The antidepressant effects of physical activity: Mediating self-esteem and self-efficacy mechanisms

The investigation of physiological mechanisms responsible for the antidepressant effects of physical activity has been hampered by the failure to control adequately for psychosocial effects and the failure to control for participant expectancies concerning exercise outcomes. This retrospective, cross-sectional study of 188 male and 193 female undergraduates used structural regression modeling to assess the adequacy of the revised version of the Exercise and Self-Esteem Model (EXSEM; Sonstroem, R. J., Harlow, L. L., Josephs, L. (1994). Exercise and self-esteem: Validity of model expansion and exercise associations. Journal of Sport Exercise Psychology, 16, 29-42), a modified version of that model, and an Exercise Self-Esteem and Efficacy Model (EXSEEM). Direct effects of physical activity on depressive symptomatology (SCL90R-D; Derogatis, L. R. (1994). SCL-90-R: Administration, scoring, and procedures manual - II for the revised version (2nd ed.). Towson, MD: Clinical Psychometric Research) were obtained using a disguised-measures procedure to minimize expectancy artifacts. However, direct activity effects were negligible when activity-based esteem and efficacy effects were added to the structural regression model. Eliminating direct physical-activity effects did not reduce the quality of fit of the EXSEEM model nor the variance accounted for in SCL90R-D scores. Direct effects of physical-self esteem, but not global self-esteem, on SCL90R-D scores were found for females. Conversely, direct effects of global self-esteem, but not physical self-esteem, on SCL90R-D scores were found for males. Supplementary analyses indicated that scheduling efficacy for aerobic exercise had a direct effect on SCL90R-D scores for males and females, but task efficacy had direct effects only on perceived endurance for both males and females. These findings are consistent with the proposed EXSEEM model and imply that independent self-esteem and self-efficacy mechanisms are sufficient to account for the antidepressant effects of physical activity. Implications for enhancing the antidepressant benefits of physical activity are considered.