title: Mediators affecting girls' levels of physical activity outside of school: findings from the trial of activity in adolescent girls.
abstract: BACKGROUND
  Providing after school activities is a community level approach for reducing the decline in physical activity of girls as they reach early adolescence.
  
  
  OBJECTIVE
  The purpose of this study was to examine psychosocial, environmental, and behavioral factors as potential mediators of after school physical activity in adolescent girls.
  
  
  METHODS
  We assessed objectively measured levels of physical activity occurring outside of school and potential predictors and mediators of activity in girls participating in the Trial of Activity in Adolescent Girls (TAAG).
  
  
  RESULTS
  We found that the TAAG intervention had a statistically significant and positive effect on out of school activity in the 2006 cohort. Self-efficacy, friends' social support, total social support, and difficulty getting to and from community activities mediated the level of moderate to vigorous physical activity in girls.
  
  
  CONCLUSIONS
  Parents, communities, and schools should provide and enhance opportunities outside of the school day for adolescents to be active. Reducing transportation barriers and enlisting social support appear to be key.
authors.affiliation: Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, 1300 South Second Street, Minneapolis, MN 55454-1054, USA. lalytle@umn.edu
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Lytle
authors.forename: David M
authors.initials: DM
authors.lastname: Murray
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Evenson
authors.forename: Jamie
authors.initials: J
authors.lastname: Moody
authors.forename: Charlotte A
authors.initials: CA
authors.lastname: Pratt
authors.forename: Lauve
authors.initials: L
authors.lastname: Metcalfe
authors.forename: Deborah
authors.initials: D
authors.lastname: Parra-Medina
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology; D015444:Exercise / Q000523:psychology*; D005260:Female; D015438:Health Behavior; D006293:Health Promotion; D006306:Health Surveys; D006801:Humans; D007398:Interpersonal Relations; D009043:Motor Activity / Q000502:physiology*; D010379:Peer Group; D015397:Program Evaluation; D012574:Schools; D020377:Self Efficacy; D012931:Social Environment; D011795:Surveys and Questionnaires