Secondary data analysis was conducted using self-reported measures of physical activity, self-esteem, depressive symptoms, and socio-demographic information completed by a sample of girls (n聽=聽2109) and boys (n聽=聽2095) during early (Mage聽=聽14.7) and late (Mage聽=聽16.2) adolescence selected from the National Longitudinal Study of Adolescent Health. Using the method suggested by , mediation was tested separately for boys and girls during early and late adolescence.
During early adolescence, self-esteem fully mediated the association between physical activity and depressive symptoms for adolescent boys only. Full mediation was obtained for both boys and girls during late adolescence.
In early and late adolescent boys, and only late adolescent girls, associations between physical activity and depressive symptoms were no longer significant once self-esteem was statistically controlled for. The study has important implications for depression prevention initiatives including the inclusion of physical activity components that are effectively structured to reliably enhance self-esteem, especially among early adolescents.