The causative factors of exercise-induced mood change remain unclear. The objective of a study by Annesi was to clarify the relationship of exercise with change in vigor (energy level). Obese women in an exercise support treatment (n = 122) or control condition (n = 70) were assessed on vigor, exercise barriers, self-efficacy, and physical self-concept at baseline and at month six. Exercise session attendance was also assessed in the treatment group. The relationship between exercise attendance and vigor change was tested. Multiple regression analyses tested whether exercise barriers, self-efficacy, and physical self-concept scores both at baseline and change predicted change in vigor over six months. Vigor, exercise barriers, self-efficacy, and physical self-concept were significantly improved in the treatment group only. Exercise session attendance was not significantly related to change in vigor. Multiple regression analyses indicated that exercise barriers, self-efficacy and physical self-concept scores, both at baseline and change from baseline to month six, explained a significant portion of the variance in changes in vigor. In post hoc analyses, entry of depressed mood (indicated by a cut point on depression score) into the regression equations increased the variance accounted for to Radj = 0.15 and 0.25, respectively.

WHAT THE STUDY MAY MEAN TO YOU AS A HEALTH CARE PROVIDER: Annesi suggested the findings supported behavioral explanations of the exercise-mood change relationship emanating from social cognitive and self-efficacy theory. The use of manageable amounts of exercise early in the weight loss intervention process was suggested.

WHAT THE STUDY MAY MEAN TO YOU AS A PATIENT: No matter what tasks you are asked to perform if you have a chronic illness, you need to develop self-efficacy that you can perform these tasks over time and across settings. That was nicely demonstrated in the study.

JJ Annesi. Dose-Response and Self-Efficacy Effects of an Exercise Program on Vigor Change in Obese Women. American Journal of Medical Science, December 16, 2009.