Associations between physical exercise and mental health among middle school students: potential psychosocial pathways and contextual heterogeneity from a healthy China perspective

IntroductionPhysical exercise has been increasingly linked to adolescent mental health, but less is known about the psychosocial pathways and contextual conditions underlying this association. This study examines the relationship between physical exercise and mental health among Chinese middle school students, focusing on academic stress, peer context, school sports facilities, and family economic status.MethodsUsing data from the China Education Panel Survey, this study analyzed a final sample of 6,713 middle school students. Fixed-effects models were used to examine the association between exercise duration and mental health, controlling for individual, family, school, and city-level factors. Robustness checks, instrumental-variable analysis, mediation analysis, and heterogeneity analysis were further conducted.ResultsLonger physical exercise duration was positively associated with better mental health. This association remained stable across alternative specifications. Mediation analyses suggested that academic stress and peer context may serve as potential psychosocial pathways. Specifically, longer exercise duration was associated with lower academic stress and more favorable peer-related contexts, which were in turn associated with better mental health. Heterogeneity analyses showed that the positive association was stronger among students attending schools with sports facilities and those from families with higher economic status.DiscussionThese findings provide large-sample observational evidence on the association between physical exercise and adolescent mental health in China. They suggest that school-based physical activity may be linked to mental health through academic and peer context, while its benefits may vary across school and family resources. Given the observational and cross-sectional nature of the data, the findings should be interpreted as associations rather than causal effects.