title: Objective and perceived availability of physical activity opportunities: differences in associations with physical activity behavior among urban adolescents.
abstract: BACKGROUND
  This study examined the associations of the perceived and objective environment with adolescent engagement in sports activities and walking and cycling in leisure time. It also explored the degree of agreement between objective and perceived availability of physical activity (PA) facilities in neighborhoods.
  
  
  METHODS
  Cross-sectional data on physical activity, the perceived availability of physical activity opportunities (perceived physical environment) was assessed through a questionnaire and the objective availability of PA opportunities (objective physical environment) was obtained through GIS data. The final sample included 654 adolescents with a mean age of 14.1 (SD = 1.2) years.
  
  
  RESULTS
  Perceived availability of sports facilities and parks was significantly associated with engaging in sports (OR: 1.73; 95% CI: 1.16-2.56) and with walking and cycling in leisure time (OR: 1.66; 95% CI: 1.07-2.57) respectively. Agreement between objective and perceived environment was low to moderate with Kappa values ranging from -0.005 to 0.053.
  
  
  CONCLUSIONS
  The perceived environment was the stronger correlate of PA behavior among adolescents. There were substantial differences between assessments of objective and perceived physical environment.
authors.affiliation: Department of Public Health, Erasmus University Medical Center, Rotterdam, the Netherlands. r.prins@erasmusmc.nl.
authors.forename: Richard G
authors.initials: RG
authors.lastname: Prins
authors.forename: Anke
authors.initials: A
authors.lastname: Oenema
authors.forename: Klazine
authors.initials: K
authors.lastname: van der Horst
authors.forename: Johannes
authors.initials: J
authors.lastname: Brug