Objectives: Considering the growing need for using a variety of new non pharmacological methods in treating depression, this quasi experimental study was conducted to investigate the effect of aerobic indoor exercise in a gym compared with green exercise in an outdoor green environment of an urban park on triple categories of affective, cognitive and somatic symptoms of depression and to examine its psychological mediators of perceived stress and coping strategies. Methods: Forty six female outpatients with major depressive disorder were divided into 3 conditions of indoor exercise + routine pharmacotherapy (n = 15), green exercise + routine pharmacotherapy (n =15), and a routine pharmacotherapy alone as the control group (n = 16). The exercise used for both indoor and green exercise conditions consisted of 36 one hour sessions (three times per week) with an intensity of 50% - 70% of the maximum heart rate. The participants completed the pre- and post-intervention depression, stress and coping questionnaires including Beck Depression Inventory-II, Perceived Stress Scale and Coping Inventory for Stressful Situations. 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 perceived stress in both exercise groups compared with the control group, but there was no significant difference between two exercise groups. With respect to the use of problem-focused, emotion-focused and avoidant-focused coping methods, there was no significant difference between post-intervention scores of all groups. Conclusion: In the clinical settings, both of the indoor exercise and green exercise programs can help to further improvement in all three categories of affective, cognitive and somatic symptoms of depression as an adjunct (or independent) treatment to the same degree, especially mediated by reducing the amount of perceived stress, but not through any significant changes in cognitive-behavioral coping strategies.

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