Physical activity and two-year change in adolescent well-being in nine countries.

The benefits of physical activity (PA) for well-being are well known; however, studies examining longitudinal effects across diverse international samples in late adolescence are limited. This study advances prior work by combining a partial longitudinal design with a multinational sample to assess the predictive effect of PA on biennial change in older adolescents' well-being, while testing for sex differences. The sample included 903 adolescents (50.4% female) from nine countries, who completed The European Health and Behavior Survey at age 16 and the EPOCH Measure of Adolescent Well-Being at ages 16 and 18. Multilevel modeling estimated the average impact of PA on change in well-being, controlling for baseline well-being. To further interrogate the findings, an additional analysis tested the effect using relative difference scores of well-being to provide a direct measure of simple change. Meta-analytic techniques then captured the degree of cross-country consistency in the estimated effect. Results indicated that more PA at age 16 significantly predicted greater EPOCH well-being at age 18, controlling for prior well-being at age 16, and that adolescent sex did not moderate this effect. The relative difference score analysis confirmed these results. The meta-analysis revealed no significant heterogeneity in the predictive effect across countries. Findings extend previous research by demonstrating the cross-cultural consistency of PA benefits during a critical developmental transition period. They suggest that PA is a modifiable behavior that can be utilized globally to enhance adolescent well-being, though individual differences and context-specific factors should be considered in public health policies and interventions.