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Neuroendocrine and Performance Responses to Eccentric-Enhanced Resistance Exercise

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 Title Page
 Dedication
 Acknowledgement
 Table of Contents
 List of Tables
 List of Figures
 Abstract
 Introduction
 Review of literature
 Methods
 Results
 Discussion
 Appendices
 References
 Biographical sketch
 

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NEUROENDOCRINE AND PERFORMANC E RESPONSES TO ECCENTRICENHANCED RESISTANCE EXERCISE By JOSHUA F. YARROW A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLOR IDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY UNIVERSITY OF FLORIDA 2006

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Copyright 2006 by Joshua F. Yarrow

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This work is dedicated to my mother, Julie Yarrow. Thanks for being incredibly supportive and always believing in me. I love you very much.

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iv ACKNOWLEDGMENTS I would like to thank my committee chair, Dr. Lesley J. White, and co-chair, Dr. Paul A. Borsa, for their constant guidance and support throughout my doctoral work. I also would like to thank my committee members Dr. Stephen E. Borst, Dr. Harry S. Sitren, and Dr. Bruce R. Stevens for their suppor t throughout the entirety of this project. I am forever indebted to all the me mbers of the Applied Human Physiology Laboratory who helped with the completion of my work (Ashley Blazina, Dr. Vanessa Castellano, Stacey Colon, Jason Drenning, Br ooke Holman, Laura Massey, Sean McCoy, and Kevin Taylor). I am also grateful to Christine Conover and Mindy Prucha for their assistance in assay preparation and troubl eshooting, Dr. Michael Mac Millan for his generous donation of equipment, Cassie Ho ward for allowing use of The Living Well facilities, and all the volunteers who participat ed in the study.

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v TABLE OF CONTENTS page ACKNOWLEDGMENTS.................................................................................................iv LIST OF TABLES...........................................................................................................viii LIST OF FIGURES...........................................................................................................ix ABSTRACT....................................................................................................................... xi CHAPTER 1 INTRODUCTION........................................................................................................1 Significance..................................................................................................................1 Specific Aims and Hypotheses.....................................................................................2 Specific Aim #1.....................................................................................................2 Hypothesis #1........................................................................................................2 Specific Aim #2.....................................................................................................2 Hypothesis #2........................................................................................................3 Specific Aim #3.....................................................................................................3 Hypothesis #3........................................................................................................3 Specific Aim #4.....................................................................................................4 Hypothesis #4........................................................................................................4 2 REVIEW OF LITERATURE.......................................................................................5 Significance..................................................................................................................5 Eccentric Exercise........................................................................................................6 EccentricEnhanced Exercise.......................................................................................9 Anabolic Hormone Responses to Resistance Training...............................................10 Testosterone.........................................................................................................11 Growth Hormone.................................................................................................13 Growth Hormone and Testosterone Re sponses to Resistance Exercise..............13 Conclusion..................................................................................................................15 3 METHODS.................................................................................................................16 Subjects....................................................................................................................... 16 Inclusionary/Exclusionary Criteria.............................................................................16 Experimental Design..................................................................................................17

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vi Baseline Testing..................................................................................................19 Exercise Training.................................................................................................19 Follow-Up Testing...............................................................................................20 Dietary Analysis..................................................................................................20 Sleep Analysis.....................................................................................................21 Blood Collection..................................................................................................21 Biochemical Analyses.........................................................................................21 Sample Size.........................................................................................................22 4 RESULTS...................................................................................................................24 Subjects....................................................................................................................... 24 Biochemical Results...................................................................................................24 Lactate........................................................................................................................ .25 Lactate Response to the St andardized Traditional Exercise Protocol in Untrained Men.................................................................................................25 Lactate Responses to Standardi zed Traditional and EccentricEnhanced Exercise in the Untrained.................................................................................26 Lactate Response to Standardiz ed Traditional and EccentricEnhanced Exercise in Trained Men..................................................................................27 Testosterone................................................................................................................27 Resting Testosterone...........................................................................................27 Testosterone Responses to the Standardi zed Traditional Exercise Protocol in Untrained Men.................................................................................................29 Testosterone Responses to Standa rdized Traditional and EccentricEnhanced Exercise in Untrained Men..............................................................................29 Testosterone Responses to Standa rdized Traditional and EccentricEnhanced Resistance Exercise in Trained Men................................................................31 Growth Hormone........................................................................................................33 Growth Hormone Response to Standardized Traditional Exercise Protocol in Untrained Men.................................................................................................33 Growth Hormone Response to Standardized Traditional and EccentricEnhanced Exercise in Untrained Men.............................................................33 Growth Hormone Response to Standardized Traditional and EccentricEnhance d Exercise in Trained Men.................................................................35 Plasma Volume...........................................................................................................35 Muscle Function.........................................................................................................36 Muscular Strength...............................................................................................36 Muscular Endurance............................................................................................36 Rating of Perceived Exertion......................................................................................37 Training Volume.........................................................................................................38 Training Volume Per Exercise Session...............................................................39 Total Accumulated Training Volume Across Five-Week Intervention..............41 Dietary Analysis.........................................................................................................42 Sleep Analysis............................................................................................................42

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vii 5 DISCUSSION.............................................................................................................44 Metabolic Response to Resistance Exercise...............................................................45 Lactate Responses to Standardi zed Traditional and EccentricEnhanced Resistance Exercise in Untrained Men............................................................45 Lactate Response to Resistance Training in Trained Men..................................47 Testosterone................................................................................................................48 Resting Testosterone...........................................................................................49 Testosterone Response to Standardized Traditional Resistance Exercise in Untrained Men.................................................................................................51 Testosterone Response to Standardized Traditional and EccentricEnhanced Exercise in Untrained Men..............................................................................52 Testosterone Responses to Traditional and EccentricEnhanced Resistance Training in Trained Men..................................................................................53 Growth Hormone........................................................................................................54 Growth Hormone Response to Standardized Traditional Resistance Exercise in Untrained Men.............................................................................................54 Growth Hormone Response to Standardized Traditional and EccentricEnhanced Exercise in Untrained Men.............................................................55 Growth Hormone Response to Traditional and EccentricEnhanced Exercise in Trained Men.................................................................................................56 Muscular Function and EccentricEnhanced Resistance Training.............................56 Muscular Strength...............................................................................................57 Muscular Endurance............................................................................................58 Training Volume.........................................................................................................59 Conclusion..................................................................................................................60 Clinical Implications...................................................................................................61 Future Directions........................................................................................................62 APPENDIX A HEALTH HISTORY QUESTIONNAIRE.................................................................65 B PHYSICAL ACTIVITY AND DIETARY QUESTIONNAIRE...............................68 C LIST OF EXCLUDED NUTRITIONAL SUPPLEMENTS......................................70 D DIETARY RECORD..................................................................................................71 E POWER CALCULATIONS.......................................................................................72 F PLASMA VOLUME FLUCTATI ONS FOLLOWING EXERCISE.........................73 LIST OF REFERENCES...................................................................................................74 BIOGRAPHICAL SKETCH.............................................................................................89

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viii LIST OF TABLES Table page 1. Overview of strength outcomes from eccentricenhanced studies...........................12 2. Subject characteristics pre and pos t 5 weeks of resistance training.........................24 3. Muscular strength values at baseline and post-intervention for the traditional and eccentricenhanced groups.......................................................................................37 4. Muscular endurance (total work) measures at baseline and post-intervention for the traditional and eccentricenhanced groups.........................................................37 5. Average reported kilocalories, carbohydr ates, protein, and fat in the traditional and eccentricenhanced groups................................................................................43 6. Percent plasma volume fluctuations following traditional and eccentricenhanced resistance training....................................................................................73

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ix LIST OF FIGURES Figure page 1 Experimental design.................................................................................................18 2 Lactate responses to trad itional resistance exercise.................................................25 3 Baseline lactate responses to traditional and eccentricenhanced resistance...........26 4 Post-intervention lactate responses to traditional and eccentric-e nhanced resistance exercise....................................................................................................27 5 Total serum testosterone before (Baseline) and after (Post) the training intervention...............................................................................................................28 6 Total bioavailable testosterone before (B aseline) and after (Post) the training intervention...............................................................................................................28 7 Total testosterone responses to standa rdized traditional resistance exercise protocol.....................................................................................................................30 8 Bioavailable testosterone responses to standardized tr aditional resistance exercise protocol......................................................................................................30 9 Total testosterone responses to standardized traditional and eccentricenhanced resistance exercise in untrained men........................................................................31 10 Bioavailable testosterone responses to standardized traditional and eccentricenhanced resistance exercise in untrained men........................................................32 11 Post-intervention total serum testosterone responses to standardized traditional and eccentricenhanced r esistance exercise protocols.............................................32 12 Post-intervention bioavailable serum te stosterone responses to standardized traditional and eccentricenhanced resistance training............................................33 13 Growth hormone responses to the standardized traditional resistance exercise protocol in untrained men........................................................................................34 14 Growth hormone responses to stan dardized traditi onal and eccentricenhanced exercise protocols, in untrained men........................................................................34

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x 15 Post-intervention growth hormone responses to standardized traditional and eccentricenhanced resistance exercise....................................................................35 16 Ratings of perceived exertion (Borg S cale) following each exercise training session......................................................................................................................38 17 Chest press training volume per session for the traditional group and eccentricenhanced groups.......................................................................................................39 18 Squat training volume per session for the traditional and eccentricenhanced ........40 19 Combined training volume per session (Che st Press + Squat) for the traditional and eccentricenhanced groups................................................................................40 20 Total chest press and squat training volume during the five week resistance exercise intervention................................................................................................41 21 Combined total training volume (Chest Press + Squat) during the five-week exercise intervention................................................................................................42

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xi Abstract of Dissertation Pres ented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy NEUROENDOCRINE AND PERFORMANC E RESPONSES TO ECCENTRICENHANCED RESISTANCE EXERCISE By Joshua F. Yarrow December 2006 Chair: Lesley J. White Cochair: Paul A. Borsa Major: Health and Human Performance Reduced skeletal muscle strength and/or mass are associated reduced mobility, increased injury risk, a loss of functional independence, and an increased risk for hypokinetic diseases. Resistan ce training may improve both muscle strength and mass, by modulating neuroendocrine factors known to increase protein synthesis. The purpose of this study was to evaluate the neuroe ndocrine, metabolic, and muscle performance responses to traditional and eccentricenhanced progressive resistance training, in previously untrained, college-age men. Participants completed a five-week traditional or eccentricenhanced resistance training intervention. Chest and leg muscular strength and endurance were assessed before and after the training intervention. Blood samples acquired at rest and following an acute exercise session, both before (untrained) and after (trained) the training intervention, were asse ssed for growth hormone, total testosterone, bioavailable testosterone, and lactate concentrations. Blood lactate accumulation was greater following eccentricenhanced compared to traditional resistance training, in the

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xii untrained state, but not the trained state. Re sting total testosterone concentrations did not change in either group, whereas resting bioava ilable testosterone concentrations were lower in the trained state, compared to the untrained state in both groups. Post-exercise serum testosterone concentrations remain ed unchanged in the untrained state, but increased in the trained stat e in both groups. Post-exercis e bioavailable testosterone concentrations increased similarly between groups, both before and after the training intervention. Post-exercise serum growth hor mone concentrations increased in both the trained and untrained state in both groups. Absolute muscular strength (1RM) increased similarly between groups; however, relative strength (1RM x body mass-1 and 1RM x lean body mass-1) improvements were greater in the traditional resi stance training group for the squat exercise, but not the chest press. Muscular endurance (t otal work) increased similarly between groups. This study sugge sts that both tradit ional and eccentricenhanced resistance training result in similar neuroendocrine and performance responses during the early phase of resi stance exercise, in previously untrained, college-age men.

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1 CHAPTER 1 INTRODUCTION Significance Skeletal muscle atrophy, reduced strengt h, and increased muscular fatigue are associated with the aging process. Interven tions involving resistance exercise have been shown to promote muscle hypertrophy, increase strength, and decrea se fatigue in both young and elderly populations.65, 104 Traditional resistance exer cise is performed with an identical load during both the concentric (s hortening) muscle contraction and eccentric (lengthening) muscle action. Eccentricenhanced weight training is an alternative form of resistance exercise performed by increas ing the load during the eccentric muscle action. In healthy populations, the major ity of studies report that eccentricenhanced training is superior for devel oping muscular strength and skel etal muscle mass, compared to traditional resistance exercise.25, 51, 86, 87, 95, 118 However, the mechanism(s) underlying the accentuated skeletal muscle adaptations following eccentricenhanced resistance exercise remain unclear, but are likely rela ted to enhanced anabolic processes. Increased anabolic hormone concentrati ons (growth hormone, total testosterone, and bioavailable testosterone ), at rest and acutely follo wing resistance exercise, are associated with the skeletal muscle adaptation process.113 It is possible that the anabolic hormone responses following eccentricenhanced resistance training may be relatively higher compared to traditional resistance tr aining, thus indicating a possible mechanism for the accentuated muscular strength and sk eletal muscle mass results accompanying eccentricenhanced resistance training. Therefore, the objective of this study was to

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2 compare specific neuroendocrine, metabolic, and muscle performance responses to traditional and eccentricenhanced resistance training. Specific Aims and Hypotheses Specific Aim #1 The first specific aim is to compare the post-exercise concentrations of wholeblood lactate and serum total testosterone, bi oavailable testosterone, and growth hormone concentrations following a single bout of eccentricenhanced resistance exercise to the post-exercise concentrations following a singl e bout of traditional resistance exercise. Hypothesis #1 The post-exercise concentrations of se rum total testosterone, bioavailable testosterone, and growth hormone will be greater following the eccentricenhanced resistance exercise bout compared to the concentrations following the traditional resistance exercise bout, whereas the whole-bl ood concentration of lactate will be lower following the eccentricenhanced resistance exercise bout comp ared to the concentrations following the traditional resistance exerci se bout. To accomplish this aim, blood was sampled immediately prior to exercise, imme diately post exercise, and every 15 minutes for 60 minutes post exercise. Blood was anal yzed for lactate, total testosterone, bioavailable testoster one, and growth hormone. Specific Aim #2 The second specific aim is to compare th e post-exercise conc entrations of blood lactate, serum total testosterone, bioavailabl e testosterone, and growth hormone after a single bout of eccentricenhanced or traditional resistance exercise (Exercise Training Session #1) to the post-exercise concentrations obtained in in dividuals after participation

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3 in a five-week eccentricenhanced or traditional resistance exercise intervention (Exercise Training Session #15). Hypothesis #2 The post-exercise concentrati ons of whole blood lactate, serum total testosterone, bioavailable testosterone, and growth hormone will be higher following the resistance exercise intervention (Exercise Training Se ssion #15) compared to the post-exercise concentrations obtained after the initial re sistance training session (Exercise Training Session #1) in both groups. Further, the postexercise concentrations of lactate will be lower in the eccentricenhanced group compared to the trad itional group at the end of the exercise intervention. Additionally, the total testosterone, bioavailable testosterone, and growth hormone concentrations w ill be higher in the eccentricenhanced group compared to the traditional group at the end of the in tervention. To accomplish this aim, blood was sampled immediately prior to exercise, imme diately post exercise, and every 15 minutes for 60 minutes post exercise. Blood was anal yzed for lactate, total testosterone, bioavailable testoster one, and growth hormone. Specific Aim #3 The third specific aim is to compare the resting concentrations of serum total testosterone and bioavailable testosterone in untrained individuals to the resting concentrations in the same individuals following a five-week eccentricenhanced or traditional resistance exercise intervention. Hypothesis #3 The resting concentrations of serum total and bioavail able testosterone will be higher at the conclusion of a five-week exercise intervention in both groups. Additionally, the resting concentrations of serum total a nd bioavailable testosterone will

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4 be greater following th e five-week eccentricenhanced training protocol compared to the traditional resistance training protocol. To accomplish this aim, blood was sampled at rest and at the same time of day at the beginning and end of a five-week exercise intervention. Blood was analyzed for total and bioavailab le testosterone. Specific Aim #4 The fourth specific aim is to compare mu scular strength and endurance following a five-week eccentricenhanced resistance exercise intervention to that following a fiveweek traditional resistance exercise intervention. Hypothesis #4 Eccentricenhanced resistance training will result in greater muscular strength and muscular endurance than traditional resistance training. To accomplish this aim, subjects will perform a one-repetition maximum (1RM) test (muscular strength) and four sets at 52.5% 1RM (muscular endurance) on both the ch est press and squat exercises prior to and after completion of the fi ve-week exercise intervention.

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5 CHAPTER 2 REVIEW OF LITERATURE Significance Skeletal muscle atrophy, reduced strength, a nd increased fatigue ar e associated with aging175 and degenerative diseases such as multiple sclerosis155 and muscular dystrophy.11 Reduced strength and increased mu scular fatigue may limit ambulatory movement and/or increase risk of musculoskele tal injury in frail and fatigued individuals. Participation in progressive resistance exer cise increases muscular strength and lean muscle mass and is associated with reduced musculoskeletal injury risk and improved functional capacity in both h ealthy and at-risk populations.65, 104 Traditional, isotonic, resist ance exercise involves a concentric (shortening) muscle action and an eccentric (lengthening) musc le action separated by a brief isometric (transition) action.104 Resistance exercise combining both concentric and eccentric muscle actions has been demonstrated to re sult in greater strength outcomes than either phase performed separately.35, 46, 76, 87, 94, 134 When movement velocity is held constant, eccentric muscle actions produce significantly greater force than concentric muscle actions,97 suggesting that during traditional resistance exercise the eccentric muscle action is underloaded. Alternative forms of resistan ce exercise such as eccentriconly35, 46, 49, 93, 119, 130, 146, 158, 163 or eccentricenhanced weight training protocols17, 25, 51, 59, 86, 87, 95, 118, 156 have been proposed as a means of supr a-maximally loading skeletal muscle to optimize training adaptations during resistan ce exercise; however, the effectiveness of such protocols has not been substantiated.

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6 A host of factors may affect skeletal muscle adaptations following resistance exercise including load or intensity, repeti tion selection, repetiti on speed, total volume, and rest periods;104 each of these factors ma y also affect hormonal6, 8, 64, 106, 109, 111, 128, 143, 171 and/or metabolic responses36, 112 following exercise. Acute elevations in serum anabolic hormone concentrati ons (i.e., total testosterone, bioavailable testosterone, and growth hormone) and metabolic f actors (i.e., lactate) during resi stance exercise have been shown to, directly or indirectly, infl uence muscle hypertrophy and performance.113 Thus, determining serum anabolic hormone concentr ations, at rest and following exercise, may provide a theoretical framework to further understand the skeletal muscle adaptation process following eccentricenhanced exercise. The following review discusses eccentric exercise and the anabolic hormone responses und erlying the muscular adaptation process. Eccentric Exercise Eccentriconly resistance exercise is an alternativ e form of weight training that is typically performed on an isokinetic dynamome ter and entails coupled eccentric actions involving antagonist muscle groups (e.g. knee flexors and extensors). Eccentriconly resistance training protocols (6 -11 weeks) have been shown to result in greater increases in muscular strength co mpared to concentriconly training.35, 49, 119, 130 The accentuated strength improvements following eccentriconly resistance exercise may be due, in part, to a ~40-50% greater maximal workload typi cally performed during the eccentric phase of exercise.46 However, some research reports that concentriconly training (4-20 weeks) results in similar93, 158, 163 or greater strength improvements146 compared to eccentriconly training. Additionally, some research demonstrates that the strength adaptations following concentriconly and eccentriconly resistance training ar e mode and/or speed

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7 specific,79, 88, 157 suggesting that a variety of facto r(s) may affect the skeletal muscle adaptation process. The energy requirements and metabolic fatigue associated with resistance exercise are of concern when prescribing weight tr aining programs for both healthy and at-risk populations. Metabolic acidosis may contribute to skelet al muscle fatigue during anaerobic exercise,16 while reduced energy requirements and/or metabolic fatigue during exercise may diminish perceived exertion a nd result in reductions in overall fatigue. Therefore, evaluating the metabolic responses to eccentriconly resistance exercise may provide a possible mechanistic understanding of the underlying factors associated with skeletal muscle fatigue. A variety of studies have evaluated the energy cost of concentric and eccentric training including cycling and traditional weight training.2, 3, 20, 30, 31, 45, 119, 129, 159 During resisted eccentriconly cycling at similar submaximal loads, the metabolic cost of exercise is 1/6th -1/7th lower than concentriconly cycling.20 The energy requirements during maximal eccentriconly cycling (~0.9-1.0 L O2/min) are reportedly equal to or lower than the energy requi rements during concentriconly cycling (~1.0-1.5 L O2/min) despite a 300-700% greater worklo ad performance during eccentriconly cycling.119 Further, Dudley et al.45 (1991) reported that during traditional resistance training the eccentric action of exercise was responsible fo r ~14% of the total energy cost, suggesting that the concentric phase of traditional re sistance exercise has a higher energy demand. Similarly, the caloric cost of isoinertial (traditional/concentric-eccentric) resistance exercise (3 sets, 8 repetitions leg press) was comparable to the caloric cost of concentriconly resistance exercise (86.10 4.83 kcal vs. 87.21 4.60 kcal, p>0.05), although

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8 significantly greater work was performed dur ing the traditional ex ercise trial (9955.23 643.10 vs. 6318.15 363.45 J, p<0.05).30 Collectively, these results suggest that the eccentric phase of exercise is less metaboli cally demanding than the concentric phase. Metabolic acidosis is associated with skeletal muscle fatigue.149 A few studies have reported that the lactate re sponses following maximal eccentriconly exercise are lower than the responses following maximal concentriconly exercise.22, 47, 83, 101 Conversely, at least one study has demonstrated no differen ce in lactate accumulation between concentric and eccentric muscle actions, when loads were held constant.102 At similar exercise volumes, the lactate a nd ammonia responses were 3-4 fold lower following an eccentriconly (60 sec-1) muscular endurance test compared to a concentriconly (180 sec-1) one-minute muscular endurance test.85 Similarly, Hollander et al.83 (2003) reported an ~5-7 fold greater lactate response following concentriconly resistance training compared to eccentriconly resistance training (4 sets of 12 reps performed at 60-65% 1RM on 4 exercises). These results suggest that eccentriconly exercise produces lower concen trations of lactate and amm onia than an equal volume of concentric exercise. In summary, it appe ars that eccentriconly resistance training results in similar or greater strength gains than concentriconly training. Further, the energy cost and metabolic fatigue associated with eccentriconly exercise appear to be less than that during concentriconly and traditional resistance trai ning, suggesting that eccentriconly exercise may be more metabolically efficient than concentriconly and traditional resistance exercise. Therefore, eccentriconly exercise may be beneficial to at-risk populations with limited cardiovascular cap abilities or those prone to fatigue.

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9 EccentricEnhanced Exercise Eccentricenhanced resistance exercise involves a concentric contraction coupled with a supramaximally loaded eccentric action. A variety of methods (e.g. manual resistance) and machines (i.e. isokinetic dyna mometers, isoload inertial strength training ergometers, and eccentricenhanced selectorized machines) are capable of providing a supramaximal eccentric overloa d during resistance exercise.21, 30, 42, 81, 95 Traditionally, isokinetic dynamometers are used to perform eccentricenhanced resistance exercise; however, limitations exist in isokinetic dyna mometry including the inability to perform bilateral exercises and lack of exercise se lection. A weight training machine called the Maxout (Myonics Corporation, Metairie, LA) is also capable of providing a supramaximal overload during the eccentr ic phase of resistance exercise.17, 95 Additionally, the Maxout can be used with a variety of bilateral multiple-joint exercises, such as the chest press or squat. Theoretically, supramaximally overloading the eccentric phase of exercise may enhance the muscular strength and hypertrophic responses as sociated with resistance training. However, it remain s unclear whether eccentricenhanced training accentuates the strength outcomes following resistance ex ercise. Several studies have reported greater increases in muscular strength 51, 86, 87, 95, 118 and skeletal muscle mass 51, 118 following (7 days-11 weeks) eccentricenhanced training compared to traditional resistance training. One study reported signifi cantly greater strength gains for the elbow extensors (+25% eccentricenhanced vs. +10% traditional; p<0.05), but not the elbow flexors (+10% eccentricenhanced vs. +10% traditional) following nine weeks of eccentricenhanced training, suggesting that the a ccentuated muscular adaptations following eccentricenhanced resistance training may be muscle specific.25 Conversely,

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10 two studies reported similar strength gains following (10-12 weeks) eccentricenhanced and traditional resistance training.17, 59 No studies have reported the effects of eccentricenhanced multiple-joint resistance training (che st press and/or squat) compared to traditional multiple-joint resistance training. Table 1 summarizes the muscular strength results form the published reports on eccentricenhanced resistance training. The metabolic demand and production of fatiguing metabolites associated with eccentricenhanced resistance training has not been reported. However, when training volume is held constant the eccentricenhanced exercising heart rate response (90 bpm vs. 102 bpm, p<0.05), mean arterial pressure (117 mm Hg vs. 132 mm Hg, p<0.05), rate pressure product (151 vs. 191, p<0.05), and rating of perceived exertion (10 vs. 13, p<0.05) are reportedly lower than tr aditional training, respectively.86 These results suggest that during eccentricenhanced resistance training th e metabolic demand and presence of fatiguing metabolites may be lower than during tr aditional resistance training; however, this remains to be fully substantiated. In summary, eccentricenhanced resistance training appears to result in similar or greater strength gains, lower cardiovascula r responses, and lower levels of perceived exertion than traditional resistance trai ning. Determining the neuroendocrine and metabolic responses to eccentricenhanced resistance exercise would improve knowledge related to the effects of this form of exercise on muscle metabolism compared to more traditional forms, as well as help explain the greater muscular adaptations associated with eccentricenhanced resistance training Anabolic Hormone Responses to Resistance Training Anabolic hormones, including testosterone a nd growth hormone (GH), have been shown to favorably affect muscle hypertrophy and ex ercise performance due to their impact on

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11 protein synthesis.38, 92, 113, 161 Traditional resistance training protocols have been shown to acutely stimulate the re lease of both GH and testosterone in a load109, 111, 128, 143, 156 and volume64, 106, 109, 111, 144, 171 dependent manner. It has been suggested that the acute postexercise elevations of serum anabolic horm one concentrations (i.e. total testosterone, bioavailable testosterone, and growth hormone) enhances the skeletal muscle hypertrophic response to resistance training.113 Thus, determining the serum anabolic hormone concentrations, following resistance exercise, may provide a basic mechanistic understanding of the skeletal muscle adapta tion process, particularly as related to eccentricenhanced training. Further information regarding the neuroendocrine responses to traditional resistance training is pr esented in several review articles.38, 113 The following sections will provide a brief overvie w of the specific metabolic responses of testosterone and GH to resistance exercise. Testosterone Testosterone is synthesized from choleste rol and secreted primarily by testicular Leydig cells, in response to a hormonal cascade beginning with the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus.168 Gonadotropinreleasing hormone stimulates both folliclestimulating hormone ( FSH) and leutenizing hormone (LH) from the anterior pituitary, wh ich exert separate effects on testosterone secretion. Leutenizing hormone directly stim ulates testosterone secretion from Leydig cells, whereas FSH upregulates LH receptors in the testis, ultimately leading to increased testosterone release.168 In vivo testosterone is present in three forms, 1) free (unbound), 2) sex-hormone-binding-globulin (SHBG)-bound, and 3) albumin-bound.172 Both albumin-bound and free testosterone readily traverse tissue membranes and thus are referred to collectively as bioavailable testosterone.139 Bioavailable testosterone is

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12 Table 1. Overview of strength outcomes from eccentricenhanced studies Author Year Length Subjects Training Test % Traditional % ECC-E nhanced Hortobagyi et al (2001) 1 week 7 sessions SED F n=30 CON 60%, ECC 100-110% 1RM 3RM+11% ECC* +27% CON* +27% ECC* +26% CON Hortobagyi et al (2000) 1 week 7 sessions UNT F n=30 CON 60%, ECC 110% 1RM 5-6 sets, 9-12 reps 3RM+18% ECC* +43% CON* +33% ECC* +43% CON Friedmann et al (2004) 4 weeks 12 sessions UNT M n=18 CON 30%, ECC 70% 1RM 3 sets, 25 reps ISO Value Not Reported +5%* Kaminski et al (1998) 6 weeks 12 sessions Healthy M n=27 CON 40%, ECC 100% 1RM 2 sets, 8 reps ECC ISO Value Not Reported +37.7%(60/sec)* +22%(180/sec)* Brandenburg et al (2002) 9 weeks 25 sessions TRN M,F n=23 CON 75%, ECC 100-110% 1RM 1RM+10% EF* +10% EE* +8% EF* +25% EE* Barstow et al (2003) 10 weeks 20 sessions UNT M n=28 CON 80%, ECC 120% 1RM 1 set, 8-12 reps 1RM CON 95%* +93%* Godard et al (1998) 12 weeks 24 sessions TRN M,F n=39 CON 66%, ECC 100% 1RM 3 sets 6-10 reps 1RM CON +13.8% +15.5% Mean strength differences were calculated or estimated. Resu lts significantly greater than baseline (p<0.05). Results signi ficantly greater than traditional resistance tr aining (p<0.05). Abbreviations: % (percent change in streng th), UNT (Untrained), TRN (trained), SED (Sedentary), M (Males), F (Females), ECC (Ecentr ic), CON (Concentric), ISO (Isokinetic), KE (Knee Extension), KF (Knee Flexion), EE (Elbow Exte nsion), EF (Elbow Flexion).

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13 capable of binding to androgen receptors located in heart, brain, liver, kidney, prostate, bone, and skeletal muscle tissues.160 Upon binding in skelet al muscle, the androgenreceptor complex 1) is directed to the cell nuc leus, 2) attaches to nuclear chromatin, 3) stimulates mRNA transcription, and 4) upre gulates protein synt hesis; therefore, contributing to skelet al muscle hypertrophy.160 Conversely, SHBGbound testosterone cannot cross tissue membranes and therefore, is unable to interact with androgen receptors.139 Detailed information regarding the effects of testosterone on muscle metabolism has been previously reported.38, 151, 160, 161 Growth Hormone Growth hormone is secreted by the anterior pituitary gland in response to elevated levels of growth hormone releasing hormone (GHRH).92 Since GH receptors are present in numerous tissues (bone, immune cells, skelet al muscle, fat cells, and liver cells), it has various effects, including: decreasing gluc ose utilization and glycogen synthesis, increasing protein synthesis, fa tty acid utilization, collagen synthesis, nitrogen retention, and amino acid transport into cells, and stimulating cartilage growth.92, 164 Growth hormone directly affects cellular amino acid uptake and enhances pr otein synthesis and thus contributes to skeletal muscle hypertrophy.92 Many of the anabolic effects of GH may also be due to its stimulatory effects on IGF-1 production.92, 133, 164 Detailed information regarding the effects of GH on muscle metabolism has been previously reported.92, 133, 164 Growth Hormone and Testosterone Re sponses to Resistance Exercise The GH and testosterone responses to tr aditional resistance exercise are well characterized. In general, it appears that higher volumes of exercise (i.e. greater number of reps/sets),64, 82 short rest periods (~1-minute),109, 111 moderate intensities (8RM-

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14 12RM),109, 111, 142, 171 and large muscle group exercise s (e.g. squats, deadlifts, etc)75, 108 result in the largest serum GH concentrations Similarly, higher volumes of exercise,24, 64, 144 short rest periods,109, 111 higher intensities (~5RM),109, 111 and large muscle group exercises75, 174 result in the largest serum free and/or total testosterone concentrations. Conversely, Ahtiainen et al. have reported that differing rest times (between sets)6 and exercise intensities8 do not alter the free and total testosterone responses following resistance exercise; however, the rest times (2-minutes vs. 5-minutes) and exercise intensities (8RM vs. 12RM) reported in thes e studies were outside the ideal ranges for testosterone release sugges ted in previous studies,109, 111 possibly confounding the results. The use of forced repetitions (i.e. repeti tions performed beyond concentric muscle failure with the assistance of a spotter) has be en reported to result in a larger GH response than traditional resistance exercise,7, 8 suggesting that work performed beyond concentric muscular fatigue may enhance the anabo lic response to exercise. Eccentricenhanced resistance exercise is an alternative method of performing work beyond concentric muscle fatigue. It is possi ble that the anabolic horm one responses to eccentricenhanced resistance exercise may be accentuated due to th e stimulus of this form of exercise. One study has reported that, at iden tical workloads, eccentriconly resistance exercise results in significantly lower lactate, GH, total testos terone, and free testoste rone responses than concentriconly resistance exercise; suggesting th at the neuroendocrine and metabolic responses to resistance training are less responsive to submaximal eccentriconly exercise.47 However, Kraemer et al. (2001) re ported that the GH response following resistance exercise is dependent upon the m ode of training and te sting. Specifically, subjects were divided into four groups, a 1) concentriconly exercise, 2) double volume

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15 concentriconly exercise, 3) concentric-eccentric ex ercise, or 4) no exercise (control) group. Following 19-weeks of training s ubjects performed separate eccentriconly and concentriconly exercise tests to evaluate th e neuroendocrine responses following differing muscle actions. The results of this study demonstrate that the GH responses for the 1) concentriconly and 2) double volume concentric gr oups were ~2-2.5 fold greater following the concentriconly exercise test compared to the eccentriconly test, whereas the GH response for the 3) concentric-eccen tric exercise group was ~70% greater following the eccentriconly exercise test, compared to the concentriconly test. These results suggest that the GH res ponse following exercise is speci fic to the mode of training and that the eccentric phase of traditional (con centric-eccentric) resistance training results in the largest GH release.105 The neuroendocrine and metabolic responses to eccentricenhanced resistance exercise remain to be determined. Conclusion Eccentriconly resistance exercise results in sim ilar, or greater, strength gains with a lower metabolic demand compared to concentriconly exercise. Similarly, eccentricenhanced resistance exercise results in greater muscular strength and skeletal muscle hypertrophy than traditional resistance exercise.25, 51, 86, 87, 95 While there are no published reports on the neuroendocrine or me tabolic responses to eccentricenhanced resistance training, it is possible that eccentricenhanced resistance training may result in accentuated neuroendocrine and/or blunted meta bolic responses. Research designed to elucidate the neuroendocrine and me tabolic responses to eccentricenhanced resistance exercise would contribute to an improve d understanding of the mechanism(s) underlying the muscular strength and hypertrophic responses to resi stance exercise.

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16 CHAPTER 3 METHODS Subjects Twenty-nine, healthy, college-aged ma les volunteered for this study. Each participant completed a health history ques tionnaire (Appendix A) physical activity and dietary questionnaire (Appendix B), and signed an informed consent document approved by the University of Florida In stitutional Review Board prior to participating in the study. Prior to data collection, a tota l of five subjects were removed from this study; four subjects were removed for failure to ab ide by study protocol and one subject was removed due to an injury unrelated to this study. During the study, two subjects completed the baseline testing/blood acquis ition sessions and subsequently asked to be removed from the study due to time constr aints. Additionally, blood could not be acquired from two subjects; therefore, a total of twenty subjects completed all portions of this study. Inclusionary/Exclusionary Criteria To be included in the stu dy, subjects had to be untrai ned (no resistance exercise during the previous six months). Subjects we re excluded if they 1) had an orthopedic injury that would limit participation, 2) had a metabolic disease, 3) had a dietary intake low in calories, fat, carbohydrates, or pr otein that could aff ect hormonal levels,154 4) were a competitive athlete or competed in pow erlifting or bodybuilding during the previous year, 5) had used any ergogenic aid within the past month, 6) had used nutritional supplements within the past month that may affect hormonal levels (Appendix C), or 7)

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17 were taking pharmacological agents that could al ter test results such as anabolic steroids or sympathoadrenal drugs. Additionally, du ring the study subjects were excluded if they missed more than four total exercise training sessions (75% attendance rate) or if they were absent for more three consecu tive exercise training sessions. Experimental Design For this randomized study, subjects participated in a total of 20 experimental sessions, including three (3) base line testing, fifteen (15) exer cise training, and two (2) follow-up testing sessions (see Figu re 1). Prior to the exercise training sessions, subjects were randomly assigned to either the traditional progressive re sistance exercise group or an eccentricenhanced progressive exercise group. During each session, subjects performed a 5-minute warm-up at moderate intensity on a stationary bicycle (Monark, Vansbro, Sweden). Following the warm-up, subjects performed bot h a chest press and squat exercise on the MaxOut exercise mach ine (Myonics Corporation, Metairie, LA), at pre-determined loads (see section entitled Ex ercise Training). Three sessions were performed per week, with a minimum of 48 hours separating each session. Dietary recalls were monitored throughout the testing period to ensure all subjects consumed a similar diet on testing days.154 During the study intervention, subjects were instructed to continue their normal activities and nutrient in takes. Additionally, subjects were asked to abstain from weight lifting not associated with this study.

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18 Figure 1. Experimental design. Abbreviati ons: Con (concentric), Ecc (eccentric). BASELINE SESSION 1 1RM Testing Anthropometrics BASELINE SESSION 2 1RM Testing BASELINE SESSION 3 4 Sets @ 52.5% 1RM Traditional TRAINING SESSION 1 Exercise Protocol TRAINING SESSION 1 Exercise Protocol ECCENTRICENHANCED GROUP 5 Weeks, 3 x Week-1 3 Sets, 1 min Rest 40% 1RM Con / 100% 1RM Ecc BLOOD SAMPLING TRADITIONAL GROUP 5 Weeks, 3 x Week-1 4 Sets, 1 min Rest 52.5% 1RM Con / 52.5% 1RM Ecc TRAINING SESSIONS 2-14 Exercise Protocol TRAINING SESSIONS 2-14 Exercise Protocol FOLLOW-UP SESSION 1 1RM Testing Anthropometrics TRAINING SESSION 15 Exercise Protocol TRAINING SESSION 15 Exercise Protocol BLOOD SAMPLING MATCHED & RANDOMIZED BLOOD SAMPLING T=0, 1, 15, 30, 45, 60 min FOLLOW-UP SESSION 2 4 Sets @ 52.5% 1RM

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19 Baseline Testing During baseline session 1, subjects were familiarized with the exercise protocol. Familiarization included 1) instruction on proper use of the chest press and squat exercise and 2) practicing the chest press and squat exer cises at a submaximal load. Subjects were subsequently asked to perform a 1RM on each ex ercise (chest press and squat), according to standard protocol.27 Additionally, subjects height and weight were measured on a medical scale and body density was determined by a 3-site skinfold measure,91 using Lange calipers (Beta Technol ogy Incorporated, Cambridge, Maryland). Body density was used to estimate body composition.28 During baseline session 2, subjects performed a 1RM on each exercise, according to standard protocol.27 During baseline session 3, subjects entered the laboratory, following a 12-hour (overnight) fast and rested for 10 minutes prior to 10ml (2 teaspoons) blood sample acquisition by a certified phlebotomist. Immediately following the initia l blood acquisition, subjects pe rformed four sets of each exercise at 52.5% 1RM; the speed of each repetition was standardized so that the concentric and eccentric actions were each pe rformed for two seconds each. Each set was separated by one minute of rest. Add itionally, 10ml blood was acquired at five additional time points, immediately post exer cise (t=1), 15 minutes (min) post exercise (t=15), 30 min post exercise (t=30), 45 min pos t exercise (t=45), and 60 min post exercise (t=60). These time points were selected as bo th testosterone and GH concentrations peak within 30 min of exercise completion and re main elevated for ~60 min post-exercise.113 Exercise Training During all exercise training sessions, the eccentricenhanced group performed three sets (40% 1RM concentric, 100% 1RM eccentric) of six repetitions each and the traditional group performed four sets (52.5% 1RM concentric, 52.5% 1RM eccentric) of

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20 six repetitions each, for each exercise. Tr aining load was increased 5-10 pounds for the subsequent training session wh en all repetitions were completed with proper form. During training, the traditional group performed an additional se t in an attempt to equate exercise volumes between groups. Each re petition was performed at a cadence of two seconds concentric and two seconds eccentric to account for possible differences in outcome measures due to the speed of movement.90, 131, 136, 177 Each set was separated by one minute of rest. Additionally, during ex ercise training sessions 1 and 15, 10ml blood was acquired at six time points, correspondi ng to the previous protocol. No blood samples were acquired during ex ercise training sessions 2-14. Follow-Up Testing During follow-up session 1, subjects perf ormed a 1RM on both the chest press and squat exercises, according to standard protocol.27 Additionally, subjec ts height, weight, and lean body mass were measured, as perfor med during baseline testing. During followup session 2, subjects performed a 1RM on bot h exercises. Additionally, during followup session 2, subjects performed four sets ( 52.5% 1RM) for both exercises, as performed during baseline testing. The 1RM testing and 52.5% 1RM testing was separated by a 10 minute break, in an effort to offset fatigue. Dietary Analysis Subjects were given standard dietary inst ructions for nutrient intake for the one day prior to blood acquisition. Intake inst ructions were based on American Heart Association Guidelines (i.e. 50-60% car bohydrate, <30% fat, 10-15% protein).120 Subjects were asked to complete a three-day dietary record at the onset of the study and one-day dietary records on the day prior to each blood draw (Appendix D). When reporting for blood draws, subjects were aske d to refrain from f ood, drink, alcohol, and

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21 caffeine consumption for 12 hours prior to blood collection (i.e. overnight fast). Analysis of total dietary kilocalories and macronutri ents consumption was performed using the DietOrganizer 2.2 (MulberrySoft ) dietary analysis program. Sleep Analysis Subjects were given standard instructi ons for sleeping on the one day prior to blood acquisition. Instructions were based on the National Sleep Federation recommendations of 7-10 hours per night. S ubjects were asked to record their total number of hours slept each night, throughout the study. Blood Collection Whole blood was collected by a certif ied phlebotomist via venipuncture or catheter from an antecubital forearm vei n. Blood samples (10mL) were collected immediately before (t=0) and after exerci se (t=1, 15, 30, 45, and 60 minutes) into serum tubes with no additives (red top) and plasma tubes with an EDTA additive (pink top). The total volume of blood collected per day wa s 60 mL. Samples were stored at 4C until centrifugation. Hematocrit, hemoglobi n, and lactate determinations were determined using whole blood and the rema ining blood was centrifuged at 3000g for 12 minutes. Serum and plasma samples were separated and stored at -80 C until analyzed. Day-to-day variability in blood parameters was minimized by collecting blood samples during the same time of day (7:00-10:30am) for each subject. Biochemical Analyses Hematocrit percent was determined by the microcapillary tube method.40 Hemoglobin concentration was determined w ith the Hgb Pro hemoglobin analyzer (ITC, Edison, New Jersey). Whole-blood lactat e was measured by the Accusport Lactate Analyzer (Roche Molecular Biochemicals, Mannheim, Germany). Serum aliquots were

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22 analyzed for growth hormone (GH), total test osterone, and bioavail able testosterone. Serum growth hormone (GH) was determined by an enzyme-linked immunosorbent assay (ELISA) (Diagnostic Systems Laboratories, Inc., Webster, Texas). Serum total testosterone was determined by enzyme immunoassay (EIA) (Diagnostic Systems Laboratories, Inc., Webster, Texas). Serum bioavailable testosterone was determined by an ammonia sulfate precipitation method.121 Briefly, a saturated ammonia sulfate/DI water solution was combined with serum (1:1 ) to induce precipitation of sex-hormone binding globulin. The combined samples were immediately vortexed and stored at room temperature for 10 minutes prior to centrif ugation. The supernatant was then analyzed by EIA (Diagnostic Systems Laboratories, Inc ., Webster, Texas). All samples were performed in duplicate and in a single r un. Serum hormone concentrations were subsequently corrected for plasma volume changes, estimated by hemoconcentration.40 Data Analysis The SPSS 12.0.1 statistical package was used fo r the statistical analysis. All values are reported as the mean SE. Preto post-comparisons were performed using a 2 (Groups) x 2 (Time) repeated measures ANOV A. Biochemical markers were compared using 2 (Groups) x 6 (Time) Repeated Meas ures ANOVAs. When necessary a Tukeys post hoc analyses was implemented. Alpha levels for all measurements were set at p 0.05. Sample Size The hormonal dependent variables in this study are serum growth hormone, total testosterone, and bioavaible te stosterone. Of these measures, growth hormone has been reported to be the most responsive to resistan ce exercise and thus was used for sample

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23 size calculations. Standard sample size calcul ations were used to estimate the number of subjects required123 and were based on previously re ported data (4 sets 12RM squat exercise).8 The results of the power calculation indicated fourteen subjects (n=7 each group) would provide a power of 80% at an alpha level of 0.05 to detect differences in growth hormone (See Power cal culation, Appendix E).

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24 CHAPTER 4 RESULTS Subjects Twenty-four previously untrained, college-aged males (21.9 0.8 years), randomized into traditional (n=12) or eccentricenhanced (n=12) groups participated in this study. No significant differences were observed for any demographic measure, between groups (Table 2). Table 2. Subject characteristics pre an d post 5 weeks of resistance training TRADITIONAL ECCENTRICENHANCED PRE POST PRE POST BMI (kg/m2) 25.9 1.2 25.8 1.1 25.8 1.3 26.2 1.4 Weight (kg) 78.8 2.9 78.5 2.7 81.1 3.0 82.1 3.2 Body Fat % 19.5 2.1 19.9 2.1 19.5 2.5 19.8 2.3 Data are expressed as Mean SE. Biochemical Results For clarity, the terms untrained and trained will be used to describe the groups at baseline (before) and following the five-w eek exercise intervention, respectively. At baseline, both groups performed tw o testing sessi ons separated by 48 hours. During session 1 both groups performed a standardized traditional resistance ex ercise protocol (4 sets x 6 reps; 52.5% 1RM), whereas during session 2, the traditional group performed the standardized traditional protocol and the eccentricenhanced group performed an eccentricenhanced (3 sets x 6 reps; 40% 1RM c oncentric, 100% 1RM ecccentric) resistance exercise protocol. At the co mpletion of the exercise intervention, subjects again completed a bout of either trad itional (4 sets x 6 reps) or eccentricenhanced (3 sets x 6 reps) exercise, utilizing the maximum load completed by the end of the five-week

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25 intervention. This study design allowed comp arison of the metabolic and neuroendocrine responses between traditional and eccentricenhanced resistance exercise, in both the untrained and trained states. Blood samples were not acquired from two subjects in the traditional group; therefore all biochemical analyses were performed on 22 subjects (n=10 traditional; n=12 eccentricenhanced ). Lactate Lactate Response to the Standardized Tr aditional Exercise Protocol in Untrained Men The (whole-blood) lactate responses after the standardized re sistance exercise protocol for both groups prior to the training intervention are presented in Figure 2. Lactate concentrations incr eased (~250%) immediately af ter exercise (p<0.05) and gradually returned to baseline by 45 minutes pos t-exercise. No significant differences in lactate concentrations were observed between groups, at any time point. Lactate Response to Traditional Resistance Exercise 1 2 3 4 5 6 7 8 9 PrePost15304560 Time Points Blood Lactate (mmol/l) Traditional Eccentric-Enhanced $ # $ # $ Exercise Post Exercise Recover y Figure 2. Lactate responses to traditional resistance exercise. Indicates significantly different than Pre; $ indicates signifi cantly different than Post; # indicates significantly different than 15 min (p<0.05). Data are Mean SE.

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26 Lactate Responses to Standardized Traditional and EccentricEnhanced Exercise in the Untrained Lactate responses following a single bout of traditional and eccentricenhanced resistance exercise protocols performed at baseline are presented in Figure 3. Before exercise, lactate concentrati ons were similar between groups (~2.5 mmol/l) and increased following exercise, representing 210% and 340% in the traditi onal and eccentricenhanced groups, respectively (p<0.05). During the post-exercise recovery period, lactate gradually returned to baseline within 45 minutes of exercise completion. The immediate post-exercise lactate concen tration was greater in the eccentricenhanced compared to the traditional group (7.8 .4 mmol/l vs. 5.8 0.3 mmol/l, p<0.05). Baseline Lactate Response to Traditional and EccentricEnhanced Resistance Exercise1 2 3 4 5 6 7 8 9 PrePost15304560 Time PointsBlood Lactate (mmol/l) Traditional Eccentric-Enhanced # # $ % $ % $ % Exercise Post Exercise Recovery Figure 3. Baseline lactate responses to traditional and eccentricenhanced resistance. Indicates significant difference betw een groups; # indicates significant difference from baseline, $ indicate s difference from post, % indicates difference from 15 minutes (p< 0.05). Data are Mean SE.

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27 Lactate Response to Standardized Traditional and EccentricEnhanced Exercise in Trained Men Following the five-week training inte rvention, the post-ex ercise lactate concentrations increased in both th e traditional (~420%) and eccentricenhanced (~340%) groups immediately following exercise (p<0.05) and gradually returned to baseline within 45 minutes of exercise cessati on (Figure 4). No signi ficant differences in lactate concentrations were observed between groups at any time point, including preand post-exercise as well as recovery. Post-Intervention Lactate Responses to Traditional and EccentricEnhanced Resistance Exercise 1 2 3 4 5 6 7 8 9 PrePost15304560 Time pointsBlood Lactate (mmol/l) Traditional Eccentric-Enhanced # # $ # $ % $ % $ % Exercise Post Exercise Recovery Figure 4. Post-intervention lactate re sponses to traditional and eccentric-e nhanced resistance exercise. # indicates di fference from baseline, $ indicates difference from post, % indicates diffe rence from 15 minutes (p<0.05). Data are expressed Mean SE. Testosterone Resting Testosterone To account for diurnal variation in testos terone secretion, tw o resting baseline blood samples were acquired 48 hours apart. No significant differences in either total (6.45 0.47 ng/ml session 1 vs. 6.96 0.55 ng/ml session 2) or bi oavailable (4.10 0.30

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28 ng/ml session 1 vs. 4.13 0.27 ng/ml) testoste rone concentrations were observed on either day; therefore, the average testoster one concentrations were used as the baseline resting value. Resting total serum testoste rone concentrations (Figure 5) remained unchanged with training for both groups. Howe ver, resting bioavail able testosterone Resting Baseline and Post-Intervention Total Testosterone Concentrations 4 5 6 7 8 9 10Testosterone (ng/ml) Baseline Post Baseline Post TRADITIONAL GROUPECCENTRIC-ENHANCED GROUP Figure 5. Total serum testosterone before (Baseline) and after (Post) the training intervention. Indicates a significant difference is present (p<0.05). Data are presented as Mean SE. Resting Baseline and Post-Intervention Bioavailable Testosterone Concentrations2 2.5 3 3.5 4 4.5 5 5.5 6Bioavailable Testosterone (ng/ml) * TRADITIONAL GROUPECCENTRICENHANCED GROUP Baseline Post Baseline Post Figure 6. Total bioavailable testosterone before (Baseline) and after (Post) the training intervention. Indicates a significant difference is present compared with baseline value (p<0.05). Data are presented as Mean SE.

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29 concentrations (Figure 6) were ~24% lo wer in both groups following the five-week resistance training intervention (p<0.05). Additionally, resti ng bioavailable testosterone accounted for 61% and 46% of total resting test osterone at baseline and post-intervention in both groups, respectively. No significant differences were observed between groups for either resting total or bioavailable testoste rone concentrations, in either the trained or untrained states. Testosterone Responses to the Standard ized Traditional Exercise Protocol in Untrained Men Following the standardized traditional re sistance exercise protocol, the postexercise total testosterone concentrations (immediately to 30 minutes post) were not significantly different from baseline (Fi gure 7); however, 45-60 minutes following training the total testosterone concentrat ions decreased below baseline (p<0.05). Similarly, the post-exercise bioavailable test osterone concentrations (immediately to 15 minutes post) were not signifi cantly different from baselin e (Figure 8); however 30-60 minutes following training the bioavailable test osterone concentrati ons decreased below baseline (p<0.05). No significant differences in either total or bioa vailable testosterone concentrations were observed betw een groups at any time point. Testosterone Responses to Standa rdized Traditional and EccentricEnhanced Exercise in Untrained Men Total testosterone responses following a standardized traditional and eccentricenhanced resistance exercise protocol (Figure 9) were not significantly different than baseline (immediate to 45 minutest post); how ever, total testosterone was lower than both baseline and immediate post concentrations at 60 minutes (p<0.05). The bioavailable testosterone concentrations (Figure 10) increased immediately following exercise and decreased to below baseline concentrations within 60 minutes of exercise completion

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30 Total Testosterone Responses to Standardized Traditional Resistance Exercise Protocol 3 4 5 6 7 8 9 10 PrePost15304560 Time PointsTestosterone (ng/ml) Traditional Eccentric-Enhanced # # Exercise Post Exercise Recovery Figure 7. Total testosterone re sponses to standardized traditional resistance exercise protocol. Indicates si gnificantly different value than Post; # indicates significantly different value than 15 mi n (p<0.05). Data are expressed as Mean SE. Bioavailable Testosterone Responses to Standardized Traditional Resistance Exercise Protocol2 2.5 3 3.5 4 4.5 5 5.5 6 PrePost15304560 Time PointsBioavailable Testosterone (ng/ml) Traditional Eccentric-Enhanced # # $ # $ % Exercise Post Exercise Recovery Figure 8. Bioavailable testoste rone responses to standardi zed traditional resistance exercise protocol. Indicat es significantly different value than Pre; # indicates significantly different value than Post; $ indicates significant ly different value than 15 min; % indicates significantly diffe rent value than 30 min (p<0.05).

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31 (p<0.05). No significant diffe rences were observed for either total or bioavailable testosterone concentrations between groups at any time poi nt, including preand postexercise as well as recovery. Total Testosterone Responses to Standardized Traditional and EccentricEnhanced Resistance Exercise 3 4 5 6 7 8 9 10 PrePost15304560 Time PointsTestosterone (ng/ml) Traditional Eccentric-Enhanced # Exercise Post Exercise Recovery Figure 9. Total testosterone responses to standardized traditional and eccentricenhanced resistance exercise in un trained men. Indicates difference from baseline; indicates difference from post. Data are expressed Mean SE. Testosterone Responses to Standa rdized Traditional and EccentricEnhanced Resistance Exercise in Trained Men At post-intervention testing, to tal testosterone concentra tions (Figure 11) increased immediately following exercise and decrease d to below baseline values within 30 minutes of exercise completion (p<0.05). Bioavailable testoster one concentrations increased immediately following exercise in both groups and remained elevated for 15 minutes (p<0.05), before returning to baseline (Figure 12). No si gnificant differences were observed between groups for either total or bioavailable testoste rone concentrations, at any time point.

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32 Bioavailable Testosterone Responses to Standardized Traditional and Eccentric-Enhanced Resistance Exercise 2 2.5 3 3.5 4 4.5 5 5.5 6 PrePost15304560 Time PointsBioavailable Testosterone (ng/ml) Traditional Eccentric-Enhanced # # # # $ Exercise Post Exercise Recover y Figure 10. Bioavailable testoste rone responses to standardized traditional and eccentricenhanced resistance exercise in untrained men. Indicates significantly different value than Pre; # indicates significantly diffe rent value than Post; $ indicates significantly different va lue than 15 min (p<0.05). Data are expressed Mean SE. Post-Intervention Testosterone Responses to Standardized Traditional and Eccentric-Enhanced Resistance Exercise Protocols 3 4 5 6 7 8 9 10 PrePost15304560 Time PointsTestosterone (ng/ml) Traditional Eccentric-Enhanced * # # $ # $ Exercise Post Exercise Recovery Figure 11. Post-intervention total serum testosterone responses to standardized traditional and eccentricenhanced r esistance exercise protocols. Indicates significantly different value than Pre; # indicates significan tly different value than Post; $ indicates sign ificantly different value than 15 min (p<0.05). Data are expressed Mean SE.

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33 Post-Intervention Bioavailable Testosterone Responses to Traditional and EccentricEnhanced Resistance Training 2 2.5 3 3.5 4 4.5 5 5.5 6 PrePost15304560 Time PointsBioavailable Testosterone (ng/ml) Traditional Eccentric-Enhanced* # $ # $ # Exercise Post Exercise Recover y Figure 12. Post-intervention bi oavailable serum testosterone responses to standardized traditional and eccentric-enhanced re sistance training. Indicates significantly different than Pre; # indicates significan tly different than Post; $ indicates significantly different than 15 min (p<0.05). Data are Mean SE. Growth Hormone Growth Hormone Response to Standardiz ed Traditional Exercise Protocol in Untrained Men Following the standardized traditional resi stance exercise prot ocol, post-exercise growth hormone (GH) concentrations incr eased above baseline 15-30 minutes after exercise cessation (p<0.05) and subsequently returned to baseline by 45 minutes, in both groups (Figure 13). No signifi cant differences in GH concentrations were noted between groups, before of after the exercise bout. Growth Hormone Response to Standa rdized Traditional and EccentricEnhanced Exercise in Untrained Men Growth hormone responses following a st andardized traditional and eccentricenhanced exercise protocol increased 15-30 mi nutes post-exercise (p <0.05) and returned to baseline by 45 minutes (Figure 14). No significant differences in GH concentrations were observed between groups, be fore or following exercise.

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34 Growth Hormone Responses to Standardized Traditional Exercise Protocol 0 0.5 1 1.5 2 2.5 3 3.5 4 PrePost15304560 Time PointsGrowth Hormone (ng/ml) Traditional Eccentric-Enhanced * Exercise Post Exercise Recovery Figure 13. Growth hormone responses to the st andardized traditional resistance exercise protocol in untrained men. Indica tes significantly different than Pre (p<0.05). Data are presented as Mean SE. Growth Hormone Responses to Traditional and EccentricEnhanced Resistance Exercise 0 0.5 1 1.5 2 2.5 3 3.5 4 PrePost15304560 Time PointsGrowth Hormone (ng/ m Traditional Eccentric-Enhanced * Exercise Post Exercise Recovery Figure 14. Growth hormone responses to standardized traditional and eccentricenhanced exercise protocols, in untrai ned men. indicates significantly different than Pre (p<0.05). Data are Mean SE.

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35 Growth Hormone Response to Standa rdized Traditional and EccentricEnhance d Exercise in Trained Men Following the five-week training interv ention, GH was unchanged from baseline immediately following exercise but increased above baseline 15-45 minutes following exercise (p<0.05) and returned to baselin e by 60 minutes (Figure 15). No significant differences in GH concentrations were obs erved between groups, at any time point. Post-Intervention Growth Hormone Responses to Traditional and EccentricEnhanced Resistance Exercise0 0.5 1 1.5 2 2.5 3 3.5 4 PrePost15304560 Time PointsGrowth Hormone (ng/ml) Traditional Eccentric-Enhanced * Exercise Post Exercise Recovery Figure 15. Post-intervention growth hormone responses to standardized traditional and eccentricenhanced resistance exercise. Indi cates significantly different value than Pre (p<0.05). Data are presented as Mean SE. Plasma Volume Preand post-exercise plasma volume values for each exercise testing/blood acquisition session are presented in Appendix F. Briefly, plasma volume was reduced immediately post-exercise (5-11%; p<0.05) and re turned to baseline within 30 minutes of exercise cessation during each testing sessi on. No significant differences in plasma volume were observed between groups, at any time point.

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36 Muscle Function Muscular strength data is reported as ab solute (1RM) and relative (1RM x kg body mass-1 and 1RM x kg lean body mass-1) values. Additionally, total work (load lifted x repetitions completed) was used to quantify muscular endurance. Two subjects from the eccentricenhanced group did not complete the tr aining intervention; therefore performance results reflect 22 subjects (n=12 traditional; n=10 eccentricenhanced ). Muscular Strength No statistical differences in strength were observed betw een groups at baseline, for the chest (press) or leg (squat) (Table 3). Following the fi ve-week exercise intervention, both groups showed similar increases in ab solute (1RM) and relative (1RM x kg body mass-1 and 1RM x kg lean body mass-1) chest strength (p<0.05). Additionally, both groups showed similar increases in absolute leg strength (p<0.05), whereas the traditional group exhibited a greater increase in relativ e leg strength compared to the eccentricenhanced group (p<0.05). Muscular Endurance Muscular endurance measures are repo rted as total work, calculated as: Total Work (kg) = Load (kg) Tota l Number of Repetitions Completed Chest and leg endurance values were simila r between groups at baseline (Table 4). Following the exercise intervention, both groups showed similar increases in chest and leg endurance (p<0.05).

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37 Table 3. Muscular strength values at baseline and post-intervention for the traditional and eccentricenhanced groups. TRADITIONAL ECCENTRICENHANCED PRE POST % PRE POST % 1RM (kg) 76.9 4.4 84.7 4.8* 10.1 75.5 4.9 82.3 5.0* 9.0 kg/mass 0.97 0.04 1.08 0.05* 11.3 0.93 0.06 1.01 0.06* 8.6 CHEST kg/FFM 1.23 0.06 1.35 0.07* 9.8 1.16 0.06 1.25 0.06*7.8 1RM (kg) 101.5 7.6 127.3 7.0* 25.4 102.7 4.6 121.8 5.8*18.6 kg/mass 1.29 0.10 1.62 0.08* # 25.6 1.28 0.06 1.49 0.06* # 16.4 SQUAT kg/FFM 1.61 0.09 2.03 0.08* # 26.1 1.59 0.06 1.86 0.07* # 17.0 Indicates difference from corresponding pretest value; # indicates difference between groups (p<0.05). % reflects the percentage change in muscular strength from baseline to post-intervention testing, mass represents body mass in kg, FFM represents fat-free mass in kg. Data are expressed as Mean SE. Table 4. Muscular endurance (tot al work) measures at baseli ne and post-intervention for the traditional and eccentricenhanced groups. TRADITIONAL ECCENTRICENHANCED PRE POST % PRE POST % Chest Press 1010 54 1100 63* 8.9% 995 61 1086 65* 9.1% Squat 1318 97 1604 104*21.7% 1353 61 1615 78* 19.4% Indicates significantly diffe rent value than corresponding pre-test value (p<0.05). % represents percentage change in muscular endurance from baselin e to post-intervention testing. Data are Mean SE. Rating of Perceived Exertion The ratings of perceived exertion (RPE)153 acquired during each exercise session throughout the five-week training intervention are presented in Figure 16. The traditional group had a significantly lower RPE during se ssions 1-4, compared to the eccentricenhanced group (p<0.05). No other significant differences were observed during any exercise training session.

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38 Ratings of Perceived Exertion Values Per Session 10 11 12 13 14 15 16 17 18 19 20 123456789101112131415 Session #RPE Value Traditional Eccentric-Enhanced * * Figure 16. Ratings of perceive d exertion (Borg Scale) foll owing each exercise training session. Indicates significantly diffe rent value between groups (p<0.05). Data are expressed as Mean SE. Training Volume Training volume is reported as, 1) training volume per ex ercise session and 2) total training volume across the five-week training intervention. Training volume per session was determined using the following equation: VOLUME = [# of CON actions CON l oad] + [# of ECC actions ECC load] Total training volume during the exercise intervention was determined by summing each per session training volume. Further, individual chest press and squat training volumes were quantified to determine the total work performed on each exercise and a combined (chest press volume + squat) tr aining volumes was calculated, as the combined training volume may be indicative of pos t-exercise hormonal responses.113

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39 Training Volume Per Exercise Session The chest press volume per session (Figur e 17) was greater dur ing sessions 2-11, 13, and 15 for the traditional group, compared to the eccentricenhanced group (p<0.05). The squat volume per session (Figure 18) was greater during sessions 9, 10, 14, and 15 for the traditional group, compared with the eccentricenhanced group (p<0.05). The combined training volume per session (Figur e 19) was greater during sessions 7 and 15 for the traditional group, co mpared to the eccentricenhanced group (p<0.05). Chest Press Volume Per Session1500 1700 1900 2100 2300 2500 2700 2900 123456789101112131415 Trainin g Session Total Load [Reps Weight (kg)] Traditional Eccentric-Enhanced * * * * * * Figure 17. Chest press trai ning volume per session for the traditional group and eccentricenhanced groups. indicates signifi cantly different value between groups at the designated session (p <0.05). Data are Mean SE.

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40 Squat Volume Per Session 2300 2500 2700 2900 3100 3300 3500 3700 3900 4100 4300 123456789101112131415 Session #Total Load [reps weight (kg)] Traditional Eccentric-Enhanced * * Figure 18. Squat training volume per sess ion for the traditional and eccentricenhanced Indicates significantly different value between groups at the designated session (p<0.05). Data are Mean SE. Combined Chest Press and Squat Volume Per Session 3500 4000 4500 5000 5500 6000 6500 7000 123456789101112131415 Session #Total Load [Reps*Weight (kg)] Traditional Eccentric-Enhanced * Figure 19. Combined training volume per session (Chest Press + Squat) for the traditional and eccentricenhanced groups. Indicates significantly different value between groups at the designate d session (p<0.05). Data are Mean SE.

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41 Total Accumulated Training Volume Across Five-Week Intervention In this section, total training volume refe rs to the total training volume performed during the entire five-week exercise interv ention. The chest press training volume (Figure 20) was greater in the traditio nal group, compared with the eccentricenhanced group (34,802 1550 kg vs. 29,438 1683 kg, p<0.05), while the total squat training volume (Figure 19) was not statistically di fferent between the traditional and eccentricenhanced groups (48151 2764 kg vs. 43020 1838 kg). The total combined training volume (chest press + squat volumes) (Figure 21) tended to be greater for the traditional group, compared with the eccentricenhanced group (83037 4082 kg vs. 72485 3164 kg); however, statistical significan ce was not achieved (p=0.061). Total Chest Press and Squat Training Volume During Exercise Intervention20000 25000 30000 35000 40000 45000 50000 55000Training Load (kg) TRAD ECC TRAD ECC CHEST PRESS SQUAT Figure 20. Total chest press and squat trai ning volume during the fi ve week resistance exercise intervention. TRAD represents the traditional group, ECC represents the eccentricenhanced group. Indicates significantly different value between groups (p<0.05). Data are expressed as Mean SE.

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42 Combined Total Training Volume (Chest Press + Squat) During Exercise Intervention 50000 55000 60000 65000 70000 75000 80000 85000 90000 95000 100000Total Training Load (kg) Traditional Eccentric-Enhanced Figure 21. Combined total tr aining volume (Chest Press + Squat) during the five-week exercise intervention. Indicates a trend towards significantly different values between groups (p=0.061). Da ta are expressed as Mean SE. Dietary Analysis No significant differences were noted between groups for any dietary measure (total daily kilocalorie, carbohydrate, protein, or fat consumption) throughout the duration of the study (Table 5). On averag e, subjects consumed ~2238 kcals per session, which was comprised of ~50.3% carbohydrates ~33.2% fat, and ~16.2% protein (~1.1g x kg body mass-1). Additionally, all subjects completed a 12 hour fast prior to blood acquisitions; as indicated by dietary reco rds and follow-up questions concerning food, drink, alcohol, and caffeine cons umption prior to blood acquisition. Sleep Analysis The average number of hours slept per nigh t in the traditional (7.2 0.4 hours) and eccentricenhanced (7.8 0.2 hours) groups were not statistically different throughout the exercise intervention. Additionally, 100% of subjects re ported 7-10 hours of sleep on the night preceding blood acquisition sessions.

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43 Table 5. Average reported kilocalories, carbohydra tes, protein, and fat in the traditional and eccentricenhanced groups. TRADITIONAL ECCENTRICENHANCED KCALS % TOTAL INTAKE KCALS % TOTAL INTAKE Total Kcals 2162 495 2320 853 Carbohydrates 1135 127 52.5% 1093 117 47.1% Protein 326 26 15.1% 427 71 18.4% Fat 689 60 31.9% 771 77 33.2% Data are presented as Mean SE.

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44 CHAPTER 5 DISCUSSION Skeletal muscle atrophy, reduced strength, and heightened fatigue are associated with aging175 and degenerative diseases such as multiple sclerosis155 and muscular dystrophy.11 Participation in progressive resistan ce training has been shown to attenuate loss of strength and function, improve f unctional capacity, and decrease hypokinetic disease risk in both youn g and elderly populations.65, 104 Thus, determining and implementing effective resistance exercise protocols may ultimately minimize the deleterious effects of both aging and degenera tive diseases on skeletal muscle quality and performance outcomes. Traditional resistance training consists of identical loading performed during both concentric (shortening) and eccentric (lengthening) muscle actions.104 Eccentricenhanced resistance exercise is performed with a greater eccentric loading (~180-250% of concentric load) and has been shown to result in similar17, 25, 59 or superior25, 51, 86, 87, 95 skeletal muscle strength and mass adaptations compared to traditional resistance training. However, the mechanism(s) underlying the purported superior muscle adaptations following eccentricenhanced resistance training have not been determined. Therefore, the purpose of our study was to te st the hypothesis that eccentricenhanced progressive resistance training would result in greater ne uroendocrine (total test osterone, bioavailable testosterone, and growth hormone) and muscle performance responses and lower metabolic (lactate) responses than traditio nal progressive resistance training. The primary findings of our research are that th e early-phase (first fi ve-week) neuroendocrine

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45 and performance responses are simila r between traditional and eccentricenhanced resistance training, in previously untrained college-age men. Only one published study has attempted to elucidate the mechanism(s) underlying the purported superior muscular adap tations associated with eccentricenhanced resistance training.51 For comparison, we used inves tigations with training programs most similar in training volume and intensity to ours; however, we were limited to 1) traditional, 2) concentric-only, and 3) eccentr ic-only resistance training protocols, as mechanistic studies on eccentricenhanced training were limited. Eccentricenhanced resistance exercise is somewhat unique in th at it includes a combination of the previously mentioned program designs; therefore, dire ct comparison between study findings should be interpreted cautiously. Metabolic Response to Resistance Exercise Metabolic acidosis, associated with lactate accumulation, may contribute to skeletal muscle fatigue during hi gh-intensity exercise.149 Strategies designed to reduce lactate accumulation during exercise may decrease overall fatigue and ultimately result in improved exercise prescriptions for both healt hy and at-risk populations We are the first to compare the blood lactate responses to eccentricenhanced resistance exercise and traditional resistance exercise, in both the trained and untrained states. Lactate Responses to Standardized Traditional and EccentricEnhanced Resistance Exercise in Untrained Men The immediate post-exercise blood lactate c oncentrations were greater in subjects following a standardized eccentricenhanced resistance exercise protocol compared to a traditional resistance exercise protocol, matched in volume. Our findings may, in part, be due to the greater eccentric-specific ex ercise intensity in the eccentricenhanced group

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46 (40% 1RM concentric; 100% 1RM eccentric), co mpared to the traditional group (52.5% 1RM concentric and eccentric). Previous re ports demonstrate that both exercise volume67 and intensity117 are associated with lact ate accumulation. Our resu lts are consistent with Lagally et al.117 (2002), who reported that higher inte nsity exercises result in greater lactate accumulation. In our study, the eccentric-specific training intensity was 48.5% greater in the eccentricenhanced group, but volume was matc hed between groups (4646 kg, traditional vs. 4344 kg, eccentricenhanced ; p>0.05). In our study, the higher eccentric-spe cific intensity in the eccentricenhanced group may reflect a greater recruitment of fast gl ycolytic (type IIx) a nd/or fast oxidative glycolytic (type IIa) muscle fibers51 and associated lactate accumulation.89 Previous research suggests that eccentric muscle actions recruit all available fast motor units (type IIa and IIx) at lower relative intensities (>60% maximal voluntary contraction) than concentric actions (>80% ma ximal voluntary contraction);122 therefore, it is possible that the eccentricenhanced group recruited a larger portion of fast motor units during exercise resulting in greate r lactate accumulation. It is also possible that diffe rences in (load dependent) skeletal muscle blood flow characteristics may have influenced the la ctate response between groups. For example, arterial blood flow to cont racting skeletal muscle has an inverse relationship with exercise intensity.150 Additionally, combined venous occlusion and low-intensity resistance exercise result in greater lactat e accumulation than low-intensity resistance exercise alone.98 Although blood flow characteristics were not evaluated in our study, greater venous occlusion and/or reductions in arterial blood flow may have occurred in

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47 the eccentricenhanced group (due to the higher eccentric-s pecific load) thus resulting in greater blood lactate concentrations. Lactate Response to Resistance Training in Trained Men The immediate post-exercise lactate respons e to the traditional resistance exercise protocol was greater following the five-week training program when compared to pretraining, possibly due to the greater exercise intensity (64% 1RM vs. 52.5% 1RM), enhanced recruitment of fast glycolytic mu scle fibers, and/or improved storage and utilization of glycogen12 in the trained state. In c ontrast, the immediate post-exercise lactate response s to eccentricenhanced exercise were similar in the trained and untrained states, despite a greater post-intervention eccentric-specific exercise intensity (~106% post-intervention 1RM vs. 100% pre-interven tion 1RM). Our results contrast the supposition by Kraemer et al.103 who suggested that the post-exercise lactate concentrations increase as the eccentric-s pecific exercise intensity increases. Similar post-exercise blood lactate concentr ations were observed in the eccentricenhanced group in both the untrained and trained states, despite the greater exercise intensity performed in the trained state. Friedmann and colleagues51 (2004) reported that eccentricenhanced but not traditional, resistan ce training upre gulates lactate dehydrogenase type (LDH) A mRNA following four weeks of training; indicating a possible lactate buffering effect associated with eccentricenhanced exercise. Additionally, improvements in intracellular lactate buffering and/or delayed lactate accumulation due to a repetitive training stim uli above anaerobic threshold have been observed84, 125, 132 and may help explain our findings. It is also possible that recruitment of a dditional type IIx (hi gh lactate generating) muscle fibers may not have occurred in the eccentricenhanced group in the trained

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48 state.122 Recall that complete recruitment of fa st motor units has been observed during eccentric-only muscle actions performed at intensities (~60% maximal voluntary contraction)122 below that used during baseline testing in our study (100% 1RM); suggesting that full recruitment of fast mo tor units may have o ccurred during baseline testing. However, Friedmann et al.51 (2004), reported that both type IIa and IIx myosin heavy chain (MHC) mRNA are increased following eccentricenhanced resistance exercise; suggesting that fast motor units are extensively recruited during eccentricenhanced exercise. Alternatively, decreased skeletal musc le glycogen content and/or decreased utilization of skeletal muscle glycogen st ores may have occurred in the eccentricenhanced group, as a result of heavy eccentric tr aining. Decreased skeletal muscle glucose transporter (GLUT4 ) protein concentrations,12, 13 impaired glycogen resynthesis,13 and decreased post-exercise glycogen accumulation (for up to 72 hours)178 have been observed following eccentric exercise; suggesting a reduced glycogen availability for subsequent exercise se ssions, following heavy eccentric exercise. Although we did not measure glycogen synthe sis rates or concentr ations, it may be possible that reduced skeletal muscle gl ycogen content limited lactate accumulation during post-intervention testing. Testosterone Testosterone has been shown to enhance muscle hypertrophy by directly increasing protein synthesis,19, 26, 50, 66, 160, 161, 170 thus it is not surprising that investigators have attempted to identify strategies to en hance endogenous free and total testosterone concentrations and optimize gains in muscle mass with resistance exercise.7, 8, 32, 47, 68, 70, 71, 78, 106-109, 111, 115, 169, 176 Total testosterone represents the combination of unbound (free)

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49 testosterone (~2% of total) and testosterone bound to eith er sex hormone binding globulin (SHBG) (~50% of total) or albumin (~50% of total).121 The combination of free and albumin-bound testosterone fractions (bioava ilable testosterone) reflect the effective androgen status, as both fractions have been shown to traverse cell membranes, bind with androgen receptors, and consequently stimulate protein translation.41, 121, 172 To date, there are no published reports on the bioa vailable (non-SHBG-bound) testosterone responses to resistance exercise. The majo rity of studies utiliz ing resistance training interventions report free testosterone7, 47, 70, 71, 169 which represents only a small portion (~4%) of bioavailab le testosterone; 121 therefore, comparison of our results to previous reports is not possible. Resting Testosterone Resting total testosterone concentrations in our subjects were within the normal eugonadal range (300-1000 ng/dl).126 Resting total testosterone concentrations remained unchanged, while the bioavailable testosterone fraction decreased w ith training in both groups. Our findings are consiste nt with previous reports dem onstrating that resting total testosterone levels are unaltered following resistan ce training interventions10, 71-73, 78, 110, 113, 128 and inconsistent with ot hers showing upward trends.167 Considering that total testosterone is comprised of three components (free, albumin-bound, and SHBG-bound), interpretation of our bioavailable testosterone results is speculative as each subfraction may infl uence the bioavailable fraction. Our results may suggest however, that 1) SHBG-bound te stosterone increased, as non-SHBG-bound (bioavailable) testosterone decreased and total testosterone remained unchanged, 2) albumin-bound testosterone decreased, and/or 3) free testosterone decreased. The literature indicates that SHBG is apparently unr esponsive to either acute180 or

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50 chronic73, 114, 128 resistance exercise, in men. Add itionally, albumin has been shown to increase following both acute4 and chronic resistance training interventions;100 suggesting that albumin-bound testosterone may not dimini sh following resistance exercise. Further, resting free testosterone has b een shown to either increase110 or remains constant5 following resistance exercise interventi ons. Although not measured in our study, alterations in the free:albumin-bound:SHBG-b ound testosterone ra tio occurred, favoring an increase in SHBG-bound and/or a decline in bioavailable testoste rone concentrations at the conclusion of our study. Alternatively, upregulation of skeletal muscle androgen receptor expression may have occurred in response to training. S upport for this idea comes from studies that report increased skeletal muscle androgen receptor expression following resistance training interventions, in both humans15, 180 and animals.39, 173 Androgen receptor upregulation with training may help explain the reduction in bioava ilable testosterone concentrations observed following th e five-week training program. Previous reports have also suggest ed that acute sleep deprivation,1, 62, 135 low dietary total caloric and fat intakes,154, 174 and/or high diet ary protein intake154 are associated with reduced resting total testoste rone concentrations. Our subjects reported normal sleep patterns (7-10 hours)14 and adequate caloric in takes (~2220 kcals; 50.3% carbohydrates, ~33.2% fat, and ~16.2% protein)120 on the day prior to each blood acquisition session. Therefore, it does not appear that slee p patterns or dietary intake influenced the resting hormone concentrations in our study.

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51 Testosterone Response to Standardiz ed Traditional Resistance Exercise in Untrained Men The total and bioavailable te stosterone responses to a si ngle bout of standardized traditional resistance exercise were simila r between groups before the initiation of training. Overall, tota l and bioavailable testosterone c oncentrations remained unchanged acutely following exercise and fell below baseli ne within 30-45 minutes of recovery. Our results support Kraemer et al.114 (1998) who reported th at total testosterone concentrations remained constant followi ng traditional resistan ce training, but are inconsistent with others i ndicating increased testosterone concentrations following resistance exercise in untrained men.5, 8, 68, 78, 109, 111, 169, 180 Additionally, the reduction in both total and bioavailable te stosterone concentrations, be low baseline, indicate that testosterone 1) followed normal metabolic pa thway biotransformation and/or 2) became bound to androgen receptors and stimulated protein synthesis.19 The total and bioavailable testosterone responses obs erved in our study may be explained in a variety of ways. First, it is possible that the acute te stosterone response to resistance exercise is an adaptive physiol ogical response occurring primarily after longer term (>5 week) resistance training protocols.114 This notion is supported by our data which demonstrate that exercise caused a transient increase in total testosterone, in trained individuals. Second, the exercise volume and/or intensity perf ormed in this study may have been insufficient stimuli to induce a change in testoster one concentrations. High volume64, 111, 144 and high-intensity109, 111, 143 resistance exercise protocols have been shown to result in greater post-exercise test osterone concentrations than low volume or low-intensity protocols. The training volume and intensity used in our study were similar to previous studies that reported elevated testoster one following resistance

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52 exercise;64, 116, 156 thus other factors such as the traini ng status of the subjects and/or the exercises performed during the study (chest pr ess and squat) may explain the disparity in findings. Testosterone Response to Standardized Traditional and EccentricEnhanced Exercise in Untrained Men In our study, the post-exercise total test osterone concentrations in untrained subjects, following tr aditional or eccentricenhanced resistance exercise decreased below baseline concentrations by 60 minutes into r ecovery; similar to our previously reported findings that indicated total testosterone concentrations decline below baseline concentrations following a standardized tr aditional resistance ex ercise protocol. However, we observed an immediate post-exerci se increase in bioavailable testosterone concentrations and gradual de cline to below baseline with in 60 minutes of exercise cessation, in both groups. As no change in tota l testosterone appeared following exercise, our previously discussed rationa le that the 1) testosterone response following resistance exercise is a long-term adaptive response to training and/or 2) training volume and intensity selected for this study were insufficien t stimuli to elicit a change in testosterone concentrations, may explain these findings. It is also possible that eccentric muscle actions do not provide an adequate stimulus (m etabolic or other) to affect post-exercise total testosterone concentr ations, in untrained males.103 The eccentric-specific exercise intensity in our study (100% 1RM, eccentricenhanced group) was greater than used in previous that reported increas ed testosterone responses to eccentric-only muscle actions47 and an unchanged testosterone response to eccentric-only muscle actions.103 While total testosterone remained unchange d immediately following a standardized bout of eccentricenhanced and traditional resistance exer cise in the untrained state,

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53 bioavailable testosterone increased. When analyzed in association with our total testosterone results, it ap pears that alterations in the free:albumin-bound:SHBG-bound testosterone ratio may occur following a bout of resistance exercise. Recall that changes in both free and albumin-bound test osterone affect the bioava ilable testosterone fraction and thus the interpretation of our data. Previous reports have indicated that free testosterone increases acutely following resistance training;7, 47, 169 although we did not directly measure free testosterone concentrations it is plausible that changes in the free testosterone fraction influen ced both our total and bioavail able testosterone results. Testosterone Responses to Traditional and EccentricEnhanced Resistance Training in Trained Men Following the five-week training interven tion, both groups exhibited an acute increase in post-exercise total and bioavailable testosterone concentrations, which subsequently fell below baseline 30-45 minutes into recovery. Similar testosterone responses have been observed following resist ance exercise interv entions in trained men7, 8, 32, 68, 78, 107-109, 111, 115, 143, 169, 176. Additionally, our results corroborate previous reports indicating that post-e xercise testosterone concentrat ions increase in trained, but not untrained men.8, 114 Total and bioavailable testos terone concentrations were similar between groups at all time points, despite a greater traini ng volume in the traditional group throughout training and post-intervention testing. Brie fly, we successfully equated training volume during baseline testing, but were unable to equate training volume during the resistance training intervention because the load and repetition dependent rate of progression accomplished in the traditional resistance training group could not be matched by the eccentricenhanced group. Considering that both ex ercise volume and intensity are

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54 thought to play integral roles in determin ing the testosterone responses following resistance training;113 the additional training volume co mpleted by the traditional group may in part, explain the similar testoste rone responses between groups. Although no difference in either bioavailable or total te stosterone concentrati ons appeared between groups, our results indicate that 1) eccentricenhanced exercise may result in similar postexercise testosterone concentrations to trad itional resistance exercise, at a lower total volume of work and/or 2) post-exercise testos terone responses may be more responsive to exercise intensity than to total exercise volume. Growth Hormone The growth hormone (GH) responses following various resistance exercise protocols have been summarized in several recent reviews.92, 113, 133, 164 Growth hormone has been shown to directly affect cellular amino acid uptake9 and protein synthesis,52-54, 74, 138 thus contributing to skelet al muscle hypertrophy. Our st udy is the first to compare the GH response between traditional and eccentricenhanced resistance exercise, in both the untrained and trained states. Growth Hormone Response to Standardiz ed Traditional Resistance Exercise in Untrained Men Resting GH concentrations were within normal, non-acromegalic, ranges (< 2.0 ng/ml) for all subjects.162 In our study, GH increased 15-30 minutes following exercise and returned to baseline concentr ations within 45 mi nutes of exercise cessation, similar to previous reports.8, 37, 73, 110, 114, 128, 152 A variety of factors, including higher training volumes,64, 82 moderate intensities (8-12 RM),109, 111, 142, 171 large muscle group exercises,75, 108 and short rest intervals109, 111 have been reported to increase the GH response to exercise. A smaller change in GH concentrations (~2 ng/ml) was observed in

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55 our study, compared to previ ous reports (~3.5-10.0 ng/ml).8, 37, 73, 110, 114, 128, 152 The training volume (4 sets x 6 reps), exercise selection (chest press and squat), and rest periods length (1 minute between sets) we se lected were similar to previous reports;8, 37, 73, 110, 114, 128, 152 however, the exercise intensity in our study (52.5% 1RM) was lower than most,8, 37, 73, 110, 114, 128, 152 but not all63 previous reports dem onstrating increased postexercise GH concentrations. Therefore, it appears that the relatively lower exercise intensity used in our study may explain the lower post-exercise GH concentrations, compared to others. Growth Hormone Response to Standa rdized Traditional and EccentricEnhanced Exercise in Untrained Men During baseline testing, we observed an increase in post-exercise GH concentrations 15-30 minutes followi ng the traditional and eccentricenhanced resistance training protocols. However, a relative ly modest change in post-exercise GH concentrations was observed in our study (~ 1.5 ng/ml) compared with prior reports (~3.510 ng/ml),8, 37, 73, 110, 114, 128, 152 similar to the response we reported following the standardized traditional resistance exercise protocol; therefore, our previously discussed rationale may apply. Additionally, several studies have reported that eccentric muscle actions result in lower post -exercise GH responses than co ncentric muscle actions, in untrained subjects;47 103, 105 suggesting that GH may be less responsive to eccentric muscle actions than concentric actions, regardless of load. Overall, the relatively low concentric-specific exercise intensity perf ormed in both groups may explain the postexercise GH responses. Growth hormone concentrations have been found to be positively associated with blood lactate69 and H+ accumulation.48 Additionally, Luger et al.124 (1992) suggested that

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56 lactate accumulation pa rtially regulates the exercise induced GH response. During preintervention testing, we observed a greater postexercise lactate response in the eccentricenhanced group, compared with the traditional gr oup, but no differences in post-exercise GH concentrations were observed. Further, we did not observe a relationship between lactate concentrations and either the postexercise GH concentra tions or GH area under the curve. Our results suggest that additional factors, beyond lactate/H+ accumulation, may regulate the post-exercise GH responses to eccentric exercise in untrained subjects, such as blood flow characteristics, nitric oxide release, and highe r brain center/anterior pituitary input.60 Growth Hormone Response to Traditional and EccentricEnhanced Exercise in Trained Men Similar to previous findings,6-8, 64, 82, 105, 106, 108, 109, 111, 113, 115, 142, 171 at postintervention testing both groups exhibite d acutely increase d post-exercise GH concentrations (15-45 minutes) that returned to baseline by 60 minutes into recovery. Additionally, no differences in GH concentra tions were observed between groups at any time point, despite a larger training volume in the traditional group. Our results are consistent with Kraemer and colleagues105 (2001), who reported that maximal eccentric muscle actions result in greater GH responses than maximal concentric muscle actions, in trained subjects; possibly indica ting that the higher exercise intensities stimulate a greater GH response. Muscular Function and EccentricEnhanced Resistance Training A myriad of positive health outcomes ar e associated with improvements in muscular strength and mass, thus determining effective resistance exercise protocols is important when prescribing weight trai ning programs in both healthy and at-risk

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57 populations.99 While traditional resistance training programs are often prescribed, recent reports demonstrate that eccentricenhanced resistance training may result in greater improvements in skeletal muscle strength and/or mass.25, 51, 86, 87, 95 We are the first to report muscular strength and e ndurance responses to eccentricenhanced resistance training, using multiple joint exercises. Muscular Strength Similar improvements were observed between groups for both chest (press) and leg (squat) muscular strength (kg), which is consis tent with reports suggesting that eccentricenhanced resistance training results in similar st rength gains compared with traditional resistance training17, 59 and in contrast to others indi cating greater strength improvements following eccentricenhanced resistance training.25, 51, 86, 87, 95 In some studies, higher training volumes have been shown to result in larger improvements in muscular strength than lower training volu mes, in untrained men;18, 23, 148 while others report no differences between low and high volume protocols.34, 147, 166 The relatively lower training volume performed by the eccentricenhanced group may have resulted in compromised strength gains relative to the tr aditional group. Give n that the eccentricenhanced group showed similar improvements in muscular strength co mpared to the traditional group, despite having a lower training volume, eccentricenhanced resistance exercise could be considered a more efficient mode of trai ning, when total work is considered. Results from a recent meta-analysis reveal that maximal strength gains are achieved at 60% 1RM, in previously untrained men;148 however, strength gains have also been observed with exercise intensities below 50% 1RM, in untrained men.56 In our study, the exercise intensity in the tr aditional group varied between 52.5-70% 1RM (similar to the suggested intensity), whereas the concentric and eccentric exercise intensities in the

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58 eccentricenhanced group were ~40% and 100-120% 1RM throughout the duration of training, respectively. Therefore, it is also pos sible that optimal exercise intensities were not selected for the eccentricenhanced group. Additionally, both traditional and eccentricenhanced resistance training may result in similar neural adaptations (e.g. im proved motor unit recruitment and/or synchronization) associated with early-phase (<12 weeks) enhancements in muscular strength, as minimal muscle hypertrophy t ypically appears during this time frame.29, 44, 55 Early-phase muscular strength ad aptations following concentriconly resistance training are similar to93, 158 or greater than146 the adaptations following eccentriconly resistance training in some studies, while others report that eccentric-only resistance training results in greater early-phase musc ular strength adaptations.35, 49, 119, 130 Recall however that type IIa and IIx MHC mRNA have been shown to increase following four weeks of eccentricenhanced resistance training, in untrained males;51 suggesting that skeletal muscle hypertrophy and associated strength imp rovements may occur during early-phase resistance training. In our study, significant improvements in muscular strength were observed, without significant concomitant increas es in lean mass; suggesting that neural adaptations, including en hanced motor unit recruitment and/or motor unit synchronization may be an important mech anism explaining our strength outcomes. However, alterations in muscle mass a nd assocoiated hypertrophy-related strength adaptations cannot be excluded as underl ying factors in the muscular strength improvements observed in our study. Muscular Endurance Both training groups displayed simila r improvements in muscular endurance following the five-week exerci se intervention, despite di ssimilar training volumes.

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59 Friedmann and colleagues51 (2004), observed improved endur ance in traditional, but not eccentricenhanced resistance training. Additionally, Marx et al.127 (2001), reported that muscular endurance outcomes are related to training volume; which, if true, would indicate that the traditional group sh ould have outperformed the eccentricenhanced group. The lack of agreement between our outcomes and previous reports may be explained by the 1) differences in training volume and/or exerci se intensity between groups, 2) presence of similar neural ad aptations and resul ting strength/endurance improvements between groups, 3) the length of the exercise interven tion, and/or 5) the presence of delayed-onset muscle soreness in the eccentricenhanced group. Training Volume Total training volume performed during exer cise interventions has been shown to affect muscular performance outcomes,18, 23, 127, 148 as well as hormonal64, 111, 144 and metabolic responses.96, 144 In our study, training volum e was matched between groups during the standardized baseline testing sessions but was unm atched during the five-week exercise intervention. The disparity in training volumes between groups may be explained by delayed-onset muscle sorene ss (DOMS) symptoms, including 1) reduced muscular strength, 2) reduced muscle activati on, 3) decreased range of motion (ROM), 4) impaired proprioception, and 5) increased muscular and connectiv e tissue inflammation 33, 61, 137, and/or delayed leukocytosis or skeletal muscle myok ines, such as interleukin (IL)-6 or IL-8,80, 140, 141, 179 in the eccentricenhanced group. In our study, cellular markers of inflammation were not measur ed, though a large pe rcentage (>50%) of subjects in the eccentricenhanced group reported (moderate to extreme) muscle soreness and impaired ROM following the initial eccentricenhanced exercise bout and throughout the first week of exercise trai ning, corresponding to th e initial four exerci se sessions. In

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60 contrast, no reports of muscle soreness occurr ed in the traditional group. Our findings are similar to previous reports, indicating that DOMS and its associated symptoms last 5-7 days following the initial eccentric exercise bout and may indicate th e presence of acute muscular microtrauma and/or inflammati on, thus reducing exercise capacity and associate performance improvements.61 Further, lactate accumulation has been a ssociated with muscular fatigue during resistance exercise and may limit exercise performance.149 Blood lactate concentrations have been shown to be greater during an exer cise test performed tw o days after eccentric training;57, 58 suggesting greater metabolic fatigue occurs following heavy eccentric training. Recall, before the onset of traini ng, we observed a greater post-exercise lactate response in the eccentricenhanced group, compared with the traditional group; therefore it is possible that a greater lactate res ponse also occurred throughout the exercise intervention. Further, a positive relationship between lactate and RPE has been reported;77, 117, 165 in our study RPE was greater dur ing training sessions 1-4 in the eccentricenhanced group, compared to the tradit ional group, lending support to the notion that greater lactate accumu lation occurred during eccentricenhanced training. These results suggest that the eccentricenhanced group may have experienced greater metabolic fatigue throughout the exercise intervention, thus attenuating progression during resistance exercise compar ed to the traditional group. Conclusion Our study determined the early-phase (single session to five-week) metabolic, neuroendocrine, and performance res ponses to traditional and eccentricenhanced resistance exercise in previously untraine d individuals. We observed that short-term eccentricenhanced resistance training results in si milar neuroendocrine and performance

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61 responses as traditional resistance training, in college-age males. The lower training volume completed by the eccentricenhanced group suggests that th is form of training may be more efficient in eliciting both anabolic stim uli and muscular strength improvements than traditional resistance training, relative to training volume. Clinical Implications Determining the neuroendocrine, metabolic and performance responses to various resistance training protocols may enable clin icians, therapists, and coaches to prescribe safe and effective training programs to both h ealthy and at-risk indivi duals. Although the results of our study indicate th at traditional and eccentricenhanced resistance training result in similar neuroendocrine and perf ormance responses, each specific form of training may have population specific advantag es. Theoretically, at hletes who practice and/or compete above their l actate threshold (e.g. boxers, wr estlers, rowers, etc.) might benefit from eccentricenhanced resistance training, as gr eater intracellu lar lactate buffering and/or delayed lactate accumulati on may occur with this form of training.84, 125 Additionally, strength trainers who have limited time to participate in resistance exercise may benefit from eccentricenhanced resistance training, evidenced by the similar improvements in muscular strength which occu rred at a lower training volume and time commitment (~66% less time to complete the eccentricenhanced protocol) following this form of training. Eccentricenhanced resistance training may not be as appropriate for clinical populations (e.g. multiple sclerosis, muscular dystrophy, etc) that experience muscular fatigue, pain, and/or weakness associated with their condition. Eccentricenhanced exercise has been show to result in moderate to extreme muscle soreness, thus limitations in mobility and muscular strength may occur at the onset of eccentricenhanced

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62 resistance training. Clearly, further research is indicated to determin e the specific effects of eccentricenhanced resistance training in various populations. Future Directions Examining both the acute and chronic anabo lic (e.g. total testoste rone, bioavailable testosterone, growth hormone, insulin-like growth factor, mechano growth factor) and catabolic (e.g. adrenocorticotropic hormone, cortisol) hormone responses to eccentricenhanced resistance training would improve curr ent understanding of the neuroendocrine responses to resistance training. Additionall y, given the influence of binding proteins on both the biological effects and measurement of testosterone, future studies designed to carefully measure the free, albumin-bound, a nd SHBG-bound fractions of testosterone are indicated. Further, evaluating androgen receptor expression a nd androgen affinity following resistance training would advance our understanding of skeletal muscle adaptations to resistance tr aining. Moreover, determining the responses of cellular proteins that regulate skeletal muscle pr otein synthesis (e.g. mTOR, AKT, etc) and degredation (myostatin, ubiquitin proteasom e pathway, etc) may advance current knowledge of the underlying mechanism(s) of muscular hypertrophy and/or atrophy. Delayed onset muscle soreness (DOMS) is commonly experienced by individuals who perform resistance training and may be indicative of muscle injury. The underlying mechanism(s) of DOMS remain unclear; th erefore, evaluating cellular markers of inflammation following heavy eccentric exerci se may enhance our understanding of the skeletal muscle injury and repair process. Evaluating both the plas ma and muscle tissue specific responses of creatine kinase, myogl obin, neutrophils, and various myokines such as IL-6 or IL-8, among others may provide va luable information for enhancing recovery from muscle injury or loss and/or reducing th e muscle soreness associated with resistance

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63 training. Since, eccentric exercise induced musc le inflammation is a stimulus for satellite cell proliferation and associated muscle repair,43, 145 evaluating satellite cell expression following eccentricenhanced exercise may improve the understanding of skeletal muscle repair/regeneration. Our data suggest that eccentricenhanced exercise results in higher metabolic (lactate) responses and RPE values than trad itional resistance exercise, in untrained individuals. Future research compari ng metabolic (e.g. lactate, heart rate, VO2, etc) and RPE responses between traditional and eccentricenhanced resistance protocols would improve our current understanding of fatigue a nd exertion as they relate to resistance exercise. Additionally, evaluating intracellu lar lactate buffering mechanisms, motor unit recruitment patterns, and blood flow characteristics during eccentricenhanced resistance exercise may provide insight into the m echanism(s) underlying lactate accumulation. We reported that eccentricenhanced resistance training provides a means of improving early-phase muscular performance in previously untrained college-age males. Future research designed to directly control intensity and volume between exercise protocols is warranted and would clarify the muscular strength res ponses to resistance exercise. Additionally, evaluating long-te rm (>12 weeks) adaptations to eccentricenhanced training may allow the individual neural and hypertrophic dependent mechanisms of muscular stre ngth enhancement to be more clearly understood. Overall, research examining the interrelationship be tween exercise intens ity, volume, and/or training status would contribu te to a more complete unders tanding of the neuroendocrine, metabolic, and muscular performance res ponses to resistance exercise.

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64 Several studies have evalua ted the effects of eccentricenhanced resistance training in healthy college-age males; however, fe w studies have evaluated the performance responses in other populations. Skeletal mu scle atrophy, reduced strength, and increased fatigue are associated with aging and degenerative diseases such as multiple sclerosis and muscular dystrophy, thus determining the effects of eccentricenhanced resistance training in at-risk populations ma y benefit clinicians and ther apists in devising safe and effective exercise protocols to reduce the de leterious effects of disease on muscle. Additionally, both athletes and recreational weight lifters utilize resistance training to improve muscular strength and mass; thus determining the performance responses to eccentricenhanced resistance training in both athletes and previous ly trained individuals would enhance current knowledge related to th e long-term training adaptations to this form of exercise.

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65 APPENDIX A HEALTH HISTORY QUESTIONNAIRE SUBJECT # _____________ Date of Birth :_____________ Height _____ Weight ______ Blood Pressure Measurement:______ /______ Do you currently have any of the following conditions or has a medical doctor ever informed you that you have any of the following conditions? 1. Diabetes mellitus Yes / No 2. High blood pressure Yes / No 3. Osteoporosis Yes / No 4. A heart condition Yes / No 5. High cholesterol Yes / No If Yes, do you know your cholesterol numbers? ______________________ 6. Thyroid problems Yes / No 7. Kidney disease Yes / No 8. Liver disease Yes / No Please answer the following questi ons regarding your general health: 1. Do you feel pain or pressure in your chest, neck shoulders, or arms during or after physical activity? Yes / No 2. Do you ever lose your balance because of dizziness Yes / No 3. Do you ever lose consciousness? Yes / No 4. Do you consider yourself to be generally healthy? Yes / No 5. Do you currently smoke? Yes / No

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66 6. Are you a former smoker? Yes / No If Yes, how long has it been since you quit smoking? ___________________ 7. Have you ever had an adverse reaction during or following a blood donation? Yes / No 8. Do you mind having blood draws? Yes / No 9. Do you currently have an injury to any area in your upper or lower body? Yes / No If Yes, please explain the injury: ____________________________________ _______________________________________________________________ _______________________________________________________________ 10. Are there any other health relate d issues we should know about? ___________ _______________________________________________________________ _______________________________________________________________ Are you currently taking any of the following products or have you taken them in the previous 2 months? 1. Anabolic steroids Yes / No 2. Creatine Yes / No 3. Protein powder Yes / No 4. Other Yes / No If Yes, please list th e specific supplements:___________________________ ______________________________________________________________ ______________________________________________________________ Please list all of the supplements you are currently taking (including vitamins): Item name Amount taken per day Length on supplement Reason a.______________________________________________________________________ b.______________________________________________________________________ c.______________________________________________________________________

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67 Please list all of the prescription medication you are currently taking Medicine Amount taken per day Length on medication Reason a.______________________________________________________________________ b.______________________________________________________________________ c.______________________________________________________________________

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68 APPENDIX B PHYSICAL ACTIVITY AND DIETARY QUESTIONNAIRE PHYSICAL ACTIVITY & DIETARY QUESTIONNAIRE Subject #:_______________________ Please answer the following questions regar ding your current exercise participation and dietary habits: 1. Do you currently participate in weight lifting? Yes / No If Yes, how often and how much resistance exercise do you perform: __________________________________________________________ __________________________________________________________ 2. During the past two years have you participated in either bodybuilding or powerlifting? Yes / No 3. Do you currently perform aerobic exercise? Yes / No If Yes: How many times per week _______________________________________ How long do you perform cardio each session ________________________ What type of exerci se (running, biking, etc) __________________________ How intense (mild, moderate, high) ________________________________ 4. Do you currently perform any recr eational sports activity or participate in any physical activity? Yes / No If Yes: How many times per week _______________________________________ How long do you perform cardio each session ________________________ What type of exerci se (running, biking, etc) __________________________ How intense (mild, moderate, high) ________________________________

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69 5. Are you currently on a diet, including a low calorie, low fat, high protein, or a low car bohydrate diet? Yes / No If Yes, please explain your diet: ____________________________________________________________ ____________________________________________________________

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70 APPENDIX C LIST OF EXCLUDED NUTRITIONAL SUPPLEMENTS Subjects were excluded from this study if they had consumed any of the following nutritional supplements within 1 mo nth from beginning the study: 1. Creatine 2. Ephedra 3. Dehydroepiandrosterone (DHEA) 4. Tribulus Terresteris 5. ZMA 6. Androstendione 7. GAKIC 8. Any other nutritional supplement/ergogenic aid that is intended to enhance exercise performance 9. Any other nutritional supplement that has been demonstrated to affect hormonal levels

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71 APPENDIX D DIETARY RECORD SUBJECT #____________ SESSION #_____________ Please record what you eat and drink for the entire day. Please be as specific as possible for serving size, how food is prepared, and amount of each serving. Time Food/Drink Brand Name/Restaurant Serving Size

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72 APPENDIX E POWER CALCULATIONS Ahtiainen et al.8 2004 (N=8) Pre Exercise Growth horm one concentrations: 0.1 0.2 g/L Post Exercise: 15.9 9.9 g/L n per group = 2[(Z -Z ) /(u1-u2)]2 Z = alpha level for two tailed Z Z = lower one-tailed Z value that is related to = maximum variance u1-u2 = difference between mean 1 and 2 n = 2[(1.96 + 0.84)(9.9)/(15.9)]2 = 2(3.08) = 6.16 subjects so, 7 subjects per group or 14 total subjects Power = 0.80 Significance = 0.05

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73 APPENDIX F PLASMA VOLUME FLUCTATI ONS FOLLOWING EXERCISE Table 6. Percent plasma volume fluctuati ons following traditional and eccentricenhanced resistance training. PLASMA VOLUME TRADITIONAL GROUP ECCENHANCED GROUP Baseline 100 % 100 % Immediately Post Exercise -7.8% 2.3* -5.3% 1.8* 15 Minutes Post Exercise -1.9% 2.1 -1.2% 1.6 30 Minutes Post Exercise -0.4% 2.6 +2.4% 1.2 45 Minutes Post Exercise +5.1% 3.1 +1.1% 1.1 TRADITIONAL RESISTANCE EXERCISE TESTING 60 Minutes Post Exercise +3.5% 2.8 +1.3% 2.3 Baseline 100% 100% Immediately Post Exercise -6.5% 2.9* -8.1% 1.6* 15 Minutes Post Exercise +6.2% 2.6 +4.3% 2.0 30 Minutes Post Exercise +2.9% 3.1 +4.1% 2.1 45 Minutes Post Exercise +7.8% 2.2* +4.5% 1.9* BASELINE TRADITIONAL VS. ECC-60 Minutes Post Exercise +2.7% 3.1 +4.5% 2.2 Baseline 100% 100% Immediately Post Exercise -11.0% 1.1* -10.6% 1.8* 15 Minutes Post Exercise -2.5% 1.9 -1.9% 1.9 30 Minutes Post Exercise +2.1% 1.3 +1.9% 1.8 45 Minutes Post Exercise +3.3% 1.7 +2.0% 2.1 POSTINTERVENTION TRADITIONAL 60 Minutes Post Exercise +0.9% 0.8 +1.0% 2.0 Indicates significant difference from corre sponding baseline value (p<0.05). Data are presented as Mean Change SE.

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89 BIOGRAPHICAL SKETCH Joshua F. Yarrow was born in Aurora, Illi nois. He moved to Phoenix, Arizona, in 1986 with his family. In 1997, Joshua gr aduated from Horizon High School, in Scottsdale, Arizona. He started his college career at Paradise Valley Community College in Phoenix, Arizona, in August 1997. One year later, he transferred to Arizona State University where he completed his bachelors degree in exercise scie nce in May 2000. In May 2002, he received a masters degree in exercise and wellness at Arizona State University. In August 2002, he began his doc toral degree in sports medicine/athletic training with a minor in human nutriti on at the University of Florida.


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Table of Contents
    Title Page
        Page i
        Page ii
    Dedication
        Page iii
    Acknowledgement
        Page iv
    Table of Contents
        Page v
        Page vi
        Page vii
    List of Tables
        Page viii
    List of Figures
        Page ix
        Page x
    Abstract
        Page xi
        Page xii
    Introduction
        Page 1
        Page 2
        Page 3
        Page 4
    Review of literature
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
    Methods
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
        Page 21
        Page 22
        Page 23
    Results
        Page 24
        Page 25
        Page 26
        Page 27
        Page 28
        Page 29
        Page 30
        Page 31
        Page 32
        Page 33
        Page 34
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
        Page 40
        Page 41
        Page 42
        Page 43
    Discussion
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
        Page 49
        Page 50
        Page 51
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        Page 53
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        Page 58
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        Page 60
        Page 61
        Page 62
        Page 63
        Page 64
    Appendices
        Page 65
        Page 66
        Page 67
        Page 68
        Page 69
        Page 70
        Page 71
        Page 72
        Page 73
    References
        Page 74
        Page 75
        Page 76
        Page 77
        Page 78
        Page 79
        Page 80
        Page 81
        Page 82
        Page 83
        Page 84
        Page 85
        Page 86
        Page 87
        Page 88
    Biographical sketch
        Page 89
Full Text












NEUROENDOCRINE AND PERFORMANCE RESPONSES TO ECCENTRIC-
ENHANCED RESISTANCE EXERCISE














By

JOSHUA F. YARROW


A DISSERTATION PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY

UNIVERSITY OF FLORIDA


2006

































Copyright 2006

by

Joshua F. Yarrow

































This work is dedicated to my mother, Julie Yarrow. Thanks for being incredibly
supportive and always believing in me. I love you very much.















ACKNOWLEDGMENTS

I would like to thank my committee chair, Dr. Lesley J. White, and co-chair, Dr.

Paul A. Borsa, for their constant guidance and support throughout my doctoral work. I

also would like to thank my committee members Dr. Stephen E. Borst, Dr. Harry S.

Sitren, and Dr. Bruce R. Stevens for their support throughout the entirety of this project.

I am forever indebted to all the members of the Applied Human Physiology

Laboratory who helped with the completion of my work (Ashley Blazina, Dr. Vanessa

Castellano, Stacey Colon, Jason Drenning, Brooke Holman, Laura Massey, Sean McCoy,

and Kevin Taylor). I am also grateful to Christine Conover and Mindy Prucha for their

assistance in assay preparation and troubleshooting, Dr. Michael Mac Millan for his

generous donation of equipment, Cassie Howard for allowing use of The Living Well

facilities, and all the volunteers who participated in the study.















TABLE OF CONTENTS



A C K N O W L E D G M E N T S ................................................................................................. iv

LIST OF TABLES .......................................... viii

LIST OF FIGURES ....................................... .. ......... ............................ ix

ABSTRACT .................................................... ................. xi

CHAPTER

1 IN TR O D U C T IO N ........ .. ......................................... ..........................................1.

Significance ....................................................................... ...................... ...............1...
Specific A im s and H ypotheses ....................................... ...................... ...............2...
Specific c A im #1 ................................................................................................ 2
H hypothesis #1 .......................................................................................... . 2
Specific Aim #2 ..................... .. ........... ...................................... ... 2
H y p oth esis # 2 ................................................... .......................................... . 3
Specific c A im #3 ................................................................................................ 3
H hypothesis #3 .......................................................................................... . 3
Specific A im #4 ................................................ ........................................ . 4
H y p oth esis # 4 ................................................... .......................................... . 4

2 REV IEW OF LITERA TU RE .......................................................................................5

Significance .............. .....................................................................5...........
E eccentric Exercise .......................................................................................... . 6
Eccentric-Enhanced Exercise .................. ... ...........................................
Anabolic Hormone Responses to Resistance Training ......................................... 10
T esto stern e ............................................................................... ... 11
G row th H orm one ........... ...... ................ .................. ............................. 13
Growth Hormone and Testosterone Responses to Resistance Exercise ..............13
C conclusion .............. .................................................... ...............15.. ....... .... 15

3 M E T H O D S ..................................................................................................... 16

Subjects ............... ... t....... ....... ..... .................... ..................... 16
Inclusionary/Exclusionary Criteria ....................................................................... 16
E xperim mental D design ...................................................................................... 17



v









B baseline T testing ............... ................ ............................................ 19
E x ercise T raining ... ... ......................................... ....................... . .......... 19
Follow -U p Testing ... ............................................................................... 20
D dietary A analysis .............. ................... ............................................... 20
Sleep A analysis ................................................................................................ 2 1
Blood Collection..................................................................... 21
B iochem ical A analyses .............. ............. .............................................. 21
Sam ple Size ................................................................................................... 22

4 R E S U L T S .......................................................................................... ..................... 2 4

Subjects ................................ ............... ................ ..................24
B io ch em ical R e su lts ...................................................................................................2 4
L a ctate .............................................. .. ................................................. .......... . ....... 2 5
Lactate Response to the Standardized Traditional Exercise Protocol in
U trained M en .................................................................. ..... ........... ...............2 5
Lactate Responses to Standardized Traditional and Eccentric-Enhanced
E exercise in the U trained ............................. .................................................... 26
Lactate Response to Standardized Traditional and Eccentric-Enhanced
Exercise in Trained M en...............................................................................27
T testosterone ................................................................................. ...................... 27
Resting Testosterone ................. ............... .................................. 27
Testosterone Responses to the Standardized Traditional Exercise Protocol in
U ntrain ed M en ...................................................... .. .... .. .... ..... .......... .. .. 2 9
Testosterone Responses to Standardized Traditional and Eccentric-Enhanced
E exercise in U trained M en .................................... .............. ..................... 29
Testosterone Responses to Standardized Traditional and Eccentric-Enhanced
R resistance Exercise in Trained M en .............................................. ...............31
G row th H orm one .... ............................... .. ..... ..... ................... ............ .. 33
Growth Hormone Response to Standardized Traditional Exercise Protocol in
U trained M en ............. .. ....................................... .. ....... .. ...... .... ......... 33
Growth Hormone Response to Standardized Traditional and Eccentric-
Enhanced Exercise in U trained M en .......................................... ................33
Growth Hormone Response to Standardized Traditional and Eccentric-
Enhanced Exercise in Trained M en........................................... ................ 35
Plasm a V olum e ........................................................................... ............ .. ........ .... 35
M u scle F u n ctio n ......................................................................................................... 3 6
M u scu lar Strength .......................................................................... ............... 36
M muscular E endurance ..................................... ................ 36
Rating of Perceived Exertion ................................................................................ 37
T rain in g V olu m e .............................................................................................3 8
Training Volume Per Exercise Session ....................... ........ ........................ 39
Total Accumulated Training Volume Across Five-Week Intervention ..............41
D dietary A n aly sis ......................................................................................................... 4 2
S leep A n aly sis ............................................................................................................ 4 2









5 D IS C U S SIO N ................................................................................................... 44

M etabolic Response to Resistance Exercise.......................................... ................ 45
Lactate Responses to Standardized Traditional and Eccentric-Enhanced
Resistance Exercise in U trained M en ....................................... ................ 45
Lactate Response to Resistance Training in Trained Men ................................47
T e sto ste ro n e ............................................................................................................... 4 8
R testing T estosterone .......................................... .. .. .... ..... ......... ........... .... 49
Testosterone Response to Standardized Traditional Resistance Exercise in
U trained M en .................. .. ......................... ................ ..................... 51
Testosterone Response to Standardized Traditional and Eccentric-Enhanced
E exercise in U trained M en ....................................................... .................. 52
Testosterone Responses to Traditional and Eccentric-Enhanced Resistance
T raining in T rained M en ............................................................. ............... 53
Growth H orm one ............................. .... ........ .. .... .. ............................... 54
Growth Hormone Response to Standardized Traditional Resistance Exercise
in U trained M en .......................................................... ......... ...... ... ...... 54
Growth Hormone Response to Standardized Traditional and Eccentric-
Enhanced Exercise in Untrained M en ................................... ..................... 55
Growth Hormone Response to Traditional and Eccentric-Enhanced Exercise
in Trained M en......................... .. .. ....................... ............... 56
Muscular Function and Eccentric-Enhanced Resistance Training .......................... 56
M uscular Strength ................ .............. ............................................ 57
M u secular E endurance ................................................ ....................... .... ......... 58
Training V olum e ............. .. .................. .................. .......................... ........... 59
C o n c lu sio n ............................................................................................................... .. 6 0
C clinical Im plication s ... ... ........................................... ....................... .. .... ....... .. 6 1
F u tu re D ire ctio n s ........................................................................................................6 2

APPENDIX

A HEALTH HISTORY QUESTIONNAIRE ............... .............. ..................... 65

B PHYSICAL ACTIVITY AND DIETARY QUESTIONNAIRE ..............................68

C LIST OF EXCLUDED NUTRITIONAL SUPPLEMENTS.................................70

D D IE T A R Y R E C O R D ..................................................................................................7 1

E PO W E R C A L C U L A TIO N S .......................................................................................72

F PLASMA VOLUME FLUCTUATIONS FOLLOWING EXERCISE...................... 73

L IST O F R E F E R E N C E S ...................................................................................................74

BIO GR APH ICAL SK ETCH .................................................................... ................ 89











LIST OF TABLES


Table page

1. Overview of strength outcomes from eccentric-enhanced studies........................ 12

2. Subject characteristics pre and post 5 weeks of resistance training......................24

3. Muscular strength values at baseline and post-intervention for the traditional and
eccentric-enhanced groups ....................................... ....................... ................ 37

4. Muscular endurance (total work) measures at baseline and post-intervention for
the traditional and eccentric-enhanced groups.................................... ............... 37

5. Average reported kilocalories, carbohydrates, protein, and fat in the traditional
and eccentric-enhanced groups ........................................................... ................ 43

6. Percent plasma volume fluctuations following traditional and eccentric-
enhanced resistance training ...................................... ...................... ................ 73














LIST OF FIGURES

Figure page

1 E xperim ental design ... .................................................................... ............... 18

2 Lactate responses to traditional resistance exercise ...........................................25

3 Baseline lactate responses to traditional and eccentric-enhanced resistance ...........26

4 Post-intervention lactate responses to traditional and eccentric-enhanced
resistance exercise ...................... .... .......... ......... ............... 27

5 Total serum testosterone before (Baseline) and after (Post) the training
in terv en tio n .............................................................................................................. 2 8

6 Total bioavailable testosterone before (Baseline) and after (Post) the training
in terv en tio n .............................................................................................................. 2 8

7 Total testosterone responses to standardized traditional resistance exercise
p ro to c o l ................................................................................................................. .. 3 0

8 Bioavailable testosterone responses to standardized traditional resistance
ex ercise p roto co l ...................................................................................................... 3 0

9 Total testosterone responses to standardized traditional and eccentric-enhanced
resistance exercise in untrained m en................................................... ................ 31

10 Bioavailable testosterone responses to standardized traditional and eccentric-
enhanced resistance exercise in untrained men...................................................32

11 Post-intervention total serum testosterone responses to standardized traditional
and eccentric-enhanced resistance exercise protocols ........................................32

12 Post-intervention bioavailable serum testosterone responses to standardized
traditional and eccentric-enhanced resistance training .......................................33

13 Growth hormone responses to the standardized traditional resistance exercise
protocol in untrained m en ........................................ ........................ ................ 34

14 Growth hormone responses to standardized traditional and eccentric-enhanced
exercise protocols, in untrained m en................................................... ................ 34









15 Post-intervention growth hormone responses to standardized traditional and
eccentric-enhanced resistance exercise............................................... ................ 35

16 Ratings of perceived exertion (Borg Scale) following each exercise training
s e s s io n ................................................................................................................... ... 3 8

17 Chest press training volume per session for the traditional group and eccentric-
enhanced groups............. .. .................... ................ .............. ......... ... ............ 39

18 Squat training volume per session for the traditional and eccentric-enhanced........40

19 Combined training volume per session (Chest Press + Squat) for the traditional
and eccentric-enhanced groups ........................................................... ............... 40

20 Total chest press and squat training volume during the five week resistance
exercise intervention .............. ...... ............. ................................................ 4 1

21 Combined total training volume (Chest Press + Squat) during the five-week
exercise intervention .............. ...... ............. ................................................ 42













Abstract of Dissertation Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Doctor of Philosophy

NEUROENDOCRINE AND PERFORMANCE RESPONSES TO ECCENTRIC-
ENHANCED RESISTANCE EXERCISE

By

Joshua F. Yarrow

December 2006

Chair: Lesley J. White
Cochair: Paul A. Borsa
Major: Health and Human Performance

Reduced skeletal muscle strength and/or mass are associated reduced mobility,

increased injury risk, a loss of functional independence, and an increased risk for

hypokinetic diseases. Resistance training may improve both muscle strength and mass,

by modulating neuroendocrine factors known to increase protein synthesis. The purpose

of this study was to evaluate the neuroendocrine, metabolic, and muscle performance

responses to traditional and eccentric-enhanced progressive resistance training, in

previously untrained, college-age men. Participants completed a five-week traditional or

eccentric-enhanced resistance training intervention. Chest and leg muscular strength and

endurance were assessed before and after the training intervention. Blood samples

acquired at rest and following an acute exercise session, both before (untrained) and after

(trained) the training intervention, were assessed for growth hormone, total testosterone,

bioavailable testosterone, and lactate concentrations. Blood lactate accumulation was

greater following eccentric-enhanced, compared to traditional resistance training, in the









untrained state, but not the trained state. Resting total testosterone concentrations did not

change in either group, whereas resting bioavailable testosterone concentrations were

lower in the trained state, compared to the untrained state in both groups. Post-exercise

serum testosterone concentrations remained unchanged in the untrained state, but

increased in the trained state in both groups. Post-exercise bioavailable testosterone

concentrations increased similarly between groups, both before and after the training

intervention. Post-exercise serum growth hormone concentrations increased in both the

trained and untrained state in both groups. Absolute muscular strength (1RM) increased

similarly between groups; however, relative strength (1RM x body mass-1 and 1RM x

lean body mass-1) improvements were greater in the traditional resistance training group

for the squat exercise, but not the chest press. Muscular endurance (total work) increased

similarly between groups. This study suggests that both traditional and eccentric-

enhanced resistance training result in similar neuroendocrine and performance responses

during the early phase of resistance exercise, in previously untrained, college-age men.














CHAPTER 1
INTRODUCTION

Significance

Skeletal muscle atrophy, reduced strength, and increased muscular fatigue are

associated with the aging process. Interventions involving resistance exercise have been

shown to promote muscle hypertrophy, increase strength, and decrease fatigue in both

young and elderly populations.65'104 Traditional resistance exercise is performed with an

identical load during both the concentric (shortening) muscle contraction and eccentric

(lengthening) muscle action. Eccentric-enhanced weight training is an alternative form

of resistance exercise performed by increasing the load during the eccentric muscle

action. In healthy populations, the majority of studies report that eccentric-enhanced

training is superior for developing muscular strength and skeletal muscle mass, compared

to traditional resistance exercise.25'51,86,87'95, 118 However, the mechanisms) underlying

the accentuated skeletal muscle adaptations following eccentric-enhanced resistance

exercise remain unclear, but are likely related to enhanced anabolic processes.

Increased anabolic hormone concentrations (growth hormone, total testosterone,

and bioavailable testosterone), at rest and acutely following resistance exercise, are

associated with the skeletal muscle adaptation process.113 It is possible that the anabolic

hormone responses following eccentric-enhanced resistance training may be relatively

higher compared to traditional resistance training, thus indicating a possible mechanism

for the accentuated muscular strength and skeletal muscle mass results accompanying

eccentric-enhanced resistance training. Therefore, the objective of this study was to









compare specific neuroendocrine, metabolic, and muscle performance responses to

traditional and eccentric-enhanced resistance training.

Specific Aims and Hypotheses

Specific Aim #1

The first specific aim is to compare the post-exercise concentrations of whole-

blood lactate and serum total testosterone, bioavailable testosterone, and growth hormone

concentrations following a single bout of eccentric-enhanced resistance exercise to the

post-exercise concentrations following a single bout of traditional resistance exercise.

Hypothesis #1

The post-exercise concentrations of serum total testosterone, bioavailable

testosterone, and growth hormone will be greater following the eccentric-enhanced

resistance exercise bout compared to the concentrations following the traditional

resistance exercise bout, whereas the whole-blood concentration of lactate will be lower

following the eccentric-enhanced resistance exercise bout compared to the concentrations

following the traditional resistance exercise bout. To accomplish this aim, blood was

sampled immediately prior to exercise, immediately post exercise, and every 15 minutes

for 60 minutes post exercise. Blood was analyzed for lactate, total testosterone,

bioavailable testosterone, and growth hormone.

Specific Aim #2

The second specific aim is to compare the post-exercise concentrations of blood

lactate, serum total testosterone, bioavailable testosterone, and growth hormone after a

single bout of eccentric-enhanced or traditional resistance exercise (Exercise Training

Session #1) to the post-exercise concentrations obtained in individuals after participation









in a five-week eccentric-enhanced or traditional resistance exercise intervention

(Exercise Training Session #15).

Hypothesis #2

The post-exercise concentrations of whole blood lactate, serum total testosterone,

bioavailable testosterone, and growth hormone will be higher following the resistance

exercise intervention (Exercise Training Session #15) compared to the post-exercise

concentrations obtained after the initial resistance training session (Exercise Training

Session #1) in both groups. Further, the post-exercise concentrations of lactate will be

lower in the eccentric-enhanced group compared to the traditional group at the end of the

exercise intervention. Additionally, the total testosterone, bioavailable testosterone, and

growth hormone concentrations will be higher in the eccentric-enhanced group compared

to the traditional group at the end of the intervention. To accomplish this aim, blood was

sampled immediately prior to exercise, immediately post exercise, and every 15 minutes

for 60 minutes post exercise. Blood was analyzed for lactate, total testosterone,

bioavailable testosterone, and growth hormone.

Specific Aim #3

The third specific aim is to compare the resting concentrations of serum total

testosterone and bioavailable testosterone in untrained individuals to the resting

concentrations in the same individuals following a five-week eccentric-enhanced or

traditional resistance exercise intervention.

Hypothesis #3

The resting concentrations of serum total and bioavailable testosterone will be

higher at the conclusion of a five-week exercise intervention in both groups.

Additionally, the resting concentrations of serum total and bioavailable testosterone will









be greater following the five-week eccentric-enhanced training protocol compared to the

traditional resistance training protocol. To accomplish this aim, blood was sampled at

rest and at the same time of day at the beginning and end of a five-week exercise

intervention. Blood was analyzed for total and bioavailable testosterone.

Specific Aim #4

The fourth specific aim is to compare muscular strength and endurance following a

five-week eccentric-enhanced resistance exercise intervention to that following a five-

week traditional resistance exercise intervention.

Hypothesis #4

Eccentric-enhanced resistance training will result in greater muscular strength and

muscular endurance than traditional resistance training. To accomplish this aim, subjects

will perform a one-repetition maximum (1RM) test (muscular strength) and four sets at

52.5% 1RM (muscular endurance) on both the chest press and squat exercises prior to

and after completion of the five-week exercise intervention.














CHAPTER 2
REVIEW OF LITERATURE

Significance

Skeletal muscle atrophy, reduced strength, and increased fatigue are associated with

aging15 and degenerative diseases such as multiple sclerosis155 and muscular

dystrophy.11 Reduced strength and increased muscular fatigue may limit ambulatory

movement and/or increase risk of musculoskeletal injury in frail and fatigued individuals.

Participation in progressive resistance exercise increases muscular strength and lean

muscle mass and is associated with reduced musculoskeletal injury risk and improved

functional capacity in both healthy and at-risk populations.65' 104

Traditional, isotonic, resistance exercise involves a concentric (shortening) muscle

action and an eccentric (lengthening) muscle action separated by a brief isometric

(transition) action.104 Resistance exercise combining both concentric and eccentric

muscle actions has been demonstrated to result in greater strength outcomes than either

phase performed separately.35'46,76, 87, 94, 134 When movement velocity is held constant,

eccentric muscle actions produce significantly greater force than concentric muscle

actions,97 suggesting that during traditional resistance exercise the eccentric muscle

action is underloaded. Alternative forms of resistance exercise such as eccentric-only35'
46, 49, 93, 119, 130, 146, 158, 163 or eccentric-enhanced weight training protocols17', 25, 51, 59, 86, 87, 95,

118, 156 have been proposed as a means of supra-maximally loading skeletal muscle to

optimize training adaptations during resistance exercise; however, the effectiveness of

such protocols has not been substantiated.









A host of factors may affect skeletal muscle adaptations following resistance

exercise including load or intensity, repetition selection, repetition speed, total volume,

and rest periods;104 each of these factors may also affect hormonal6' 8,64, 106, 109, 111, 128, 143,

171 and/or metabolic responses36' 112 following exercise. Acute elevations in serum

anabolic hormone concentrations (i.e., total testosterone, bioavailable testosterone, and

growth hormone) and metabolic factors (i.e., lactate) during resistance exercise have been

shown to, directly or indirectly, influence muscle hypertrophy and performance.113 Thus,

determining serum anabolic hormone concentrations, at rest and following exercise, may

provide a theoretical framework to further understand the skeletal muscle adaptation

process following eccentric-enhanced exercise. The following review discusses eccentric

exercise and the anabolic hormone responses underlying the muscular adaptation process.

Eccentric Exercise

Eccentric-only resistance exercise is an alternative form of weight training that is

typically performed on an isokinetic dynamometer and entails coupled eccentric actions

involving antagonist muscle groups (e.g. knee flexors and extensors). Eccentric-only

resistance training protocols (6-11 weeks) have been shown to result in greater increases

in muscular strength compared to concentric-only training.35'49, 119, 130 The accentuated

strength improvements following eccentric-only resistance exercise may be due, in part,

to a -40-50% greater maximal workload typically performed during the eccentric phase

of exercise.46 However, some research reports that concentric-only training (4-20 weeks)

results in similar93, 158, 163 or greater strength improvements146 compared to eccentric-only

training. Additionally, some research demonstrates that the strength adaptations

following concentric-only and eccentric-only resistance training are mode and/or speed









specific,79, 88, 157 suggesting that a variety of factors) may affect the skeletal muscle

adaptation process.

The energy requirements and metabolic fatigue associated with resistance exercise

are of concern when prescribing weight training programs for both healthy and at-risk

populations. Metabolic acidosis may contribute to skeletal muscle fatigue during

anaerobic exercise,16 while reduced energy requirements and/or metabolic fatigue during

exercise may diminish perceived exertion and result in reductions in overall fatigue.

Therefore, evaluating the metabolic responses to eccentric-only resistance exercise may

provide a possible mechanistic understanding of the underlying factors associated with

skeletal muscle fatigue.

A variety of studies have evaluated the energy cost of concentric and eccentric

training including cycling and traditional weight training.2' 3, 20, 30, 31, 45, 119, 129, 159 During

resisted eccentric-only cycling at similar submaximal loads, the metabolic cost of

exercise is 1/6th -1/7th lower than concentric-only cycling.20 The energy requirements

during maximal eccentric-only cycling (-0.9-1.0 L 02/min) are reportedly equal to or

lower than the energy requirements during concentric-only cycling (-1.0-1.5 L 02/min)

despite a 300-700% greater workload performance during eccentric-only cycling.119

Further, Dudley et al.45 (1991) reported that during traditional resistance training the

eccentric action of exercise was responsible for -14% of the total energy cost, suggesting

that the concentric phase of traditional resistance exercise has a higher energy demand.

Similarly, the caloric cost of isoinertial (traditional/concentric-eccentric) resistance

exercise (3 sets, 8 repetitions leg press) was comparable to the caloric cost of concentric-

only resistance exercise (86.10 4.83 kcal vs. 87.21 4.60 kcal, p>0.05), although









significantly greater work was performed during the traditional exercise trial (9955.23 +

643.10 vs. 6318.15 363.45 J, p<0.05).30 Collectively, these results suggest that the

eccentric phase of exercise is less metabolically demanding than the concentric phase.

Metabolic acidosis is associated with skeletal muscle fatigue.149 A few studies

have reported that the lactate responses following maximal eccentric-only exercise are

lower than the responses following maximal concentric-only exercise.22'47,83,101

Conversely, at least one study has demonstrated no difference in lactate accumulation

between concentric and eccentric muscle actions, when loads were held constant.102 At

similar exercise volumes, the lactate and ammonia responses were 3-4 fold lower

following an eccentric-only (600. sec-) muscular endurance test compared to a

concentric-only (1800. sec1) one-minute muscular endurance test.85 Similarly, Hollander

et al.83 (2003) reported an -5-7 fold greater lactate response following concentric-only

resistance training compared to eccentric-only resistance training (4 sets of 12 reps

performed at 60-65% 1RM on 4 exercises). These results suggest that eccentric-only

exercise produces lower concentrations of lactate and ammonia than an equal volume of

concentric exercise.

In summary, it appears that eccentric-only resistance training results in similar or

greater strength gains than concentric-only training. Further, the energy cost and

metabolic fatigue associated with eccentric-only exercise appear to be less than that

during concentric-only and traditional resistance training, suggesting that eccentric-only

exercise may be more metabolically efficient than concentric-only and traditional

resistance exercise. Therefore, eccentric-only exercise may be beneficial to at-risk

populations with limited cardiovascular capabilities or those prone to fatigue.









Eccentric-Enhanced Exercise

Eccentric-enhanced resistance exercise involves a concentric contraction coupled

with a supramaximally loaded eccentric action. A variety of methods (e.g. manual

resistance) and machines (i.e. isokinetic dynamometers, isoload inertial strength training

ergometers, and eccentric-enhanced selectorized machines) are capable of providing a

supramaximal eccentric overload during resistance exercise.21'30, 42, 81, 95 Traditionally,

isokinetic dynamometers are used to perform eccentric-enhanced resistance exercise;

however, limitations exist in isokinetic dynamometry including the inability to perform

bilateral exercises and lack of exercise selection. A weight training machine called the

Maxout (Myonics Corporation, Metairie, LA) is also capable of providing a

supramaximal overload during the eccentric phase of resistance exercise.17' 95

Additionally, the Maxout can be used with a variety of bilateral multiple-joint exercises,

such as the chest press or squat.

Theoretically, supramaximally overloading the eccentric phase of exercise may

enhance the muscular strength and hypertrophic responses associated with resistance

training. However, it remains unclear whether eccentric-enhanced training accentuates

the strength outcomes following resistance exercise. Several studies have reported

greater increases in muscular strength 51, 86, 87, 95, 118 and skeletal muscle mass 51, 118

following (7 days-11 weeks) eccentric-enhanced training compared to traditional

resistance training. One study reported significantly greater strength gains for the elbow

extensors (+25% eccentric-enhanced vs. +10% traditional; p<0.05), but not the elbow

flexors (+10% eccentric-enhanced vs. +10% traditional) following nine weeks of

eccentric-enhanced training, suggesting that the accentuated muscular adaptations

following eccentric-enhanced resistance training may be muscle specific.25 Conversely,









two studies reported similar strength gains following (10-12 weeks) eccentric-enhanced

and traditional resistance training. 17,59 No studies have reported the effects of eccentric-

enhanced multiple-j oint resistance training (chest press and/or squat) compared to

traditional multiple-joint resistance training. Table 1 summarizes the muscular strength

results form the published reports on eccentric-enhanced resistance training.

The metabolic demand and production of fatiguing metabolites associated with

eccentric-enhanced resistance training has not been reported. However, when training

volume is held constant the eccentric-enhanced exercising heart rate response (90 bpm

vs. 102 bpm, p<0.05), mean arterial pressure (117 mm Hg vs. 132 mm Hg, p<0.05), rate

pressure product (151 vs. 191, p<0.05), and rating of perceived exertion (10 vs. 13,

p<0.05) are reportedly lower than traditional training, respectively.86 These results

suggest that during eccentric-enhanced resistance training the metabolic demand and

presence of fatiguing metabolites may be lower than during traditional resistance

training; however, this remains to be fully substantiated.

In summary, eccentric-enhanced resistance training appears to result in similar or

greater strength gains, lower cardiovascular responses, and lower levels of perceived

exertion than traditional resistance training. Determining the neuroendocrine and

metabolic responses to eccentric-enhanced resistance exercise would improve knowledge

related to the effects of this form of exercise on muscle metabolism compared to more

traditional forms, as well as help explain the greater muscular adaptations associated with

eccentric-enhanced resistance training

Anabolic Hormone Responses to Resistance Training

Anabolic hormones, including testosterone and growth hormone (GH), have been shown

to favorably affect muscle hypertrophy and exercise performance due to their impact on









protein synthesis.38' 92, 113, 161 Traditional resistance training protocols have been shown to

acutely stimulate the release of both GH and testosterone in a load109' 111, 128, 143, 156 and

volume64, 106, 109, 111, 144, 171 dependent manner. It has been suggested that the acute post-

exercise elevations of serum anabolic hormone concentrations (i.e. total testosterone,

bioavailable testosterone, and growth hormone) enhances the skeletal muscle

hypertrophic response to resistance training.113 Thus, determining the serum anabolic

hormone concentrations, following resistance exercise, may provide a basic mechanistic

understanding of the skeletal muscle adaptation process, particularly as related to

eccentric-enhanced training. Further information regarding the neuroendocrine responses

to traditional resistance training is presented in several review articles.38' 113 The

following sections will provide a brief overview of the specific metabolic responses of

testosterone and GH to resistance exercise.

Testosterone

Testosterone is synthesized from cholesterol and secreted primarily by testicular

Leydig cells, in response to a hormonal cascade beginning with the release of

gonadotropin-releasing hormone (GnRH) from the hypothalamus.168 Gonadotropin-

releasing hormone stimulates both follicle-stimulating hormone (FSH) and leutenizing

hormone (LH) from the anterior pituitary, which exert separate effects on testosterone

secretion. Leutenizing hormone directly stimulates testosterone secretion from Leydig

cells, whereas FSH upregulates LH receptors in the testis, ultimately leading to increased

testosterone release.168 In vivo, testosterone is present in three forms, 1) free (unbound),

2) sex-hormone-binding-globulin (SHBG)-bound, and 3) albumin-bound.172 Both

albumin-bound and free testosterone readily traverse tissue membranes and thus are

referred to collectively as bioavailable testosterone.139 Bioavailable testosterone is













Table 1. Overview of strength outcomes from eccentric-enhanced studies
Author Year Length Subjects Training Test % A % A
Traditional ECC-Enhanced
Hortobagyi et al 1 week SED F CON 60%, ECC 100-110% 3RM +11% ECC* +27% ECC*t
(2001) 7 sessions n=30 1RM +27% CON* +26% CON *
Hortobagyi et al 1 week UNT F CON 60%, ECC 110% 1RM 3RM +18% ECC* +33% ECC*t
(2000) 7 sessions n=30 5-6 sets, 9-12 reps +43% CON* +43% CON
Friedmann et al 4 weeks UNT M CON 30%, ECC 70% 1RM ISO Value Not +5%*
(2004) 12 sessions n=18 3 sets, 25 reps Reported
Kaminski et al 6 weeks Healthy M CON 40%, ECC 100% 1RM ECC Value Not +37.7%(60/sec)* t
(1998) 12 sessions n=27 2 sets, 8 reps ISO Reported +22%(180/sec)* t
Brandenburg et al 9 weeks TRN M,F CON 75%, ECC 100-110% 1RM +10% EF* +8% EF*
(2002) 25 sessions n=23 1RM +10% EE* +25% EE*t
Barstow et al 10 weeks UNT M CON 80%, ECC 120% 1RM 1RM 95%* +93%*
(2003) 20 sessions n=28 1 set, 8-12 reps CON
Godard et al 12 weeks TRN M,F CON 66%, ECC 100% 1RM 1RM +13.8% +15.5%
(1998) 24 sessions n=39 3 sets 6-10 reps CON
Mean strength differences were calculated or estimated. Results significantly greater than baseline (p<0.05). t Results significantly
greater than traditional resistance training (p<0.05). Abbreviations: % A (percent change in strength), UNT (Untrained), TRN
(trained), SED (Sedentary), M (Males), F (Females), ECC (Ecentric), CON (Concentric), ISO (Isokinetic), KE (Knee Extension), KF
(Knee Flexion), EE (Elbow Extension), EF (Elbow Flexion).









capable of binding to androgen receptors located in heart, brain, liver, kidney, prostate,

bone, and skeletal muscle tissues.160 Upon binding in skeletal muscle, the androgen-

receptor complex 1) is directed to the cell nucleus, 2) attaches to nuclear chromatin, 3)

stimulates mRNA transcription, and 4) upregulates protein synthesis; therefore,

contributing to skeletal muscle hypertrophy.160 Conversely, SHBG-bound testosterone

cannot cross tissue membranes and therefore, is unable to interact with androgen

receptors.139 Detailed information regarding the effects of testosterone on muscle

metabolism has been previously reported.38' 151, 160, 161

Growth Hormone

Growth hormone is secreted by the anterior pituitary gland in response to elevated

levels of growth hormone releasing hormone (GHRH).92 Since GH receptors are present

in numerous tissues (bone, immune cells, skeletal muscle, fat cells, and liver cells), it has

various effects, including: decreasing glucose utilization and glycogen synthesis,

increasing protein synthesis, fatty acid utilization, collagen synthesis, nitrogen retention,

and amino acid transport into cells, and stimulating cartilage growth.92' 164 Growth

hormone directly affects cellular amino acid uptake and enhances protein synthesis and

thus contributes to skeletal muscle hypertrophy.92 Many of the anabolic effects of GH

may also be due to its stimulatory effects on IGF-1 production.92'133,164 Detailed

information regarding the effects of GH on muscle metabolism has been previously

reported.92, 133, 164

Growth Hormone and Testosterone Responses to Resistance Exercise

The GH and testosterone responses to traditional resistance exercise are well

characterized. In general, it appears that higher volumes of exercise (i.e. greater number

of reps/sets),64' 82 short rest periods (-1-minute),109, 111 moderate intensities (8RM-









12RM),109, 111, 142, 171 and large muscle group exercises (e.g. squats, deadlifts, etc)75, 108

result in the largest serum GH concentrations. Similarly, higher volumes of exercise,24'64,
144 short rest periods,109' 111 higher intensities (-5RM),109' 111 and large muscle group

exercises75, 174 result in the largest serum free and/or total testosterone concentrations.

Conversely, Ahtiainen et al. have reported that differing rest times (between sets)6 and

exercise intensities8 do not alter the free and total testosterone responses following

resistance exercise; however, the rest times (2-minutes vs. 5-minutes) and exercise

intensities (8RM vs. 12RM) reported in these studies were outside the ideal ranges for

testosterone release suggested in previous studies,109' 111 possibly confounding the results.

The use of forced repetitions (i.e. repetitions performed beyond concentric muscle

failure with the assistance of a spotter) has been reported to result in a larger GH response

than traditional resistance exercise, '8 suggesting that work performed beyond concentric

muscular fatigue may enhance the anabolic response to exercise. Eccentric-enhanced

resistance exercise is an alternative method of performing work beyond concentric

muscle fatigue. It is possible that the anabolic hormone responses to eccentric-enhanced

resistance exercise may be accentuated due to the stimulus of this form of exercise. One

study has reported that, at identical workloads, eccentric-only resistance exercise results

in significantly lower lactate, GH, total testosterone, and free testosterone responses than

concentric-only resistance exercise; suggesting that the neuroendocrine and metabolic

responses to resistance training are less responsive to submaximal eccentric-only

exercise.47 However, Kraemer et al. (2001) reported that the GH response following

resistance exercise is dependent upon the mode of training and testing. Specifically,

subjects were divided into four groups, a 1) concentric-only exercise, 2) double volume









concentric-only exercise, 3) concentric-eccentric exercise, or 4) no exercise (control)

group. Following 19-weeks of training subjects performed separate eccentric-only and

concentric-only exercise tests to evaluate the neuroendocrine responses following

differing muscle actions. The results of this study demonstrate that the GH responses for

the 1) concentric-only and 2) double volume concentric groups were -2-2.5 fold greater

following the concentric-only exercise test compared to the eccentric-only test, whereas

the GH response for the 3) concentric-eccentric exercise group was -70% greater

following the eccentric-only exercise test, compared to the concentric-only test. These

results suggest that the GH response following exercise is specific to the mode of training

and that the eccentric phase of traditional (concentric-eccentric) resistance training results

in the largest GH release.105 The neuroendocrine and metabolic responses to eccentric-

enhanced resistance exercise remain to be determined.

Conclusion

Eccentric-only resistance exercise results in similar, or greater, strength gains with

a lower metabolic demand compared to concentric-only exercise. Similarly, eccentric-

enhanced resistance exercise results in greater muscular strength and skeletal muscle

hypertrophy than traditional resistance exercise.25' 51, 86, 87,95 While there are no published

reports on the neuroendocrine or metabolic responses to eccentric-enhanced resistance

training, it is possible that eccentric-enhanced resistance training may result in

accentuated neuroendocrine and/or blunted metabolic responses. Research designed to

elucidate the neuroendocrine and metabolic responses to eccentric-enhanced resistance

exercise would contribute to an improved understanding of the mechanisms) underlying

the muscular strength and hypertrophic responses to resistance exercise.














CHAPTER 3
METHODS

Subjects

Twenty-nine, healthy, college-aged males volunteered for this study. Each

participant completed a health history questionnaire (Appendix A), physical activity and

dietary questionnaire (Appendix B), and signed an informed consent document approved

by the University of Florida Institutional Review Board prior to participating in the study.

Prior to data collection, a total of five subjects were removed from this study; four

subjects were removed for failure to abide by study protocol and one subject was

removed due to an injury unrelated to this study. During the study, two subjects

completed the baseline testing/blood acquisition sessions and subsequently asked to be

removed from the study due to time constraints. Additionally, blood could not be

acquired from two subjects; therefore, a total of twenty subjects completed all portions of

this study.

Inclusionary/Exclusionary Criteria

To be included in the study, subjects had to be untrained (no resistance exercise

during the previous six months). Subjects were excluded if they 1) had an orthopedic

injury that would limit participation, 2) had a metabolic disease, 3) had a dietary intake

low in calories, fat, carbohydrates, or protein that could affect hormonal levels,154 4) were

a competitive athlete or competed in powerlifting or bodybuilding during the previous

year, 5) had used any ergogenic aid within the past month, 6) had used nutritional

supplements within the past month that may affect hormonal levels (Appendix C), or 7)









were taking pharmacological agents that could alter test results such as anabolic steroids

or sympathoadrenal drugs. Additionally, during the study subjects were excluded if they

missed more than four total exercise training sessions (75% attendance rate) or if they

were absent for more three consecutive exercise training sessions.

Experimental Design

For this randomized study, subjects participated in a total of 20 experimental

sessions, including three (3) baseline testing, fifteen (15) exercise training, and two (2)

follow-up testing sessions (see Figure 1). Prior to the exercise training sessions, subjects

were randomly assigned to either the traditional progressive resistance exercise group or

an eccentric-enhanced progressive exercise group. During each session, subjects

performed a 5-minute warm-up at moderate intensity on a stationary bicycle (Monark,

Vansbro, Sweden). Following the warm-up, subjects performed both a chest press and

squat exercise on the MaxOut exercise machine (Myonics Corporation, Metairie, LA), at

pre-determined loads (see section entitled Exercise Training). Three sessions were

performed per week, with a minimum of 48 hours separating each session. Dietary

recalls were monitored throughout the testing period to ensure all subjects consumed a

similar diet on testing days.154 During the study intervention, subjects were instructed to

continue their normal activities and nutrient intakes. Additionally, subjects were asked to

abstain from weight lifting not associated with this study.











BASELINE SESSION 1
1RM Testing
Anthropometrics



BASELINE SESSION 2
1RM Testing


BASELINE SESSION 3
4 Sets @ 52.5% 1RM Traditional


MA TCHED &

ECCENTRIC-ENHANCED GROUP
5 Weeks, 3 x Week-1
3 Sets, 1 min Rest
40% 1RM Con / 100% 1RM Ecc


RANDOMIZEDN,

TRADITIONAL GROUP
5 Weeks, 3 x Week-1
4 Sets, 1 min Rest
52.5% 1RM Con / 52.5% 1RM Ecc


TRAINING SESSION 1
Exercise Protocol


BLOOD
SAMPLING
I4 --


TRAINING SESSION 1
Exercise Protocol


TRAINING SESSIONS 2-14
Exercise Protocol


TRAINING SESSIONS 2-14
Exercise Protocol


TRAINING SESSION 15
Exercise Protocol


BLOOD
SAMPLING
----


TRAINING SESSION 15
Exercise Protocol


FOLLOW-UP SESSION 1
1RM Testing
Anthropometrics


FOLLOW-UP SESSION 2
4 Sets @ 52.5% 1RM


Figure 1. Experimental design. Abbreviations: Con (concentric), Ecc (eccentric).


BLOOD SAMPLING
T=0, 1, 15, 30, 45, 60
mnin


I I









Baseline Testing

During baseline session 1, subjects were familiarized with the exercise protocol.

Familiarization included 1) instruction on proper use of the chest press and squat exercise

and 2) practicing the chest press and squat exercises at a submaximal load. Subjects were

subsequently asked to perform a 1RM on each exercise (chest press and squat), according

to standard protocol.27 Additionally, subject's height and weight were measured on a

medical scale and body density was determined by a 3-site skinfold measure,91 using

Lange calipers (Beta Technology Incorporated, Cambridge, Maryland). Body density

was used to estimate body composition.28 During baseline session 2, subjects performed

a 1RM on each exercise, according to standard protocol.27 During baseline session 3,

subjects entered the laboratory, following a 12-hour (overnight) fast, and rested for 10

minutes prior to 10ml (2 teaspoons) blood sample acquisition by a certified phlebotomist.

Immediately following the initial blood acquisition, subjects performed four sets of each

exercise at 52.5% 1RM; the speed of each repetition was standardized so that the

concentric and eccentric actions were each performed for two seconds each. Each set

was separated by one minute of rest. Additionally, 10ml blood was acquired at five

additional time points, immediately post exercise (t=l), 15 minutes (min) post exercise

(t=15), 30 min post exercise (t=30), 45 min post exercise (t=45), and 60 min post exercise

(t=60). These time points were selected as both testosterone and GH concentrations peak

within 30 min of exercise completion and remain elevated for -60 min post-exercise.113

Exercise Training

During all exercise training sessions, the eccentric-enhanced group performed three

sets (40% 1RM concentric, 100% 1RM eccentric) of six repetitions each and the

traditional group performed four sets (52.5% 1RM concentric, 52.5% 1RM eccentric) of









six repetitions each, for each exercise. Training load was increased 5-10 pounds for the

subsequent training session when all repetitions were completed with proper form.

During training, the traditional group performed an additional set in an attempt to equate

exercise volumes between groups. Each repetition was performed at a cadence of two

seconds concentric and two seconds eccentric, to account for possible differences in

outcome measures due to the speed of movement.90', 131, 136, 177 Each set was separated by

one minute of rest. Additionally, during exercise training sessions 1 and 15, 10ml blood

was acquired at six time points, corresponding to the previous protocol. No blood

samples were acquired during exercise training sessions 2-14.

Follow-Up Testing

During follow-up session 1, subjects performed a 1RM on both the chest press and

squat exercises, according to standard protocol.27 Additionally, subject's height, weight,

and lean body mass were measured, as performed during baseline testing. During follow-

up session 2, subjects performed a 1RM on both exercises. Additionally, during follow-

up session 2, subjects performed four sets (52.5% 1RM) for both exercises, as performed

during baseline testing. The IRM testing and 52.5% 1RM testing was separated by a 10

minute break, in an effort to offset fatigue.

Dietary Analysis

Subjects were given standard dietary instructions for nutrient intake for the one

day prior to blood acquisition. Intake instructions were based on American Heart

Association Guidelines (i.e. 50-60% carbohydrate, <30% fat, 10-15% protein).120

Subjects were asked to complete a three-day dietary record at the onset of the study and

one-day dietary records on the day prior to each blood draw (Appendix D). When

reporting for blood draws, subjects were asked to refrain from food, drink, alcohol, and









caffeine consumption for 12 hours prior to blood collection (i.e. overnight fast). Analysis

of total dietary kilocalories and macronutrients consumption was performed using the

DietOrganizer 2.2 (MulberrySoft) dietary analysis program.

Sleep Analysis

Subjects were given standard instructions for sleeping on the one day prior to

blood acquisition. Instructions were based on the National Sleep Federation

recommendations of 7-10 hours per night. Subjects were asked to record their total

number of hours slept each night, throughout the study.

Blood Collection

Whole blood was collected by a certified phlebotomist via venipuncture or

catheter from an antecubital forearm vein. Blood samples (10mL) were collected

immediately before (t=0) and after exercise (t=l, 15, 30, 45, and 60 minutes) into serum

tubes with no additives (red top) and plasma tubes with an EDTA additive (pink top).

The total volume of blood collected per day was 60 mL. Samples were stored at 4C

until centrifugation. Hematocrit, hemoglobin, and lactate determinations were

determined using whole blood and the remaining blood was centrifuged at 3000g for 12

minutes. Serum and plasma samples were separated and stored at -800C until analyzed.

Day-to-day variability in blood parameters was minimized by collecting blood samples

during the same time of day (7:00-10:30am) for each subject.

Biochemical Analyses

Hematocrit percent was determined by the microcapillary tube method.40

Hemoglobin concentration was determined with the Hgb Pro hemoglobin analyzer (ITC,

Edison, New Jersey). Whole-blood lactate was measured by the Accusport Lactate

Analyzer (Roche Molecular Biochemicals, Mannheim, Germany). Serum aliquots were









analyzed for growth hormone (GH), total testosterone, and bioavailable testosterone.

Serum growth hormone (GH) was determined by an enzyme-linked immunosorbent assay

(ELISA) (Diagnostic Systems Laboratories, Inc., Webster, Texas). Serum total

testosterone was determined by enzyme immunoassay (EIA) (Diagnostic Systems

Laboratories, Inc., Webster, Texas). Serum bioavailable testosterone was determined by

an ammonia sulfate precipitation method.121 Briefly, a saturated ammonia sulfate/DI

water solution was combined with serum (1:1) to induce precipitation of sex-hormone

binding globulin. The combined samples were immediately vortexed and stored at room

temperature for 10 minutes prior to centrifugation. The supernatant was then analyzed by

EIA (Diagnostic Systems Laboratories, Inc., Webster, Texas). All samples were

performed in duplicate and in a single run. Serum hormone concentrations were

subsequently corrected for plasma volume changes, estimated by hemoconcentration.40

Data Analysis

The SPSS 12.0.1 statistical package was used for the statistical analysis. All values

are reported as the mean + SE. Pre- to post-comparisons were performed using a 2

(Groups) x 2 (Time) repeated measures ANOVA. Biochemical markers were compared

using 2 (Groups) x 6 (Time) Repeated Measures ANOVAs. When necessary a Tukey's

post hoc analyses was implemented. Alpha levels for all measurements were set at p <

0.05.

Sample Size

The hormonal dependent variables in this study are serum growth hormone, total

testosterone, and bioavaible testosterone. Of these measures, growth hormone has been

reported to be the most responsive to resistance exercise and thus was used for sample






23


size calculations. Standard sample size calculations were used to estimate the number of

subjects required123 and were based on previously reported data (4 sets 12RM squat

exercise).8 The results of the power calculation indicated fourteen subjects (n=7 each

group) would provide a power of 80% at an alpha level of 0.05 to detect differences in

growth hormone (See Power calculation, Appendix E).














CHAPTER 4
RESULTS

Subjects

Twenty-four previously untrained, college-aged males (21.9 0.8 years),

randomized into traditional (n=12) or eccentric-enhanced (n=12) groups participated in

this study. No significant differences were observed for any demographic measure,

between groups (Table 2).

Table 2. Subject characteristics pre and post 5 weeks of resistance training
TRADITIONAL ECCENTRIC-ENHANCED
PRE POST PRE POST
BMI (kg/m2) 25.9 1.2 25.8 1.1 25.8 1.3 26.2 1.4
Weight (kg) 78.8 2.9 78.5 2.7 81.1 3.0 82.1 3.2
Body Fat % 19.5 2.1 19.9 2.1 19.5 2.5 19.8 2.3
Data are expressed as Mean SE.

Biochemical Results

For clarity, the terms untrained and trained will be used to describe the groups at

baseline (before) and following the five-week exercise intervention, respectively. At

baseline, both groups performed two testing sessions separated by > 48 hours. During

session 1 both groups performed a standardized traditional resistance exercise protocol (4

sets x 6 reps; 52.5% 1RM), whereas during session 2, the traditional group performed the

standardized traditional protocol and the eccentric-enhanced group performed an

eccentric-enhanced (3 sets x 6 reps; 40% 1RM concentric, 100% 1RM ecccentric)

resistance exercise protocol. At the completion of the exercise intervention, subjects

again completed a bout of either traditional (4 sets x 6 reps) or eccentric-enhanced (3 sets

x 6 reps) exercise, utilizing the maximum load completed by the end of the five-week









intervention. This study design allowed comparison of the metabolic and neuroendocrine

responses between traditional and eccentric-enhanced resistance exercise, in both the

untrained and trained states. Blood samples were not acquired from two subjects in the

traditional group; therefore all biochemical analyses were performed on 22 subjects

(n=10 traditional; n=12 eccentric-enhanced).

Lactate

Lactate Response to the Standardized Traditional Exercise Protocol in Untrained
Men

The (whole-blood) lactate responses after the standardized resistance exercise

protocol for both groups prior to the training intervention are presented in Figure 2.

Lactate concentrations increased (-250%) immediately after exercise (p<0.05) and

gradually returned to baseline by 45 minutes post-exercise. No significant differences in

lactate concentrations were observed between groups, at any time point.


Lactate Response to Traditional Resistance Exercise
9 Traditional
-- Eccentric-Enhanced
8


V6-
5//
4 $#


2 -
Exercise Post Exercise Recovery
1
I -I I I I I I
Pre Post 15 30 45 60
Time Points

Figure 2. Lactate responses to traditional resistance exercise. Indicates significantly
different than Pre; $ indicates significantly different than Post; # indicates
significantly different than 15 min (p<0.05). Data are Mean + SE.









Lactate Responses to Standardized Traditional and Eccentric-Enhanced Exercise in
the Untrained

Lactate responses following a single bout of traditional and eccentric-enhanced

resistance exercise protocols performed at baseline are presented in Figure 3. Before

exercise, lactate concentrations were similar between groups (-2.5 mmol/1) and increased

following exercise, representing 210% and 340% in the traditional and eccentric-

enhanced groups, respectively (p<0.05). During the post-exercise recovery period,

lactate gradually returned to baseline within 45 minutes of exercise completion. The

immediate post-exercise lactate concentration was greater in the eccentric-enhanced,

compared to the traditional group (7.8 0.4 mmol/1 vs. 5.8 0.3 mmol/l, p<0.05).


Baseline Lactate Response to Traditional and Eccentric-
Enhanced Resistance Exercise
# Traditional
AX Eccentric-Enhanced



/$ O < $%


Exercise


Pre P


Post Exercise Recovery


lost


Time Points

Figure 3. Baseline lactate responses to traditional and eccentric-enhanced resistance.
Indicates significant difference between groups; # indicates significant
difference from baseline, $ indicates difference from post, % indicates
difference from 15 minutes (p<0.05). Data are Mean SE.


9
8
7
'-6
5
4
03
12
1


Of /









Lactate Response to Standardized Traditional and Eccentric-Enhanced Exercise in
Trained Men

Following the five-week training intervention, the post-exercise lactate

concentrations increased in both the traditional (-420%) and eccentric-enhanced

(-340%) groups immediately following exercise (p<0.05) and gradually returned to

baseline within 45 minutes of exercise cessation (Figure 4). No significant differences in

lactate concentrations were observed between groups at any time point, including pre-

and post-exercise as well as recovery.


Post-Intervention Lactate Responses to Traditional and
Eccentric-Enhanced Resistance Exercise
-* Traditional
^ -* Eccentric-Enhanced



##$%
/A ,,.


, Exercise

Pre Post


/0 $ %

Post Exercise Recovery


Time points
Figure 4. Post-intervention lactate responses to traditional and eccentric-enhanced
resistance exercise. # indicates difference from baseline, $ indicates
difference from post, % indicates difference from 15 minutes (p<0.05). Data
are expressed Mean SE.

Testosterone

Resting Testosterone

To account for diurnal variation in testosterone secretion, two resting baseline

blood samples were acquired 48 hours apart. No significant differences in either total

(6.45 0.47 ng/ml session 1 vs. 6.96 0.55 ng/ml session 2) or bioavailable (4.10 + 0.30









ng/ml session 1 vs. 4.13 0.27 ng/ml) testosterone concentrations were observed on

either day; therefore, the average testosterone concentrations were used as the baseline

resting value. Resting total serum testosterone concentrations (Figure 5) remained

unchanged with training for both groups. However, resting bioavailable testosterone


Resting Baseline and Post-Intervention Total Testosterone
Concentrations


9 TRADITIONAL GROUP


ECCENTRIC-ENHANCED
GROUP
T


4


Figure 5. Total serum testosterone before (Baseline) and after (Post) the training
intervention. Indicates a significant difference is present (p<0.05). Data are
presented as Mean SE.


Resting Baseline and Post-Intervention Bioavailable
Testosterone Concentrations


TRADITIONAL GROUP


ECCENTRIC-ENHANCED
GROUP


nasellnne rosi asenne rosi
Figure 6. Total bioavailable testosterone before (Baseline) and after (Post) the training
intervention. Indicates a significant difference is present compared with
baseline value (p<0.05). Data are presented as Mean SE.


5.5
o
5
S 4.5
4
S3.5
^ 3
2.5
2









concentrations (Figure 6) were -24% lower in both groups following the five-week

resistance training intervention (p<0.05). Additionally, resting bioavailable testosterone

accounted for 61% and 46% of total resting testosterone at baseline and post-intervention

in both groups, respectively. No significant differences were observed between groups

for either resting total or bioavailable testosterone concentrations, in either the trained or

untrained states.

Testosterone Responses to the Standardized Traditional Exercise Protocol in
Untrained Men

Following the standardized traditional resistance exercise protocol, the post-

exercise total testosterone concentrations (immediately to 30 minutes post) were not

significantly different from baseline (Figure 7); however, 45-60 minutes following

training the total testosterone concentrations decreased below baseline (p<0.05).

Similarly, the post-exercise bioavailable testosterone concentrations (immediately to 15

minutes post) were not significantly different from baseline (Figure 8); however 30-60

minutes following training the bioavailable testosterone concentrations decreased below

baseline (p<0.05). No significant differences in either total or bioavailable testosterone

concentrations were observed between groups at any time point.

Testosterone Responses to Standardized Traditional and Eccentric-Enhanced
Exercise in Untrained Men

Total testosterone responses following a standardized traditional and eccentric-

enhanced resistance exercise protocol (Figure 9) were not significantly different than

baseline (immediate to 45 minutest post); however, total testosterone was lower than both

baseline and immediate post concentrations at 60 minutes (p<0.05). The bioavailable

testosterone concentrations (Figure 10) increased immediately following exercise and

decreased to below baseline concentrations within 60 minutes of exercise completion










Total Testosterone Responses to Standardized Traditional
Resistance Exercise Protocol

N-- Traditional
U-4 Eccentric-Enhanced


8

7

" 6
5


Exercise Post Exercise Recovery


Post


Time Points


Figure 7. Total testosterone responses to standardized traditional resistance exercise
protocol. Indicates significantly different value than Post; # indicates
significantly different value than 15 min (p<0.05). Data are expressed as
Mean SE.

Bioavailable Testosterone Responses to Standardized
Traditional Resistance Exercise Protocol


-0-Traditional
0- Eccentric-Enhanced



- *# $ %


4

3.5
3
2.5


Exercise Post Exercise Recovery


Post


15 30
Time Points


Figure 8. Bioavailable testosterone responses to standardized traditional resistance
exercise protocol. Indicates significantly different value than Pre; # indicates
significantly different value than Post; $ indicates significantly different value
than 15 min; % indicates significantly different value than 30 min (p<0.05).









(p<0.05). No significant differences were observed for either total or bioavailable

testosterone concentrations between groups at any time point, including pre- and post-

exercise as well as recovery.


Total Testosterone Responses to Standardized Traditional and
Eccentric-Enhanced Resistance Exercise
10 Traditional

9 ~- Eccentric-Enhanced


7




4 Exercise Post Exercise Recovery

3
Pre Post 15 30 45 60
Time Points

Figure 9. Total testosterone responses to standardized traditional and eccentric-enhanced
resistance exercise in untrained men. Indicates difference from baseline;
indicates difference from post. Data are expressed Mean + SE.

Testosterone Responses to Standardized Traditional and Eccentric-Enhanced
Resistance Exercise in Trained Men

At post-intervention testing, total testosterone concentrations (Figure 11) increased

immediately following exercise and decreased to below baseline values within 30

minutes of exercise completion (p<0.05). Bioavailable testosterone concentrations

increased immediately following exercise in both groups and remained elevated for 15

minutes (p<0.05), before returning to baseline (Figure 12). No significant differences

were observed between groups for either total or bioavailable testosterone concentrations,

at any time point.











Bioavailable Testosterone Responses to Standardized
Traditional and Eccentric-Enhanced Resistance Exercise


b Traditional
S Eccentric-Enhanced


Exercise Post Exercise Recovery


Post


Time Points


Figure 10. Bioavailable testosterone responses to standardized traditional and eccentric-
enhanced resistance exercise in untrained men. Indicates significantly
different value than Pre; # indicates significantly different value than Post; $
indicates significantly different value than 15 min (p<0.05). Data are
expressed Mean SE.

Post-Intervention Testosterone Responses to Standardized
Traditional and Eccentric-Enhanced Resistance Exercise
Protocols


10
f 9
8
7
S6
5
S4


- Traditional
e Eccentric-Enhanced


Exercise Post Exercise Recovery
I


Pre Post 15 30 45 60
Time Points


Figure 11. Post-intervention total serum testosterone responses to standardized
traditional and eccentric-enhanced resistance exercise protocols. Indicates
significantly different value than Pre; # indicates significantly different value
than Post; $ indicates significantly different value than 15 min (p<0.05). Data
are expressed Mean SE.


: 5.5
S 5
,-,4.5
4

n 3.5
S 3
a 2.5










Post-Intervention Bioavailable Testosterone Responses to
Traditional and Eccentric-Enhanced Resistance Training
6 Traditional
5.5 -
o WEccentric-Enhanced
S 5 *
4.5 $
#$
4 -


3 3
S2.5 Exercise Post Exercise Recovery
2 -
Pre Post 15 30 45 60
Time Points

Figure 12. Post-intervention bioavailable serum testosterone responses to standardized
traditional and eccentric-enhanced resistance training. Indicates
significantly different than Pre; # indicates significantly different than Post; $
indicates significantly different than 15 min (p<0.05). Data are Mean + SE.

Growth Hormone

Growth Hormone Response to Standardized Traditional Exercise Protocol in
Untrained Men

Following the standardized traditional resistance exercise protocol, post-exercise

growth hormone (GH) concentrations increased above baseline 15-30 minutes after

exercise cessation (p<0.05) and subsequently returned to baseline by 45 minutes, in both

groups (Figure 13). No significant differences in GH concentrations were noted between

groups, before of after the exercise bout.

Growth Hormone Response to Standardized Traditional and Eccentric-Enhanced
Exercise in Untrained Men

Growth hormone responses following a standardized traditional and eccentric-

enhanced exercise protocol increased 15-30 minutes post-exercise (p<0.05) and returned

to baseline by 45 minutes (Figure 14). No significant differences in GH concentrations

were observed between groups, before or following exercise.










Growth Hormone Responses to Standardized Traditional
Exercise Protocol


Exercise ,
-HI


Post Exercise Recovery
-N Traditional


* Eccentric-Enhanced


Pre Post 15 30 45 60
Time Points


Figure 13. Growth hormone responses to the standardized traditional resistance exercise
protocol in untrained men. Indicates significantly different than Pre
(p<0.05). Data are presented as Mean SE.

Growth Hormone Responses to Traditional and Eccentric-
Enhanced Resistance Exercise
4 -- Traditional
5 3.5 -w- Eccentric-Enhanced


Exercise


= 3
32.5
I 2
, 1.5
1

0.5
0


Post Exercise Recovery
I


Pre Post 15 30 45 60
Time Points


Figure 14. Growth hormone responses to standardized traditional and eccentric-
enhanced exercise protocols, in untrained men. indicates significantly
different than Pre (p<0.05). Data are Mean SE.


i3.5
= 3
=2.5
S2
S1.5


Q 0.5
0









Growth Hormone Response to Standardized Traditional and Eccentric-Enhanced
Exercise in Trained Men

Following the five-week training intervention, GH was unchanged from baseline

immediately following exercise but increased above baseline 15-45 minutes following

exercise (p<0.05) and returned to baseline by 60 minutes (Figure 15). No significant

differences in GH concentrations were observed between groups, at any time point.


Post-Intervention Growth Hormone Responses to Traditional
and Eccentric-Enhanced Resistance Exercise

4 Traditional

3.5 Eccentric-Enhanced

i 3
Exercise Post Exercise Recovery
2.5 -I

2
0 1.5 *
1.5


0.5

0
Pre Post 15 30 45 60
Time Points

Figure 15. Post-intervention growth hormone responses to standardized traditional and
eccentric-enhanced resistance exercise. Indicates significantly different
value than Pre (p<0.05). Data are presented as Mean + SE.

Plasma Volume

Pre- and post-exercise plasma volume values for each exercise testing/blood

acquisition session are presented in Appendix F. Briefly, plasma volume was reduced

immediately post-exercise (5-11%; p<0.05) and returned to baseline within 30 minutes of

exercise cessation during each testing session. No significant differences in plasma

volume were observed between groups, at any time point.









Muscle Function

Muscular strength data is reported as absolute (1RM) and relative (1RM x kg body

mass-1 and 1RM x kg lean body mass-1) values. Additionally, total work (load lifted x

repetitions completed) was used to quantify muscular endurance. Two subjects from the

eccentric-enhanced group did not complete the training intervention; therefore

performance results reflect 22 subjects (n=12 traditional; n=10 eccentric-enhanced).

Muscular Strength

No statistical differences in strength were observed between groups at baseline, for

the chest (press) or leg (squat) (Table 3). Following the five-week exercise intervention,

both groups showed similar increases in absolute (1RM) and relative (1RM x kg body

mass-1 and 1RM x kg lean body mass-1) chest strength (p<0.05). Additionally, both

groups showed similar increases in absolute leg strength (p<0.05), whereas the traditional

group exhibited a greater increase in relative leg strength compared to the eccentric-

enhanced group (p<0.05).

Muscular Endurance

Muscular endurance measures are reported as total work, calculated as:

Total Work (kg) = Load (kg) Total Number of Repetitions Completed

Chest and leg endurance values were similar between groups at baseline (Table 4).

Following the exercise intervention, both groups showed similar increases in chest and

leg endurance (p<0.05).









Table 3. Muscular strength values at baseline and post-intervention for the traditional and
eccentric-enhanced groups.
TRADITIONAL ECCENTRIC-ENHANCED
PRE POST % A PRE POST % A
1RM 76.9 4.4 84.7 4.8* 10.1 75.5 4.9 82.3 5.0* 9.0
S(kg)
kg/mass 0.97 0.04 1.08 0.05* 11.3 0.93 0.06 1.01 0.06* 8.6

kg/FFM 1.23 0.06 1.35 0.07* 9.8 1.16 0.06 1.25 0.06* 7.8

1RM 101.5 + 7.6 127.3 + 7.0* 25.4 102.7 4.6 121.8 + 5.8* 18.6
(kg)
kg/mass 1.29 0.10 1.62 0.08* 25.6 1.28 0.06 1.49 0.06* 16.4

kg/FFM 1.61 + 0.09 2.03 0.08* 26.1 1.59 + 0.06 1.86 + 0.07* 17.0

* Indicates difference from corresponding pre-test value; # indicates difference between
groups (p<0.05). % A reflects the percentage change in muscular strength from baseline
to post-intervention testing, mass represents body mass in kg, FFM represents fat-free
mass in kg. Data are expressed as Mean SE.

Table 4. Muscular endurance (total work) measures at baseline and post-intervention for
the traditional and eccentric-enhanced groups.
TRADITIONAL ECCENTRIC-ENHANCED
PRE POST % A PRE POST % A
Chest 1010 54 1100 63* 8.9% 995 61 1086 65* 9.1%
Press
Squat 1318 97 1604 104* 21.7% 1353 61 1615 78* 19.4%

* Indicates significantly different value than corresponding pre-test value (p<0.05). % A
represents percentage change in muscular endurance from baseline to post-intervention
testing. Data are Mean SE.

Rating of Perceived Exertion

The ratings of perceived exertion (RPE)153 acquired during each exercise session

throughout the five-week training intervention are presented in Figure 16. The traditional

group had a significantly lower RPE during sessions 1-4, compared to the eccentric-

enhanced group (p<0.05). No other significant differences were observed during any

exercise training session.












Ratings of Perceived Exertion Values Per Session

20 Traditional
19 U Eccentric-Enhanced
18 -* *
17 -
.216
15 -
14 -
13 -
12 -
11 -
10
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Session #

Figure 16. Ratings of perceived exertion (Borg Scale) following each exercise training
session. Indicates significantly different value between groups (p<0.05).
Data are expressed as Mean SE.


Training Volume

Training volume is reported as, 1) training volume per exercise session and 2) total

training volume across the five-week training intervention. Training volume per session

was determined using the following equation:

VOLUME = [# of CON actions CON load] + [# of ECC actions ECC load]

Total training volume during the exercise intervention was determined by summing each

per session training volume. Further, individual chest press and squat training volumes

were quantified to determine the total work performed on each exercise and a combined

(chest press volume + squat) training volumes was calculated, as the combined training

volume may be indicative of post-exercise hormonal responses.113









Training Volume Per Exercise Session

The chest press volume per session (Figure 17) was greater during sessions 2-11,

13, and 15 for the traditional group, compared to the eccentric-enhanced group (p<0.05).

The squat volume per session (Figure 18) was greater during sessions 9, 10, 14, and 15

for the traditional group, compared with the eccentric-enhanced group (p<0.05). The

combined training volume per session (Figure 19) was greater during sessions 7 and 15

for the traditional group, compared to the eccentric-enhanced group (p<0.05).

Chest Press Volume Per Session
2900 Traditional

2700 Eccentric-Enhanced *

2500 -

2300 -- "

2100 -

1900 -

1700 ..

1500
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Training Session
Figure 17. Chest press training volume per session for the traditional group and
eccentric-enhanced groups. indicates significantly different value between
groups at the designated session (p<0.05). Data are Mean SE.










Squat Volume Per Session

-,Traditional
U4 Eccentric-Enhanced
*


1 2 3 4 5 6 7 8 9
Session #


10 11 12 13 14 15


Figure 18. Squat training volume per session for the traditional and eccentric-enhanced.
Indicates significantly different value between groups at the designated
session (p<0.05). Data are Mean SE.

Combined Chest Press and Squat Volume Per Session


7000

- 6500

, 6000

5500

P4 5000

4500

o 4000


* Traditional


U Eccentric-Enhanced


3500


1 2 3 4 5 6 7 8 9
Session #


10 11 12 13 14 15


Figure 19. Combined training volume per session (Chest Press + Squat) for the
traditional and eccentric-enhanced groups. Indicates significantly different
value between groups at the designated session (p<0.05). Data are Mean +
SE.


4300
4100
3900
3700
3500
3300
3100
2900
2700
2500
2300


* *









Total Accumulated Training Volume Across Five-Week Intervention

In this section, total training volume refers to the total training volume performed

during the entire five-week exercise intervention. The chest press training volume

(Figure 20) was greater in the traditional group, compared with the eccentric-enhanced

group (34,802 1550 kg vs. 29,438 1683 kg, p<0.05), while the total squat training

volume (Figure 19) was not statistically different between the traditional and eccentric-

enhanced groups (48151 2764 kg vs. 43020 1838 kg). The total combined training

volume (chest press + squat volumes) (Figure 21) tended to be greater for the traditional

group, compared with the eccentric-enhanced group (83037 4082 kg vs. 72485 + 3164

kg); however, statistical significance was not achieved (p=0.061).


Total Chest Press and Squat Training Volume During Exercise
Intervention
55000 SQUAT
50000 -
45000 -

o 40000 CHEST PRESS
S35000 -
30000
25000
20000
TRAD ECC TRAD ECC

Figure 20. Total chest press and squat training volume during the five week resistance
exercise intervention. TRAD represents the traditional group, ECC represents
the eccentric-enhanced group. Indicates significantly different value
between groups (p<0.05). Data are expressed as Mean SE.










Combined Total Training Volume (Chest Press + Squat)
During Exercise Intervention
100000 -
S95000 Traditional
"- 90000 Eccentric-Enhanced
S85000 -
S80000 -
S75000 -
70000 -
65000 -
60000 -
55000 -
50000

Figure 21. Combined total training volume (Chest Press + Squat) during the five-week
exercise intervention. Indicates a trend towards significantly different
values between groups (p=0.061). Data are expressed as Mean SE.

Dietary Analysis

No significant differences were noted between groups for any dietary measure

(total daily kilocalorie, carbohydrate, protein, or fat consumption) throughout the

duration of the study (Table 5). On average, subjects consumed -2238 kcals per session,

which was comprised of -50.3% carbohydrates, -33.2% fat, and -16.2% protein (1. lg x

kg body mass1). Additionally, all subjects completed a 12 hour fast prior to blood

acquisitions; as indicated by dietary records and follow-up questions concerning food,

drink, alcohol, and caffeine consumption prior to blood acquisition.

Sleep Analysis

The average number of hours slept per night in the traditional (7.2 0.4 hours) and

eccentric-enhanced (7.8 0.2 hours) groups were not statistically different throughout

the exercise intervention. Additionally, 100% of subjects reported 7-10 hours of sleep on

the night preceding blood acquisition sessions.









Table 5. Average reported kilocalories, carbohydrates,
and eccentric-enhanced grou s


protein, and fat in the traditional


TRADITIONAL ECCENTRIC-ENHANCED
KCALS % TOTAL KCALS % TOTAL
INTAKE INTAKE
Total Kcals 2162 + 495 2320 + 853

Carbohydrates 1135 127 52.5% 1093 117 47.1%

Protein 326 26 15.1% 427 71 18.4%

Fat 689 60 31.9% 771 77 33.2%

Data are presented as Mean SE.














CHAPTER 5
DISCUSSION

Skeletal muscle atrophy, reduced strength, and heightened fatigue are associated

with aging175 and degenerative diseases such as multiple sclerosis155 and muscular

dystrophy.11 Participation in progressive resistance training has been shown to attenuate

loss of strength and function, improve functional capacity, and decrease hypokinetic

disease risk in both young and elderly populations.65'104 Thus, determining and

implementing effective resistance exercise protocols may ultimately minimize the

deleterious effects of both aging and degenerative diseases on skeletal muscle quality and

performance outcomes.

Traditional resistance training consists of identical loading performed during both

concentric (shortening) and eccentric (lengthening) muscle actions.104 Eccentric-

enhanced resistance exercise is performed with a greater eccentric loading (-180-250%

of concentric load) and has been shown to result in similar17'25, 59 or superior25, 51, 86, 87, 95

skeletal muscle strength and mass adaptations compared to traditional resistance training.

However, the mechanisms) underlying the purported superior muscle adaptations

following eccentric-enhanced resistance training have not been determined. Therefore,

the purpose of our study was to test the hypothesis that eccentric-enhanced progressive

resistance training would result in greater neuroendocrine (total testosterone, bioavailable

testosterone, and growth hormone) and muscle performance responses and lower

metabolic (lactate) responses than traditional progressive resistance training. The

primary findings of our research are that the early-phase (first five-week) neuroendocrine









and performance responses are similar between traditional and eccentric-enhanced

resistance training, in previously untrained college-age men.

Only one published study has attempted to elucidate the mechanisms) underlying

the purported superior muscular adaptations associated with eccentric-enhanced

resistance training.51 For comparison, we used investigations with training programs

most similar in training volume and intensity to ours; however, we were limited to 1)

traditional, 2) concentric-only, and 3) eccentric-only resistance training protocols, as

mechanistic studies on eccentric-enhanced training were limited. Eccentric-enhanced

resistance exercise is somewhat unique in that it includes a combination of the previously

mentioned program designs; therefore, direct comparison between study findings should

be interpreted cautiously.

Metabolic Response to Resistance Exercise

Metabolic acidosis, associated with lactate accumulation, may contribute to skeletal

muscle fatigue during high-intensity exercise.149 Strategies designed to reduce lactate

accumulation during exercise may decrease overall fatigue and ultimately result in

improved exercise prescriptions for both healthy and at-risk populations. We are the first

to compare the blood lactate responses to eccentric-enhanced resistance exercise and

traditional resistance exercise, in both the trained and untrained states.

Lactate Responses to Standardized Traditional and Eccentric-Enhanced Resistance
Exercise in Untrained Men

The immediate post-exercise blood lactate concentrations were greater in subjects

following a standardized eccentric-enhanced resistance exercise protocol compared to a

traditional resistance exercise protocol, matched in volume. Our findings may, in part, be

due to the greater eccentric-specific exercise intensity in the eccentric-enhanced group









(40% 1RM concentric; 100% 1RM eccentric), compared to the traditional group (52.5%

1RM concentric and eccentric). Previous reports demonstrate that both exercise volume67

and intensity117 are associated with lactate accumulation. Our results are consistent with

Lagally et al.117 (2002), who reported that higher intensity exercises result in greater

lactate accumulation. In our study, the eccentric-specific training intensity was 48.5%

greater in the eccentric-enhanced group, but volume was matched between groups (4646

kg, traditional vs. 4344 kg, eccentric-enhanced; p>0.05).

In our study, the higher eccentric-specific intensity in the eccentric-enhanced group

may reflect a greater recruitment of fast glycolytic (type IIx) and/or fast oxidative

glycolytic (type IIa) muscle fibers51 and associated lactate accumulation.89 Previous

research suggests that eccentric muscle actions recruit all available fast motor units (type

IIa and IIx) at lower relative intensities (>60% maximal voluntary contraction) than

concentric actions (>80% maximal voluntary contraction);122 therefore, it is possible that

the eccentric-enhanced group recruited a larger portion of fast motor units during

exercise resulting in greater lactate accumulation.

It is also possible that differences in (load dependent) skeletal muscle blood flow

characteristics may have influenced the lactate response between groups. For example,

arterial blood flow to contracting skeletal muscle has an inverse relationship with

exercise intensity.150 Additionally, combined venous occlusion and low-intensity

resistance exercise result in greater lactate accumulation than low-intensity resistance

exercise alone.98 Although blood flow characteristics were not evaluated in our study,

greater venous occlusion and/or reductions in arterial blood flow may have occurred in









the eccentric-enhanced group (due to the higher eccentric-specific load) thus resulting in

greater blood lactate concentrations.

Lactate Response to Resistance Training in Trained Men

The immediate post-exercise lactate response to the traditional resistance exercise

protocol was greater following the five-week training program when compared to pre-

training, possibly due to the greater exercise intensity (64% 1RM vs. 52.5% 1RM),

enhanced recruitment of fast glycolytic muscle fibers, and/or improved storage and

utilization of glycogen12 in the trained state. In contrast, the immediate post-exercise

lactate responses to eccentric-enhanced exercise were similar in the trained and untrained

states, despite a greater post-intervention eccentric-specific exercise intensity (-106%

post-intervention 1RM vs. 100% pre-intervention 1RM). Our results contrast the

supposition by Kraemer et al.103 who suggested that the post-exercise lactate

concentrations increase as the eccentric-specific exercise intensity increases.

Similar post-exercise blood lactate concentrations were observed in the eccentric-

enhanced group in both the untrained and trained states, despite the greater exercise

intensity performed in the trained state. Friedmann and colleagues51 (2004) reported that

eccentric-enhanced, but not traditional, resistance training upregulates lactate

dehydrogenase type (LDH) A mRNA following four weeks of training; indicating a

possible lactate buffering effect associated with eccentric-enhanced exercise.

Additionally, improvements in intracellular lactate buffering and/or delayed lactate

accumulation due to a repetitive training stimuli above anaerobic threshold have been

observed84, 125, 132 and may help explain our findings.

It is also possible that recruitment of additional type IIx (high lactate generating)

muscle fibers may not have occurred in the eccentric-enhanced group in the trained









state.122 Recall that complete recruitment of fast motor units has been observed during

eccentric-only muscle actions performed at intensities (-60% maximal voluntary

contraction)122 below that used during baseline testing in our study (100% 1RM);

suggesting that full recruitment of fast motor units may have occurred during baseline

testing. However, Friedmann et al.51 (2004), reported that both type IIa and IIx myosin

heavy chain (MHC) mRNA are increased following eccentric-enhanced resistance

exercise; suggesting that fast motor units are extensively recruited during eccentric-

enhanced exercise.

Alternatively, decreased skeletal muscle glycogen content and/or decreased

utilization of skeletal muscle glycogen stores may have occurred in the eccentric-

enhanced group, as a result of heavy eccentric training. Decreased skeletal muscle

glucose transporter (GLUT4) protein concentrations,12, 13 impaired glycogen

resynthesis,13 and decreased post-exercise glycogen accumulation (for up to 72 hours)178

have been observed following eccentric exercise; suggesting a reduced glycogen

availability for subsequent exercise sessions, following heavy eccentric exercise.

Although we did not measure glycogen synthesis rates or concentrations, it may be

possible that reduced skeletal muscle glycogen content limited lactate accumulation

during post-intervention testing.

Testosterone

Testosterone has been shown to enhance muscle hypertrophy by directly increasing

protein synthesis,19' 26, 50, 66, 160, 161, 170 thus it is not surprising that investigators have

attempted to identify strategies to enhance endogenous free and total testosterone

concentrations and optimize gains in muscle mass with resistance exercise.7' 8, 32, 47, 68, 70,
71, 78, 106-109, 111, 115, 169, 176 Total testosterone represents the combination of unbound (free)









testosterone (-2% of total) and testosterone bound to either sex hormone binding globulin

(SHBG) (-50% of total) or albumin (-50% of total).121 The combination of free and

albumin-bound testosterone fractions (bioavailable testosterone) reflect the effective

androgen status, as both fractions have been shown to traverse cell membranes, bind with

androgen receptors, and consequently stimulate protein translation.41'121,172 To date,

there are no published reports on the bioavailable (non-SHBG-bound) testosterone

responses to resistance exercise. The majority of studies utilizing resistance training

interventions report free testosterone7' 47, 70, 71, 169 which represents only a small portion

(-4%) of bioavailable testosterone; 121 therefore, comparison of our results to previous

reports is not possible.

Resting Testosterone

Resting total testosterone concentrations in our subjects were within the normal

eugonadal range (300-1000 ng/dl).126 Resting total testosterone concentrations remained

unchanged, while the bioavailable testosterone fraction decreased with training in both

groups. Our findings are consistent with previous reports demonstrating that resting total

testosterone levels are unaltered following resistance training interventions 10, 71-73, 78, 110,
113, 128 and inconsistent with others showing upward trends. 167

Considering that total testosterone is comprised of three components (free,

albumin-bound, and SHBG-bound), interpretation of our bioavailable testosterone results

is speculative as each subfraction may influence the bioavailable fraction. Our results

may suggest however, that 1) SHBG-bound testosterone increased, as non-SHBG-bound

(bioavailable) testosterone decreased and total testosterone remained unchanged, 2)

albumin-bound testosterone decreased, and/or 3) free testosterone decreased. The

literature indicates that SHBG is apparently unresponsive to either acutes80 or









chronic73,114,128 resistance exercise, in men. Additionally, albumin has been shown to

increase following both acute4 and chronic resistance training interventions;100 suggesting

that albumin-bound testosterone may not diminish following resistance exercise. Further,

resting free testosterone has been shown to either increase110 or remains constant5

following resistance exercise interventions. Although not measured in our study,

alterations in the free:albumin-bound:SHBG-bound testosterone ratio occurred, favoring

an increase in SHBG-bound and/or a decline in bioavailable testosterone concentrations

at the conclusion of our study.

Alternatively, upregulation of skeletal muscle androgen receptor expression may

have occurred in response to training. Support for this idea comes from studies that

report increased skeletal muscle androgen receptor expression following resistance

training interventions, in both humans15' 180 and animals.39' 173 Androgen receptor

upregulation with training may help explain the reduction in bioavailable testosterone

concentrations observed following the five-week training program.

Previous reports have also suggested that acute sleep deprivation,1' 62, 135 low

dietary total caloric and fat intakes,154, 174 and/or high dietary protein intake154 are

associated with reduced resting total testosterone concentrations. Our subjects reported

normal sleep patterns (7-10 hours)14 and adequate caloric intakes (-2220 kcals; 50.3%

carbohydrates, -33.2% fat, and -16.2% protein)120 on the day prior to each blood

acquisition session. Therefore, it does not appear that sleep patterns or dietary intake

influenced the resting hormone concentrations in our study.









Testosterone Response to Standardized Traditional Resistance Exercise in
Untrained Men

The total and bioavailable testosterone responses to a single bout of standardized

traditional resistance exercise were similar between groups before the initiation of

training. Overall, total and bioavailable testosterone concentrations remained unchanged

acutely following exercise and fell below baseline within 30-45 minutes of recovery. Our

results support Kraemer et al.114 (1998) who reported that total testosterone

concentrations remained constant following traditional resistance training, but are

inconsistent with others indicating increased testosterone concentrations following

resistance exercise in untrained men.5' 8, 68, 78, 109, 111, 169, 180 Additionally, the reduction in

both total and bioavailable testosterone concentrations, below baseline, indicate that

testosterone 1) followed normal metabolic pathway biotransformation and/or 2) became

bound to androgen receptors and stimulated protein synthesis.19

The total and bioavailable testosterone responses observed in our study may be

explained in a variety of ways. First, it is possible that the acute testosterone response to

resistance exercise is an adaptive physiological response occurring primarily after longer

term (>5 week) resistance training protocols.114 This notion is supported by our data

which demonstrate that exercise caused a transient increase in total testosterone, in

trained individuals. Second, the exercise volume and/or intensity performed in this study

may have been insufficient stimuli to induce a change in testosterone concentrations.

High volume64' 111, 144 and high-intensity109, 111, 143 resistance exercise protocols have been

shown to result in greater post-exercise testosterone concentrations than low volume or

low-intensity protocols. The training volume and intensity used in our study were similar

to previous studies that reported elevated testosterone following resistance









exercise;64, 116, 156 thus other factors such as the training status of the subjects and/or the

exercises performed during the study (chest press and squat) may explain the disparity in

findings.

Testosterone Response to Standardized Traditional and Eccentric-Enhanced
Exercise in Untrained Men

In our study, the post-exercise total testosterone concentrations in untrained

subjects, following traditional or eccentric-enhanced resistance exercise decreased below

baseline concentrations by 60 minutes into recovery; similar to our previously reported

findings that indicated total testosterone concentrations decline below baseline

concentrations following a standardized traditional resistance exercise protocol.

However, we observed an immediate post-exercise increase in bioavailable testosterone

concentrations and gradual decline to below baseline within 60 minutes of exercise

cessation, in both groups. As no change in total testosterone appeared following exercise,

our previously discussed rationale that the 1) testosterone response following resistance

exercise is a long-term adaptive response to training and/or 2) training volume and

intensity selected for this study were insufficient stimuli to elicit a change in testosterone

concentrations, may explain these findings. It is also possible that eccentric muscle

actions do not provide an adequate stimulus (metabolic or other) to affect post-exercise

total testosterone concentrations, in untrained males.103 The eccentric-specific exercise

intensity in our study (100% 1RM, eccentric-enhanced group) was greater than used in

previous that reported increased testosterone responses to eccentric-only muscle actions47

and an unchanged testosterone response to eccentric-only muscle actions.103

While total testosterone remained unchanged immediately following a standardized

bout of eccentric-enhanced and traditional resistance exercise in the untrained state,









bioavailable testosterone increased. When analyzed in association with our total

testosterone results, it appears that alterations in the free:albumin-bound:SHBG-bound

testosterone ratio may occur following a bout of resistance exercise. Recall that changes

in both free and albumin-bound testosterone affect the bioavailable testosterone fraction

and thus the interpretation of our data. Previous reports have indicated that free

testosterone increases acutely following resistance training;7' 47, 169 although we did not

directly measure free testosterone concentrations it is plausible that changes in the free

testosterone fraction influenced both our total and bioavailable testosterone results.

Testosterone Responses to Traditional and Eccentric-Enhanced Resistance Training
in Trained Men

Following the five-week training intervention, both groups exhibited an acute

increase in post-exercise total and bioavailable testosterone concentrations, which

subsequently fell below baseline 30-45 minutes into recovery. Similar testosterone

responses have been observed following resistance exercise interventions in trained

men7, 8, 32, 68, 78, 107-109, 111, 115, 143, 169, 176 Additionally, our results corroborate previous

reports indicating that post-exercise testosterone concentrations increase in trained, but

not untrained men.8' 114

Total and bioavailable testosterone concentrations were similar between groups at

all time points, despite a greater training volume in the traditional group throughout

training and post-intervention testing. Briefly, we successfully equated training volume

during baseline testing, but were unable to equate training volume during the resistance

training intervention because the load and repetition dependent rate of progression

accomplished in the traditional resistance training group could not be matched by the

eccentric-enhanced group. Considering that both exercise volume and intensity are









thought to play integral roles in determining the testosterone responses following

resistance training;113 the additional training volume completed by the traditional group

may in part, explain the similar testosterone responses between groups. Although no

difference in either bioavailable or total testosterone concentrations appeared between

groups, our results indicate that 1) eccentric-enhanced exercise may result in similar post-

exercise testosterone concentrations to traditional resistance exercise, at a lower total

volume of work and/or 2) post-exercise testosterone responses may be more responsive to

exercise intensity than to total exercise volume.

Growth Hormone

The growth hormone (GH) responses following various resistance exercise

protocols have been summarized in several recent reviews.92'113, 133, 164 Growth hormone

has been shown to directly affect cellular amino acid uptake9 and protein synthesis,5254'

74, 138 thus contributing to skeletal muscle hypertrophy. Our study is the first to compare

the GH response between traditional and eccentric-enhanced resistance exercise, in both

the untrained and trained states.

Growth Hormone Response to Standardized Traditional Resistance Exercise in
Untrained Men

Resting GH concentrations were within normal, non-acromegalic, ranges (< 2.0

ng/ml) for all subjects.162 In our study, GH increased 15-30 minutes following exercise

and returned to baseline concentrations within 45 minutes of exercise cessation, similar to

previous reports.8'37,73, 110, 114, 128, 152 A variety of factors, including higher training

volumes,64,82 moderate intensities (8-12 RM),109', 111,142, 171 large muscle group

exercises,75' 108 and short rest intervals109' 111 have been reported to increase the GH

response to exercise. A smaller change in GH concentrations (-2 ng/ml) was observed in









our study, compared to previous reports (-3.5-10.0 ng/ml).8, 37,73,110,114,128,152 The

training volume (4 sets x 6 reps), exercise selection (chest press and squat), and rest

periods length (1 minute between sets) we selected were similar to previous reports;8'37,
73, 110, 114, 128, 152 however, the exercise intensity in our study (52.5% 1RM) was lower than

most,8', 37, 73, 110, 114, 128, 152 but not all63 previous reports demonstrating increased post-

exercise GH concentrations. Therefore, it appears that the relatively lower exercise

intensity used in our study may explain the lower post-exercise GH concentrations,

compared to others.

Growth Hormone Response to Standardized Traditional and Eccentric-Enhanced
Exercise in Untrained Men

During baseline testing, we observed an increase in post-exercise GH

concentrations 15-30 minutes following the traditional and eccentric-enhanced resistance

training protocols. However, a relatively modest change in post-exercise GH

concentrations was observed in our study (-1.5 ng/ml) compared with prior reports (-3.5-

10 ng/ml),8' 37, 73, 110, 114, 128, 152 similar to the response we reported following the

standardized traditional resistance exercise protocol; therefore, our previously discussed

rationale may apply. Additionally, several studies have reported that eccentric muscle

actions result in lower post-exercise GH responses than concentric muscle actions, in

untrained subjects;47 103, 105 suggesting that GH may be less responsive to eccentric

muscle actions than concentric actions, regardless of load. Overall, the relatively low

concentric-specific exercise intensity performed in both groups may explain the post-

exercise GH responses.

Growth hormone concentrations have been found to be positively associated with

blood lactate69 and H+ accumulation.48 Additionally, Luger et al.124 (1992) suggested that









lactate accumulation partially regulates the exercise induced GH response. During pre-

intervention testing, we observed a greater post-exercise lactate response in the eccentric-

enhanced group, compared with the traditional group, but no differences in post-exercise

GH concentrations were observed. Further, we did not observe a relationship between

lactate concentrations and either the post-exercise GH concentrations or GH area under

the curve. Our results suggest that additional factors, beyond lactate/H+ accumulation,

may regulate the post-exercise GH responses to eccentric exercise in untrained subjects,

such as blood flow characteristics, nitric oxide release, and higher brain center/anterior

pituitary input.60

Growth Hormone Response to Traditional and Eccentric-Enhanced Exercise in
Trained Men

Similar to previous findings,6-8' 64, 82, 105, 106, 108, 109, 111, 113, 115, 142, 171 at post-

intervention testing both groups exhibited acutely increased post-exercise GH

concentrations (15-45 minutes) that returned to baseline by 60 minutes into recovery.

Additionally, no differences in GH concentrations were observed between groups at any

time point, despite a larger training volume in the traditional group. Our results are

consistent with Kraemer and colleagues105 (2001), who reported that maximal eccentric

muscle actions result in greater GH responses than maximal concentric muscle actions, in

trained subjects; possibly indicating that the higher exercise intensities stimulate a greater

GH response.

Muscular Function and Eccentric-Enhanced Resistance Training

A myriad of positive health outcomes are associated with improvements in

muscular strength and mass, thus determining effective resistance exercise protocols is

important when prescribing weight training programs in both healthy and at-risk









populations.99 While traditional resistance training programs are often prescribed, recent

reports demonstrate that eccentric-enhanced resistance training may result in greater

improvements in skeletal muscle strength and/or mass.25, 51, 86, 87, 95 We are the first to

report muscular strength and endurance responses to eccentric-enhanced resistance

training, using multiple joint exercises.

Muscular Strength

Similar improvements were observed between groups for both chest (press) and leg

(squat) muscular strength (kg), which is consistent with reports suggesting that eccentric-

enhanced resistance training results in similar strength gains compared with traditional

resistance training17' 59 and in contrast to others indicating greater strength improvements

following eccentric-enhanced resistance training.5'51,86,87,95 In some studies, higher

training volumes have been shown to result in larger improvements in muscular strength

than lower training volumes, in untrained men;18, 23, 148 while others report no differences

between low and high volume protocols.34' 147, 166 The relatively lower training volume

performed by the eccentric-enhanced group may have resulted in compromised strength

gains relative to the traditional group. Given that the eccentric-enhanced group showed

similar improvements in muscular strength compared to the traditional group, despite

having a lower training volume, eccentric-enhanced resistance exercise could be

considered a more efficient mode of training, when total work is considered.

Results from a recent meta-analysis reveal that maximal strength gains are achieved

at 60% 1RM, in previously untrained men;148 however, strength gains have also been

observed with exercise intensities below 50% 1RM, in untrained men.56 In our study, the

exercise intensity in the traditional group varied between 52.5-70% 1RM (similar to the

suggested intensity), whereas the concentric and eccentric exercise intensities in the









eccentric-enhanced group were -40% and 100-120% 1RM throughout the duration of

training, respectively. Therefore, it is also possible that optimal exercise intensities were

not selected for the eccentric-enhanced group.

Additionally, both traditional and eccentric-enhanced resistance training may result

in similar neural adaptations (e.g. improved motor unit recruitment and/or

synchronization) associated with early-phase (<12 weeks) enhancements in muscular

strength, as minimal muscle hypertrophy typically appears during this time frame.9'44,55

Early-phase muscular strength adaptations following concentric-only resistance training

are similar to93' 158 or greater than146 the adaptations following eccentric-only resistance

training in some studies, while others report that eccentric-only resistance training results

in greater early-phase muscular strength adaptations.35'49,119,130 Recall however that type

IIa and IIx MHC mRNA have been shown to increase following four weeks of eccentric-

enhanced resistance training, in untrained males;51 suggesting that skeletal muscle

hypertrophy and associated strength improvements may occur during early-phase

resistance training. In our study, significant improvements in muscular strength were

observed, without significant concomitant increases in lean mass; suggesting that neural

adaptations, including enhanced motor unit recruitment and/or motor unit

synchronization may be an important mechanism explaining our strength outcomes.

However, alterations in muscle mass and associated hypertrophy-related strength

adaptations cannot be excluded as underlying factors in the muscular strength

improvements observed in our study.

Muscular Endurance

Both training groups displayed similar improvements in muscular endurance

following the five-week exercise intervention, despite dissimilar training volumes.









Friedmann and colleagues51 (2004), observed improved endurance in traditional, but not

eccentric-enhanced resistance training. Additionally, Marx et al.127 (2001), reported that

muscular endurance outcomes are related to training volume; which, if true, would

indicate that the traditional group should have outperformed the eccentric-enhanced

group. The lack of agreement between our outcomes and previous reports may be

explained by the 1) differences in training volume and/or exercise intensity between

groups, 2) presence of similar neural adaptations and resulting strength/endurance

improvements between groups, 3) the length of the exercise intervention, and/or 5) the

presence of delayed-onset muscle soreness in the eccentric-enhanced group.

Training Volume

Total training volume performed during exercise interventions has been shown to

affect muscular performance outcomes,18'23,127,148 as well as hormonal64' 111,144 and

metabolic responses.96' 144 In our study, training volume was matched between groups

during the standardized baseline testing sessions but was unmatched during the five-week

exercise intervention. The disparity in training volumes between groups may be

explained by delayed-onset muscle soreness (DOMS) symptoms, including 1) reduced

muscular strength, 2) reduced muscle activation, 3) decreased range of motion (ROM), 4)

impaired proprioception, and 5) increased muscular and connective tissue inflammation
33, 61, 137, and/or delayed leukocytosis or skeletal muscle myokines, such as interleukin

(IL)-6 or IL-8,80' 140, 141,179 in the eccentric-enhanced group. In our study, cellular

markers of inflammation were not measured, though a large percentage (>50%) of

subjects in the eccentric-enhanced group reported (moderate to extreme) muscle soreness

and impaired ROM following the initial eccentric-enhanced exercise bout and throughout

the first week of exercise training, corresponding to the initial four exercise sessions. In









contrast, no reports of muscle soreness occurred in the traditional group. Our findings are

similar to previous reports, indicating that DOMS and its associated symptoms last 5-7

days following the initial eccentric exercise bout and may indicate the presence of acute

muscular microtrauma and/or inflammation, thus reducing exercise capacity and

associate performance improvements.61

Further, lactate accumulation has been associated with muscular fatigue during

resistance exercise and may limit exercise performance.149 Blood lactate concentrations

have been shown to be greater during an exercise test performed two days after eccentric

training;57'58 suggesting greater metabolic fatigue occurs following heavy eccentric

training. Recall, before the onset of training, we observed a greater post-exercise lactate

response in the eccentric-enhanced group, compared with the traditional group; therefore

it is possible that a greater lactate response also occurred throughout the exercise

intervention. Further, a positive relationship between lactate and RPE has been

reported;77, 117, 165 in our study RPE was greater during training sessions 1-4 in the

eccentric-enhanced group, compared to the traditional group, lending support to the

notion that greater lactate accumulation occurred during eccentric-enhanced training.

These results suggest that the eccentric-enhanced group may have experienced greater

metabolic fatigue throughout the exercise intervention, thus attenuating progression

during resistance exercise compared to the traditional group.

Conclusion

Our study determined the early-phase (single session to five-week) metabolic,

neuroendocrine, and performance responses to traditional and eccentric-enhanced

resistance exercise in previously untrained individuals. We observed that short-term

eccentric-enhanced resistance training results in similar neuroendocrine and performance









responses as traditional resistance training, in college-age males. The lower training

volume completed by the eccentric-enhanced group suggests that this form of training

may be more efficient in eliciting both anabolic stimuli and muscular strength

improvements than traditional resistance training, relative to training volume.

Clinical Implications

Determining the neuroendocrine, metabolic, and performance responses to various

resistance training protocols may enable clinicians, therapists, and coaches to prescribe

safe and effective training programs to both healthy and at-risk individuals. Although the

results of our study indicate that traditional and eccentric-enhanced resistance training

result in similar neuroendocrine and performance responses, each specific form of

training may have population specific advantages. Theoretically, athletes who practice

and/or compete above their lactate threshold (e.g. boxers, wrestlers, rowers, etc.) might

benefit from eccentric-enhanced resistance training, as greater intracellular lactate

buffering and/or delayed lactate accumulation may occur with this form of training.84' 125

Additionally, strength trainers who have limited time to participate in resistance exercise

may benefit from eccentric-enhanced resistance training, evidenced by the similar

improvements in muscular strength which occurred at a lower training volume and time

commitment (-66% less time to complete the eccentric-enhanced protocol) following this

form of training.

Eccentric-enhanced resistance training may not be as appropriate for clinical

populations (e.g. multiple sclerosis, muscular dystrophy, etc) that experience muscular

fatigue, pain, and/or weakness associated with their condition. Eccentric-enhanced

exercise has been show to result in moderate to extreme muscle soreness, thus limitations

in mobility and muscular strength may occur at the onset of eccentric-enhanced









resistance training. Clearly, further research is indicated to determine the specific effects

of eccentric-enhanced resistance training in various populations.

Future Directions

Examining both the acute and chronic anabolic (e.g. total testosterone, bioavailable

testosterone, growth hormone, insulin-like growth factor, mechano growth factor) and

catabolic (e.g. adrenocorticotropic hormone, cortisol) hormone responses to eccentric-

enhanced resistance training would improve current understanding of the neuroendocrine

responses to resistance training. Additionally, given the influence of binding proteins on

both the biological effects and measurement of testosterone, future studies designed to

carefully measure the free, albumin-bound, and SHBG-bound fractions of testosterone

are indicated. Further, evaluating androgen receptor expression and androgen affinity

following resistance training would advance our understanding of skeletal muscle

adaptations to resistance training. Moreover, determining the responses of cellular

proteins that regulate skeletal muscle protein synthesis (e.g. mTOR, AKT, etc) and

degredation (myostatin, ubiquitin proteasome pathway, etc) may advance current

knowledge of the underlying mechanisms) of muscular hypertrophy and/or atrophy.

Delayed onset muscle soreness (DOMS) is commonly experienced by individuals

who perform resistance training and may be indicative of muscle injury. The underlying

mechanisms) of DOMS remain unclear; therefore, evaluating cellular markers of

inflammation following heavy eccentric exercise may enhance our understanding of the

skeletal muscle injury and repair process. Evaluating both the plasma and muscle tissue

specific responses of creatine kinase, myoglobin, neutrophils, and various myokines such

as IL-6 or IL-8, among others may provide valuable information for enhancing recovery

from muscle injury or loss and/or reducing the muscle soreness associated with resistance









training. Since, eccentric exercise induced muscle inflammation is a stimulus for satellite

cell proliferation and associated muscle repair,43' 145 evaluating satellite cell expression

following eccentric-enhanced exercise may improve the understanding of skeletal muscle

repair/regeneration.

Our data suggest that eccentric-enhanced exercise results in higher metabolic

(lactate) responses and RPE values than traditional resistance exercise, in untrained

individuals. Future research comparing metabolic (e.g. lactate, heart rate, V02, etc) and

RPE responses between traditional and eccentric-enhanced resistance protocols would

improve our current understanding of fatigue and exertion as they relate to resistance

exercise. Additionally, evaluating intracellular lactate buffering mechanisms, motor unit

recruitment patterns, and blood flow characteristics during eccentric-enhanced resistance

exercise may provide insight into the mechanisms) underlying lactate accumulation.

We reported that eccentric-enhanced resistance training provides a means of

improving early-phase muscular performance in previously untrained college-age males.

Future research designed to directly control intensity and volume between exercise

protocols is warranted and would clarify the muscular strength responses to resistance

exercise. Additionally, evaluating long-term (>12 weeks) adaptations to eccentric-

enhanced training may allow the individual neural and hypertrophic dependent

mechanisms of muscular strength enhancement to be more clearly understood. Overall,

research examining the interrelationship between exercise intensity, volume, and/or

training status would contribute to a more complete understanding of the neuroendocrine,

metabolic, and muscular performance responses to resistance exercise.









Several studies have evaluated the effects of eccentric-enhanced resistance training

in healthy college-age males; however, few studies have evaluated the performance

responses in other populations. Skeletal muscle atrophy, reduced strength, and increased

fatigue are associated with aging and degenerative diseases such as multiple sclerosis and

muscular dystrophy, thus determining the effects of eccentric-enhanced resistance

training in at-risk populations may benefit clinicians and therapists in devising safe and

effective exercise protocols to reduce the deleterious effects of disease on muscle.

Additionally, both athletes and recreational weight lifters utilize resistance training to

improve muscular strength and mass; thus determining the performance responses to

eccentric-enhanced resistance training in both athletes and previously trained individuals

would enhance current knowledge related to the long-term training adaptations to this

form of exercise.














APPENDIX A
HEALTH HISTORY QUESTIONNAIRE

SUBJECT # Date of Birth :


Height Weight Blood Pressure Measurement: /


Do you currently have any of the following conditions or has a medical doctor ever
informed you that you have any of the following conditions?

1. Diabetes mellitus Yes / No

2. High blood pressure Yes / No

3. Osteoporosis Yes /No

4. A heart condition Yes / No

5. High cholesterol Yes /No
If Yes, do you know your cholesterol numbers?

6. Thyroid problems Yes / No

7. Kidney disease Yes / No

8. Liver disease Yes / No

Please answer the following questions regarding your general health:

1. Do you feel pain or pressure in your chest, neck shoulders, or arms
during or after physical activity? Yes / No

2. Do you ever lose your balance because of dizziness Yes / No

3. Do you ever lose consciousness? Yes / No

4. Do you consider yourself to be generally healthy? Yes / No

5. Do you currently smoke? Yes / No









6. Are you a former smoker? Yes / No
If Yes, how long has it been since you quit smoking?

7. Have you ever had an adverse reaction during or following a
blood donation? Yes / No

8. Do you mind having blood draws? Yes / No
9. Do you currently have an injury to any area in your upper or
lower body? Yes / No
If Yes, please explain the injury:



10. Are there any other health related issues we should know about?



Are you currently taking any of the following products or have you taken them in
the previous 2 months?

1. Anabolic steroids Yes / No

2. Creatine Yes / No

3. Protein powder Yes / No

4. Other Yes / No
If Yes, please list the specific supplements:



Please list all of the supplements you are currently taking (including vitamins):

Item name Amount taken per day Length on supplement Reason

a.

b.

c.







67



Please list all of the prescription medication you are currently taking

Medicine Amount taken per day Length on medication Reason

a.

b.

C.














APPENDIX B
PHYSICAL ACTIVITY AND DIETARY QUESTIONNAIRE

PHYSICAL ACTIVITY & DIETARY QUESTIONNAIRE

Subject #:


Please answer the following questions regarding your current exercise participation
and dietary habits:

1. Do you currently participate in weight lifting? Yes / No
If Yes, how often and how much resistance exercise do you perform:



2. During the past two years have you participated in either
bodybuilding or powerlifting? Yes / No

3. Do you currently perform aerobic exercise? Yes / No

If Yes:
How many times per week

How long do you perform cardio each session

What type of exercise (running, biking, etc)

How intense (mild, moderate, high)

4. Do you currently perform any recreational sports activity or
participate in any physical activity? Yes / No

If Yes:
How many times per week

How long do you perform cardio each session

What type of exercise (running, biking, etc)

How intense (mild, moderate, high)






69



5. Are you currently on a diet, including a low calorie, low fat,
high protein, or a low carbohydrate diet? Yes / No
If Yes, please explain your diet:














APPENDIX C
LIST OF EXCLUDED NUTRITIONAL SUPPLEMENTS

Subjects were excluded from this study if they had consumed any of the following

nutritional supplements within 1 month from beginning the study:

1. Creatine

2. Ephedra

3. Dehydroepiandrosterone (DHEA)

4. Tribulus Terresteris

5. ZMATM

6. Androstendione

7. GAKIC

8. Any other nutritional supplement/ergogenic aid that is intended to enhance exercise
performance

9. Any other nutritional supplement that has been demonstrated to affect hormonal
levels










APPENDIX D
DIETARY RECORD


SUBJECT #


SESSION #


Please record what you eat and drink for the entire day. Please be as specific as
possible for serving size, how food is prepared, and amount of each serving.

Time Food/Drink Brand Name/Restaurant Serving Size


_ ____ I ____ I __


_ ____ I ____ I __














APPENDIX E
POWER CALCULATIONS

Ahtiainen et al.8 2004 (N=8)

Pre Exercise Growth hormone concentrations: 0.1 + 0.2 tg/L
Post Exercise: 15.9 9.9 [g/L

n per group = 2[(Zca-Zp)o/(ui-u2)]2

Zc = alpha level for two tailed Z
Zp = lower one-tailed Z value that is related to 13
a = maximum variance
ul-u2 = difference between mean 1 and 2

n = 2[(1.96 + 0.84)(9.9)/(15.9)]2

= 2(3.08) = 6.16 subjects
so, 7 subjects per group or 14 total subjects

Power = 0.80
Significance = 0.05















APPENDIX F
PLASMA VOLUME FLUCTUATIONS FOLLOWING EXERCISE



Table 6. Percent plasma volume fluctuations following traditional and eccentric-
enhanced resistance training.


PLASMA VOLUME


TRADITIONAL
GROUP


ECC-
ENHANCED
GROUP


Baseline 100 % 100 %
Immediately Post Exercise -7.8% + 2.3* -5.3% + 1.8*
15 Minutes Post Exercise -1.9% + 2.1 -1.2% + 1.6
30 Minutes Post Exercise -0.4% + 2.6 +2.4% + 1.2
45 Minutes Post Exercise +5.1% + 3.1 +1.1% + 1.1
60 Minutes Post Exercise +3.5% + 2.8 +1.3% + 2.3
Baseline 100% 100%
Immediately Post Exercise -6.5% + 2.9* -8.1% + 1.6*
15 Minutes Post Exercise +6.2% + 2.6 +4.3% + 2.0
30 Minutes Post Exercise +2.9% + 3.1 +4.1% + 2.1
45 Minutes Post Exercise +7.8% + 2.2* +4.5% + 1.9*


60 Minutes Post Exercise


+2.7% + 3.1


+4.5% + 2.2


4 Baseline 100% 100%
4 Immediately Post Exercise -11.0% + 1.1* -10.6% + 1.8*
H 15 Minutes Post Exercise -2.5% + 1.9 -1.9%+ 1.9
O R 30 Minutes Post Exercise +2.1%+ 1.3 +1.9%+ 1.8
45 Minutes Post Exercise +3.3% + 1.7 +2.0% +2.1
H 60 Minutes Post Exercise +0.9% + 0.8 +1.0% + 2.0


* Indicates significant difference from corresponding baseline value (p<0.05). Data are
presented as Mean Change SE.


H















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