Purpose: The objective was to study how sedentary behaviour (SB) and physical activity (PA)change during a 6-months multimodal lifestyle intervention including a Multimodal Lifestyle Intervention, a Multimodal Lifestyle and Medical food intervention and a control subgroup, for people with prodromal Alzheimer's disease (AD). Further, the aim was to explore the predictive value of outcome expectancies and self-efficacy beliefs on level of PA in the two intervention subgroups.  Methods: A secondary analysis of existing data (n=66) from MIND-AD trial with a descriptive evaluation design was conducted. Descriptive and non-parametric statistical analysis were used for between- and within groups analysis. To explore the predictive value of a model with self-efficacy and outcome expectancies at baseline on PA at 6 months, regression analysis was conducted. Effect size was calculated for between-group and withingroup differences. Results: Objectively measured PA increased in the Multimodal Intervention subgroup. SB did not change during the intervention. Outcome expectancies for that impact of exercise is beneficial for health in the long run increased during the intervention. Participants higherinitial outcome expectancies for the impact of exercise would lead to less AD-related difficulties predicted higher PA level at 6 months. Self-efficacy for exercise or outcome expectancies for the impact of exercise on AD-related difficulties did not change during the intervention. Conclusions: PA increased in the Multimodal Intervention subgroup. This difference could not be shown with PA measured by questionnaire which indicates that objective measurements are better suited to measuring PA in people with prodromal AD than subjective measurements. Increased outcome expectancies for that impact of exercise arebeneficial for health in the long run demonstrate the participants strengthened intentions to improve their long-term health. Increasing outcome expectancies to manage AD-related difficulties can be an important part of interventions targeting PA in people with prodromal AD.

Children and adults with cerebral palsy (CP) perform reduced physical activity (PA) levels and increased sedentary behaviour (SB), which predisposes them to negative health outcomes. SB is characterized in the typically developing population by an energy expenditure component of ≤1.5 metabolic equivalents of task (METs) while sitting, reclining or lying. There is no consensus on an operationalized definition of SB for the CP population. Furthermore, there are no established outcomes to inform guidelines promoting PA in this population. I will address these two research gaps by investigating the operationalization of SB and by identifying important health outcomes of PA, through expert opinions, in individuals with CP. The first chapter is a scoping review of the operationalization of SB in individuals with CP. I found that, in individuals with CP, i) the definition for SB in the typically developing population of ≤1.5 METs generally applies to sitting and lying, and ii) sitting and lying are reported as operationalizations of SB. The second chapter was a conference-based survey to identify critical and important health outcomes for PA in individuals with CP. Clinicians and researchers (n=55) who attended a workshop on PA in CP rated nine pre-determined health outcomes on a 9-point Likert-type scale from the Grading of Recommendations Assessment, Development and Evaluation Approach. The experts identified both the psychological aspects of health (i.e. anxiety and depression) as being critical. The physical health outcomes rated as critical were sleep, nutrition, and cardiorespiratory endurance, and those rated as important were body size, body composition, blood lipids and glucose, and blood pressure. Together, this research suggests that the operationalization of SB in individuals with CP is similar to that of the typically developing population, and that both the physical and mental aspects of health must be considered in future PA management. / Thesis / Master of Science Rehabilitation Science (MSc)

Aim of research: to describe TV viewing trajectories from age 5 to 40 months

Contexte : Chez les adolescents, les différences sociales dans les pratiques d’activité physique (AP) et les comportements sédentaires restent peu expliquées. Les interventions universelles proportionnées visant la réduction des inégalités sociales chez les adolescents en situation de surpoids/obésité sont rares. Objectifs : Explorer les relations entre l’AP, la sédentarité, les facteurs sociaux, familiaux et scolaires chez les adolescents. Quatre axes de recherche ont été définis : identification des facteurs associés à l'AP et à la sédentarité, étude de la participation des adolescents en situation de surpoids/obésité socialement moins favorisés à une intervention universelle proportionnée en milieu scolaire, analyse de la perception des adolescents de leurs pratiques et évaluation de l'efficacité de l'intervention. Méthodes : Ces travaux sont issus d’essais en milieu scolaire : PRALIMAP (PRomotion de l'ALIMentation et de l'Activité Physique) et PRALIMAP-INÈS (INÈgalité de Santé). Le questionnaire international d’AP (IPAQ) a été utilisé pour mesurer l’AP et la sédentarité. Le niveau social a été défini à partir des catégories socioprofessionnelles et de l’échelle d’aisance familiale (FAS). Des entretiens individuels ont permis le recueil des perceptions. Des régressions logistiques ont été réalisées. Résultats : L'AP était dépendante des caractéristiques sociales, familiales et scolaires. La dépense énergétique totale n’était pas suffisante pour identifier les différences sociales en AP. Les freins perçus à la pratique d’AP étaient majoritairement individuels et étaient différents selon le niveau social et le sexe. Une intervention universelle proportionnée en milieu scolaire a permis la mobilisation de ces adolescents et de réduire les inégalités sociales d’AP. Conclusion : Ces travaux soulignent l’importance de la mise en œuvre en milieu scolaire d’actions spécifiques en AP pour les adolescents en situation de surpoids/obésité socialement moins favorisés / Background: Among adolescents, social differences in physical activity (PA) and sedentary behaviour (SB) are seldom explained. Proportionate universal interventions aimed at reducing social inequalities among overweight adolescents are uncommon. Objectives: To explore correlations between PA, SB, social, family and school-related factors among adolescents. Four research topics were elaborated: identifying factors associated with PA and SB, analysing socially less-advantaged overweight adolescents’ participation in a proportionate universal school intervention, analysing adolescents' perceptions of their PA practice, and evaluating the effectiveness of this intervention. Methods: This work is the result of two trials in the school setting: (PRomotion de l'ALIMentation et de l'Activité Physique) and PRALIMAP-INÈS (INÈgalité de Santé). The International PA Questionnaire (IPAQ) was used to measure PA and SB. Social status was defined according to socio-professional categories and the family affluence scale (FAS). Data on perceptions was collected from individual interviews. Individual interviews allowed data collection of perceptions. Logistic regressions were also carried out. Results: PA was dependent on social, family and school-related characteristics. Total energy expenditure was not sufficient to identify social differences in PA. The perceived barriers to PA practice were mostly individual and were different according to social status and gender. The proportionate universal intervention in schools successfully engaged these adolescents and reduced social inequalities related to PA. Conclusion: This work emphasises the importance of implementing specific activities in PA for socially less advantaged overweight adolescents

There is a growing public health concern over the effects that sedentary lifestyles are having on the health of young people, particularly in relation to overweight and obesity. This thesis presents five studies which examine the prevalence, incidence and determinants of sedentary behaviour among youth. The rationale for eachs tudy derives from a framework of behaviourale. pidemiology applied to physical activity and health. Study I presents four systematic reviews of literature. The first review presents a descriptive epidemiology of youth sedentary behaviour. The second review presents a summary of empirical correlates of television viewing, the most prevalent sedentary behaviour among young people. 'Me third and fourth reviews present quantitative syntheses of empirical relationships between television viewing and body composition (review 3) and sedentary behaviour and physical activity (review 4). Study 2 examines the prevalence and interrelationships among different sedentary behaviours and physical activity in a cross-nationa(l USA & UK) sample of 2,494 youth ages 11-15. Study 3 uses a qualitative strategy to generate a grounded framework from which to understand the choices young people make about how to spend their free-time. Study 4 adopts a micro-behavioural approach for understandingt he incidence and temporal patterning of sedentary behaviour among 162 adolescents (age 13-16). Study 5 presents an evaluation of a behaviour change theory useful for increasing levels of physical activity and reducing sedentary behaviour. Sedentary behaviour and physical activity do not appear to be two sides of the same coin and appear to have different sets of determinants. This is an important finding becausee fforts to increase levels of physical activity may not reduce levels of sedentary behaviour. While television viewing, video games and computer use are consistent referents in the academic and media panic surrounding youth inactivity, it is unlikely that these behaviours play a substantialr ole in epidemiologic trends of adolescent overweight and obesity. Further study should attempt to examine how contemporary lifestyles contribute to the growing prevalence of overweight and obesity among adolescents.

The purpose of this study lies in investigating the embodied learning of applied aesthetics in our sense of balance in the educational space and how it can contribute to change one of a present major public health related problem, the problem of sedentary behaviour in school and society. The investigation is not an effect study, but aims to question our sensorial cultural practice of applied aesthetics, by looking at how we use our ability to balance in the educational space.  Introducing and including elements from the field of art, the aesthetics field of knowledge and life science, the question of acknowledging embodied learning is explored mainly in the sensorial cultural praxis of our ability to balance. Embodied praxis is represented by the Alexander Technique and Elsa Gindler’s concept, with relation to modern neuromechanics. An educational view of knowledge that unilaterally enhances and rewards abstraction as well as theoretical thinking, by validating matrices and merit points, creates unbalance. Treating this unbalance solely with physical exercises enhances the conflict of how to use learning time in school and seems not to lead to a solution. By seeing the educational space as a space of embodied practice the investigation is built around participants’ sense of balance in embodied learning during a school day. The established sensorial cultural practice of how we are using our sense of balance in movement responses is observed during a school day and in a complementary inquiry explored and discussed with the children. Also the time of sitting is measured. The qualitative analysis or reading in this research of embodied learning is done by analysing directions or pointing in poise in momentum for finding inclusive or exclusive corresponsive sensorial tendencies in relation to sensorial cultural practice, including individual, social and regulative aspects. The minor quantitative part in this investigation is looking at the time spent sitting during the school day in the given conditions for defining the pupils’ sedimentary behaviour. The found embodied learning was not noticably acknowledged and not commented by the teacher.  The learning sessions were varying in space, form and in their content. In spite of the attempt of the teacher to create moveability, the children were sitting 54%  or more of the day in school. Inclusive dynamic responsiveness gave ability to balance and promoted embodied learning. Isolated or excluded responsiveness did not noticably engage the sense of balance and did not promote embodied learning. It resulted into pointing or directing downwards and leaning forward, backward or inwards into supportive furniture in accordance with gravitation. The study finds that inclusive responsiveness increases aligned balancing in poise in momentum. In its conclusion the study recognizes the value and effect of physical activity, but argues that moving to be healthy is not effectively changing sedentary behaviour. It argues instead for embodied health sufficient moving on a general sensorial level.  To be able to use our sense of balance as function of intelligence, we still need to increase acknowledgment of our evolutionary inherited skill further. / Studiens syfte ligger i att undersöka möjligheten, att med embodied learning, lärandet genom estetisk sensorisk kommunikation och förtrogen inlärning, finna möjligheter att påverka ett av de stora folkhälsoproblemen, stillasittande beteende i skolan och i samhället. Arbetet utgör ingen effektstudie, utan syftar till att ifrågasätta vår sensoriska kulturella praxis och estetik, genom att undersöka hur vi använder oss av vårt balanssinne i skolan.  En pedagogisk syn på kunskap som ensidigt främjar och belönar abstraktion liksom teoretisk konception, genom meritpoäng och bedömningsmatriser, skapar obalans. Att genom enbart fysisk aktivitet försöka lösa denna obalans, förstärker konflikten om hur tiden i skolan ska fördelas och verkar inte leda till en tillfredsställande lösning av problemet.  Studien har en tvärvetenskaplig karaktär, där utbildningsvetenskapliga aspekter, konstnärlig forskning och naturvetenskap först presenteras och sedan inkluderas i frågan om hur embodied learning i relation till vår färdighet att balansera är igenkänd i skolans sensoriska kulturella praxis och estetik. Embodied praxis och dess användning, representerad genom Alexandertekniken och Elsa Gindlers koncept, är sedan närmare diskuterad, samt dess relation till modern neuromekanik. Genom att se skolan som en plats för embodied praxis, estetisk sensorisk praktik och förtrogenhetspraktik, bygger undersökningen på deltagarnas användning av balanssinnet, sett i hållningen i ögonblicket under en skoldag. Etablerad sensorisk kulturell praxis om hur vi använder vår förmåga att vara i balans observeras från ett intersubjektivt perspektiv. Detta kompletteras med samtal och enstaka explorationer, som utgör endast en mindre del i undersökningen. Även tiden för stillasittande mäts.  Den framtagna empirin av embodied learning analyseras kvalitativt. Detta sker genom att analysera riktningar i hållningen i ögonblicket, för att hitta inkluderande eller exkluderande motsvarande sensoriska tendenser i relation till individuell, social och reglerande sensorisk kulturell praxis. Den mindre kvantitativa delen i denna undersökning består av att mäta tiden som eleverna sitter under skoldagen, för att kunna analysera elevernas sedimentära beteende.   Resultaten visar att embodied learning inte var märkbart igenkänd och inte kommenterad av läraren. Undervisningspassen var varierande i rum, form och innehåll. Trots lärarens ihållande försök att skapa rörlighet, satt barnen minst 54 % av skoldagen. Inkluderande dynamisk sensorisk korrespondens resulterade i en väl fungerande funktionell användning av balanssinnet och främjade embodied learning. Isolerande eller uteslutande respons främjade inte den funktionella användningen av balanssinnet eller embodied learning märkbart. Resultatet visar också att elevernas hållningar största delen av tiden, visade riktningar som pekade nedåt, de lutade sig framåt, bakåt eller inåt och sjönk ner i möblerna i enlighet med tyngdlagen. Visade de en inkluderande korrespondens, ökade balanssinnets fungerande i hållningen i ögonblicket. Studien tillstår i sin slutsats att fysisk aktivitet är nödvändig och har effekt, men argumenterar, att röra sig för att vara frisk är inget effektivt sätt för att förändra stillasittande beteende. Resonemanget i studien leder i stället till att vi behöver röra oss generellt på ett införlivat hälsofrämjande sätt. För att kunna använda oss av vårt balanssinne på ett intelligent sätt, behöver vi fortfarande fördjupa förståelsen av vår evolutionärt nedärvda färdighet ytterligare. / <p>This interdisciplinary study in educational science includes elements from the field of art and aesthetics as well as life science.  The investigation is not an effect study. It is about our sensorial cultural use of balance, from the perspective of an embodied practitioner.</p>

Muskuloskeletala besvär (MSD) utgör ett stort hälsoproblem. Besvären består av smärta i muskler, leder, ligament och omgivande vävnad. Två orsaker till MSD på arbetsplatsen är stress och stillasittande. Syftet med studien var att testa hypoteserna att stress och stillasittande associerar var för sig till MSD och associerar mer till MSD tillsammans än separat. Deltagarantalet var 100 kontorsarbetare, 48 kvinnor och 52 män, med höj- och sänkbara bord. Medelåldern på samtliga deltagare var 42 år. De besvarade en webbenkät för att mäta variablerna stress och stillasittande i förhållande till MSD. Standardiserade instrumenten PSS-10 (Perceived Stress Scale - 10) och NMQ (Nordic Musculoskeletal Questionnaire) användes bland annat i enkäten. Data analyserades med multipel linjär regression, två separata enkla linjära regressioner och stegvis regression. Resultaten visade statistisk signifikans för modellen med stress och stillasittande tillsammans där endast stress associerade med MSD (p=0.011). Resultatet för de två enkla linjära regressionerna gav att stress associerade till MSD (p=0.008) medan stillasittande inte gjorde det (p=0.280). Nollhypoteserna kunde inte förkastas eftersom stillasittande inte associerade till MSD och en jämförelse mellan justerad R2 gav stress för sig (justerat R2=0.061) en bättre modell än stress och stillasittande tillsammans (justerat R2=0.056). / Musculoskeletal disorders (MSD) constitute a major health problem. The symptoms consist of pain in muscles, joints, ligaments and surrounding tissues. Two causes of MSD in office work are stress and sedentary behaviour. The purpose of this study was to test the hypotheses that stress and sedentary behaviour are associated individually with MSD and associates more with MSD together than separately. The number of participants was 100 office workers, 48 women and 52 men, with sit and stand tables. The average age of all participants was 42 years. They responded to a five-piece web questionnaire to measure the variables stress and sedentary behaviour in relation to MSD. The standardized instruments PSS-10 (Perceived Stress Scale - 10) and NMQ (Nordic Musculoskeletal Questionnaire) were used, among other things, in the survey. Data was analyzed with multiple linear regression, two separate simple linear regressions and stepwise regression. The results showed statistical significance for stress and sedentary behavior together, only stress was associated with MSD (p = 0.011). The result of the two simple linear regressions resulted in stress associated with MSD (p = 0.008) while sedentary behavior did not (p = 0.280). the null hypotheses could not be rejected because sedentary behaviour did not associate with MSD and a comparison between adjusted R2 gave stress separately (adjusted R2 = 0.061) a better model than stress and sedentary behavior together (adjusted R2 = 0.056).

Contexte: Les liens entre l'activité physique (AP), la sédentarité et la santé ont été analysés mais très souvent de façon séparée. Or, la prise en compte simultanée des ces deux comportements reste une condition essentielle pour comprendre leurs effets sur la santé des individus. Objectifs: Analyser les relations entre l'AP, la sédentarité et la santé en population française (adolescents et adultes). Cet objectif se décline en trois axes de recherche: (1) identification des facteurs associés à l'AP et à la sédentarité, (2) la mesure de l'impact de ces comportements sur la santé et (3) évaluation de l'efficacité d'intervention visant à modifier favorablement ces comportements. Méthode: Nous avons utilisé les données issues de plusieurs enquêtes ou études menées en population générale ou spécifique. Nous avons utilisé les données de l'étude PRALIMAP (PRomotion de l'ALImentation et de l'Activité Physique) chez les adolescents, l'étude SUVIMAX (SUpplémentation en VItamines et Minéraux Anti-oXydants) chez les adultes et les Baromètres Santé 2005 et 2008 en population générale. Pour l'axe 1, nous avons recherché les facteurs sociodémographiques et économiques associés à l'AP et à la sédentarité. Pour l'axe 2, nous avons analysé les effets propres et communs de l'AP et de la sédentarité sur le surpoids et la qualité de vie liée à la santé (QVLS). Enfin pour l'axe 3, nous avons évalué l'efficacité de l'étude PRALIMAP sur les modifications de l'AP et de la sédentarité ainsi que le lien entre ces modifications et l'évolution de la corpulence. Résultats: L'AP et la sédentarité sont fortement dépendantes des caractéristiques socio-économiques aussi bien chez l'adolescent que chez l'adulte. Nous avons pu montrer, à travers une analyse bidirectionnelle associée à une prise en compte des contextes de pratique chez les adolescents et les adultes que le niveau d'AP ou de sédentarité pouvait être à la fois causes et conséquences du niveau de QVLS. Une intervention (PRALIMAP) était efficace pour l’amélioration de l’AP et de la sédentarité et cette amélioration explique en partie la réduction du surpoids. Conclusion: Ce travail confirme l’importance de l’AP et de la sédentarité comme déterminants de la santé quelle que soit la période de vie (adolescents ou adultes) notamment en termes de réduction du surpoids et d’amélioration de la QVLS. / Background: Relationships between physical activity (PA), sedentary behaviour (SB) and health have been usually investigated independently. However, taking into account these two components simultaneously is an essential requirement to understand their health effects. Objectives: To investigate the relationships between PA, SB and health in French population (adolescents and adults). This aim can be divided in 3 different research headings: (1) identification of the correlates of PA and SB, (2) measurement of the health impact of PA and SB, (3) evaluation of the effectiveness of intervention aimed to improve PA and SB. Methods: We used data from different survey and studies carried out in French general or specific population. The PRALIMAP trial (PRomotion de l'ALImentation et de l'Activité Physique) in adolescents, the SUVIMAX trial (SUpplémentation en VItamines et Minéraux Anti-oXydants) in adults and the health Barometer Surveys (2005 and 2008) in general population. For the heading 1 we investigated the socio-demographic and economic correlates of PA and SB. For the heading 2 we analyzed the common and specific effects of PA and SB on health, especially health-related quality of life (HRQoL) and overweight prevalence. For the heading 3 we assessed the effectiveness of intervention on PA and SB change and its relationship with overweight reduction. Results: PA and SB were highly correlates to socio-economic characteristics in both adolescents and adults. In bidirectional analyses taking into account the domains of PA and SB, we yielded that PA and SB could be both causes and consequences of HRQoL. Intervention (PRALIMAP) was effective in improving PA and SB and this improvement partly mediated the weight reduction. Conclusion: The results of this work emphases the importance of PA and SB as health determinants whatever the life period (adolescents and adults) particularly in terms of weight reduction and HRQoL improvement.

[Truncated abstract] This descriptive study identified correlates of electronic media use among pre-adolescent children (10-12 year olds). It specifically focused on the potential influence of individual factors and the social and physical environment within the family home setting. The prevalence of overweight/obesity in children is escalating. Sedentary behaviour in the form of electronic media use (comprised of television (TV) and video/DVD viewing, video and computer gaming, and computer use) is a contributing and a modifiable risk factor for overweight/obesity. To date, research focused on sedentary behaviour has been largely derived from physical (in)activity data where the absence or observed low levels of physical activity participation or TV viewing only has been used as a proxy for sedentariness. Little is known about the specificities of children's electronic media use; its impact on children's overall leisure and screen-time; and, the potential influencing factors that may operate at the home level. The family home is a context-specific setting where electronic media use is a daily practice for most children. To better understand electronic-based sedentary behaviour among children the following specific aims were addressed; 1) To describe children's leisure time, particularly time spent with electronic media. 2) To explore children and parents' perceptions about electronic-based sedentary behaviour. 3) To determine the prevalence of children's electronic-media use at home. 4) To examine the influence of individual, family social and home physical factors associated with different levels of electronic media use by children. ... The availability and accessibility of a variety of electronic equipment at home, especially in the child's bedroom (particularly among boys), was also associated with children's screen behaviour. Physical aspects of the family home (i.e., lay-out and yard size) had a mixed effect on children's electronic media use. Overall, the nature of electronic media use among children is complex and is influenced by dimensions that present at children's individual, family social and physical home level. The knowledge generated from this study about specific correlates of electronic media use has extended the understanding about its impact on children's discretionary time. Future prospective longitudinal research is warranted given that most studies investigating electronic media and sedentary behaviour are of cross-sectional design. Including other forms of sedentary behaviour such as sitting and talking with friends and family, reading and/or using telephones may provide a more comprehensive measure of sedentariness in the future. Further studies should use multivariate statistical analyses (i.e., modelling) to improve clarity of relationships between multiple variables and gauge mediating factors. This study also calls for future intervention research. Findings on gender-specific correlates of electronic media use provide superior information for the development of tailored behaviour modification strategies aimed at girls and boys respectively. Active involvement of household members in the intervention is also warranted. Utilising this study's findings may strengthen intervention outcomes towards a more directed and sustained behaviour change

Obesity during childhood and adolescence is a serious public health concern in Canada and globally. Obesity is a complex disease with genetic, environmental, social, and behavioural determinants. However, our understanding of obesity and its development is limited by a reliance on proxy measurements of adiposity such as body mass index (BMI) and cross-sectional study designs that limit our ability to assess temporality. In this dissertation, I present the first set of body fat percent (BF%) accrual and velocity percentile curves for Canadian children and youth, investigate the relationship between BMI- and BF%-based definitions of obesity, and examine the longitudinal influence of sedentary time, moderate-to-vigorous physical activity (MVPA) and caloric intake on the development of BF%. My analyses are based on the UBC Healthy Bones III Study (HBSIII), a mixed longitudinal study of boys and girls aged 8-12 years at baseline, measured between 1999 and 2012. In HBSIII, adiposity was measured directly as BF% from total body dual energy x-ray absorptiometry (DXA) scans and MVPA and sedentary time were measured objectively using accelerometers. For the first study in my dissertation, I used generalized additive models for location scale and shape (GAMLSS) to develop sex- and ethnic-specific BF% accrual and velocity percentile curves. I present separate curves for Asian and Caucasian boys and girls aged 9-19 years at the 3rd, 10th, 25th, 50th, 75th, 95th, and 97th centiles. In this descriptive study, I found materially different shaped BF% percentile curves for Asian and Caucasian girls but not for boys. Second, I examined the relationship between BMI- and BF%-based definitions of obesity for Asian and Caucasian boys and girls aged 9-19 years. I used multivariable regression models, sensitivity and specificity analysis, receiver operating characteristic (ROC) curves, and Youden’s Index to explore this relationship. I found that BMI identified <50% of those classified with obesity based on BF%, and that classification performance of BMI differed significantly by age and sex subgroups for Asian and Caucasians. In my third analysis, I explored the longitudinal relationship between BF% and sedentary time, MVPA, and caloric intake as boys and girls mature. I fit polynomial multilevel models using MO (years from age at peak height velocity, APHV) as the time variable. Rate of change in BF% across maturity differed between boys and girls and differences in MVPA, sedentary time, and caloric intake between individuals influenced BF% at APHV (MO=0) and rate of change in BF% across maturity. Together, these studies advance our understanding of how body fat accrues as children and youth mature, and highlight the heterogeneity in predictors of adiposity and adiposity measurement accuracy across age, sex, and ethnic groups. / Graduate