title: The role of motivation in understanding social contextual influences on physical activity in underserved adolescents in the ACT Trial: a cross-sectional study.
abstract: BACKGROUND
  Previous research has shown that social contextual factors are important in understanding physical activity (PA) behavior, although little is known about how these factors may relate to PA, especially in underserved adolescents (low income, minorities). This study examined how motivation may differentially mediate the relationship of two social contextual variables (i.e., peer and parent social support) and moderate-to-vigorous PA (MVPA).
  
  
  METHODS
  Baseline data (n = 1421 sixth graders, 54% female, 72% African American) from the Active by Choice Today (ACT) trial in underserved adolescents were analyzed. Motivation was examined as a mediator of the relationships between peer social support, parent social support, and MVPA (measured by 7-day accelerometer estimates).
  
  
  RESULTS
  Motivation and peer but not parent support were significantly related to MVPA overall. Significant mediation effects were found indicating motivation partially mediated the relation between peer social support and MVPA and to a lesser degree parent support and MVPA.
  
  
  CONCLUSIONS
  These findings provide support for the importance of social contextual influences, especially peer social support, on underserved adolescents' PA and motivation for PA.
authors.affiliation: Center for Obesity Research and Education, Temple University School of Medicine, Philadelphia, PA, USA.
authors.forename: Hannah G
authors.initials: HG
authors.lastname: Lawman
authors.forename: Dawn K
authors.initials: DK
authors.lastname: Wilson
authors.forename: M Lee
authors.initials: ML
authors.lastname: Van Horn
authors.forename: Nicole
authors.initials: N
authors.lastname: Zarrett
mesh_terms: D000293:Adolescent; D001741:Black or African American; D015992:Body Mass Index; D002648:Child; D015444:Exercise / Q000523:psychology*; D005260:Female; D006801:Humans; D008297:Male; D009042:Motivation; D010379:Peer Group; D012737:Sex Factors; D012931:Social Environment; D035862:Vulnerable Populations / Q000523:psychology*