Dose–response relationship between physical activity and mental health outcomes in adolescents

Background Physical activity is generally associated with improved adolescent mental health, yet its dose–response relationship remains unclear. This study examined how physical activity relates to stress perception, psychological resilience, and self-efficacy among adolescents. Methods A cross-sectional survey was conducted in September 2024 among 2,270 students aged 12–15 years from 4 middle schools in Shanghai, China. Multivariable linear regression and restricted cubic spline (RCS) models were used to examine association and dose–response relationships, adjusting for demographic and academic covariates. Results Higher physical activity was significantly associated with lower stress perception ( B = −0.13, p < 0.001), higher psychological resilience ( B = 0.33, p < 0.001), and higher self-efficacy ( B = 0.25, p < 0.001). RCS analyses revealed dose–response relationships. At lower physical activity levels, the slopes were −5.65 for stress perception, 8.59 for psychological resilience, and 12.10 for self-efficacy (all p < 0.001), while at higher physical activity levels, the associations were substantially attenuated. Gender-stratified analyses indicated stronger associations in males than in females. Conclusion Physical activity is associated with better mental health in adolescents, particularly among those with lower activity levels. The findings highlight the importance of targeting less active adolescents in school-based interventions.