The influence of social support, social affiliation and intrinsic motivation for increasing underserved youth's physical activity: A social climate-based intervention study

The purpose of this study was to investigate the influences of intrinsic motivation, social affiliation orientations and reciprocal social support for physical activity (PA) on underserved youths' afterschool period moderate-to-vigorous (MVPA) changing trajectories across the 16-week Connect through PLAY intervention, a social-motivational climate intervention. A total of 113 youth (61.06% African American, 56.64% girls) provided full data. Youths' intrinsic motivation, social affiliation orientations and social support were measured by youth responses to a set of surveys at baseline and post-intervention. Youths' afterschool period MVPA was measured using data from 7-day ActiGraph accelerometer wear at baseline, midpoint and post-intervention. Hierarchical linear modelling analysis found that youth daily afterschool period (3pm-6pm) MVPA increased, on average, 37.94 min across the 16-week intervention. Increases in intrinsic motivation, social affiliation orientations and social support were positive predictors of youth afterschool MVPA changing trajectory. The findings clarify the contributions that a social-motivational climate intervention can have on youth afterschool period MVPA through increasing youth intrinsic motivation, social affiliation and reciprocal social support.