Impact of School-Based Physical Activity on Mental Health Outcomes in Adolescents: A Longitudinal Field Study

Thesis Abstract

The escalating prevalence of mental health concerns among adolescents and the increasing integration of physical activity (PA) into school curricula underscore the need to understand how school-based PA influences mental health outcomes over time. This study addresses the problem of limited longitudinal evidence linking structured PA within school settings to adolescent mental health trajectories, considering potential mediators such as self-esteem, social connectedness, and sleep quality. The aim is to examine how school-based physical activity affects depressive symptoms, anxiety, and overall well-being among middle and high school students over two academic years, and to identify mechanisms through which PA exerts its effects. Specific objectives include (1) assessing longitudinal changes in depressive symptoms, anxiety, and well-being in relation to PA participation; (2) evaluating dose–response relationships between PA frequency/duration and mental health outcomes; (3) testing mediating roles of sleep quality, self-esteem, and peer social support; and (4) exploring potential moderating effects of gender, socioeconomic status, and baseline activity levels. A longitudinal, mixed-methods design will be employed. The quantitative component will target a cohort of 1,200 students aged 12–16 years from 12 secondary schools, with data collected at three time points across two school years. PA exposure will be measured via school attendance records for physical education (PE) classes, completed activity logs, and accelerometer-derived moderate-to-vigorous physical activity (MVPA) durations. Primary mental health outcomes will be assessed using validated instruments the Patient Health Questionnaire-9 (PHQ-9) for depressive symptoms, the Generalized Anxiety Disorder 7-item scale (GAD-7) for anxiety, and the Warwick-Edinburgh Mental Well-being Scale (WEMWBS) for overall well-being. Mediators and moderators will include the Pittsburgh Sleep Quality Index (PSQI), Rosenberg Self-Esteem Scale, and the Social Provisional Belonging Scale. Multilevel growth models will analyze trajectories, while structural equation modeling (SEM) will test mediation pathways. Regression analyses will explore dose–response relationships, controlling for age, gender, body mass index, socioeconomic status, baseline mental health, and baseline PA. The qualitative component will include 40 in-depth interviews with a purposive subsample of students and 12 focus group discussions with PE teachers and school counselors to contextualize quantitative findings and illuminate perceived barriers and facilitators to PA participation and its perceived mental health benefits. Thematic analysis will be conducted to identify recurring patterns related to social environment, motivation, and school policy. The study will be guided by Social Cognitive Theory and Self-Determination Theory to interpret motivational and social-contextual processes linking PA to mental health outcomes. Expected findings include (a) a positive association between higher sustained school-based MVPA and reductions in depressive and anxiety symptoms, and improvements in well-being over the two-year period; (b) a dose–response relationship indicating greater mental health benefits with increased PA exposure, particularly through PE classes complemented by extracurricular activity; (c) mediation by sleep quality and self-esteem, with social support buffering effects; and (d) moderation by gender and SES, with differential effects reflecting access to quality PE, resources, and cultural norms. The study contributes to knowledge by providing robust longitudinal evidence from diverse school settings on how school-based PA shapes adolescent mental health, clarifying mechanisms, and informing policy and practice for optimizing PE curricula and school-based interventions. From these results, practical implications include recommendations for increasing MVPA during school hours, integrating sleep hygiene and social-emotional learning components into PE, and tailoring programs to address gender and SES disparities. The study concludes that sustained, high-quality school-based physical activity has a meaningful, compensatory role in promoting adolescent mental health, underscoring the necessity for policy support, resource allocation, and faculty development to maximize benefits within regular schooling.