Does physical activity in childhood or adolescence predict future anxiety, depression, or wellbeing? A systematic review of 98 prospective cohort studies.

Physical activity (PA) is a modifiable health behaviour that can support and improve mental health. The tendency for activity levels to track over time suggests that through continued participation, those most active in youth may experience better long-term mental health than less active peers. Exploring the extent to which mental health benefits of child/adolescent PA persevere over time helps advocates and policy-makers determine whether PA promotion in youth constitutes effective allocation of public health resources and a viable means of reducing the global burden of common mental disorders and suboptimal wellbeing across the lifespan. This systematic review synthesised evidence for childhood/adolescent PA as a predictor of future anxiety, depression and wellbeing indicators (PROSPERO: CRD42021242555). Systematic searches of CINAHL, Medline, PsycInfo, and Scopus (conducted 27th October 2022) returned 12,703 articles with 98 retained. Included: prospective, quantitative, longitudinal designs; PA measured ages 5-17 years; anxiety, depression, and/or wellbeing indicators measured at least 12 months later; generally healthy populations. Excluded: severe mental illnesses. Risk of bias and quality of evidence were assessed following the GRADE framework. Effect sizes from moderate- and high-quality studies are discussed narratively. Studies are grouped by mental health outcome, PA type, domain, and whether participants adhered to current World Health Organisation PA guidelines. PA was negatively associated with depression in 41/67 studies (61.2%); anxiety in 20/35 studies (57.1%); and positively associated with wellbeing in 25/39 studies (64.1%). Effect sizes for all outcomes were small and evidence quality low across all timeframes. Team sports were the most consistently predictive type of PA. Whether domain-specific activities or guideline (non)adherence have differential effects remains unclear. Heterogeneity was attributed to the vastness of associations tested and psychometric measures used. Current literature offers low-quality partial evidence that childhood/adolescent PA has small beneficial effects for prospective anxiety, depression and wellbeing at least 12 months later.