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Small amount of exercise may protect against depression

Recent findings indicated as little as 1 hour of physical activity each week protected against future depression but not anxiety.

“We’ve known for some time that exercise has a role to play in treating symptoms of depression, but this is the first time we have been able to quantify the preventative potential of physical activity in terms of reducing future levels of depression,” Samuel B. Harvey, FRANZCP, PhD, of King’s College London, said in a press release.

To determine protective effects of exercise on anxiety and depression, Harvey and colleagues followed a “healthy” cohort of 33,908 adults with no symptoms of common mental disorders or limiting physical health conditions for 11 years.

Regular leisure-time exercise was associated with decreased incidence of future depression, with the majority of this protective effect occurring at low levels of exercise, regardless of intensity. Researchers reported no association between leisure-time exercise and anxiety.

After adjusting for confounders, the population attributable fraction suggested that 12% of future depression cases could be prevented if participants engaged in at least 1 hour of physical activity each week, assuming a causal relationship.

Social and physical health benefits of exercise explained a small proportion of the protective effect, according to results.

Biological mechanisms, such as changes in parasympathetic vagal tone, did not influence the protective effect of exercise on depression.

“Most of the mental health benefits of exercise are realized within the first hour undertaken each week,” Harvey said in the release. “With sedentary lifestyles becoming the norm worldwide and rates of depression growing, these results are particularly pertinent as they highlight that even small lifestyle changes can reap significant mental health benefits.” – by Amanda Oldt

Disclosures: Harvey reports receiving funding from NSW Health and a grant from the Institute of Social Psychiatry. Please see the study for all other authors’ relevant financial disclosures.