Research regarding the protective effects of early physical activity on depression has yielded conflicting results.
Our objective was to synthesize observational studies examining the association of physical activity in childhood and adolescence with depression.
Studies (from 2005 to 2015) were identified by using a comprehensive search strategy.
The included studies measured physical activity in childhood or adolescence and examined its association with depression.
Data were extracted by 2 independent coders. Estimates were examined by using random-effects meta-analysis.
Fifty independent samples (89 894 participants) were included, and the mean effect size was significant (r = –0.14; 95% confidence interval [CI] = –0.19 to –0.10). Moderator analyses revealed stronger effect sizes in studies with cross-sectional versus longitudinal designs (k = 36, r = –0.17; 95% CI = –0.23 to –0.10 vs k = 14, r = –0.07; 95% CI = –0.10 to –0.04); using depression self-report versus interview (k = 46, r = –0.15; 95% CI = –0.20 to –0.10 vs k = 4, r = –0.05; 95% CI = –0.09 to –0.01); using validated versus nonvalidated physical activity measures (k = 29, r = –0.18; 95% CI = –0.26 to –0.09 vs k = 21, r = –0.08; 95% CI = –0.11 to –0.05); and using measures of frequency and intensity of physical activity versus intensity alone (k = 27, r = –0.17; 95% CI = –0.25 to –0.09 vs k = 7, r = –0.05; 95% CI = –0.09 to –0.01).
Limitations included a lack of standardized measures of physical activity; use of self-report of depression in majority of studies; and a small number of longitudinal studies.
Physical activity is associated with decreased concurrent depressive symptoms; the association with future depressive symptoms is weak.