Independent and Interactive Associations of Family Support for Physical Activity and the School PA-Supportive Environment With Physical Activity Among Rural Chinese Adolescents: A Three-Wave Longitudinal Study

Background This study examined the prospective associations of family support for physical activity and the perceived school PA-supportive environment with physical activity (PA) among rural adolescents and whether their interaction was more consistent with a synergistic or compensatory pattern. Methods A three-wave longitudinal study was conducted among 621 students in Grades 7 and 8 from 4 rural junior high schools in Hunan Province, China. Models examined family support, the school PA-supportive environment, and their interaction in relation to subsequent PA, adjusting for prior PA, sex, grade, BMI-for-age z score, and school fixed effects. Results Family support (β = .187 and .149) and the school PA-supportive environment (β = .142 and .093) were positively associated with subsequent PA across both intervals. Their interaction was negative from T1 to T2 (β = −.135, P < .001) and from T2 to T3 (β = −.088, P = .018). Simple-slope analyses showed that each source of support was more strongly associated with subsequent PA when the other was relatively low, indicating a compensatory pattern. Sensitivity analyses yielded similar findings. Conclusions Family support and the school PA-supportive environment were independently associated with subsequent PA among rural adolescents, and their joint association was more consistent with compensation than synergy.