Naturally occurring changes in physical activity are inversely related to depressive symptoms during early adolescence

Objective: We examined the relationship between naturally occurring changes in physical activity and depressive symptoms across a 2-year period among adolescent boys and girls. Methods: Participants (N = 4594) reported their frequency of physical activity outside of school and completed the Center for Epidemiological Studies Depression scale in the Fall of 1998 (beginning of 7(th) grade; baseline data), Spring of 1999 (end of 7(th) grade; interim data), and Spring of 2000 (end of 8(th) grade; follow-up data). Results: Latent growth modeling indicated that a I SD unit change in the frequency of leisure-time physical activity was inversely related to a .25 SD unit change in depressive symptoms. This relationship was attenuated but remained statistically significant when simultaneously controlling for the confounding variables of sex, socioeconomic status, smoking, alcohol consumption, and the value participants placed on their health, appearance, and achievement. Conclusions: Naturally occurring changes in physical activity were negatively related with changes in depressive symptoms. The results encourage randomized controlled trials to experimentally determine whether an increase in physical activity reduces depression risk among adolescent boys and girls.