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Fat and fit? Physical activity and fitness as predictors of quality of life in overweight youth.

Permanent Link: http://ufdc.ufl.edu/UFE0042959/00001

Material Information

Title: Fat and fit? Physical activity and fitness as predictors of quality of life in overweight youth.
Physical Description: 1 online resource (50 p.)
Language: english
Creator: GRAEF,DANIELLE M
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2011

Subjects

Subjects / Keywords: ACTIVITY -- CHILDHOOD -- FITNESS -- OBESITY -- OVERWEIGHT -- QOL
Clinical and Health Psychology -- Dissertations, Academic -- UF
Genre: Psychology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: The rising rates of childhood overweight and obesity is of great health concern given the associated increased risk of hypertension, diabetes, CVD, and impaired Quality of Life (QOL) compared to normal-weight peers. Researchers have made a ?fit and fat? argument, suggesting that obese adults who are more active and fit report higher QOL due to improved physical functioning and health compared to those who are less active or fit. Currently, there is mixed evidence about the role physical activity plays in predicting QOL in children and a dearth of research on physical fitness. The current study examined: (1) the relation between weight status, physical fitness and activity, (2) the relation between weight status and child-reported QOL, (3) the relation between physical activity and fitness with QOL, and (4) physical activity and fitness as moderators between weight status and QOL. Participants were 96 overweight or obese youth, ages 8-12, participating in a multi-wave obesity intervention study. All data for this study is from baseline data collection. BMI z-score was not significantly associated with physical activity or total QOL. BMI z-score was positively associated with physical QOL, such that as weight status increased, physical QOL decreased. BMI z-scores had a unique relationship with physical fitness, such that there was a linear decline in fitness as weight status increased and an accelerated decline in fitness for those children who were considered extremely obese. While this finding is significant given the positive association between fitness and both total QOL and physical QOL, fitness was no longer significant once controlling for BMI z-score. Physical activity did not have a significant association with either total or physical QOL. Physical activity and physical fitness did not serve as moderators of the BMI z-score and total QOL or physical QOL relationships. This study suggests that future interventions for overweight youth may benefit from placing a dual focus on both improved weight status and physical fitness. Future longitudinal research should focus on further examining the current results in order to determine if improvements in weight status or fitness are predictive of improved QOL in overweight and obese children.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by DANIELLE M GRAEF.
Thesis: Thesis (M.S.)--University of Florida, 2011.
Local: Adviser: Janicke, David M.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2012-04-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2011
System ID: UFE0042959:00001

Permanent Link: http://ufdc.ufl.edu/UFE0042959/00001

Material Information

Title: Fat and fit? Physical activity and fitness as predictors of quality of life in overweight youth.
Physical Description: 1 online resource (50 p.)
Language: english
Creator: GRAEF,DANIELLE M
Publisher: University of Florida
Place of Publication: Gainesville, Fla.
Publication Date: 2011

Subjects

Subjects / Keywords: ACTIVITY -- CHILDHOOD -- FITNESS -- OBESITY -- OVERWEIGHT -- QOL
Clinical and Health Psychology -- Dissertations, Academic -- UF
Genre: Psychology thesis, M.S.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract: The rising rates of childhood overweight and obesity is of great health concern given the associated increased risk of hypertension, diabetes, CVD, and impaired Quality of Life (QOL) compared to normal-weight peers. Researchers have made a ?fit and fat? argument, suggesting that obese adults who are more active and fit report higher QOL due to improved physical functioning and health compared to those who are less active or fit. Currently, there is mixed evidence about the role physical activity plays in predicting QOL in children and a dearth of research on physical fitness. The current study examined: (1) the relation between weight status, physical fitness and activity, (2) the relation between weight status and child-reported QOL, (3) the relation between physical activity and fitness with QOL, and (4) physical activity and fitness as moderators between weight status and QOL. Participants were 96 overweight or obese youth, ages 8-12, participating in a multi-wave obesity intervention study. All data for this study is from baseline data collection. BMI z-score was not significantly associated with physical activity or total QOL. BMI z-score was positively associated with physical QOL, such that as weight status increased, physical QOL decreased. BMI z-scores had a unique relationship with physical fitness, such that there was a linear decline in fitness as weight status increased and an accelerated decline in fitness for those children who were considered extremely obese. While this finding is significant given the positive association between fitness and both total QOL and physical QOL, fitness was no longer significant once controlling for BMI z-score. Physical activity did not have a significant association with either total or physical QOL. Physical activity and physical fitness did not serve as moderators of the BMI z-score and total QOL or physical QOL relationships. This study suggests that future interventions for overweight youth may benefit from placing a dual focus on both improved weight status and physical fitness. Future longitudinal research should focus on further examining the current results in order to determine if improvements in weight status or fitness are predictive of improved QOL in overweight and obese children.
General Note: In the series University of Florida Digital Collections.
General Note: Includes vita.
Bibliography: Includes bibliographical references.
Source of Description: Description based on online resource; title from PDF title page.
Source of Description: This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility: by DANIELLE M GRAEF.
Thesis: Thesis (M.S.)--University of Florida, 2011.
Local: Adviser: Janicke, David M.
Electronic Access: RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2012-04-30

Record Information

Source Institution: UFRGP
Rights Management: Applicable rights reserved.
Classification: lcc - LD1780 2011
System ID: UFE0042959:00001


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1 FAT AND FIT? PHYSICAL ACTIVITY AND FITNESS AS PREDICTORS OF QUAL ITY OF LIFE IN OVERWEIGHT YOUTH By DANIELLE M. GRAEF A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2011

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2 2011 Danielle M. Graef

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3 ACKNOWLEDGMENTS I would like to acknowledge my mentor, Dr. David Janicke, for his guidance and support throughout my work at the University of Florida and this project. Additionally I want to recognize the members of my supervisory committee: Dr. Stephen Boggs, Dr. William Perlstein, and Dr. Patricia Durning. I lastly want to thank my family, friends, and colleagues for their support and advice throughout my work on this project.

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4 TABLE OF CONTENTS P age ACKNOWLEDGMENTS ................................ ................................ ................................ .. 3 LIST OF TABLES ................................ ................................ ................................ ............ 6 LIST OF FIGURES ................................ ................................ ................................ .......... 7 ABSTRACT ................................ ................................ ................................ ..................... 8 CHAPTER 1 INTRODUCTION ................................ ................................ ................................ .... 10 Childhood Obesity ................................ ................................ ................................ .. 10 Prevalence. ................................ ................................ ................................ ...... 10 Etiology. ................................ ................................ ................................ ............ 10 Health Risks. ................................ ................................ ................................ .... 11 Psychosocial Risks ................................ ................................ .......................... 12 Quality of Life ................................ ................................ ................................ .......... 12 Weight Status and Quality of Life. ................................ ................................ .... 12 Psychosocial Predictors of Quality of Life. ................................ ........................ 13 Physical Activity and Physical Fitness ................................ ................................ .... 13 Weight Status, Physical Activity, and Physical Fitness. ................................ .... 14 Demographic Differences in Activity and Fitness. ................................ ............ 15 Relationship of Activity and Fitness to Psychosocial and Health Risks. ........... 16 Physical Activity, Physical Fitness and Quality of Life ................................ ............ 17 Purpose and Summary ................................ ................................ ........................... 20 Aim 1 ................................ ................................ ................................ ................ 20 Aim 2 ................................ ................................ ................................ ................ 21 Aim 3 ................................ ................................ ................................ ................ 21 Aim 4 ................................ ................................ ................................ ................ 21 2 METHODS ................................ ................................ ................................ .............. 22 Participants ................................ ................................ ................................ ............. 22 Procedures ................................ ................................ ................................ ............. 22 Measures ................................ ................................ ................................ ................ 23 Pediatric Quality of Life Inventory. ................................ ................................ .... 23 Height and Weight. ................................ ................................ ........................... 24 20 meter Shuttle Run. ................................ ................................ ...................... 24 Accelerometer. ................................ ................................ ................................ 25 Demographic Inform ation. ................................ ................................ ................ 26 Data Analysis ................................ ................................ ................................ .......... 26 3 RESULTS ................................ ................................ ................................ ............... 28

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5 4 DISCUSSION ................................ ................................ ................................ ......... 36 LIST OF REFERENCES ................................ ................................ ............................... 43 BIOGRAPHICAL SKETCH ................................ ................................ ............................ 50

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6 LIST OF TABLES Table page 3 1 Demographic characteristics of sample. ................................ ............................. 31 3 2 Intercorrelati ons of predictor variables and QOL. ................................ ............... 31 3 3 Mean QOL scores, physical activity, and physical fitness. ................................ 32 3 4 BMI z score in relation to child levels of physical fitness. ................................ ... 32 3 5 Weight status in relation to child reported physical quality of life. ....................... 32 3 6 Physical fitness and child reported total quality of life, controlling for weight status. ................................ ................................ ................................ ................. 32 3 7 Physical fitness and child reported physical quality of life, controlling for weight status. ................................ ................................ ................................ ...... 33 3 8 Physical activity as a moderator between weight status and total quality of life. ................................ ................................ ................................ ...................... 33 3 9 Physical activity as a moderator between weight status and physical quality of life. ................................ ................................ ................................ .................. 33 3 10 Physical fitness as a moderator between weight status and total quality of life. ................................ ................................ ................................ ...................... 33 3 11 Physical fitness as a hypothesized moderator between weight status and physical quality of life. ................................ ................................ ......................... 34

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7 LIST OF FIGURES Figure P age 3 1 Linear and quadratic relationship between weight status and physical fitness. .. 35

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8 A bstract of Thesis Presented to the Graduat e School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science FAT AND FIT ? PHYSICAL ACTIVITY AND FITNESS AS PREDICTORS OF QUAL ITY OF LIFE IN OVERWEIGHT YOUTH By Danielle M. Graef May 2011 Chair: David M. Janicke Major: Psychology The rising rates of childhood overweight and obesity is of great health concern given the associated increased risk of hypertension, diabetes, CVD, and impaired Quality of Life ( QOL ) compared to normal w eight peers. R obese adults who are more active and fit report higher QOL due to improved physical functioning and health compared to those who are less active or fit Currently, there is mixe d evidence about the role physical activity plays in predicting QOL in children and a dearth of research on physical fitness. The current study examined: (1) the relation between weight status physical fitness and activity, (2) the relation between weight status and child reported QOL (3) the relation between physical activity and fitness with QOL and (4 ) physical activity and fitness as moderators between weight status and QOL Participant s were 9 6 overweight or obese youth, ages 8 12, participating in a multi wave obesity intervention study. All data for this study is from baseline data colle ction. BMI z score was not significantly ass ociated with physical activity or total QOL BMI z s core was positively associated with physical QOL, such that as weight status increased, physical QOL decreased. BMI z scores had a unique relationship with

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9 physical fitness, such that there was a linear decline in fitness as weight status increased and an accelerated decline in fitness for those children who were considered extremely obese. While this finding is significant given the positive association between fitness and both total QOL and physical QOL fitn ess was no longer significant once controlling for BMI z score. Physical activity did not have a significant association with either total or physical QOL Physical activity and physical fitness did not serve as moderators of the BMI z score and total QOL or physical QOL relationship s Th is study suggests that future interventions for overweight youth may benefit from placing a dual focus on both improved weight status and physical fitness. Future longitudinal research should focus on further examining the current results in order to dete rmine if improvements in weight status or fitness are predictive of improved QOL in overweight and obese children.

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10 CHAPTER 1 INTRODUCTION Childhood Obesity Prevalence. The i ncreasing prevalence of childhood obesity in the United States are of great health concern. Among children and adolescents (ages 2 to 19 years old) from 2007 2008, 31.7 % were overweight or obese (i.e., body mass index (BMI) above the 85 th percent ile for age and gender), while 11.9 % were considered obese (i.e., BMI above the 95 th percentile for age and gender; Ogden, Carroll, Curtin, Lamb, & Flegal, 2010). Having one or both parents who are overweight or obese is predictive of childhood risk of obesity (Magarey, Daniels, Boulton, & Cockington 2003; Whitaker, Wright, Pep e, Seidel, & Dietz, 1997). For instance, Magarey and colleagues (2003) found that children between the ages of 8 and 11 years had between a 4.1 and 12.2 higher relative risk of being overweight or obese if one parent was overweight, and between an 8.4 and 26.7 higher relative risk if both parents were overweight, compared to children with normal weight parents. Children who are obese also have a higher likelihood of adult obesity compared to non obese children ( Raitakari, Juonala, & Viikari, 2005; Whitake r et al., 1997 ). For overweight and obese children ages 8 12 years th e increased probability of overweight (54 86%) and obesity (14 59%) in adulthood is often dependent on age, gender, and BMI percentile in childhood (Guo, Chumlea, & Roche, 2002). Etiology Given the increased prevalence of childhood overweight and obesity it is important to consider the etiological factors contributing to childhood obesity. Pediatric

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11 obesity is due to a wide variety of factors. At the fundamental level, pediatri c obesity is due to an im balance in the energy equation which suggests that excess body weight is expenditure (Goran, 2000). What ultimately plays an important role in chil dhood obesity are a number of e nvironmental factors that influence dietary intake and energy expenditure, includ ing increases in the availability of calorically dense and high sugar and high fat foods, increased food portion sizes, parental shaping and mod eling of eating behaviors, and changes in technology and transportation that have decreased requirements for physical act ivity (Birch, 2006; Hill, 2006). It is also important to note that some individuals have different genetic vulnerabilities, acquired m edical conditions, or take medication that can leave them at greater risk for obesity (Hill, 2006). The etiology and prevalence of childhood obesity is especially important given the negative health and psychosocial consequences associated with being over weight or obese. Health Risks. Research ers ha ve consistently shown the health risks of obesity such as increased risk of hypertension (Freedman, Dietz, Srinivasan, & Berenson, 1999 ) diabetes mellitus (Wabitsch et al., 2004) hyperlipidemia (Dietz, 1998), insulin resistance ( Srinivasan, Myers, & Berenson 2002 ) and metabolic syndrome ( Freedman et al., 1999; Wickham et al., 2009). Childhood obe sity has also been linked to cardiovascular disease risk during adolescence and later life (Garnett, Baur, Srinivasan, Lee, & Cowell, 2007; Raitakari et al., 2005). Children who are overweight have a 2.4 to 12.6 higher likelihood of high cholesterol, triglycerides, or glucose levels compared to normal weight children (Freedman et al., 1999). Eight year old ch ildren who are overweight are also seven times more likely than normal weight peers to have several cardiovascular risk

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12 factors in adolescence such as having higher fasting glucose, cholesterol, triglycerides, hypertension, and insulin resistance (Garnett et al., 2007). This is particularly important given the increased risk of mortality later in life. Being overweight or obese in adolescence is associated with a 30 to 80% and 30 to 100% increased risk of death in adulthood compared to normal weight peer s for males and females, respectively, with higher risk being associated with higher weight status (Engeland, Bj rge, S gaard, & Tverdal, 2003 ). Psychosocial Risks. Obese children and adolescents are also at an increased risk of experiencing various psycho social difficulties. Overweight and obese children are particularly more likely to encounter problems such as peer victimization (Janicke et al., 2007; Janssen, Craig, Boyce, & Pickett, 2004), poorer self e steem (McClure et al., 2010 ) body dissatisfaction (Davison, Markey, & Birch, 2003) and parental distress ( Davis, Davies, & Priest, 2008 ), all of which are associated with significantly poorer child self report and parent proxy report of quality of life (Janicke et al., 2007). Quality of Life Weight Status and Quality of Life. Given the negative health and psychological consequences associated with higher weight status, children and adolescents who are overweight or obese are more likely to report impaired quality of life than their norma l weight peers (Pinhas Hamiel et al., 2006; Williams, W ake, Hesketh, Maher, & Waters 2005). Health related q uality of life ( QOL ) is a concept referring to a multidimensional approach for assessing self perceived well being across se veral d omain s includin g overall physical health emotional, social, and school functioning (Varni, Burwinkle, Seid & Skarr, 2003)

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13 Compared to normal weight peers, children and adolescents who are obese are between 2 and 5.5 times more likely to report poorer quality of life in both physical and psychosocial domains than their normal weight peers and report QOL similar to that of children with cancer (Friedlander, Larkin, Rosen, Palermo, & Redline, 2003; Schwimmer et al., 2003; Zhang et al., 2008). While the literature has d emonstrated the association between weight status and QOL in large samples of both healthy individuals and those with chronic health conditions, the literature is less clear on differences in QOL within overweight and obese populations. Shoup and colleagu es (2008) found that very obese children and adolescents (i.e., above the 95.6 th percentile) report ed significantly lower physical and psychosocial quality of life co mpared to those who were overweight. Psychosocial Predictors of Quality of Life. The liter ature suggests that there are a number of psychosocial variables that may be associated with poor er QOL in o verweight and obese youth Youth who are overweight or obese are more likely to report higher depressive symptoms (Zeller & Modi, 2006 ) and poor er self esteem (Friedlander et al., 2003; Stern et al., 2007) than normal weight peers. Increased weight related teasing and peer victimization are associated with p oorer self esteem and poorer QOL (Stern et al., 2007) Higher parental stress is associated with lower parent proxy reports of QOL in children (Guilfoyle, Zeller, & Modi, 2010), which is significant given that parent reports of child QOL are oftentimes utilized and can influence health care use and assessment ( Guilfoyle et al., 2010 ). Physical Activity and Physical Fitness While there is often a focus of psychosocial predictors of QOL in overweight youth, health behaviors such as physical activity and physical fitness likely also play an

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14 important role not only in future health risk, but also se lf reported QOL. Activity and fitness are at times used interchangeably; therefore, it is important to distinguish between the two. Physical activity refers to the engagement in body movement that result in increased energy expenditure, while physical fi tness is an indicator of an Ortega, Ruiz, Castillo, & Sjstrm, 2008 ). Common methods for assessing physical activity in youth include retrospective self report measures and the use of accelerometers, while assessment methods for physical fitness include a treadmill run test, muscle strength and flexibility, and the 20 meter shuttle run. Weight Status, Physical Activity, and Physical Fitness. Having a higher weight status in childho od is associated with low physical activity (Blair & Church, 2004; Dowda Ainsworth, Addy, Saunders, Riner 2001; Ortega et al., 2008; Soric & Misigoj Durakovic, 2009) and poor er physical fitness (Ara, Moreno, Leiva, Gutin, & Gasaj s, 2007; Eliakim et al., 2002; Suminski, Ryan, Poston, & Jackson, 2004) when compared to those children of lower weight status Energy expenditure in overweight children is approximately 45% less than that of normal weight peers, especially during the weekend (Soric & Misigoj Du rakovic, 2009). This is a significant concern as engagement in physical activity is an important predictor of long term weight status in children. Specifically, children who engage in physical activities such as sports are significantly less likely to be overweight during adolescence than children who are less active (Dowda et al. 2001). In child populations, there is also a strong association between level of physical fitness and weight status. Even within an overweight and obese population, children who are more fit are more likely to have lower fatness levels than unfit children (Ara et al., 2007; Nassis, Psarra, & Sidossis, 2005). In l ongitudinal

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15 intervention programs, children who receive treatment aimed to increase fitness exhibit more improved w eight status when compared to a control group (Eliakim et al., 2002). Demographic Differences in Activity and Fitness Levels of physical activity and fitness in children appear to differ based on demographic factors, such as age and gender. Older children are significantly less likely to engage in physical activity compared to younger children (Nyberg, Nordenfelt, Ekelun d, & Marcus, 2009; Trost, Pate, Freedson, Sallis, & Taylor, 2002). Researchers have also found sex differences in physical activity engagement, with boys participating in more physical activity than girl s (Dowda et al., 2001; Nyberg et al., 2009; Soric & Misigoj Durakovic, 2009). Some studies have found that boy s are also more likely to be more physically fit than girl s (Lindquist, Reynolds, & Goran, 1999; Suminski et al., 2004), with boy s completing more laps and running faster than girls on a 20 meter s huttle run test. However, other researchers have found no significant sex differences in physical fitness (Manios, Kafatos, & Codrington, 1999) or have found smaller sex differences when using objective measures of physical activity (Trost et al., 2002). Also, sex differences in physical activity shrinks with age, as boy s have a larger decline in physical activity as they get older than girl s (Telama & Yang, 2000). Given the mixed findings for gender differences in fitness, further research is necessary to examine these differences. Some research indicates that ethnic and racial minority adolescents are less likely to be physically active than whites (Felton et al., 2002; Gordon Larsen, McMurray, & Popkin, 1999); however, there are mixed findings on raci al/ethnic differences in childhood. Some researchers f ound no differences (Lindquist et al. 1999; Pate et al., 1997; Troian o & Flegal, 1998), while other researchers found that some

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16 racial/ethnic minorities such as non Hispanic Blacks (Anderson, Economos & Must, 2008) and Hispanics (Sallis et al., 1993) engaged in less physical activity than whites. Relationsh ip of Activity and Fitn ess to Psychosocial and Health Risks. signific ant role in lowering the psychosocial and health risk factors that are associated with high weight status (Ortega et al., 2008). Specifically, researchers have suggested depression, anxiety, and general mood status (Ortega et al., 2008). Physical activity and fitness are also important in physical health in individuals, irrespective of weight status. Older adolescents who are less fit are 3 to 6 times more likely to deve lop diabetes, hypertension, and metabolic syndrome than those who are more fit (Carnethon et al., 2003). However, Blair and Church (2004) argued that physical status in ind ividuals, suggesting that physical activity is the important variable to target in intervention s In adult populations, engagement in physical activity and being more physically fit is associated with a significantly lower risk of cardiovascular disease (Giannini, Mohn, & Chiarelli, 2006; Wessel et al., 2004). Being unfit is associated with higher relative risk of death in both normal weight (3.1 RR) and overweight (4.5 RR) individuals when compared to those who are fit and of normal weight, even after controlling for other cardiovascular risk factors (Wei et al., 1999). Interestingly, overweight and obese men who are fit have much lower risk for death compared to men who are of normal weight and unfit (Wei et al., 1999), suggesting that fitness is a m ore important predictor of negative health consequences than weight status. If physical activity and/or fitness are

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17 more important than weight status in health outcomes in children, they may also explain the QOL differences that we see in this population. However, currently there are inconsistent findings on QOL differences within overweight and obese samples of individuals. This study adds to the literature by examining the relationship between physical activity, physical fitness, and QOL more closely i n a sample of overweight and obese children. Physical Activity, Physical Fitness and Quality of Life Given the positive physical benefits of being active and fit, activity and fitness (Ortega et al., 2008) and self perceived well being (i.e., quality of life) in overweight children and adolescents (Chen et al., 2005; Shoup et al. 2008 ). However, there is currently a dearth of research in the role that activity plays in childhood quality of life. The little research that does exist has mixed findings (Boyle, Jones, & Walters, 2010; Chen et al., 2005; Shoup et al., 2008). Boyle and colleagues (2010) found that while higher BMI was associated with significantly lower levels of average daily minutes of physical activity, activity was not a significant predictor across any of the domains of quality of life. Contrary to the previous study, Chen and colleagues (2005) found that less engagement in physical activity predicted poorer childhood quality of life, even after controlling for weight status. It is important to note that less than one quarter of the sample was overweight or obese in the Boyle et al. study (2010) and that while Chen and colleagues (2005) specified that they controlled for weight s tatus, they did not report the BMI of children in their sample. Other researchers (Shoup et al., 2008) have found that within an obese sample of children those who d id not meet recommendations for 60 minutes of daily physical activity report ed significan tly lower physical quality of life than children who did.

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18 S everal methodological issues in the studies examining the role of physical activity should be considered when evaluating the se findings. All of the studies were cross sectional, limiting their a bility to make causal statements or determine whether changes in physical activity predict QOL improvement ( Boyle et al. 2010; Chen et al., 2005; Shoup et al., 2008). O nly Shoup et al. used objective measures of physical activity (i.e., accelerometers), while the other studies used less reliable self report measures of physical activity frequency and/or duration (Boyle et al., 2010; Chen et al., 2005). However, t he Shoup et al. study categorized the activity data, which removed sample variability in this measure. While two of the studies used a validated measure of QOL (i.e., PedsQL 4.0; Boyle et al., 2010; Shoup et al., 2008), Chen and colleagues (2005) used a measure of QOL that had low reliability and validity (i.e., with some kappa coefficient s being at .50). While there are several studies examining the role of physical activity in predicting childhood QOL there is scant research examining the relationship between physical fitness and quality of life in child populations. Kriemler and colleagues (2010) found that after a school based physical activity intervention for both overweight and non overweight children children displayed improved weight status, level of daily physical activity, and physical fitness; however, there were no significant changes in total or physical QOL Due to the limited research or mixed findings in the literature, the impact of physical activity and fitness on the QOL in overweight a nd obese youth is still unclear Bring ing greater clarity to the role that activity and fitness play in health and QOL outcomes will help in determining which areas should receive grea t er focus in future interventions for overweight or obese youth

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19 Resear chers on quality of life in adult s have more consistent findings on the relationship between QOL and physical activity (Peterson et al., 2006; Ross et al., 2009). In the area of physical activity, some researchers have suggested that the positive associat ion between activity and quality of life is dependent upon the intensity of the activity (Blacklock, Rhodes, & Brown, 2007). This suggests that engagement in physical activity will not help to maintain or increase quality of life unless individuals engage in moderate to vigorous activities. There are similar findings in adult literature on the association between fitness and QOL Researchers have proposes that those who are overweight and physically fit would se e less of a negative impact on their QOL than those who are less fit but of normal weight. In older adults, those who are more physically fit are more likely to report better mood and higher QOL than those who were less fit (Stewart et al., 2003) Other researchers have suggested that levels of physical fitness are more likely to impact physical health domains of QOL (Bennett et al., 2008; Ross et al., 2009). In longitudinal research, improvements in fitness predict significant increases in physical func tioning in overweight adults, even after controlling for change in BMI (Ross et al., 2009). When examining health outcomes, researchers have found that obese adults who have high cardiovascular fitness have a lower likelihood of cardiovascular disease and death than those individuals who are of normal weight and unfit (Blair & Church, 2004; Wessel et al., 2004 ). The se findings in the adult literature suggest that, even within an overweight and obese sample the level of physical fitness plays a significant role in both physical health and QOL Given the

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20 mixed findings and scarce amount of literature in this area in child overweight populations, there remain many unanswered questions P urpose and Summary The pu rpose of the current study was to address the limitations within the existing literature on weight status, physical activity and fitness as predictors of QOL in overweight and obese child populations. While researchers have found differences in QOL depen ding on weight status ( Friedlander et al. 2003; Pinhas Hamiel et al., 2006; Zhang et al., 2008 ), the association between weight status and QOL is currently less clear in populations of exclusively overweight or obese individuals (Pinhas Hamiel et al., 200 6; Shoup et al., 2008) Moreover, t he literature is considerably scarce in the examination of physical activity and fitness as predictors of QOL in child overweight populations. The few studies that do exist have mixed findings or methodological issues, such as subjective reports of activity and less valid measures of QOL This lack of research on physical activity and fitness is noteworthy given the role they play in long term physical health and how informative they may be in ch ild weight management interventions Therefore, this study attempts to extend the literature by examin ing the relationship between QOL, physical activity, and physical fitness in a sample of overweight and obese youth by using objective measures of physic al activity and physical fitness. Specifically, the aims and hypotheses are as follows : Aim 1 The first aim of the study was t o describe the relationship between weight status (i.e., as expressed by BMI z score) and physical activity and physical fitnes s. Hypothesis 1 I t was hypothesized that in this overweight and obese sample, child weight status would be negatively associated with physical activity and physical

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21 fitness, such that children with a higher weight status w ould be less physically active and fit than their peers who were less obese. Aim 2 and both total and physical QOL in treatment se eking overweight and obese youth. Hypothesis 2 It was hypothesized that weight status would be negatively associated with child total and physical QOL such that children with a higher weight status would report lower QOL than children of lower weight status Aim 3 The third aim was to examine the r elationship between levels of physical activity and fitness with child reported total and physical QOL Hypothesis 3 It was hypothesized that within this sample of overweight and obese children, those who participate d in more physical activity and were more physically fit w ould report higher total and physical QOL that children who were less active and fit. Aim 4 The last aim of the study was to determine whether physical activity and fitness served as moderators of the proposed relationship between BMI z score and both total and physical QOL Hypothesis 4 I t was hypothesized that physical activity and fitness would serve as protective factor s of the negative impact that higher weight status had on total and physical QOL

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22 CHAPTER 2 METHODS Participants Participants were 9 6 overweight or obese children between the ages of 8 and 12 years old and their parent or legal guardian attending their baseline appointment as part of their participation in a behavioral weight management program for over weight and obese youth A trained member of the research team measured height and weight in order to verify weight status and eligibility for the study. C hildren were considered eligible for the current study if they were accompanied by thei r parent or legal guardian resided in a rural Florida county, and if they were considered overweight or obese. In this study, overweight was classified as a child being at or above the 85 th percentile in Body Mass Index (BMI) for age and gender, while pa rticipants were considered obese if their BMI was at or above the 95 th percentile. Children who were identified as having severe developmental delays, taking medication for weight loss, or participating in another weight management program were excluded f rom participation. Procedures The current study uses data from a larger grant funded intervention study, the Extension Family Lifestyle Intervention Project (E FLIP for Kids). Recruitment for participants living in rural counties in north central Flo rida was conducted through direct mailings to households and health care providers, press releases to local radio stations, and through brochure distribution to local schools, churches, and community organizations and events. Interested families were able to contact the research office through a toll free phone number in order to learn more about the study and complete the initial phone screening. Families who met the initial eligibility criteria were

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23 scheduled for an in person initial screening visit, fo llowed by a pre study baseline assessment visit at their local Cooperative Extension office to complete the assessment measures. At the initial in person screening visit, trained study personnel provided families with information about the research study b efore obtaining written child assent and parent or legal guardian consent for themselves and their child. At the baseline visit, both parents and children completed a series of questionnaires and physical assessments. Time to complete the questionnaires and physical assessments during their baseline visit was approximately 75 minutes. The baseline visits occurred approximately 5 to 10 days before the start of the intervention. Measures Pediatric Quality of Life Inventory. The Pediatric Quality of Life Inventory (PedsQL 4.0; Varni et al., 2003 ) is a 23 item general QOL instrument to assess self perceived well being across physical, social emotional, and school dimensions. Children rated how difficult specific situations or behaviors were for them in the previous month on a 4 physical health score, and ps ychosocial health score (i.e., social, emotional, and school). The focus of the current study was to examine physical health in overweight children and therefore utilized the total and physical health scores of the PedsQL Higher scores indicated higher self perceived quality of life in those domains. The PedsQL 4.0 has excellent reliability, clinical validity, and is practical to use in large community based samples (Varni et al., 2003). It demonstrated adequate construct

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24 validity when distinguishing a healthy sample from acutely and chronically ill children, as well as acceptable internal consistency reliability for both the Total Score (alpha=0.91) and Physical Health Score (alpha=0.82) for child self report for children ages 8 to 12 years (Varni et a l., 2003 ). Height and Weight. A trained member of the m edical nearest 0.1 centimeter using a Harpendon Stadiometer Weight was measured to the nearest 0.1 kilogram using a digital scale. Height and weight were used to calculate child BMI. BMI z scores were calculated for the children using the modified LMS method from the Center for Disease Control and Prevention (Kuczmarski et al., 2002). The LMS procedure provided parameter estimates of lambda (L), mu (M), and sigma (S) for each age (in months) for males and females, which allows for smoothing of the BMI curve in order to calculate BMI z scores (Kim et al., 2005; Kuczmarski et al., 2002). 20 meter Shuttle Run. Trained members of the research team measured physical fitness through a 20 meter shuttle run test. Children were asked to run in between two orange cones on a flat smooth surface, either out side or inside to music and beeps on a CD The beeps on the CD indicated when t he children should reach the next cone, with the frequency of beeps gradually increasing over time. In order to ensure understanding of instructions, a facilitator modeled one to two laps alongside the child. Children were asked if they had any questions or needed further practice prior to beginning the shuttle run test. Children ran to the pace of the beeps on the CD until they could no longer maintain the pace, as assessed by the children not reaching the cone in the require d am oun t of time on two non consecutive laps. The fitness test was

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25 not conducted if a child had a fever, an ankle or leg injury, or if their blood pressure was over 140/100. While VO 2 peak (i.e., also known as VO 2 max ) is considered the gold standard in fitness assessment, t he 20 meter shuttle run is considered a reliable and valid estimate of VO 2 peak in children ( Artero et al., 2010; Mahoney, 1992). The number of laps completed by each child was used as the measure of fitness for analys i s in this study. Accelerometer. Child ren were instructed to wear a Sensewear Armband Accelerometer (Bodymedia, Inc., Pittsburgh, PA) for 24 hours per day for seven consecutive days at the start of treatment (i.e., prior to making behavioral changes) except when bathing or swimming. The Sens ewear armband was worn on the back of their upper arm, opposite of the hand they write with. The accelerometer was an objective measure of the physical activity expenditure has about a 90% accuracy in detecting energy expenditure ( Liden et al., 2002 ) reliability and validity (Liden et al., 2001 ) While studies examining the validation of the armband have reported the mean BMI of their sample that include overweight children (e.g., An dreacci, Dixon, Dube, & McConnell, 2007), they often have not specified the number of overweight or obese children in the study and have not examined validation separately from normal weight children. For the analyses in the current study, average daily minutes of physical activity was used, which was assessed using time spent in activity that was more than 3 METs (i.e., metabolic equivalents for moderately intense activity ) Data was obtained from the accelerometers using the SenseWear Professional Soft ware version 7.0. In order to include data in the study, children needed to wear the accelerometer for at least 3

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26 weekdays and 1 weekend day for at least 16 h ou r s of each of those days. This criteria is consistent with previous research and with suggest ions to maintain reliability of at least 0.80 (Trost Pate, Freedson, Sallis, & Taylor 200 0 ) Parents or legal guardians completed the following measures: Demographic Information. Parents completed a questionnaire of background information at the time of their initial screening visit. Collected background demographic information that was used for the current study included child race and ethnicity, child age, and household income. Data Analysis In order to describe the sample, descriptive statistics ( means, SDs) were calculated for demographic variables, child BMI z scores, physical activity, physical fitness, and quality of life (i.e., total QOL and physical health summary score) Next, the primary variable s were examined for normality using histogra ms and the Kolmogorov Smirnov test. Physical fitness, total QOL, and physical QOL were found to be non normal, so they were transformed and normalized prior to conducting the analyses. More specifically, total QOL, physical QOL and physical fitness were square root transformed, while physical activity was log transformed Once transformed, any individual cases in the regression s that had a standardized residual in excess of 3 were removed from the analyses. Removal was due to the possible distort ion of the relationship between the independent and dependent variables. Correlation analyses were used to determine if there were age or sex differences in the independent or dependent variables and an analysis of variance (ANOVA) was used to determine if ther e were ethnic/racial differences. Any significant demographic

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27 differences were accounted for in later analyses. Subsequently, correlation analyses were used to examine the relationship between weight status (BMI z score), physical activity, physical fitn ess, and child reported quality of life. Hierarchical r egression s were conducted as follow up analyses to significant correlations between independent and dependent variables in order to further examine the relationship betwe en those variables Any demog raphic variables that were significantly associated with total or physical QOL were entered into block 1, followed by the independent variables in block 2. In order to investigate whether physical fitness or physical activity served as moderators of the relationship between weight status and quality of life, a regression with centering approach was used for each moderator variable ( Preacher, Curr an, & Bauer, 2006)

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28 CHAPTER 3 RESULTS There were 1 71 children enrolled in the study that completed study questionnaires at baseline However 25 children dropped out of the study prior to the first treatment session and 6 children did not complete the fitness test. Of the remaining 140 children who were given an accelerometer during the first session of tre atment, 4 4 of the children did not w ear the armband for the required amount of time for useful data analysis. Thus, 96 participants were used in the analyses for the current study There were no significant differences in demographics, physical fitness, total QOL, or physical QOL in those who did and did not have enough physical activity dat a to be included in the analyses. T he final sample consisted of 9 6 children ( 55 girls 41 boy s) between the ages of 8 and 12 years (M=10. 55 SD=1. 4 ) The sample was primarily obese, with the mean BMI being 28. 38 kg/m 2 (SD=5.37 ) and the mean BMI z score being 2.1 3 (SD=0.4). The sample consisted of 55 girls ( 57.3 %) and 41 boys (42. 7 %). The majority of the sample was Caucasian (61.5 %) and approximately 30% of the sample was African American or Hispanic. The median family income ranged from $40,000 to 59,999. D emographic informati on for the sample is presented in Table 3 1. Preliminary analyses for the study included examining possible significant demogr aphic differences across either the independent (i.e., BMI z score, physical activity, or physical fitness) or dependent variables (i.e., total and physical QOL ). Child age was negatively correlated with physical activity ( r = 0.22, p <.01) with increasin g age being associated with less physical activity There were no other significant demographic differences in the independent or dependent variables. Additional

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29 information of the variable intercorrelations is shown in Table 3 means a nd standard deviations for the independent and dependent variables are displayed in Table 3 3. The first aim of the study was to describe the relationship between BMI z score and both physical activity and fitness. While BMI z score was not significantly correlated with physical activity ( r = 0.1 3 p >.05 ), it was negatively associated with physical fitness such that c hildren with higher weight status were significantly less physically fit ( r = 0.4 2 p < .01). Follow up regression analyses were conducted in order to further examine the relationship between BMI z score and physical fitness. BMI z score had both a significant linear ( t ( 9 3 )= 4.42 R 2 =.1 72 p <.001) and quadratic ( t ( 92 )= 2. 161 2 =.0 38 p =.0 33 ) relationship with fitness. This finding indicates that there is a linear decline in fitness as weight status increases, but for those who are considered extremely obese (i.e., BMI z score > 2.0), there was an accelerated decline in fitness. Result s can be seen in Table 3 4 and Figure 3 1. The second aim of the study was to examine the relationship between weight status and both total and physical QOL There was no significant association between weight status and total QOL ( r = 0.14, p > .05) with in this treatment seeking overweight and obese sample However, h aving a higher BMI z score was associated with significantly lower child reports of physical QOL ( t ( 93 )= 2.712 R 2 =.0 73 p =.00 8 ) As weight status increased, there were significant declines in child reported physical QOL ( see Table 3 5 ). The third aim of the study was to examine the association that physical activity and fitness had with total and physical QOL Physical activity was not a significant

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30 correlate of either total ( r = .0 3 p >.05) or physical QOL ( r = .0 5 p >.05). F itness on the other hand, was positively associated with both total QOL ( r =0.2 1 p <.0 5 ) and physical QOL ( r =0.2 1 p <.0 5 ) However, when controlling for child BMI z score, fitness was no longer associated with either total ( t (92)=1.579, R 2 =.026, p =.118 ) or physical ( t (92)=.991, R 2 =.01, p =.324 ) QOL ( see Tables 3 6 and 3 7 ) The fourth aim of the study was to determine whether physical activity or fitness served as moderators of the relationship between weight status and both total and physical QOL Neither physical activity nor fitness served as moderators in the current stu dy. There were no centered main effects or interactions for any of the analyses, except for the centered main effect of BMI z score in relation to physical QOL (see Tables 3 8 through 3 11 ).

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31 Table 3 1. Demographic characteristics of sample. Mean SD Child Age Child BMI BMI z score 10.5 5 28. 38 2.1 3 1.42 5. 37 0.40 % Gender Boys Girls 4 2.7 5 7.3 Child Race/Ethnicity Caucasian African American 61.5 1 5.6 Hispanic American Indian 14.6 1.0 Biracial 7.3 Median Family Income Below $19,999 $20,000 $39,999 16.3 31.5 $40,000 $59,999 $60,000 79,999 22.8 16.3 $80,000 $99,999 Above $100,000 6.50 6.50 SD, Standard deviation Table 3 2 Intercorrelations of predictor variables and QOL Measure 1 2 3 4 5 6 7 8 9 1. BMI z score 2. Child Age 0.0 9 3. Family income 0. 05 0. 06 4. Gender 0 .10 0. 09 0. 36 5. Race 0. 01 0. 21* 0.15 0.04 6. Physical activity 0.1 3 0.2 2 0. 20 0.19 0.17 7. Physical fitness 0.4 2 0.0 8 0.0 2 0.03 0. 09 0.23* 8. PedsQL total score 0.1 4 0.1 6 0. 07 0.02 0.0 5 0.0 3 0.2 1* 9. Physical summary score 0.2 7 0. 08 0. 07 0.06 0.0 5 0.0 5 0.2 1* 0.8 0 PedsQL, Pediatric Quality of Life Inventory p <.05

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32 Table 3 3 Mean QOL scores, physical activity, and physical fitness. Mean SD Range Quality of Life PedsQL total score 73.89 14.58 30.43 to 96.74 Physical health summary score 7 7.64 15.10 37.50 to 100.0 Physical Activity ( Avg min/day) 120. 49 68.89 31.50 to 431.0 Physical Fitness (# laps completed) 7.99 3.31 1.00 to 17 .00 PedsQL, Pediatric Quality of Life SD, standard deviation Table 3 4. BMI z score in relation to child levels of physical fitness. B SE B R 2 Constant 4. 173 292 Linear BMI z score .6 55 .1 35 .4 51 203 Quadratic BMI z score .544 .252 196 .038 p <.01 Table 3 5 Weight status in relation to child reported physical quality of life. B SE B R 2 Constant 6.917 .925 BMI z score 1.159 .427 .271 .073 p <.01 Table 3 6 Physical fi tness and child reported total quality of life controlling for weight status B SE B R 2 Step 1 .022 Constant 5.793 .862 BMI z score .572 .398 .148 Step 2 .048 Constant 3.790 1.530 BMI z score .258 .442 .066 Fitness .480 .304 .180 p

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33 Table 3 7 Physical fitness and child reported physical quality of life, controlling for weight status B SE B R 2 Step 1 .073 Constant 6.917 .925 BMI z score 1.159 .427 .271 Step 2 .083 Constant 5.556 1.656 BMI z score .945 .479 .221* Fitness .326 .329 .111 p =.051 p <.01 Table 3 8 Physical activity as a moderator between weight status and total quality of life. B SE B R 2 Constant 4.579 .160 .025 BMIz (centered) .576 .402 149 Activity (centered) .134 .316 .044 BMIz*Activity .341 .822 .043 p values >.05 Table 3 9 Physical activity as a moderator between weight status and physical quality of life. B SE B R 2 Constant 4.474 .171 .087 BMIz (centered) 1.11 .429 .260 Activity (centered) .096 .337 .029 BMIz*Activity 1.11 .877 .127 p =.011 Table 3 1 0 Physical fitness as a moderator between weight status and total quality of life. B SE B R 2 Constant 4.588 .166 .05 0 BMIz (centered) .258 .432 .067 Fitness (centered) .473 .290 .182 BMIz*Fitness .186 .567 .033 p values > .05

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34 Table 3 1 1 Physical fitness as a hypothesized moderator between weight status and physical quality of life. B SE B R 2 Constant 4.440 .180 .084 BMIz (centered) .919 .468 .215 Fitness (centered) .353 .314 .123 BMIz *Fitness .045 .615 .007 p =.053

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35 Figure 3 1. Linear and quadratic relationship between weight status and physical fitness.

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36 CHAPTER 4 DISCUSSION Childhood overweight and obesity is linked to significantly higher risk of health problems, adult mortality, and lower quality of life ( QOL; Engeland et al., 2003; Freedman et al., 1999; Friedlander et al., 2003) Therefore, it is important to examine possible protective factors that could be a focus of current interventions Being physically active and fit is predictive of a significantly lower risk of health difficulties associated with being overweight or obese (Carnethon et al., 2003; Garnett et al., 2007; Ortega et al., 2008). H owever, little research has been conducted o n the impact that activity and fitness have on QOL in overweight or obese children ( Boyle et al., 2010; Chen et al., 2005; Kriemler et al., 2010; Shoup et al., 2008 ) Given that childhood overweight is likely to extend into adulthood ( Guo et al., 2002; Wh itaker et al., 1997 ) and that fitness and activity impact health and QOL in adult populations ( Hulens et al., 2002; Peterson et al., 2006; Ross et al., 2009; Stewart et al., 2003 ) it is essential that further research be conducted in this area for child p opulations. The current study extends the literature in this area by utilizing more objective measures of physical activity and fitness (i.e., through the use of accelerometers and 20 meter shuttle run, respectively) and examining the association they have with both overall (total) and physical health domains of QOL in a strictly overweight and obese treatment seeking sample of children. The composition of the sample is an important consideration when interpreting the results of the study. Participant s in the study were primarily obese, with approximately ninety percent of the sample being obese Although there was a significant restriction of range in weight status, there was still excellent diversity in the

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37 remaining demographics in our sample. Sli ghtly more than half the sample included girls and approximately 38% of the sample consisted of ethnic and racial minorities. Even in this weight restricted sample of children higher weight status was associated with lower physical QOL This finding is important in further d emonstrating the negative association between weight status and QOL in physical domains in an overweight and obese sample of children. C hildren in our sample reported lower total QOL (M= 73.9 SD=14. 6 ) when compared to a published normative study with healthy, acutely ill, and chronically ill samples of children ( Varni, 2001 ) but lower physical QOL (M=77.6, SD=15.1) only when compared to the healthy sample of children The fact that the overweight and obese children in our sample reported significant impairments in overall functioning compared to children with acute and chronic health conditions sheds being T here were less consistent findings when c omparing this sample to other reports of QOL in published studies with overweight or obese children Specifically, c hildren in this study reported significantly higher total and physical QOL when compared to the findings of Schwimmer and co lleagues (2003) While children in this study did not differ from chi ldren in other obese samples on total QOL (Janicke et al., 2007; Pinhas Hamiel et al., 2006) there were mixed findings in the physical domain Physical QOL in our study was not different from what was found in one study ( i.e., Janicke et al., 2007) but was significantly higher than that of another ( i.e., Pinhas Hamiel et al., 2006) Thus, in samples of strictly overweight and obese children, there are less consistent findin gs of child reported QOL, especially in the physical domain.

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38 There are two important matters to consider when comparing our sample to the Sch w immer et al. (2003) and Pinhas Hamiel et al. (2006) studies First, the mean BMI z score for our study was much lower than that of the Schwimmer study (i.e., M=2.1 4 and M=2.6, respectively). Therefore, it is likely that we found such significant differences in QOL between the two samples due to greater variability of weight status in our sample. Second, children participating in the Schwimmer study were physician referred and a subset of the sample in the Pinhas Hamiel study was recruited from hospital clinics. Therefore, the poorer QOL reported in th ose sample s is likely a reflection of higher weight status and more health concerns than our sample. Interestingly, BMI z score had a unique rela tionship with physical fitness. As other studies have found ( Ara et al., 2007; Nassis et al. 2005 ), there was a linear decline in fitness as weight status increased. However, a distinct finding in our study was the accelerated decline in fitness for those children who were considered extremely obese (i.e., z score above approximately 2.0 ) To our knowledge, this is the first study to repor t on this unique relationship between child BMI z score and physical fitness. This accelerated decline in fitness for those obese individuals has significant implications into the functional limitations these children may face. Functional limitations ass ociated with childhood obesity suggest that both weight status and fitness are important targets for intervention. By addressing these markers of health, children will be better able to engage in basic everyday activities and improve upon their health. Fo r children in this study, having low fitness levels was associated with significantly lower total and physical QOL compared to those who were more f it. To date, there is only one previous study to examine the association between fitness and

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39 QOL (Kriemler et al., 2010). In the adult literature, improvements in fitness are predictive of improved physical functioning, even after controlling for change in BMI (Ross et al., 2009). However, o nce controlling for child weight status i n our sample, fitness was no longer significantly associated with either total or physical QOL. This is contrary to what Ross and colleagues (2009) found in adult populations but similar to what was found in child populations (Kriemler et al., 2010). G iven the dearth of research o n this area in child populations, our study is unique and informative for future interventions. Certainly future research is needed before definitive conclusions can be drawn. In the current sample, the overall fitness level of the children was poor The median number of laps completed in the shuttle run test was seven, which is far below a age and gender based normative sample. For instance, a 1 2 year old female who is considered o bese (i.e., 9 5% percentile in BMI) would need to run at least 46 la ps (i.e., 9 minutes running) (Cooper Institute, 2010). Because fitness levels were extremely low in our overweight and obese sample of children, future interventions may benefit from placi ng a dual focus on improv ed weight status and physical fitness especially given that these are both important markers of health in adulthood ( Giannini et al. 2006 ; Wei et al., 1999 ) BMI z score was not significantly associated with physical activity in our study. One possible explanation for the lack of a relationship found in our study is that the sample engaged in much more physical activity overall than expected. Children in the sample averaged approximately 2 hours of daily physical activity, wh ich is more than the recommended 60 minutes of daily physical activity for childre n ( Centers for Disease

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40 Control [CDC], 2010 ). While it appears that the children are obtaining adequate levels of activity, these activity levels consisted primarily of moderate physical activity (i.e., 3 to 6 METs ). The CDC (2010) currently recommends that children engage in vigorous physical activity (i.e., > 6 METs) 3 days per week as part of the daily activity recommendat ions. C hildren in the current study engaged in an average of 5. 35 minutes of vigorous acti vity per da y (i.e., after excluding a single outlier of 67.25 average minutes) which was consistent with the poor fitness levels of this sample This finding is si gnificant given that vigorous activity is also an integral component of physical health and activity recommendations in children Researchers in adul t literature have suggested that the positive impact of physical activity might be more likely to be found when individuals engage in more vigorous levels of activity ( Blacklock et al., 2007 ). This has significant clinical implications for weight management interventions for children Th e current study suggests that future interventions for overweight youth may benefit from placing more of a focus on increasing vigorous physical a ctivity and improved fitness. Older children in our study were less likely to be physicall y active than younger childr en which was consistent with previous research ( Nyberg et al., 2009; Trost et al. 2002 ) These a ge related differences in physical activity may be due to increased time spent with peers as children get older. Physical activity and physical fitness did not serve as moderators of the BMI z score and QOL relationship in our study Therefore, neither activity nor fitness explained the relationship between higher weight status and QOL in our study.

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41 There are several strengths and limitations to the current study. Strengths of the study include the use of objective assessments of physical activity and fitness, as well as the use of a validated measure of child QOL The main limitation of the study is the cross sectional design tha t limits our ability to make causal statements in our results. A second limitation of our study is that given the low mean number of laps completed, we could not validly estimate VO 2 peak for a majority of the children, as at least ten completed laps are needed to calculate VO 2 peak ( Cooper Institute, 2010 ) Therefore, the number of laps completed was used in the analyses of our study which was not 2 max A third limitation of the study was th e use of 1 min ute sampling intervals for the accelerometers to obtain activity data. Previous researchers have argued that the utilization of 1 minute intervals to estimate energy expenditure instead of 10 second intervals tends to underestimate vigorous activity in ch ildren ( Rowlands, 2007 ). Clinically, this suggests that use of 1 minute epoch s may underestimate any changes in vigorous activity in intervention studies. Also, this suggests that examination of the association between the intensity of physical activity and QOL is less reliable with the use of 1 minute epochs Therefore, it is important to use the more reliable 10 second interval to estimate energy expenditure in treatment studies targeting physical activity and when examining QOL outcomes. A final and significant limitation in our study is the number of participants (i.e., N=44) that were excluded due to the lack of adequate physical activity data. While this suggests that there were possible biases impacting the findings of the study, there were no si gnificant differences between those who did and did not have enough activity data.

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42 Future research should focus on st rengthening the results of the current study. More specifically, research would benefit from further examining the intervals used in ac celerometer measurement and whether samples of overweight children continue to display inadequate levels of vigorous physical activity when 10 second intervals are used Given the increasing rates of obesity and the decreasing levels of physical activity and fitness in children research would also benefit from the validation of the 20 meter shuttle run for individuals running less than 10 laps in order to enable researchers to reliably estimate VO 2 max Also, f uture weight management studies would benefit from examining changes in weight status, physical activity, and physical fitness in order to determine if improvements are predictive of improved QOL in overweight and obese children. This next step in research could inform future interventions and shed light on whether changes in physical activity and fitness are more important methods for improving physical and psychosocial health in overweight and obese children.

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43 LIST OF REFERENCES Anderson, S.E., Economos, C.D., & Must, A. (2008). Active play and s creen time in U.S. children aged 4 to 11 years in relation to sociodemographic and weight status characteristics: a nationally representative cross sectional analysis. BMC Public Health 8 366 379. doi: 10.1186/1471 2458 8 336 Andreacci, J.L., Dixon, C.B., Dube, J.J., & McConnell, T.R. (2007). Validation of the Sensewear Pro armband to assess energy expenditure during treadmill exercise in children 7 10 years of age. Journal of Exercise Physiology online 10 (4) 35 42. Ara, I., Moreno, L.A., Leiva, M.T., Gutin, B., Casajs, A. (2007). Adiposity, physical activity, and physical fitness among children from Aragn, Spain. Obesity, 15 (8) 1918 1924. doi: 10.1038/oby.2007.228 Artero, E.G., Espaa Romero, V., Castro Piero, J., Ortega, F.B., Suni, J., Castillo Garzon, M.J., & Ruiz, J.R. ( in press ). Reliability of Field Based Fitness Tests in Youth. International Journal of Sports Medicine doi: 10.1055/s 0030 1268488 Bennett, W.L., Ouyang, P., Wu, A.W., Barone, B.B., Stewart, K.J. (2008). Fatness and fitness: how do they influence health related quality of life in type 2 diabetes mellitus? Health and Quality of Life Outcomes 6( 110 ) doi:10.1186/1477 7525 6 110 10.1186/1477 7525 6 110 Birch, L.L. (2006). Child feeding practices and the etiology of obesity. Obesity 14 (3) 343 344. doi: 10.1038/oby.2006.45 Blacklock, R.E., Rhodes, R.E., & Brown, S.G. (2007). Relationship between regular walking, physical activity, and health re lated quality of life. Journal of Physical Activity & Health 4 138 152. Blair, S.N., Church, T.S. (2004). The fitness, obesity, and health equation: Is physical activity the common denominator? JAMA, 292 (10), 1232 1234. doi:10.1001/ jama.292.10.1232 Boyle, S.E., Jones, G.L., & Walters, S.J. (2010). Physical activity, quality of life, weight status, and diet in adolescence. Quality of Life Research 19(7), 943 954. doi: 10.1007/ s11136 010 9659 8 Carnethon, M.R., Gidding, S.S., Nehgme, R., Sidne y, S., Jacobs, D.R., Liu, K. (2003). Cardiorespiratory fitness in young adulthood and the development of cardiovascular disease risk factors. JAMA 290 (23), 3092 3100. doi:10.1001/ jama.290.23.3092

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44 Centers for Disease Control, National Center for Chronic Disease Prevention and Health Promotion (2010). Physical activity for everyone: How much physical activity do children need? Retrieved from http://cdc.gov/physicalactivity/ everyone/guidelines/children.html Chen, X., Sekine, M., Hamanishi, S., Yamagami, T., & Kagamimori, S. (2005). Associations of lifestyle factors with quality of life (QOL) in Japanese children: A 3 year follow up of the Toyama Birth Cohort Study. Child: Care, Health & Development 31 (4), 433 439. doi: 10.1111/j.1365 2214.2005.00529.x Cooper Institute (2010). Aer obic Capacity and Body Mass Index Healthy Fitness Zone Retrieved January 28 th 2011, from http://www.cooperinstitute.org/youth/ Davis, E., Davies, B., Waters, E. and Priest, N. (2008), The relationship between proxy reported health related quality of life and parental distress: gender differences. Child : Care, Health and Development 34 (6) 830 837. doi: 10.1111/j.1365 2214.2008.00866.x Dietz WH. (1998). Health consequences of obesity in youth: childhood predictors of adult disease. Pediatrics, 101 518 525. Dowda, M., Ainsworth, B.E., Addy, C.L., Saunders, R., Riner, W. (2001). Environmental influences, physical activity, and weight status in 8 to 16 year olds. Archives of Pediatri c Adolescent Medicine 155 711 717. Eliakim, A., Kaven, G., Berger, I., Friedland, O., Wolach, B., & Nemet, D. (2002). The effect of a combined intervention study on body mass index and fitness in obese children and adolescents a clinical experience. European Journal of Pediatrics 161 449 454. doi: 10.1007/s00431 002 0980 2 Engeland, A., Bjrge, T., Sgaard, A.J., & Tverdal, A. (2003). Body mass index in adolescence in relation to total mortality: 32 year follow up of 227,000 Norwegian boys and girls. American Journal of Epidemiology 157 (6), 517 523. doi: 10.1093/aje/kwf219 Felton, G. M., Dowda, M., Ward, D. S., Dishman, R. K., Trost, S. G., Saunders, R., & Pate, R. R. (2002). Differences in physical activity between black and white girls living in rural and urban areas. Journal of School Health 72 (6) 250 255. doi: 10.1111/j.1746 1561.2002.tb07338.x Freedman, D.S., Dietz, W.H., Srinivasan, S.R., & Berenson, G.S. (1999). The relation of overweight to cardiovascular risk factors among chi ldren and adolescents: the Bogalusa Heart Study. Pediatrics, 103 ( 6 ), 1175 1182. doi: 10.1542/peds. 103.6.1175

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49 Trost, S.G., Pate, R.R., Sallis, J.F., Freedson, P.S., Taylor, W.C., Dowda, M., & Sirard, J. (2002). Age and gender differences in objectively measured physical activity in youth. Medicine and Science in Sports and Exercise, 34 (2), 350 355. doi: 10.1097/00005768 200202000 00025 Van Mechelen, W., Hlobil, H., & Kemper, H.C.G. (1986). Validation of two running tests as estimates of maximal aerobic power in children. European Jo urnal of Applied Physiology and Occupational Physiology 55( 5 ), 503 506. doi: 10.1007/ BF00421645 Varni, J.W., Burwinkle, T.M., Seid, M., & Skarr, D. (2003). The PedsQL 4.0 as a Pediatric Population Health Measure: Feasibility, reliability, and validity Ambulatory Pediatrics, 3 (6), 329 341. doi: 10.1367/1539 4409(2003) 003<0329:TPAAPP>2.0.CO;2 Wabitsch, M., Hauner, H., Hertrampf, M., Muche, R., Hay, B., Maye (2004). Type II diabetes mellitus and impaired glucose regulation in Caucasian children and adolescents with obesity living in Germany. International Journal of Obesity, 28 307 313. doi: 10.1038/sj.ijo. 0802555 Wei, M., Kampert, J .B., Barlow, C.E., Nichamann, M.Z., Gibbons, L.W., Paffenbarger, R.S., & Blair, S.N. (1999). Relationship between low cardiorespiratory fitness and mortality in normal weight, overweight, and obese men. JAMA 282 (16), 1547 1553. doi: 10.1001/jama.282.1 6.1547 C.N.B. (2004). Relationship of physical fitness vs body mass index with coronary artery disease and cardiovascular events in women. JAMA, 292 (10), 1179 1187. doi: 10.1001/jama.292.10.1179 Whitaker, R.C., Wright, J.A., Pepe, M.S., Seidel, K.D., & Dietz, W.H. (1997). Predicting obesity in young adulthood from childhood and parental obesity. New England Journal of Medicine 337 869 873. doi:10.1056/NEJM199709253371301 Williams, J., Wake, M., Hesketh, K., Maher, E., & Waters, E. (2005). Health related quality of life in overweight and obese children. JAMA, 293 (1), 70 76. doi: 10.1001/jama.293.1.70 Zeller, M.H. & Modi, A.C. (2006). Predictors of health related quality of life in obese youth. Obesity 14, 122 130. doi: 10.1038/oby.2006.15 Zhang, L., Fos, P.J., Johnson, W.D., Kamali, V., Cox, R.G., Zuniga, M.A., & Kittle, T. (2008). Body mass index and health related quality of life in elementary school children: A pilot study. Health and Quality of Life Outcomes 6 (77). doi: 10.1186/ 1477 7525 6 77

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50 B IOGRAPHICAL SKETCH Danielle is a second year graduate student in the Cli nical and Health Psychology Program at the University of Fl orida, with a concentration in pediatric p sychology. She comp sychology at the University of Missouri in 2009. During her undergraduate education, she worked with s everal faculty members on research projects including cognitive aging in older adults and the relationship between family functioning and juvenile delinquency. Danielle is currently involved in working on a family based weight management program for overw eight children residing in rural counties in Florida She is also working on a study examining the association between disease severity, behavior health factors, psychosocial functioning, and quality of life of adolescents with inflammatory bowel disease.