A landmark study led by the Black Dog Institute has revealed that regular exercise of any intensity can prevent future depression — and just one hour can help. Published in the American Journal of Psychiatry, the results show even small amounts of exercise can protect against depression, with mental health benefits seen regardless of age or gender. In the largest and most extensive study of its kind, the analysis involved 33,908 Norwegian adults who had their levels of exercise and symptoms of depression and anxiety monitored over 11 years. The international research team found that 12 percent of cases of depression could have been prevented if participants undertook just one hour of physical activity each week.

The findings follow the Black Dog Institute’s recent Exercise Your Mood campaign, which ran throughout September and encouraged Australians to improve their physical and mental wellbeing through exercise. Researchers used data from the Health Study of Nord-Trøndelag County (HUNT study) — one of the largest and most comprehensive population-based health surveys ever undertaken — which was conducted between January 1984 and June 1997. A healthy cohort of participants was asked at baseline to report the frequency of exercise they participated in and at what intensity: without becoming breathless or sweating, becoming breathless and sweating, or exhausting themselves. At follow-up stage, they completed a self-report questionnaire (the Hospital Anxiety and Depression Scale) to indicate any emerging anxiety or depression. The research team also accounted for variables which might impact the association between exercise and common mental illness. These include socio-economic and demographic factors, substance use, body mass index, new onset physical illness and perceived social support. Results showed that people who reported doing no exercise at all at baseline had a 44 percent increased chance of developing depression compared to those who were exercising one to two hours a week.