by “We found big, significant results,” said Andreas Heissel, a sports scientist at the University of Potsdam in Germany who led the study.
For people struggling with depression, the results show they don’t need to run marathons or otherwise strenuous exercise to benefit. “Something is better than nothing,” said Heissel.
The effects were strong enough that the study authors hope the finding will encourage making exercise a standard, prescribed therapy for depression.
This approach would represent a remarkable shift. The 2019 updated clinical practice guidelines from the American Psychological Association recommend seven types of psychotherapy and several antidepressant drugs to treat depression, but make no mention of physical activity. The World Health Organization promotes exercise for mental health as an adjunct to traditional treatments – not alone.
But the authors of the study are confident. “We expect this review to result in updated guidelines and recommendations for exercise as a first-line treatment option,” Heissel said.
Some depression experts hesitate. “I think this exercise should prescribed to anyone with depression,” said Murray B. Stein, professor and vice chair of clinical research in the Department of Psychiatry at the University of California, San Diego, who was not involved in the study. “However, I believe the evidence that exercise is considered a first-line treatment for depression is weak.”
The research behind exercise and depression
Scientists and clinicians have known for some time that exercise protects us from developing depression. In large-scale epidemiological studies, active men and women are much less likely to become depressed than sedentary people, even if they exercise for just a few minutes a day or a few days a week.
But it’s more difficult to test exercise as a treatment for existing depression. You have to study it, like any drug, by recruiting people with the disease and randomly assigning them to the intervention — in this case, exercises — or to a control group and closely monitoring what happens.
Because these experiments are usually complicated and expensive, previous studies of exercise for depression have been small, typically involving only a few dozen people, making it difficult to draw firm conclusions about whether and how well exercise treats depression.
In the study, published in February in the British Journal of Sports Medicine, a global group of researchers compiled all recent experiments using physical activity as a therapy for depression. They landed on data from 41 studies involving 2,265 volunteers, which is the largest sample on the subject to date.
The studies’ exercise programs included walking, running, and strength training. Some consisted of group lessons, others individual training, some supervised, some not. But all showed people with depression getting up and moving more.
Exercise of any kind treats depression
Taken together, the effects were strong. Overall, people with depression who exercised in some way improved their symptoms by almost five points on one commonly accepted diagnostic scale and by about 6.5 points on another. For both scales, an improvement of three points or more is considered clinically meaningful, the authors of the study write.
In practice, these numbers suggest that for every two people with depression who start exercising, one of them should experience “a large reduction in depressive symptoms,” Heissel said.
Those statistics represent “slightly better” results than recent studies of psychotherapy and drug treatment for depression, said Felipe Schuch, a professor of exercise and mental health at the University of Santa Maria in Brazil and the study’s senior author.
In general, effects were best when people exercised moderately, e.g. B. walking, although more vigorous exercise, including running, cycling, and strength training, was almost as effective, and even light activity like gardening reduced symptoms.
Overall, “the study shows that exercise is another effective treatment option in its own right,” says Heissel.
The study did not examine how exercise might improve mental health. Previous studies in depressed mice, as well as in humans, found increased levels of various biochemicals in the brain and bloodstream known to be involved in mood elevation during exercise. It has also often increased people’s self-efficacy, meaning a feeling that you are capable of more than you once believed, a change usually associated with better mental health.
However, the exact mechanisms by which body movements alter brain functions to improve mood remain unclear, as do differences in people’s responses. In every study the researchers included, depression subsided in some people, while symptoms remained stubbornly unchanged in others. (Similar differences can also be observed in almost all studies on psychotherapy and drug treatments.)
What is the right dose of exercise?
“To formulate exercise as a prescription for medication, we need more research to understand the optimal type, frequency, and amount of exercise for different people,” said Karmel Choi, clinical psychologist and assistant professor at Harvard Medical School’s Center for Precision Psychiatry and Massachusetts General Hospital. She has studied exercise and depression but was not involved in the new review.
“Depression doesn’t come in one size fits all,” she said, “so treatment should always be tailored to the individual.”
UCSD’s Murray Stein agrees. “Exercise has so many health benefits that it should be prescribed for virtually everything that ails mankind,” he said.
However, he is not convinced that it should be a primary treatment for depression. “I would prescribe exercise as a complementary approach for patients with moderate to severe depression,” he said, with psychotherapy or an antidepressant as the main therapy.
Certainly more research is needed. “We don’t know enough about dose, intensity and type of exercise,” Heissel said, or whether early improvements related to activity persist. Future studies should address these questions and compare exercise directly to psychotherapy and antidepressants, he said.
Perhaps most importantly, researchers and clinicians need to recognize how daunting exercise can be for someone who is depressed.
“Many people find it difficult to become active,” said Heissel. “So the first step is to understand which exercise is more acceptable and fun.”
If you or someone you care about is feeling depressed, Heissel said, talk to a doctor about exercise, either as initial therapy or in addition to other treatments. Experiment with different activities until you decide on one you enjoy.
“The best exercise is that which is actually done,” Heissel said, “and that means exercise that is rewarding or enjoyable.”
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