Is it "Who we are" or "Where we live"? —A multilevel investigation on the Effects of Socio-demographic and Urban Neighborhood Characteristics on Out of School Physical Activity

Objectives: To estimate the prevalence of out of school moderate-to-vigorous physical activity (MVPA), and to examine the association of individual characteristics and neighborhood characteristics with out of school MVPA, among minority adolescents living in an urban environment.

Methods: This is a cross-sectional study conducted with a sample of 250 high school (grades 9 to 12) students in Baltimore, Md. Both individual level and neighborhood level data were obtained. Address geo-coding and spatial analyses were conducted with ArcGIS 9.2 (ESRI, Redlands, Calif.). Bivariate and multivariate analyses were used to study factors associated with MVPA. Linear mixed effects models are employed to study the joint effects of individual level and neighborhood level factors on MVPA. All statistical analyses were conducted using SAS version 9.2 (Cary, N.C.).

Results: The sample consisted of adolescents aged between 14 and 18 years (mean =15.7, SD=1.21), with 69% Black and 60% female. Bivariate and multivariate analyses show that younger adolescents are more active than older adolescents. Females spend 1.27% less leisure time for moderate and vigorous activity than males do (P=0.01). Blacks spend 1.50% and 1.23% more leisure time for moderate and vigorous activity than Whites and other groups, respectively. MVPA is also affected by neighborhood-level variables. After controlling for individual level characteristics, the percent of population with travel time more than 30 minutes (P<0.001) and median house sale price (P=0.04) are both negatively related to adolescents' MVPA; while abandoned property rates are positively related to MVPA (P=0.05).