Exercise may relieve depression as effectively as antidepressants

Many of us experience mood boost after workoutand now an updated review has shown just how powerful it can be. Even mild exercise, such as walking or gardening, can relieve symptoms of depression as effectively as talk therapy or antidepressants.

“This further confirms that exercise is an option for people with depressive symptoms and confirms that exercise can be as effective as psychotherapy and antidepressants,” says Andrew Clegg at Lancashire University in the UK.

Previous studies including key review published by the Cochrane Library in 2013found that exercise can relieve symptoms of depression as effectively as standard treatments, including antidepressants and cognitive behavioral therapy (CBT), where the therapist helps people change their thoughts, feelings and behavior.

This has led health organizations to recommend regular exercise to combat depression. For example, the UK's National Institute for Health and Care Excellence (NICE) recommends weekly aerobic exercise such as jogging for 10 weeks – usually in combination with other treatments, which on their own may not benefit everyone.

But dozens more studies have been conducted since the 2013 review, so the Cochrane Library is publishing an updated review. “This latest review [almost] doubles the evidence base of the previous one,” says Clegg, one of the review authors.

Clegg and colleagues analyzed the results of 69 randomized controlled trials involving nearly 5,000 adults who were either clinically diagnosed with mild, moderate or severe depression, or who recorded a score on a depression symptom scale that is generally considered to be an indicator of the condition. First, the researchers focused on 57 studies in which participants were randomly assigned to either a group that exercised regularly or a control group that was not offered any treatment or was placed on a waiting list for treatment.

Trials varied in design, but typically asked participants to exercise weekly over several weeks or months, with exercise styles ranging from low- or moderate-intensity activities such as gardening and brisk walking, respectively, to vigorous activities such as sprinting or playing soccer. “Trials involving yoga or stretching were not included because they often involve meditation and breathwork, and the team wanted to focus more on the effects of physical activity alone,” says Clegg.

The team found that exercise moderately reduced the severity of depressive symptoms, such as frequent feelings of sadness or loss of interest in other people.

“They found a clinically significant change – people will feel the difference,” says Brandon Stubbs at King's College London, which was not involved in the review.

The team then focused on 10 of the 59 studies that compared exercise with CBT, and five studies in which some participants took antidepressants but did not include an exercise component at all. This showed that, on average, regular exercise worked just as well as the other two treatments. “There was no difference between them,” says Emily Hurd at University College London, who was not involved in the study.

Taking a closer look, the team found that light-to-moderate exercise seemed more effective than vigorous exercise, perhaps simply because it was easier to do, Stubbs says. “If you start training hard, people quit training and stop exercising, and that may be why you don't see the same effects.” [as with less strenuous activity]”, he says.

Exactly how exercise provides benefits is unclear, but it likely works in multiple ways, Stubbs says. Group exercise, for example, can improve people's social well-being, and learning new skills can improve self-esteem, both of which can help people make positive changes in their lives, he says.

Research has also shown that during exercise, chemicals released by muscles called myokines help relieve inflammation This is thought to contribute to symptoms of depression, Stubbs says. One particular myokine, called brain-derived neurotrophic factor, also stimulates the growth of new brain cells, which can help the brain rewire itself and break free of negative thought patterns, Stubbs says. Consistent with this idea, Clegg and his colleagues found that resistance training, which results in greater myokine release than other forms of exercise, was more effective than aerobic exercise alone, Stubbs says.

Taken together, the findings support guidelines that recommend exercise for the treatment of depression. However, in all of the studies reviewed, participants knew whether they were in the treatment group or the control group. This raises the possibility that at least some of the improvements associated with exercise may be due to a placebo effect, where people's expectations lead to improved symptoms, Hird says. What's more, she said, most studies involved relatively small numbers of participants, making their conclusions less reliable.

Larger studies are needed to better understand what types of exercise, including those not included in the review, are most beneficial, for whom and why, Hird says. “At the moment we don’t really understand who will benefit from what,” she says. For example, people with more severe types of depression may find it harder to go out and exercise, so they may benefit from CBT or antidepressants – both of which the review found are as effective as exercise for treating depression. It's also possible that someone who is able to exercise may benefit more from one type of exercise over another, depending on the underlying cause of their depression, she says.

However, the evidence available to date consistently shows that exercise has benefits for both mental and physical health, Stubbs says. “Whether it’s running, the gym, Pilates, yoga, it all has different beneficial effects. The most important thing is to give people the opportunity to do what they like,” he says.