Dose-dependent association between physical activity and mental health, and mitigation effects on risk behaviors

Understanding the dose-response effects of physical activity on mental health and risk behavior mitigation is crucial for mental health promotion. This study using restricted cubic spline and piecewise regression analyses based on a representative national sample of 30,054 Chinese adults, revealed reverse J-shaped (p for nonlinear <0.001) but monotonic beneficial associations between physical activity and depression, anxiety, and stress symptoms, with optimal thresholds identified at 2.15 METs-hour/day for depression and anxiety, and 3.25 METs-hour/day for stress. Engaging in 1-3 METs-hour/day of physical activity appeared to mitigate the adverse effects of unhealthy food intake on depression and anxiety, whereas 4-6 METs-hour/day could offset the impact of short sleep duration on depression, anxiety, and stress. The findings suggest that physical activity prescription could be effective in mitigating the adverse effects of certain risk behaviors on common mental symptoms, and excessive physical activity might not be necessary for mental health promotion.