Objectives: Considering the growing need for encouraging greater use of a variety of non-pharmacological methods in treating depression, the aim of this quasi experimental study was to examine the effect of aerobic exercise on triple categories of affective, cognitive and somatic symptoms of depression and to investigate its psychological mediators of perceived stress and coping strategies.Methods: Forty five female outpatients with major depressive disorder were divided into three groups including exercise + usual pharmacotherapy (n = 15), psychotherapy + usual pharmacotherapy (n = 14) and a control group receiving only usual pharmacotherapy (n = 16). The exercise used was included 36 one hour session (three sessions per week) with a low to medium intensity of 50% to 70% of the maximal heart rate. The psychotherapy used in this study was the behavioral activation treatment for depression revised. The Persian version of Beck Depression Inventory-II, Perceived Stress Scale and Coping Inventory for Stressful Situations were applied to assess the pre- and post-intervention depression, perceived stress, and coping strategies.Results: The findings indicated a significant decrease in the post-intervention scores of all three categories of affective, cognitive and somatic symptoms of depression and the perceived stress level in the adjunctive exercise and psychotherapy conditions compared with the control condition (p = 0.001), but there was no significant difference between the exercise and psychotherapy groups. In addition, no significant improvement was observed regarding the problem-centered, emotion-centered and avoidant-centered stress coping methods in the post-intervention scores of the exercise group compared with the control group. Conclusion: An adjunctive aerobic exercise program can be as effective as adding the psychotherapy to usual pharmacotherapy in further improvement in all three categories of depression symptoms especially mediated by reducing the amount of perceived stress, but not through any significant change in cognitive-behavioral coping strategies.

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