Abstract
Adolescence and emerging adulthood represent critical life stages for the onset of internalizing problems and declines in physical activity. To date, however, no systematic reviews have examined the relationship between physical activity and internalizing symptoms during the transition into emerging adulthood. The purpose of this study was to conduct a systematic review of prospective/longitudinal studies investigating the associations between physical activity and depressive symptoms, symptoms of anxiety, and stress across this life transition. A total of 3956 studies were screened and selected if it included a: prospective/longitudinal design; mean sample age between 15 and 25 years; non-clinical sample; and physical activity measure or intervention with at least one assessment of internalizing symptom. A total of 19 studies were included, with 16 being intervention trials, and three using an observational design. Eleven of 13 intervention studies found a significant inverse relationship between physical activity and depressive symptoms; however, only five of 11 and four of seven studies found a significant physical activity effect on symptoms of anxiety and stress, respectively. Overall, results reinforce the benefits of physical activity for reducing depressive symptoms but also highlight a paucity of longitudinal research examining physical activity and internalizing symptoms during this broader transitory period.