“We found big, significant results,” said Andreas Heissel, an exercise scientist at the University of Potsdam in Germany, who led the study.
For people struggling with depression, he said, the findings show that you don’t need to run marathons or otherwise exercise vigorously to benefit. “Something is better than nothing,” Heissel said.
The effects were robust enough that the study authors hope the finding will be an impetus for making exercise a standard, prescribed therapy for depression.
That approach would represent a remarkable shift. The American Psychological Association’s clinical practice guidelines, updated in 2019, recommend seven types of psychotherapy and several antidepressants for the treatment of depression, but make no mention of exercise. The World Health Organization promotes physical activity for mental health as an adjunct to traditional treatments – not on its own.
But the study authors are confident. “We expect this review to lead to updated guidelines and recommendations for exercise as a first-line treatment option,” Heissel said.
Some depression experts are hesitant. “I think that exercise should are prescribed to anyone with depression,” said Murray B. Stein, a professor and vice chairman for clinical research at the University of California San Diego Department of Psychiatry, who was not involved in the study. “However, I still feel that the evidence is weak that exercise is considered a first-line treatment for depression.”
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 only 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 condition and randomly assigning them to the intervention – in this case exercise – or a control group and closely monitoring what happens.
Because these experiments are often complicated and expensive, previous studies of using exercise for depression have been small, typically involving only a few dozen people, making it difficult to draw definitive 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 collected every recent experiment using physical activity as depression therapy. They ended up with data from 41 studies on 2,265 volunteers, representing the largest sample to date on the subject.
The studies’ exercise programs included walking, running, and strength training. Some consisted of group classes, others solo workouts, some supervised, some not. But all people with depression characterized themselves by getting up and moving more.
Exercise of any kind treats depression
Pooled, the effects were powerful. Overall, people with depression who exercised in any way improved their symptoms by nearly five points using one widely recognized diagnostic scale, and by about 6.5 points using another. For both scales, an improvement of three points or more is considered clinically meaningful, the study authors write.
In practical terms, 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 those found in recent studies of psychotherapy and drug treatment of depression, said Felipe Schuch, a professor who researches exercise and mental health at the University of Santa Maria in Brazil and senior author of the study.
In general, the effects were best when people exercised moderately, for example by walking, although more vigorous exercise, including running, cycling and strength training, was almost as effective, and even light activities such as gardening relieved symptoms.
Overall, the study “shows that exercise is a further effective standalone treatment option” for depression, Heissel said.
The study did not look at how exercise might improve mental health. In previous research on depressed mice, as well as humans, increased levels in the brain and bloodstream of several biochemicals known to be involved in mood enhancement. It also often increased people’s self-reliance, the feeling that you are capable of more than you ever thought, a change usually associated with better mental health.
But the precise 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, some people’s depression disappeared, while others’ symptoms remained stubbornly unchanged. (Similar differences are also seen in nearly all studies of psychotherapy and drug treatments.)
What is the right dose of exercise?
“To formulate exercise as a prescription drug, we still need more research to understand the optimal type, frequency and amount of exercise for different people,” said Karmel Choi, a clinical psychologist and assistant professor at the Center for Precision Psychiatry from Harvard Medical. School and the Massachusetts General Hospital. She has studied exercise and depression, but was not involved in the new review.
“Depression is not one size fits all,” she said, “so treatment should always be tailored to the individual.”
Murray Stein of UCSD agrees. “Exercise has so many health benefits that it should be prescribed for virtually everything that ails humanity,” he said.
But he’s still not convinced 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.
More research is certainly needed. “We don’t know enough about dose, intensity and type of exercise,” Heissel said, whether early improvements related to activity persist. Future studies should address these questions and directly compare exercise with psychotherapy and antidepressants, he said.
Perhaps most importantly, researchers and clinicians need to recognize how daunting exercise can be for someone who is depressed.
“A lot of people struggle to get active,” Heissel said. “So the first step is trying to understand which practice is most likely to be accepted and generate pleasure.”
If you or someone you care about is feeling depressed, Heissel said, talk to a doctor about exercise, either as initial therapy or as an adjunct to other treatments. Experiment with different activities until you settle on one you enjoy.
“The best exercise is the one that is actually done,” Heissel said, “and that means exercise that is rewarding or pleasurable.”
Do you have a fitness question? E-mail YourMove@washpost.com and maybe we’ll answer your question in a future column.