prior literature that supports different mental health outcomes and a variable reaction to trauma, we Female Combat Amputees Have Higher Rates of Posttraumatic Stress Disorder Disability MAJ Jessica C Rivera, MC, USA CPT (P) Chad A. Krueger, MC, USA LTC (P) Anthony E Johnson, MC, USA ABSTR A CT Background: The civilian trauma literature suggests that the sexes differ in physical and mental health outcomes following traumatic injury. In order to determine if the reaction to combat injury is different between the sexes of male and female amputees. Methods: All US combatants who sustained a major extremity amputation between October 2001 and July 2011 were examined for demographic and injury information from the Department of Defense Trauma Registry and men with various disabling conditions were compared using Fishers Exact Test and the mean disability ratings for each condition were compared using students t tests. Findings: Among 1,107 amputees, 21 were female. There was no difference in the average age, military rank, or Injury Severity Score between the sexes. While the most common military occupation of male amputees was infantry service, the most common occupation for the female amputee was military police. The overall disability ratings between females and males were not different (82% for females, 75% for males). Female amputees had more frequent disability from posttraumatic stress disorder (PTSD, 8/21 [38%] vs 168/818 [17%]). Disability ratings from PTSD tended to also be higher in women. Conclusions: Outside of variable occupational descriptions, both male and female amputees were exposed to explosions resulting in their injuries. Consistent with many civilian trauma and veterans population studies, female amputees have higher frequencies of disability from PTSD. These results support the need for additional reduce disability and promote return to duty. Because certain conditions, such as PTSD, may be more or less
April June 2015 65 hypothesize that female amputees will have different METHODS This study was conducted in accordance with a research protocol approved by the Brooke Army Medical Center Institutional Review Board. All military patients who sustained a major limb amputation between October of 2001 and July 2011 were queried in the Department of Defense Trauma Registry (DoDTR, Joint Base San An tonio Fort Sam Houston, Texas) for demographic and injury information to include age, sex, military rank, mechanism of injury, and Injury Severity Score (ISS). occurring proximal to the carpus in the upper extremity and proximal to the tarsal bones in the lower extremity. Injury and demographic data were cross-checked for the female amputees in the Military Orthopaedic Trauma Registry (MOTR, Joint Base San Antonio Fort Sam Houston, Texas). We then queried the resultant subjects bases which are maintained separately for the Army, Air Force, and Navy (including Marine Corps). The Physical Evaluation Board (PEB) is responsible for determining an adequate period of recovery which is determined by the various treating physicians. If the service member is not able to perform his or her active duty job description, the PEB helps determine if the ser vice member should be medically separated or retired from the mil itary, or be retained temporarily for additional treatment or recov ery. The high physical demands of military service make the PEB determinations important follow ing orthopaedic injury. Subjects with complete DoDTR injury data who were medically retired or separated from active duty service by the PEB were included in this analysis. For service members who are medically retired by the PEB, the diagnoses that affect their inability to return to duty disabling condition is also assigned a percentage on a much that individual condition contributes to the ser vice members inability to perform his or her active duty position. For example, for a service member with a transtibial amputation, the PEB assigned a percent disability to the amputation diagnosis of 40%. This in dicates that the amputation diagnosis detracts 40% of ability to perform his or her job. The percent disabil ity can therefore be evaluated on a spectrum of severity. The disability rating for each of the separate conditions is totaled according to the Veterans Affairs (VA) Sched ule for Rating Disabilities formula to yield a total per cent disability. While the PEB rating is different from the service connected disability designation a veteran receives from the VA, the VA rating scheme is used by the PEB for this Department of Defense disability rating. We present demographic and injury descriptions com pared between the sexes. The proportions of related disabling conditions between men and women were compared using Fishers Exact Test. The mean percent disabilities (continuous variables from 0% to 100% re conditions were compared between the sexes using un paired students t tests. Calculations were performed us ing Graph Pad Prism 6 software (GraphPad Software, Inc, La Jolla, CA). RESULTS Of the 1,107 amputees who were evaluated by the PEB, 21 were female and 986 were male. Average age, me dian military rank, and average ISS were not different between the sexes as shown in Table 1. A majority of both women and men sustained their amputations in a battle injury of explosion mecha nism. One female sustained a transtibial amputation in a non battle machinery accident. The distribution of amputation sites were also similar with the major ity of amputations being of the lower extremities as illustrated in the Figure. Because of certain restrictions on women serving in direct combat roles, job descrip tions for males and females did differ as most male amputees served in infantry units. Ten of the females with amputations served as Military Police, 4 in supply/ transport, 3 as mechanics, 2 in human resources, one as The frequencies of orthopaedic related disabling condi tions were not different between the sexes. Outside of the disability received for the amputation diagnoses, posttraumatic arthritis was the most common condition affecting male amputees and the second most common condition affecting female amputees. Among the non orthopaedic conditions, female amputees had a higher proportion of PTSD related disability compared to male amputees, with PTSD being the most common disabling Table 1 US Military Combatants with Major Ex tremity Amputations who underwent Physical Evaluation Board Review, October 2001 July 2011 (N= 1,007 ) Women (n=21, 2%) Men (n=986, 98%) Age (meanSD) 275 255 Rank (median, range) E-6 (E3-O3) E-7 (E1-O6) Battle Injury 20, 95% 976, 99% ISS (meanSD) 197 2110
66 http://www.cs.amedd.army.mil/amedd_journal.aspx condition in women aside from the amputations them selves as shown in Table 2. The overall disability ratings and the percent disability rating assigned to upper extremity amputations tended to Table 3. The average percent disability ratings assigned to individual orthopaedic and nonorthopaedic conditions were also not different for males versus females, shown and eligible for medical retirement based on their dis ability ratings, 3 women were able to continue on active duty in a limited or altered job description through a Continuation on Active Duty (COAD) appeals process. Females who COAD were of average age 23 years old and enlisted rank E-4, while the 89 males who returned to duty or were able to COAD were of average age 28 and enlisted rank E-7. None of the women who were COAD were assigned disability related to PTSD; and only one male who was COAD had a PTSD disability. CO MM ENT Among a population of wounded service members who sustained similar injuries by similar mechanisms, a comparison of resultant disabilities is possible. We population, with the expected differences in job descrip tion, are similar for male and female combat amputees. Consistent with prior literature in the civilian population, we found that female amputees have a higher propor tion of PTSD diagnoses compared to similarly injured males. The disability percentage ratings, however, were not different between the sexes. The high proportion of posttraumatic arthritis being similar between the sexes is notable, though, as idiopathic osteoarthritis is more common in females than males. 16-18 Current literature on the veteran population is mixed re garding the presence or absence of difference in rates of PTSD in male and female veterans. Haskell et al found that the female sex was negatively correlated with a posi tive screen for PTSD or VA service connected disability for PTSD, while other studies have found no difference between the sexes. 10,11,19 However, studies that account for other levels of interpersonal trauma, prior history of trauma, and sexual trauma in the military indicated that personal history and type of trauma exposure contrib uted to higher rates of PTSD and depression in female veterans. 20-23 A recent study of homeless veterans found that homeless women were more likely than men to have PTSD, but were less likely to have substance abuse and incarceration histories. 24 Studies of PTSD rates use vari able methods for measuring and diagnosing PTSD, mak 25 We found a higher rate (40%) of PTSD in our cohort than previously published or expected based on re cent epidemiologic studies of veterans. 26,27 We believe this study shows a true difference in the frequency of PTSD among female service members when the injury mechanism and injury pattern are considered. Because of the similarities across the board in our male and Table 2 Service Disqualifying Conditions per Sex Women N=21 (n, %N) Men N=986 (n, %N) P Value PTSD 8, 40% 168, 17% .0193 Scar 4, 20% 89, 9% .1207 TBI 4, 20% 99, 10% .2605 Arthritis 7, 35% 247, 25% .4453 Back Pain 1, 5% 20, 2% .3605 Abdomen/Pelvic Condition 1, 5% 20, 2% .3605 General Pain 1, 5% 30, 3% .4849 Muscle Condition 2, 10% 79, 8% .6832 Nerve-Loss of Function 3, 15% 150, 15% 1 Two-tailed P value calculated using Fishers Exact Test. PTSD indicates posttraumatic stress disorder; TBI, traumatic brain injury. One Subject: bilateral upper extremity amputation One Subject: transfemoral & contralateral transtibial amputation 3 Subjects: bilateral amputations at or below the transtibial level 2 Subjects: transradial amputations 7 Subjects: transfemoral amputations 6 Subjects: amputations at or below the transtibial level One Subject: shoulder disarticulation Amputation levels of 21 female amputees. FEMALE COMBAT AMPUTEES HAVE HIGHER RATES OF POSTTRAUMATIC STRESS DISORDER DISABILITY
April June 2015 67 female cohorts, the comparison of frequencies is use ful. Additionally, in order for a condition to be deemed a disabling condition, the service member must have undergone an adequate time for treatment and recovery and have undergone subspecialty evaluation and diag physician diagnosed disorders rather than self-reported incidences. The disability percentages were not differ ent among the sexes, suggesting that the severity of the injuries and resultant disability are no different, even in light of frequency differences for PTSD. Other studies on female veterans demonstrate other pos sible sex differences following trauma. Female veterans from multiple prior wars have reported increased issues in reproductive health including higher incidence of birth defects, higher incidence of severe premenstrual nant. 6,7,28 Other studies demonstrate higher rates of anxi ety and depression among female service members. 19,29 One study by Nunes et al demonstrated higher rates of psychological diagnoses in civilian female amputees versus males. 30 Other studies have found that female veterans have more pain disorders and higher healthcare utilization for pain versus male veterans. 31,32 Our study did not demonstrate higher frequencies of other mental health diagnoses, pain disorders, or gynecological prob lems in this cohort. In this small population of amputees, dent to the PEB a relatively short time following injury, with time as suggested in some studies published from the VA. male amputees is the number and characteristics of the women who were able to return to an active duty role through the COAD process. COAD is an appeals pro cess that allows select service members to be retained on active duty in limited or altered job roles despite ies on return to duty after a variety of orthopaedic injuries have found that the service members who were able to continue on active duty in some fashion were typically older and higher rank. 33-35 This makes the 3 female amputees on COAD unique as their av erage age was 23 and median military rank E-4. We speculate that the ability for these young soldiers to continue active duty service in a new job description is related to job descriptions which might be ame nable to an altered level of physical activity. For ex ample, the most common job description for the male amputee, infantry, would rarely be achievable for the duties required of the young, junior-enlisted infan tryman. 36 The new job roles to which the COAD soldiers returned to duty were not available for analysis. How ever, the absence of PTSD may also have contributed to these womens ability and desire to return to duty. Our study does have several limitations. For one, the PEB results and disposition are unique to the military setting. We believe that with the rising number of com bat veterans from our most current wars, military re lated disability will become an increasingly important issue in the VA and in treatment centers outside the VA. Furthermore, the PEB system serves as essentially a workmans compensation system comparable to that found in the civilian trauma environment. Secondly, our data is limited to retrospective evaluations which limits our ability to demonstrate causation. We have attempted validating the demographic and injury information in our Military Orthoapedic Trauma Registry which was injury, treatment, and complication information. Finally, our most concerning limitation is the small sample size cult when comparing the sexes. While this remains the largest cohort of female amputees to be reported from the most comprehensive combat injury registry avail able, this is a limitation of the patient population, but we Table 4. Mean Disability Ratings per Condition (range) Women Men P Value PTSD 49% (10%-80%) 44% (0-70%) .5553 Nerve-Loss of Function 45% (10%-80%) 33% (0-40%) .4636 Muscle Condition 40% (40%) 29% (0-70%) .4142 Arthritis 33% (10%-40%) 22% (0-40%) .2527 TBI 30% (10%-40%) 40% (0-100%) .4968 Scar 27% (10%-50%) 30% (0-70%) .3893 Back Pain 20% 13% (0-20%) n/a Abdomen/Pelvic Condition 20% 58% (0-80%) n/a General Pain 0% 15% (0-30%) n/a Disability ratings assigned as a continuous variable between 0 and 100% Two tailed P value comparing means were calculated using students t test. PTSD indicates posttraumatic stress disorder; TBI, traumatic brain injury. Table 3. Mean Overall Disability Ratings (range) Women Men P Value Upper Extremity Amputation 85% (70%-100%) 76% (40%-100%) .2933 Lower Extremity Amputation 66% (40%-100%) 65% (40%-100%) .9781 Overall Combined Disability 82% (40%-100%) 75% (40%-100%) .2042 Disability ratings assigned as a continuous variable between 0 and 100% Two tailed P value comparing means were calculated using students t test.
68 http://www.cs.amedd.army.mil/amedd_journal.aspx believe the information is useful by further supporting other military and civilian amputee literature. SU MMA RY In a cohort of recent combat veterans with similar in jury mechanisms and patterns over a 10-year span, the not entirely different. Female amputees are more likely to have PTSD as a service disqualifying condition than male amputees, though the severity of the PTSD is not statistically different between the sexes. Proportions and severities of the orthopaedic disabling conditions were not different between the sexes. There appears to be a demographic difference in female amputees who were able to continue on active duty which may be related to small cohort of female military amputees add additional information on the importance of understanding differ ences in response to combat injury for both physical and mental disorders such as PTSD in the female veteran population. REFERENCES 1. Womens Health Services, US Department of Veterans Affairs; 2013. Available at: http://www. womenshealth.va.gov/WOMENSHEALTH/docs/ 2014. 2. Resnick EM, Mallampalli M, Carter CL. Current challenges in female veterans health. J Womens Health 2012;21:895-900. 3. Cross JD, Johnson AE, Wenke JC, Bosse MJ, Ficke JR. Mortality in female war veterans of Operations Enduring and Iraqi Freedom. Clin Orthop Relat Res 2011;469:1956-1961. 4. Haider AM, Crompton JG, Oyetunji T, et al. Fe males have fewer complications and lower mortal ity following trauma then similarly injured males: a risk adjusted analysis of adults in the National Trauma Data Bank. Surgery 2009;146:308-315. 5. Wohltmann CD, Franklin GA, Boaz MSN, et al. A multicenter evaluation of whether gender dimor phism affects survival after trauma. Am J Surg 2001;181:297-300. 6. Kang HK, Li B, Mahan CM, Eisen SA, Engel CC. Health of US veterans of 1991 Gulf War: a fol low-up survey in 10 years. J Occup Environ Med 2009;51:401-410. 7. Kang H, Magee C, Mahan C, et al. Pregnancy out comes among U.S. Gulf War veterans: a population based survey of 30,000 veterans. Ann Epidemiol 2001;11:504-511. 8. Olff M, Langeland W, Draijer N, Gersons BP. Gen der differences in posttraumatic stress disorder. Psychol Bull 2007;133:183-204. 9. Tolin DF, Foa EB. Sex differences in trauma and posttraumatic stress disorder: a quantita tive review of 25 years of research. Psychol Bull 2006;132:959-992. 10. Hoge CW, Auchterlonie JL, Milliken CS. Mental health problems, use of mental health services, and attrition from military service after returning from deployment to Iraq or Afghanistan. JAMA 2006;295:1023-1032. 11. Fear NT, Jones M, Murphy D, et al. What are the consequences of deployment to Iraq and Afghani stan on the mental health of the UK armed forces? A cohort study. Lancet 2010;375:1728-1797. 12. Medical evacuations from Afghanistan during Operation Enduring Freedom, active and reserve component, U.S. Armed Forces, 7 October 2001-31 December 2012. MSMR 2013;20:2-8. 13. Medical evacuation from Operation Iraqi Free dom. Operation New Dawn, active and reserve components, U.S. armed forces, 2003-2011. MSMR 2012;19:18-21. 14. thoapedic injuries cause the majority of long-term disabilities. J Am Acad Orthop Surg 2011;19(suppl 1):S1-S7. 15. Starr AJ, Smith WR, Frawley WH, et al. Symptoms of posttraumatic stress disorder after orthopaedic trauma. J Bone Joint Surg Am 2004;86:1115-1121. 16. Hanna FS, Teichtahl AJ, Wluka AE, et al. Women have increased rates of cartilage loss and progres sion of cartilage defects at the knee than men: a gender study of adults without clinical knee osteo arthritis. Menopause 2009;16:666-670. 17. Kopec JA, Rahman MM, Berthelot, et al. Descrip tive epidemiology of osteoarthritis in British Co lumbia, Canada. J Rheumatol 2007;34:386-393. 18. Felson DT, Naimark A, Anderson J, Kazis L, Cas telli W, Meenan RF. The prevalence of knee osteo arthritis in the elderly. The Framingham Osteoar thritis Study. Arthritis Rheum 1987;30:914-918. 19. Haskell SG, Gordon KS, Mattocks K, et al. Gen der differences in rating of depression, PTSD, pain, obesity, and military sexual trauma among Con necticut war veterans of Iraq and Afghanistan. J Womens Health 2010;19:267-271. 20. Fontana A, Rosenheck R, Desai R. Female vet erans of Iraq and Afghanistan seeking care from VA specialized PTSD programs: comparison with male veterans and female war zone veterans of pre vious eras. J Womens Health 2010;19:751-757. FEMALE COMBAT AMPUTEES HAVE HIGHER RATES OF POSTTRAUMATIC STRESS DISORDER DISABILITY
April June 2015 69 21. Hassija CM, Jakupcak M, Maguen S, Shipherd JC. on PTSD, depression, and alcohol misuse in U.S. Gulf War and OEF/OIF women veterans. J Trauma Stress 2012;25:216-219. 22. Kang H, Dalager N, Mahan C, Ishii E. The role of sexual assault on the risk of PTSD among Gulf War veterans. Ann Epidemiol 2005;15:191-195. 23. Wolfe J, Erickson DJ, Sharkansky EJ, King DW, King LA. Course and predictors of posttrau matic stress disorder among Gulf War veterans: a prospective analysis. J Consult Clin Psychol 1999;67:520-528. 24. Tsai J, Rosenheck RA, Kane V. Homeless female US veterans in a national supported housing pro gram: comparison of individual characteristics and outcomes with male veterans. Psychol Serv 2014;11:309-316. 25. Street AE, Vogt D, Dutra L. A new generation of women veterans: stressors faced by women de ployed to Iraq and Afghanistan. Clin Psych Rev 2009;29:685-694. 26. Gates MA, Holowka DW, Vasterling JJ, Keane TM, Marx BP, Rosen RC. Posttraumatic stress disorder in veterans and military personnel: epidemiol ogy, screening, and care recognition. Psychol Serv 2012;9:361-382. 27. Gradus JL. Epidemiology of PTSD [internet]. Na tional Center for PTSD, US Department of Veter ans Affairs; January 30, 2014. Available at: http:// www.ptsd.va.gov/professional/PTSD-overview/ epidemiological-facts-ptsd.asp. Accessed April 23, 2014. 28. Cohen BE, Maguen S, Bertenthal D, Shi Y, Jacoby V, Seal KH. Reproductive and other health out comes in Iraq and Afghanistan women veterans us ing VA health care: association with mental health diagnoses. Womens Health Issues 2012;22:461-471. 29. Wells TS, Leard Mann CA, Fortuna SO, et al. A prospective study of depression following combat deployment in support of the wars in Iraq and Af ghanistan. Am J Public Health 2010;100:90-99. 30. Nunes MA, de Barros N, Miranda F, Baptista-Silva JC. Common mental disorders in patients under going lower limb amputation: a population-based sample. World J Surg 2012;36:1011-1015. 31. Haskell SG, Brandt CA, Krebs EE, Skanderson M, Kerns RD, Goulet JL. Pain among Veter ans of Operations Enduring Freedom and Iraqi Freedom: do women and men differ? Pain Med 2009;10:1167-1173. 32. Haskell SG, Ning Y, Krebs E, et al. Prevalence of painful musculoskeletal conditions in female and male veterans in 7 years after return from deploy ment in Operation Enduring Freedom/Operation Iraqi Freedom. Clin J Pain 2012;28:163-167. 33. Cross JD, Stinner DJ, Burns TC, Wenke JC, Hsu JR, Skeletal Trauma Research Consortium. Return to duty after type III open tibia fracture. J Orthop Trauma 2012;26:43-47. 34. Krueger CA, Wenke JC. Initial injury severity and social factors determine ability to deploy after com bat-related amputation. Injury 2014;45:1231-1235. 35. Stinner DJ, Burns TC, Kirk KL, Ficke JR. Re turn to duty rates of amputee soldiers in the cur J Trauma 2010;68:1476-1479. 36. Belisle JG, Wenke JC, Krueger CA. Return-to-du ty-rates among US military combat-related ampu tees in the global war on terror: job description mat ters. J Trauma Acute Care Surg 2013;75:279-286. AUTHORS MAJ Rivera is with the US Army Institute of Surgical Research, San Antonio Military Medical Center, Texas. CPT (P) Krueger is with the Department of Orthopae dics and Rehabilitation, Brooke Army Medical Center, San Antonio, Texas. LTC (P) Johnson is Chairman, Department of Orthopae dics and Rehabilitation, Brooke Army Medical Center, San Antonio, Texas.
70 http://www.cs.amedd.army.mil/amedd_journal.aspx in Iraq and Afghanistan over the last 12 years, 1 and dur ing this time there have been changes in the nature and severity of casualties, especially as compared to previ 2-4 There is previous literature which addressed treatment of casualties based on mechanism of injury such as blast injuries that have been common 2,4,5 Further studies looked into prevention of injury including body armor and eye protection 3 and 6,7 Less research has focused on identifying differences in the individuals being in demographic information, especially when comparing 8,9 However, there is very little that can be found from any investigation into casualty dif Some studies in the civilian trauma literature indicate that there is a difference in survival rates for women 10 Both animal studies and retrospective reviews of civilian trauma data have indicated that women may have a biologi cal advantage when it comes to surviving trauma, 10-12 at least if there are no medical complications after the studied mortality in combat which indicated that female Comparison of Female and Male Casualty Cohorts from Conflicts in Iraq and Afghanistan ABSTR A CT questions pertained: operation, or other demographic characteristics? P P P P P P P
April June 2015 71 casualties with battle injuries of a similar severity to their male counterparts were more likely to die of their 13 This disparity indicates that more research is tries around the world including Israel, which is the only nation that mandates service for all citizens, men and 14 15,16 and their contributions are serving in support roles for the troops were not con in 1948 when federal legislation mandated that women 16 triculation of women at military academies occurred in 1976, and a small contingent of women was deployed to 16 icy that established a ban on assignment of women to ground combat units considered to be front-line posi 16 that womens invaluable contributions to the military are no longer required only behind the front lines of acknowledged this fact in 2013 when he lifted the 1994 prohibition, allowing women to hold direct combat po sitions, including infantry and even potentially special 15,17 Given these changes in the role of the female service member, it is more important than ever to learn if there physicians must not only look at the injuries sustained know what the differences might be between men and 13 For the purposes of this study, the following questions pertained: Do female and male casualties from the US military tary operation, or other demographic characteristics? Do female and male casualties from the US military and injury date? METHODS under and in accordance with a protocol approved by of casualty data, which was then placed into one of 2 served and were injured in Operation Iraqi Freedom of 425 female and 14,982 male subjects who met the Age, branch of military service, military rank, military injury type, injury cause, and injury date were collect also marked as either injured either during battle or in a consecutively as information of casualties is received and processed, the data pulled from this database pro vides a consecutive sample of all casualties for the above variables were not normally distributed among men,
72 http://www.cs.amedd.army.mil/amedd_journal.aspx age, combined ISS, individual AIS values between the 2 tions of the male and female groups in military branch, The study population is comprised of all active duty, ac tivated reservist, and National Guard service members in the US military, with all branches included: Army, the study parameters, there are 425 females and 14,982 RESULTS The collected data revealed that women comprised P military branches, the Army as a whole had the greatest percentage of both men and women, depicted graphi 2 comparison, it was shown that a greater proportion of female casualties P again a higher percentage of female and male casualties 2 analysis showed that proportion P The analysis of the injury characteristics also showed with a higher score being related with more severe in P when comparing the mean of all casualties together P P P comparing battle versus nonbattle-related injury, wom en were less likely to be injured in battle than the male Figure 2, women were less likely to be injured due to CO MM ENT the overarching question: are female casualties different from their male counterparts? This does not address fe male and male Soldiers or other service members pre-in jury, but rather questions if their injuries were sustained tion presented on female mortalities in the US military indicated that the casualty death rate in women may be 13 There are also earlier stud 18-20 addressing questions involving comparisons of cause identify only basic information about the service mem bers and their injuries with descriptors of general injury characteristics such as blunt versus penetrating, but not Marine Corps Air Force Navy Army Men Women 73% 82% 3% 8% 3% 4% 21% 6% 80% 90% 70% 60% 50% 30% 20% 10% 0% 40% Figure 1 Distribution by gender of all casualties examined in the study across the military services. COMPARISON OF FEMALE AND MALE CASUALTY COHORTS FROM CONFLICTS IN IRAQ AND AFGHANISTAN
April June 2015 73 in battle and nonbattle injuries individually reveals no cause of the number of males injured in battle, the mean the study is not inclusive of all casualties but rather fo The percentage of casualties who are female in our study 9,13 One previous study showed the female case fa directly comparable to our investigation of total casualty The difference shown in age with females being slightly younger may be due to the age range, in that there are fewer women past the age of 40 still within the mili 9,21 9,21,22 ghanistan are inherently different due to the nature of the that there were potentially more special forces troops since women were not allowed to be assigned to direct combat roles during the entire studied timeframe, includ previous work on female mortalities showed high ISS 13 13 ever, when this is broken down into battle and nonbattle groups, there is no statistical difference in the mean Figure 2 Distribution of the most common causes of injury to male and female servicemembers respectively. GSW indicates gunshot wound; MVC, motor vehicle collision. 28% 21% 12% 10% 8% 2% 3% 4% 4% 4% 4% Women Men 55% 17% 7% 2% 3% 4% 5% 1% 2% Crush Blunt Object Bullet/GSW Knife Explosive Fall Other Machinery MVC Unknown Sports
74 http://www.cs.amedd.army.mil/amedd_journal.aspx mean ISS when they sustain battle related injury com comparing all females to all males is due to a higher Further research to investigate any differences is still match males and females for a cohort study where more CONCLUSIONS The statistical analysis comparing female to male US alties sustained similar ISSs when broken down into bat vious evidence that the case fatality rate may be higher for females, it is apparent that additional investigation is required to further study the effect of battle and non REFERENCES of combat injuries sustained during the surge por tion of Operation Iraqi Freedom by a US Army bri J Trauma of death in US Special Operations Forces in the US Army Med Dep J J Trauma J Orthop Trauma J Trauma Foot Ankle Clin J Or thop Trauma Popul Health Metr Mil Med males have fewer complications and lower mortal ity following trauma than similarly injured males: a risk adjusted analysis of adults in the National Surgery Shock der differential in outcome after blunt or penetrat Shock Clin Orthop Relat Res The Jerusalem Post Army News Service mil/article/118930/Army_to_open_33_000_posi Norfolk Daily News [on in-the-military/article_a21c355a-d822-11e2-87e3FoxNews.com tics/2013/01/24/panetta-opens-combat-roles-toCOMPARISON OF FEMALE AND MALE CASUALTY COHORTS FROM CONFLICTS IN IRAQ AND AFGHANISTAN
April June 2015 75 Nurs Clin North Am Gen Hosp Psychiatry women veterans: stressors faced by women de Clin Psych Rev National Public Radio Army.mil mil/article/110447/Sisters_in_Arms__Breaking_ AUTHORS
76 http://www.cs.amedd.army.mil/amedd_journal.aspx The number of women in the military has steadily in creased since the Selective Service draft ended in 1973 and now comprises 15% of the active duty military population and 10% of the deployed population. 1 Con gress mandated that, starting in January 2016, military women would be afforded the same opportunities for combat assignments as men. As a result, women could be serving in the most austere conditions. Women will compete with men for these once restricted combat as signments under the same physical and performance standards. In order to ensure the health and well-being of women as they progress in military roles and/or op timize their health in their current military roles, mili tary health care professionals and leaders should consult current evidence-based knowledge on womens health issues and care. The research that is currently available is typically published in peer reviewed journals, yet is not readily accessible to military care providers and de cision makers. The Military Womens Health Research Interest Group (MWHRIG) was founded to address the lack of a consolidated review. the need to compile all peer reviewed research publica tions on military womens health issues and care in the past decade to promote awareness in the professional military community. The initial goal of the MWHRIG was to identify and grade existing research and build a database with the results that could be searchable and accessible to military clinicians and leaders charged with making evidence-based decisions. To advance the science of military womens health, the next steps were to perform a systematic review of the published litera ture, examine utilization of the Military Healthcare Sys they strove to create a military womens health research paramount that research be available, but it must also be highly relevant to guide decision-making as the De demographic shift and force multiplier. EST A BLISHING THE PUR P OSE OF THE M WHRIG the systematic review and gap analysis efforts with a strong position paper. The MWHRIG foundational pa per was entitled, A Call to Action for Evidence-Based Military Womens Health Care: Developing a Womens Health Research Agenda that Addresses Sex and Gender in Health and Illness. 2 The article highlighted female lance Centers Medical Surveillance Monthly Reports trends by female service members within the MHS. information relevant to military womens occupational promotion programs. It was concluded that this absence Creating and Sustaining a Military Womens Health Research Interest Group ABSTR A CT to improve servicewomens health inspired them to commit to a rigorous schedule of planning, developing, and health policy and practice through research. The ultimate goal of the Military Womens Health Research Interest Group (MWHRIG) is to support military clinicians and leaders in making evidence-based practice and policy decisions. They developed a 4-pronged approach to cultivate the science of military womens healthcare: evaluate the existing evidence, develop a research agenda that addresses gaps in knowledge, facilitate the collaboration of multidisciplinary research, and build the bench of future researchers. The MWHRIG has been a resource to key leaders; its value has been validated by multiservice and multidisciplinary consultations. However, the journey to goal attainment has only been achieved by the enduring commitment of these MWHRIG leaders and their passion to their journey of dedication.
April June 2015 77 of information could contribute to the lack of essen tial preventive medicine and interventions to improve the health, safety, and performance of military women. The authors postulated that there may be a require health care needs of women, particularly as they move into expanded military roles. The article described the need for a concerted effort to synthesize the literature on womens health care needs and thus designated the genesis of the MWHRIG. The role of the MWHRIG in knowledge about military womens health issues and the subsequent development of research priorities were described. The ultimate goal was to identify gaps in the literature to inform future research and policy changes. While the primary objectives of the MWHRIG were to systematically conduct an extensive literature re view and evaluate published articles related to military womens health, they also endeavored to create an on line searchable database of the reviewed literature. A centralized online repository will be vital in supporting military womens health needs through evidence-based practice and policies. This database will assist scientists with research proposal development and funding efforts by providing a search for the state of the science on any given womens health topic relevant to service women. BUILDING THE TE AM Realizing that implementing a systematic review of a de cades worth of literature that is relevant to the health of women in all of the military services would require sup port, the MWHRIG reached out to the Veterans Admin istration (VA) Greater Los Angeles Health Services Re search and Development (HSR&D) Center of Excellence Agenda Planning Group for guidance in the systematic review process. In 2006, the VA Greater Los Angeles HSR&D Center of Excellence had conducted a system atic review and developed an online database for veteran womens health research that the MWHRIG felt was ap propriate to replicate. Since the MWHRIG envisioned an analysis with goals comparable to the VA Womens Health Research Agenda 3 they contacted the VAs Agenda Planning Group for guidance in the systematic review process. Besides the expertise in the review pro cess, the MWHRIG hoped to foster collaboration with the VA HSR&D that would enhance the possibility for combined efforts in the future. With the initial guidance from the VA womens health research agenda leaders, the MWHRIG adopted a similar 4-step approach to con ducting the review of the literature and gap analysis. In addition to developing a research agenda, the MWH RIG initiated simultaneous efforts to create a community of scientists dedicated to advancing military womens health through research. They enacted 2 avenues of approach to cultivate the science of military womens healthcare: facilitate the collaboration of multidisci plinary research, and build the bench of future scientists. as MWHRIG Core Leaders, the MWHRIG built a team by recruiting the most experienced research scientists in teer members from every military service, as well as the VA, and academia, the MWHRIG developed a base of 64 Subject Matter Experts (SMEs) whom they could em ploy in the conduct of the systematic review of literature. SU PP ORTING AGENCIES In the fall of 2008, the MWHRIG Core Leaders met Health Sciences in Bethesda, Maryland, to discuss the groups purpose and planned goal attainment. The goals of the MWHRIG meshed seamlessly with the mission nursing research, optimize the health of military mem bers, expand the cadre of military researchers, build an infrastructure to support nursing research, and foster collaborative research. It was at this meeting that the MWHRIGs vision for cataloging and grading research to identify gaps in military womens health and facil itate future research became a possibility. In order to substantiate their efforts, the MWHRIG created a char ter and developed a timeline for achieving milestones. source Center assisted the MWHRIG by lending infra structure to support and sustain the efforts of the MWH RIG, technology to support strategic communication of research interest group members, and the coordination for the development of partnerships with academic and other research institutions. tematic reviewgather and catalog all peer reviewed literature on military womens health research from 2000-2010they requested assistance from several recognized the groups need for the technical support of http://www.usuhs.mil/tsnrp/AboutTSNRP/WhoWeAre/ mission.php
78 http://www.cs.amedd.army.mil/amedd_journal.aspx masters prepared civilian nurse with extensive research experience as the program coordinator. In addition to supported the MWHRIG core leaders to attend research courses and conferences, telecommunications, interac tive video conference lines for frequent virtual meet and logistical costs for dissemination of key MWHRIG products. The team reached out to their partners for guidance on the database development. The Research Programming Womens Health Research Agenda Planning Group with their data collection for the systematic review. Accord used web-based systematic review program designed of a systematic review when collecting their VA wom ens health research article reviews. The MWHRIG pro gram coordinator developed a comprehensive cost-ben acquisition of the program. This critical component of The online data management tool allowed the core lead ers and SMEs to access the uploaded full text article and input their review and grade determination. Instead of cataloging individually scanned review documents, which presented a data management nightmare for the program coordinator, the on-line system served as a re al-time repository to input the systematic reviews. The on-line system allowed the team to export the evalua tions to set the foundation for a searchable database. Creating a searchable database for military researchers tion technology (IT) experts. With an introduction and support to develop the website repository. Permission to use the coding behind the VAs systematic review data base was granted (P. Shekelle, oral communication, June 7, 2013). Meeting with the research interest group pro interface adapted from the VAs online interface coding. The Military Womens Health Research Literature da tabase was created from work group systematic review data collection spreadsheets and served as the backbone for importing the data from the systematic review soft ware. This program was created so that the MWHRIG database would mirror the VA Womens Health litera ture database making future collaboration possible. ACCO MP LISH M ENTS OF THE M WHRIG The Systematic Review With the development of multiple synergistic relation ships, the MWHRIG was able to accomplish 16 mile product is the systematic review. A 3-level screening process was used to evaluate a decades worth of sci ticle searches were completed using predetermined title search criteria for Level 1, abstract approval criteria for Level 2, and grading and analysis criteria for Level 3. Articles advanced to Level 3 review if all four of the criteria based on the predetermined criteria used for the Level 2 screening. The MWHRIG garnered the support of the SMEs from the military, academic, and civilian research communities to grade the level of evidence and quality of the research studies. Both a core leader and same core leader established congruency between the 2 reviews and research quality grades. Once completed, these data were ready for upload into the searchable da tabase, ultimately depicted as an article summary with a tion of the database, the MWHRIG was able to draw the evidence tables from the systematic review program and produce the systematic review summary. Encouraging Collaboration in Military Womens Health In order to boost collaboration, the MWHRIG engaged in a multimedia approach to develop a community of re search scientists with a common desire to improve mili created a handbook, Military Womens Health Research ers Guide now in its 6th version, which lists all of the MWHRIG members and SMEs, including their abbre viated curriculum vitae and publications as relevant to military womens health research. The guide serves to connect multidisciplinary research scientists with simi lar interests or subject matter expertise in collaborative Resource Center funded production of hard copies of the guide, as well as various marketing products, such as business and information cards for dissemination der to promote the connections among those interested in advancing evidence-based womens health care, the events, publications, and news about military womens tions among both seasoned and aspiring researchers, links appropriate SMEs for areas of research interest, https://www.facebook.com/pages/Military-Womens-HealthResearch-Interest-Group/117532448302481 CREATING AND SUSTAINING A MILITARY WOMENS HEALTH RESEARCH INTEREST GROUP
April June 2015 79 and provides the contact information to requesting an interests groups, and, based on the success of the MWH RIG, inaugurated 3 more research interest group web pages (behavioral health, en route care, and anesthesia). ed or participated in various research, development, and collaborative forums, such as the VA Womens Health Services Research Conference, the Department of De Veterans, the Women in the Military Service for Amer Symposium, and multiple national womens health con ferences. The MWHRIG has contributed valuable evi dence on military womens health issues to guide the Assistant Secretary of Defense for Health Affairs Wom ens Health Issues Working Group. The MWHRIG has been a resource to key proponents for the advancement of military womens health. It has been consulted by the 4,5 on 2 reports on the health of servicewomen and by the Defense De partment Advisory Committee on Women in the Ser vices for their 2012 report 6 and recommendations on the health of deployed servicewomen. STRENGTH THROUGH THE TE AM CH A R A CTERISTICS In addition to the research experience of this team, over time we determined a key strength of the MWHRIG on active duty. They are personally familiar with the triumphs and struggles military women face through out the course of a military career which included many psychosocial adaptations to multiple duty station relo cations, personal illnesses, illnesses of family members, births, deaths, loss of friendships and support systems, promotions with added responsibilities, the threat of rations from family, and the eventual transition into the VA system upon retirement. The 4 nurse scientists are also licensed independent providers, one midwife and 3 nurse practitioners. The fact that these researchers are also clinicians helps them critique the science and its Timeline of Progress for the Military Womens Health Research Interest Group Publish the MWH Research Agenda Foster Collaborative Efforts in New Research that Address the MWH Research Agenda Conduct Research that Addresses the MWH Research Agenda FUTURE Beta Test Website Repository Completed 511 Level 2 Screeners Completed 320 Level 3 Reviews Obtained Utilization Data Conducted Gap Analysis Drafted Systematic Review 2014 Initiated Web-based Review Software Conducted Article Level 2 Screeners Began Level 3 Grading of the Literature Designed Online Research Repository 2013 Gathered Literature Conducted Level 1 Article Screening of 1411 Titles Used Subject Matter Experts in Review of Literature Designed Online Communities (Facebook & TSNRP Website) 2011 Conducted Article Level 2 Screeners Reviewed Exisiting Utilization Data Planned Gap Analysis Developed a Dissemination Plan for Products Began Mentorship of New MWH Researchers 2012 Developed a Charter Identified Core Leaders Began Visionary Manuscript 2009 Published Manuscript Recruited Project Manager Collaborated With VA Health Services Research and Development Recruited Subject Matter Experts Published First MWH Researcher Guide 2010
80 http://www.cs.amedd.army.mil/amedd_journal.aspx potential contribution to womens healthcare. Over the total of 12 permanent changes of station (PCS) moves of tings, and numerous temporary duty assignments. The multiple international assignments of group members led to scheduling challenges due to multiple time zones with up to a 14-hour time difference. Many meetings were conducted after or before the duty day in order program coordinator was critical in the success of the project. She kept scheduled weekly conference lines, created meeting agendas, provided review updates, and emailed reminders to complete pending tasks. FUTURE OF THE M WHRIG As of the time of this publication, goals for the immedi ate future are anticipated to be complete, including the completion and publication of the systematic review of the military womens health research from 2000 through 2010, as well as the debut of the online database. A followup review of literature published from 2011 through 2014 is already under way. Long term goals include obtain ing support for the maintenance of the article repository and allocating responsibility as an enduring requirement to ensure that the evidence base on military womens health issues continues to be expanded. Marketing strat egies are required for the multidisciplinary and triser vice use of these valuable resources, as well as continued literature input and subject matter expertise. We hope and be the meeting place for innovative research as in spired by the military womens health research agenda. SU MMA RY The creation and sustainment of this team has been made possible by the vision and drive of 4 military nurse sci entists who felt passionately about the advancement of womens health for the support of the inclusion of women in combat roles. The products this team has generated and continue to develop will be a sound resource to in form lawmakers and military leaders about the research port women as they forge new paths within the DoD. The MWHRIG will continue to be valuable resource to the triservice research community and military leaders. ACKNOWLEDGE M ENT gram for its support of the Military Womens Health Re search Interest Group. This work would not have been provided by the Program. REFERENCES 1. Womens Research and Education Institute. Wom en in the Military: Where They Stand 8th ed. 2013. Available at: http://www.wrei.org/WIM_ 2. evidence-based military womens health care: de veloping a womens health research agenda that ad dresses sex and gender in health and illness. Biol Res Nurs 2010;12:171-177. 3. a VA womens health research agenda: setting ev idence-based priorities to improve the health and health care of women veterans. J Gen Intern Med 2006;21:S93-S101. 4. Military Personnel: DOD Has Taken Steps to Meet the Health Needs of Deployed Servicewomen, but Ac tions Are Needed to Enhance Care for Sexual As sault Victims GAO-13-182. Available at: http://www.gao.gov/as sets/660/651624.pdf. Accessed March 23, 2015. 5. DOD Health Care: Domestic Health Care for Female Service Members port GAO-13-205. Available at: http://www.gao. gov/assets/660/651620.pdf. Accessed March 23, 2015. 6. Defense Department Advisory Committee on Women in the Services. 2012 Report Washington, dacowits.defense.gov/ReportsMeetings.aspx. Ac AUTHORS Joint Base Andrews, Maryland. Clinical Inquiry, Brooke Army Medical Center, San An tonio Military Medical Center, Texas. Center, San Diego, California. LTC (Ret) Steele is an Associate Professor, Brooks Col Medicine, Pittsburgh, Pennsylvania. CREATING AND SUSTAINING A MILITARY WOMENS HEALTH RESEARCH INTEREST GROUP
April June 2015 81 HISTORY A man 19 years of age with a history of complex dextrotransposition of the great arteries (d-TGA) repaired dur ing infancy presented with intermittent palpitations at rest. He denied orthopnea, edema, paroxysmal noctur nal dyspnea, and exertional chest pain. Taussig shunt at 10 days of age followed by a comple tion Rastelli repair at 10 months of age with VSD patch restriction at the VSD and intermittent high-grade AV age after resumption of normal sinus rhythm, how been stable without symptoms for the past 5 years. His crescendo-decrescendo systolic murmur at the left and right upper sternal borders and a widely split S2 with Electrocardiogram showed normal sinus rhythm with a Echocardiography and cardiac computed tomography ing arterioplasty, retained epicardial lead, and the symp toms described. IMA GING FINDINGS nial projection demonstrating the Rastelli conduit (open and anastomosing at the main pulmonary artery (not nary artery (solid arrow) arises from the aorta (Ao) and (arrow). The course of the Rastelli graft (1) immediately deep to the sternum is appreciated and the anastomosis atrophic right pulmonary artery ( ) is also seen cours ing superior to the aortic root. Additionally, a mildly ob (2) with good appreciation of the misalignment of the age which shows the bifurcation of the main pulmonary artery (1). The size disparity between the normal left pulmonary artery (2), measuring 17 mm, and the atro phied right pulmonary artery ( ), measuring 9 mm, is preciated, which is secondary to the leftward origin of the ascending aorta compared with normal anatomy. phy due to anatomical position, body habitus, or surgical scarring. Complex d-TGA Status Post Rastelli Repair Presenting with Palpitations: Cardiac CTA Imaging Findings and Discussion of Long-Term Outcomes
82 http://www.cs.amedd.army.mil/amedd_journal.aspx CO MM ENT Transposition of the great arteries (TGA) is an uncom mon congenital heart disease with a reported incidence 1 D-transposition (d-TGA) is a cya arterial connections leading to parallel pulmonary and systemic circulations that is best surgically corrected Patients with d-TGA are dependent upon intracardiac septal defect, VSD, or patent ductus arteriosus. 2 Early, maybe under recognized and the patient may present cedure attempts to increase intracardiac blood mixing through balloon dilation of an atrial septal defect. The nary artery shunt that uses a PTFE interposition graft between the innominate artery and the right branch pul monary artery (with left aortic arch) to palliate until de the pulmonary circulation. Then oxygenated pulmonary these operations, including sinus node dysfunction, ar COMPLEX D-TGA STATUS POST RASTELLI REPAIR PRESENTING WITH PALPITATIONS: CARDIAC CTA IMAGING FINDINGS AND DISCUSSION OF LONG TERM OUTCOMES Figure 2 Multiplanar reformat demonstrating a repaired ven tricular septal defect (arrow), the Rastelli graft ( 1 ) immediately deep to the sternum, and the anastomosis with the main pul monary artery is well visualized. The atrophic right pulmonary artery ( ) is also seen coursing superior to the aortic root is shown ( 2 ) with evidence of aortic root misalignment with Figure 1 oblique, cranial projection demonstrating the Rastelli conduit and anastomosing at the main pulmonary artery (not visual ized). The left anterior descending coronary artery (solid ar row) arises from the aorta (Ao) and courses in the anterior
April June 2015 83 failure. 5 translocation of the coronary arteries, and establishment 6 tery to direct blood to the lungs for oxygenation. 7 Regardless of the type of surgical correction, all patients 5 branch pulmonary arteries, conduit (if present) and cor 8,9 for anatomic and hemodynamic assessment. 5 Echocar Figure 4 Apical 3 and 5 Figure 3 Axial image showing the bifurcation of the main pul monary artery ( 1 ). The size disparity between the normal left pulmonary artery ( 2 ), measuring 17 mm, and the atrophied right pulmonary artery ( ), measuring 9 mm, is better appreci ated. The left-sided aortic course ( 3 ) is appreciated, which is secondary to the leftward origin of the ascending aorta com pared with normal anatomy.
84 http://www.cs.amedd.army.mil/amedd_journal.aspx need further imaging in addition to echocardiography, ing cardiac computed tomography angiography. 8,9 Ventriculaire procedures, data on long-term outcomes of Rastelli repair for complex d-TGA is still being com associated with reduced morbidity and mortality. 10 Ac complex d-TGA corrected with the Rastelli operation from 1988 to 2008, freedom from death or cardiac 11 Horer data showed freedom from death or transplantation at 12 11,12 tion. 11,12 11,12 post arterial switch operation are reduced exercise toler REFERENCES 1. heart defects in metropolitan Atlanta, 1998-2005. J Pediatr COMPLEX D-TGA STATUS POST RASTELLI REPAIR PRESENTING WITH PALPITATIONS: CARDIAC CTA IMAGING FINDINGS AND DISCUSSION OF LONG TERM OUTCOMES Figure 5 Apical 3 and 5
April June 2015 85 2. Goor DA, Edwards JE. The spectrum of transposi Circulation sure of patent ductus arteriosus. Pediatr Cardiol fants and older children. Ann Card Anaesth 5. Circulation 6. Jatene AD, Fontes VF, Paulista PP, de Souza anatomic correction of transposition of the great Arq Bras Cardiol 7. repair of transposition of the great arteries. Mayo Clin Proc 8. multidetector computed tomography scan illustrat ing Damus-Kaye-Stansel operation. Circulation 9. for tetralogy of fallot, transposition of the great ar J Cardio vas Comput Tomogr 10. costs for neonates with transposition of the great arteries. J Am Coll Cardiol 11. septal defect and pulmonary stenosis. Ann Thorac Surg Figure 6 to visualize by echocardiography due to anatomical position, body habitus, or surgical scarring.
86 http://www.cs.amedd.army.mil/amedd_journal.aspx 12. Rastelli repair for transposition of the great arteries. Ann Thorac Surg Congenit Heart Dis AUTHORS Houston, Texas. Sam Houston, Texas. COMPLEX D-TGA STATUS POST RASTELLI REPAIR PRESENTING WITH PALPITATIONS: CARDIAC CTA IMAGING FINDINGS AND DISCUSSION OF LONG TERM OUTCOMES
October December 2014 87 Borden Institutes latest publication was authored by Norman Camp, a retired Army psychiatrist who led a psychiatric unit during the war in Vietnam. The result is a story that is both scholarly and intensely personal, ecdotes and case histories that illustrate his perspectives and opinions, as well as the points of view of many of his pages are replete with illustrations and correspondence from the Vietnam era. The story is presented in a fresh wayfrom a psychiatrists point of viewalthough it is now nearly 50 years since the war was fought. The American ground war in Vietnam lasted from 1965 to 1973. Just as the current Army has evolved in re sponse to social issues over the past decade, the Army culture of the time. This was a time of upheavalwors ening racial tensions, widespread use of illicit drugs, and, of course, the antiwar movementall coinciding in ways that posed threats to our social institutions, in cluding the US Army. At home, the many aspects of and political controversy. Although Army morale re on and the Army became increasingly draftee depen in Vietnam. The effects were manifest as a growing tolerance for the hardships of an assignment in Vietnam. Matters became substantially worse in 1970 when a an unprecedented problem that seriously undermined Soldier health, morale, and military preparedness. The American had a street value of hundreds of dollars, was scribing the dramatic political and military events of 1968, the de facto turning point in the war; the pre-Tet buildup under Lyndon Johnson; and the 1969 to 1973 post-Tet years during which Richard Nixon directed the withdrawal from combat. The wars bloodiest year was 1968, with more than 16,000 American casualties. On January 31, 1968, Viet Cong guerillas and North Viet historic city on the border with North Vietnam, as well as American resistance during a prolonged siege of the US Marine combat base at Khe Sahn. In the month of across South Vietnam. Although there were few tacti cal gains for the communist forces, the political gains were substantial. According to some, US media reports of these events as defeats for US forces led to the loss of political and popular support for the war, and the call for don Johnson had proposed the end of aerial bombing and the start of peace negotiations in March 1968, and Americans began pulling out of Vietnam in mid-1969. The recognition that there could be no US victory in the country and the Army. The troops commitment in the A New Offering from the Borden Institute History Series US Army Psychiatry in the Vietnam War Norman M. Camp, MD COL (Ret) US Army Medical Corps
88 http://www.cs.amedd.army.mil/amedd_journal.aspx build-up years evolved into worsening morale, apathy, Among many aspects of the war that placed the mental were the following: The opposition Vietnamese forces included the North Vietnamese army, who staged relatively con most active and fought a guerilla/counterinsurgen cy war built on terrorizing citizens living in the vil lages of South Vietnam. Many South Vietnamese were too intimidated by the Viet Cong to become American allies. The enemy was elusive but often Soldiers located in forward bases ventured out side of the wire to engage the enemy in searchand-destroy missions. There was no way to control territory. The war had evolved into a protracted, In the United States, Americans had become in power movements, the emerging youth countercul public that increasingly showed dissatisfaction with the war were met head on by conservative mem bers of the population who opposed these ideas. The members of the US military were caught in the middle. Instead of deploying as a unit as the Army does to of Soldiers in and out of theater and in and out of often lead for shorter time periods, typically 3 to 6 months. These rotations were intended to give each resulted in diminished leadership continuity and unit cohesiveness. The previsouly mentioned decision to begin peace embraced the mission, there was to be no victory, dramatic loss of morale. Soldiers clearly and openly expressed concerns regarding the reason for the zone: We are the Unwilling, led by the Unquali Changes in American culture also affected psychia trists and the care they provided. Over the course of the war, approximately one-third of the Army psychiatrists deployed to Vietnam were military trained, while two-thirds were civilian trained. The great majority were recent graduates of psychia try training programs, with relatively little mili coupled with the cultural changes that occurred in the Army as the war raged, led to the dramatic in crease in rates for psychiatric out-of-country evacu Vietnam veterans returned to an unwelcoming so ciety. Much has been written about the many epi sodes of rejection by the American public of return trists practicing in Vietnam after 1968 recognized adverse effect on morale. In one of the Borden Institutes strongest productions, the author has addressed a complicated subject and iden of Soldiers with behavioral issues that show the situa tion these men faced, and how he and his colleagues at Army values. This is a story about events that have been in the American military consciousness for more than a generation, with many of these ideas bubbling below the surface for years and only now being presented. We trists for addressing these issues and providing quality care to our fellow Soldiers. AUTHOR US ARMY PSYCHIATRY IN THE VIETNAM WAR A NEW OFFERING FROM THE BORDEN INSTITUTE HISTORY SERIES
October December 2014 89 National Guard, and in the Reserve by following the instructions on the Borden Institute website, http://www.cs.amedd.army.mil/borden/. It will soon be available for purchase from the US Gov
90 http://www.cs.amedd.army.mil/amedd_journal.aspx The headquarters and primary instructional facility of the Army Medical Department Center and School, Joint Base San Antonio Fort Sam Houston, Texas.
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