Millions of Americans suffer from clinical depression each year. Most depressed patients first seek treatment from their primary care providers. Generally, depressed patients treated in primary care settings receive pharmacologic therapy alone. There is evidence to suggest that the addition of cognitive-behavioral therapies, specifically exercise, can improve treatment outcomes for many patients. Exercise is a behavioral intervention that has shown great promise in alleviating symptoms of depression. The current review discusses the growing body of research examining the exercise-depression relationship that supports the efficacy of exercise as an adjunct treatment. Databases searched were Medline, PsycLit, PubMed, and SportsDiscus from the years 1996 through 2003. Terms used in the search were clinical depression, depression, exercise, and physical activity. Further, because primary care physicians deliver important mental health services to the majority of depressed patients, several specific recommendations are made regarding counseling these patients on the adoption and maintenance of exercise programs.
Many studies have examined the efficacy of exercise to reduce symptoms of depression, and the overwhelming majority of these studies have described a positive benefit associated with exercise involvement. For example, 30 community-dwelling moderately depressed men and women were randomly assigned to an exercise intervention group, a social support group, or a wait-list control group. The exercise intervention consisted of walking 20 to 40 minutes 3 times per week for 6 weeks. The authors reported that the exercise program alleviated overall symptoms of depression and was more effective than the other 2 groups in reducing somatic symptoms of depression
Research also suggests that the benefits of exercise involvement may be long lasting. Depressed adults who took part in a fitness program displayed significantly greater improvements in depression, anxiety, and self-concept than those in a control group after 12 weeks of training (BDI reduction of 5.1 [fitness program] vs. 0.9 [control], p < .001). The exercise participants also maintained many of these gains through the 12-month follow-up period.
While the research is consistent and points to a relationship between exercise and depression, the mechanisms underlying the antidepressant effects of exercise remain unclear. Several credible physiologic and psychological mechanisms have been described, such as the thermogenic hypothesis, the endorphin hypothesis, the monoamine hypothesis, the distraction hypothesis, and the enhancement of self-efficacy. However, there is little research evidence to either support or refute most of these theories.
With increasing evidence to support the efficacy of this behavioral intervention in reducing symptoms of depression, we encourage primary care providers to recommend exercise involvement to their depressed patients. However, if physicians are to recommend physical activity as adjunct therapy, there are a few practical considerations that should be addressed. First, patients with depression are typically sedentary and may lack motivation to begin an exercise program. The American College of Sports Medicine has made the recommendation that all adults should exercise at least 30 minutes per day, on all or most (5) days per week, at a moderate-vigorous intensity. Such a recommendation is likely to be overwhelming to someone who is currently sedentary and depressed. Based on the meta-analytic findings in this area, an exercise prescription of 20 minutes per day, 3 times per week, at a moderate intensity is sufficient to significantly reduce symptoms of depression. Therefore, we suggest that physicians begin with this prescription as an initial recommendation.
The mechanisms underlying the antidepressant effects of exercise remain in debate; however, the efficacy of exercise in decreasing symptoms of depression has been well established. Data regarding the positive mood effects of exercise involvement, independent of fitness gains, suggest that the focus should be on frequency of exercise rather than duration or intensity until the behavior has been well established. The addition of self-monitoring techniques may increase awareness of the proximal benefits of exercise involvement, which is generally reinforcing to the patient.
Physician advice is likely to go a long way toward providing motivation and support for exercise. Follow-up contact may also be important during exercise adoption. While this follow-up may present a time challenge to the provider, less time-consuming interactions such as brief telephone contact and automated telephone contact have been shown to increase adherence to exercise programs. Finally, it is interesting to note that while depression may be an additional risk factor for exercise noncompliance, reported drop-out rates among depressed patients are not too different from those in the general population.