Abstract
PURPOSE: Youth physical activity (PA) levels differ by race/ethnicity and socioeconomic status (SES). It is well established that various multilevel factors may influence changes in PA. The present study examined whether the association between the change in individual, interpersonal, and environmental factors and the change in PA is modified by race/ethnicity or SES. METHODS: This study followed 643 youths and their parents from suburban and rural South Carolina participating in the Transitions and Activity Changes in Kids (TRACK) Study in 2008-2009 and 2010-2011. We assessed total PA in youth using accelerometry and categorized youth and parent survey data into blocks based on the socioecological model. Multivariate regression growth curve models evaluated whether the association between change in independent variables and change in PA was modified by race/ethnicity or SES. RESULTS: PA declined from fifth to seventh grade among all racial/ethnic and SES groups. Associations between the range of variables and change in PA were modified by race/ethnicity but not SES. Blacks did not share any common predictors of change in PA with whites or Hispanics. However, child-reported number of active friends was associated with total PA, and enjoyment of PA was associated with change in PA among both whites and Hispanics. Significant interactions by time varied by racial/ethnic group. CONCLUSIONS: The factors that influence changes in youth PA vary by race/ethnicity but not SES. These findings reinforce the complex nature of addressing PA behavior in diverse samples and further support the need for culturally appropriate interventions to promote PA in youth.