title: A social ecological assessment of physical activity among urban adolescents.
abstract: OBJECTIVE
  To examine the physical, social and temporal contexts of physical activity, as well as sex variations of the associations among 314 urban adolescents.
  
  
  METHODS
  Three-day physical activity recall measured contextual information of physical activities. Logistic regressions and generalized estimating equation models examined associations among physical activity types and contexts, and sex differences.
  
  
  RESULTS
  Active transportation was the most common physical activity. Home/neighborhood and school were the most common physical activity locations. School was the main location for organized physical activity. Boys spent more time on recreational physical activity, regardless of the social context, compared to girls. The average physical activity level was significantly lower for girls than for boys after school.
  
  
  CONCLUSIONS
  Physical activity promotion interventions need to target physical activity environments and social contexts in a sex-specific manner.
authors.affiliation: Joseph J. Zilber School of Public Health, University of Wisconsin-Milwaukee, Milwaukee, WI, USA. yanf@uwm.edu.
authors.forename: Alice Fang
authors.initials: AF
authors.lastname: Yan
authors.affiliation: Maryland School of Public Health, College Park, MD, USA.
authors.forename: Carolyn C
authors.initials: CC
authors.lastname: Voorhees
authors.affiliation: Maryland School of Public Health, College Park, MD, USA.
authors.forename: Kenneth H
authors.initials: KH
authors.lastname: Beck
authors.affiliation: Maryland School of Public Health, College Park, MD, USA.
authors.forename: Min Qi
authors.initials: MQ
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D001741:Black or African American; D015142:Baltimore; D016001:Confidence Intervals; D015444:Exercise; D005260:Female; D015438:Health Behavior; D006801:Humans; D016013:Likelihood Functions; D016015:Logistic Models; D008297:Male; D016017:Odds Ratio; D012111:Residence Characteristics; D012737:Sex Factors; D012931:Social Environment; D014505:Urban Population; D044465:White People