Theoretical Foundations for School-Based Physical Activity Programmes on Adolescent Mental Health in South African Townships Not applicable (Theoretical Framework Article) This theoretical framework provides insights into the mechanisms through which physical activity can influence mental health, offering a foundation for future empirical research. Future studies should focus on longitudinal impact and explore the specific types of physical activities that are most effective in improving adolescent mental health. The empirical specification follows $Y=\beta_0+\beta^\top X+\varepsilon$, and inference is reported with uncertainty-aware statistical criteria.