A meta-analysis published in the journal Current Sports Medicine Reports analyzed pooled data on 49 prospective studies including nearly 267,000 participants. This meta-analysis found physical activity reduces the odds of developing depression by 17 percent, after adjustment for other factors. The protective effect was significant in all countries and across patient subgroups.

Physical activity is also an effective treatment for depression – some studies have shown that a single exercise session can reduce symptoms in patients with major depressive disorder. The authors performed another meta-analysis of 25 randomized trials in which nearly 1,500 people with depression were assigned to exercise training or comparison groups. The results suggested a “very large and significant antidepressant effect” of exercise.

Another study, by Blumenthal, et al, published in The Archives of Internal Medicine, found that a brisk 30-minute walk or jog around the track three times a week may be just as effective in relieving the symptoms of major depression as the standard treatment of anti-depressant medications, according to the results of a Duke University Medical Center study.  Read more here.