In Exercise and the Prevention of Depression, a study of 33,908 adults in Norway by the University of New South Wales, researchers found that one hour of exercise a week reduced depression in 12 percent of the subjects.

The purpose of the study was to address whether exercise protects against new-onset depression and anxiety and if so, the intensity and amount of exercise required. They concluded that regular leisure-time exercise of any intensity provides protection against future depression, but not anxiety. Thus, increasing the population of people exercising may provide public mental health benefits and prevent a substantial number of new cases of depression.