Discussion
REGRESSION
This study set out to examine changes in the MVPA of at-risk adolescents participating in a 16-week PA social-motivational climate-based intervention within ASPs, with specific focus on whether changes in self-determination motivations leads to increases in daily PA engagement. Therefore, the following research questions were addressed: (a) to what extent does adolescents’ daily MVPA change from baseline to endpoint during a 16-week SDT-based intervention within ASPs, and does this change vary by gender and race? And (b) to what extent does change of adolescent intrinsic and autonomous extrinsic motivations across the 16-week intervention influence the trajectory of their daily MVPA over the 16-week period. There were three key findings from this study. First, adolescents’ daily MVPA was found, on average, to increase by 12.72 minutes from baseline to endpoint. Second, despite clear gender and race differences in youth MVPA at baseline, gender and race were not significant predictors of adolescents’ daily MVPA change trajectories, suggesting that across gender and race, youth had a similar rate of change in MVPA across the 16-week intervention. Third, change in intrinsic motivation, but not autonomous extrinsic motivation, was a significant predictor of adolescents’ daily MVPA changes.Although there are significant benefits of MVPA to the health and well-being of youth [Although baseline regression analyses and HLM Model C clearly showed that youth baseline intrinsic and autonomous extrinsic motivations did not significantly predict baseline daily MVPA, the change in intrinsic motivation was observed as a significant positive predictor while the change in autonomous extrinsic motivation was not a significant predictor. The results may shed new light on our understanding of the role of intrinsic and autonomous extrinsic motivations change. The observed increase in intrinsic motivation indicates that facilitating a socially-based SDT PA-climate may improve and maintain adolescents’ intrinsic motivation to participate into MVPA over time. The results support the notion that intrinsic motivation supports the most desirable and long-lasting levels of engagement [Furthermore, ASPs should tailor their programming in ways that provide equal access, and a wide range of PA opportunities that appeal to and support all adolescents across age, gender, race/ethnicity, and family socioeconomic status [This study has three limitations. First, staff variables (e.g., staff interaction with adolescents, staff motivation, and staff attitude) and social development variables (e.g., social affiliation, social support) are not integrated into this study. Future studies are needed to examine the impact of staff’s support of adolescents’ basic psychological needs for autonomy, competence, and relatedness and social development variables on adolescents’ MVPA changing trajectory. Secondly, given this study did not include the active comparison group, future research with the full randomized controlled trial sample upon the completion of the 5-year intervention should ultimately be used to determine the effects of social-motivational climate on youth MVPA change. Thirdly, although controlled motivation was not measured as part of the study, future research should examine youth change in motivation as a continuum across regulatory orientations throughout an SDT-based intervention, with the goal of youth movement towards more autonomous, and ultimately, intrinsic motivation.