AI Insight
This systematic review and meta-analysis examined mechanisms through which physical activity may reduce depressive symptoms in youth aged 6-27 years, analyzing 87 studies with 39 contributing quantitative data. The analysis found that physical activity was inversely associated with depressive symptoms, with psychological resilience, self-esteem, and social support emerging as statistically significant mediating pathways. However, the predominantly cross-sectional nature of the studies prevents establishing causal direction, and reverse pathways remain plausible.
Why it matters
Understanding how physical activity relates to mental health in young people could inform more targeted interventions for youth depression. The findings suggest that physical activity programs might be most effective when they simultaneously build psychological resilience, self-esteem, and social connections, though longitudinal research is needed to confirm causal mechanisms.
Understand the Science
BackgroundPhysical activity is consistently associated with fewer depressive symptoms in young people, yet the mechanisms underlying this association remain unclear. This systematic review and meta-analytic structural equation modelling (MASEM) study aimed to identify potential mediators linking physical activity with depressive symptoms in youth and quantitatively synthesise repeatedly examined mediation pathways.MethodsSix electronic databases were searched for observational quantitative studies examining physical activity, potential mediators, and depressive symptoms in children, adolescents, and young adults within a prespecified eligibility range of 6–27 years. Potential mediators were synthesised narratively and categorised into conceptually related domains. A random-effects meta-analysis was conducted within the mediation-focused quantitative subset, followed by two-stage random-effects MASEM for mediator constructs with sufficient independent studies and complete correlation data.ResultsEighty-seven studies were included in the broader systematic review, of which 80 formally examined at least one mediator and 39 contributed to the quantitative evidence base. Within this mediation-focused quantitative subset, physical activity was, on average, inversely associated with depressive symptoms (r = −0.234, 95% CI −0.281 to −0.187), although heterogeneity was substantial (I2 = 98.29%) and the 95% prediction interval included zero (−0.499 to 0.070). Narrative synthesis identified potential pathways involving psychological resources and self-related perceptions, social factors, behavioural and lifestyle factors, cognitive-emotional processes, maladaptive behavioural factors, and physical or neurobiological factors. Construct-specific MASEM supported statistical indirect associations through psychological resilience (ab = −0.108, 95% CI −0.172 to −0.061), self-esteem (ab = −0.134, 95% CI −0.239 to −0.062), and social support (ab = −0.127, 95% CI −0.220 to −0.059). Sleep quality showed a significant indirect association in an exploratory model based on three studies.ConclusionPsychological resilience, self-esteem, and social support emerged as repeatedly examined candidate pathways linking physical activity with depressive symptoms. However, the predominantly cross-sectional and just-identified MASEM models cannot establish temporal ordering, and alternative-direction analyses indicated that at least the resilience correlation structure was also compatible with a reverse indirect pathway. The findings should therefore be interpreted as statistical indirect associations rather than established causal mechanisms.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/recorddashboard, identifier (CRD420261355504).