School-based interventions can modestly increase adolescents' physical activity in the short term, but their effects diminish over time. Sustaining behavioural change may require long-term, system-level strategies that involve schools, families, and communities. Overall, the certainty of evidence was low to moderate, and findings should be interpreted with caution due to high heterogeneity across studies.
Moin et al. (Fri,) studied this question.