title: Physical activity growth curves relate to adiposity in adolescents.
abstract: OBJECTIVE
  Findings from prospective studies on associations between physical activity and adiposity among youth are inconsistent. Our aim was to describe physical activity trajectories during secondary school and examine the association with change in adiposity in youth.
  
  
  METHODS
  Physical activity was measured in 20 survey cycles from 1999 to 2005; anthropometrics were measured in survey cycles 1, 12, and 19. Individual growth curves modeling moderate-to-vigorous physical activity (MVPA) and vigorous physical activity (VPA) were estimated. Estimates of initial level and rate of decline in MVPA and VPA bouts per week were included as potential predictors of body fat% and body mass index using age- and sex-specific linear regression.
  
  
  RESULTS
  Complete data were available for 840 and 760 adolescents aged 12-13 years at baseline, followed from survey cycles 1-12 and 12-19, respectively. Among girls, yearly declines of one MVPA and one VPA bout per week during earlier adolescence were associated with increases of 0.19 (95% confidence interval [CI], 0.02-0.36) and 0.47 (95% CI, 0.015-0.92) units of body fat%, respectively. In boys, a yearly decline of one MVPA bout per week was associated with an increase of 0.38 (95% CI, 0.05-0.70) units of body fat% during later adolescence.
  
  
  CONCLUSIONS
  Obesity prevention programs should include strategies to prevent declines in physical activity.
authors: Department of Exercise Science, Concordia University, Montreal, Quebec, Canada. tracie.barnett@gmail.com
authors: Tracie A
authors: TA
authors: Barnett
authors: Katerina
authors: K
authors: Maximova
authors: Catherine M
authors: CM
authors: Sabiston
authors: Andraea
authors: A
authors: Van Hulst
authors: Jennifer
authors: J
authors: Brunet
authors: Andrée L
authors: AL
authors: Castonguay
authors: Mathieu
authors: M
authors: Bélanger
authors: Jennifer
authors: J
authors: O'Loughlin
mesh_terms: D050154:Adiposity; D000293:Adolescent; D015992:Body Mass Index; D015444:Exercise; D005260:Female; D005500:Follow-Up Studies; D057238:Growth Charts; D006306:Health Surveys; D006801:Humans; D016014:Linear Models; D008297:Male; D009043:Motor Activity; D009765:Obesity / Q000453:epidemiology / Q000517:prevention & control; D011446:Prospective Studies; D012737:Sex Factors; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires
keywords: Adiposity; Adolescent; Body composition; Exercise; Longitudinal studies; Obesity; Physical activity