Physical activity and adolescent mental health across 45 countries: Exploring the role of country-level perceived health

Purpose: Physical activity (PA) has been linked to better adolescent mental health, yet most evidence comes from single-country studies. Although a recent meta-analysis established that this association varies significantly by country, the specific country-level factors underlying this variability remain untested. This study examined whether cross-national variability in the PA–mental health association is related to country-level differences in adolescents' perceived health. We examined the PA–mental health association in a large cross-national sample and tested country-level perceived health as a moderator to provide a more holistic perspective on the interplay between physical activity, its context and outcomes. Methods: This cross-sectional study used data from the 2018 Health Behaviour in School-aged Children survey of adolescents aged 11, 13, and 15 from 45 countries (N = 217,384). Mental health was measured using self-reported life satisfaction and psychological health complaints. PA was assessed as the number of days per week with at least 60 min of moderate-to-vigorous activity. Multilevel linear regression models were estimated, with adolescents nested within countries. Random intercepts and slopes were included to capture cross-national variability, and cross-level interactions were tested to assess moderation by country-level perceived health. Results: Higher PA was consistently associated with better mental health across all outcomes (all ps < 0.001). Marginal R2 ranged from 0.012 to 0.051, and conditional R2 from 0.040 to 0.095, indicating meaningful country-level variance. A non-significant trend toward moderation by country-level perceived health was observed for life satisfaction (b = 0.15, p =. 076) and sleep difficulty (b = 0.08, p =. 092), though neither reached the pre-specified significance threshold (p <. 05). Conclusions: Findings suggest that country-level context may play a role in the PA–mental health association, though this requires confirmation in future research. Programs promoting mental health through PA should encompass the role of the broad context, considering cross-national differences and adapting strategies to local health perceptions.