Exercise can form part of an effective treatment for depression
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Many of us experience a mood-boost after exercise, and now an updated review has revealed just how powerful it can be. Even light exercise, like walking or gardening, may ease the symptoms of depression as effectively as talking therapies or antidepressants.
“It really reiterates that exercise provides an option for people who have depressive symptoms, and confirms that exercise may be as effective as psychotherapy and antidepressants,” says Andrew Clegg at the University of Lancashire in the UK.
Prior studies, including a key review published by the Cochrane Library in 2013, have found that exercise may ease symptoms of depression as effectively as standard therapies, including antidepressants and cognitive behavioural therapy (CBT), where a therapist helps people change their thoughts, feelings and behaviour.
This has prompted healthcare organisations to recommend regular exercise for managing depression. For instance, 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 therapies, which, on their own, don’t benefit everyone.
But since the 2013 review, dozens more trials have been conducted, so the Cochrane Library is now publishing an updated review. “This latest review [almost] doubles the evidence base that was in the previous one,” says Clegg, one of the review authors.
Clegg and his colleagues analysed results from 69 randomised controlled trials involving nearly 5000 adults who were either clinically diagnosed with mild, moderate or severe depression, or who register a score on a depression symptom scale that is generally considered indicative of the condition. First, the researchers focused on 57 of the trials in which participants were randomly assigned either to a group that exercised regularly or to a control group that was offered no treatment or that was placed on a waiting list for treatment.
The trials varied in design, but they usually involved asking participants to exercise on a weekly basis for a few weeks to months, with the style of exercise ranging from low- or moderate-intensity activities such as gardening and brisk walking, respectively, to vigorous activities such as sprinting or playing football. Trials involving yoga or stretching weren’t included as these 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 seems to moderately reduce the severity of depressive symptoms, such as often feeling sad, or losing interest in other people.
“They found a clinically meaningful change – people will feel the difference from that,” says Brendon Stubbs at King’s College London, who wasn’t involved in the review.
Next, the team focused on 10 trials among the 59 that compared exercise to CBT, and five trials in which some participants took antidepressants but there was no exercise component at all. This revealed that, on average, regular exercise worked as well as the two other therapies. “There wasn’t a difference between them,” says Emily Hird at University College London, who wasn’t involved in the study.
By taking a closer look, the team found that light and moderate exercise seem to be more effective than vigorous kinds, which may simply be because they are easier to stick with, says Stubbs. “If you start going hard, then people drop out and stop exercising, and that could be why you don’t see the same effects [as with less strenuous activity],” he says.
How exactly exercise brings its benefits is unclear, but it probably works in several ways, says Stubbs. Group exercise, for instance, can boost people’s social well-being, while learning a new skill can improve self-esteem, both of which can help people to make positive changes in their lives, he says.
Studies have also shown that, during exercise, chemicals released from muscles, called myokines, help to mop up inflammation that is thought to contribute to depressive symptoms, says Stubbs. One particular myokine, called brain-derived neurotrophic factor, also spurs the growth of new brain cells, which could help the brain to rewire itself and break free of negative thought patterns, says Stubbs. In line with this idea, Clegg and his colleagues found that resistance training – which leads to a greater release of myokines versus other forms of exercise – was more effective than aerobic exercise alone, says Stubbs.
Together, the findings support guidelines that recommend exercise for treating depression. However, in all the studies reviewed, participants knew whether they were in a treatment group or control group. This raises the possibility that at least some of the exercise-related improvements could be down to the placebo effect, where people’s expectations lead to an improvement in symptoms, says Hird. What’s more, most of the studies involved relatively small numbers of participants, which makes their conclusions less reliable, she says.
Larger studies are needed to better understand which types of exercise – including those not included in the review – are most beneficial, for whom, and why that is, says Hird. “We don’t really understand who is going to benefit from what at the moment,” she says. For instance, people with more severe kinds of depression may find it harder to get out and exercise, so they may benefit from CBT or antidepressants – both of which the review confirms are as effective as exercise for treating depression. It’s also possible that someone who is in a position to exercise may benefit more from a specific kind of exercise over another depending on the underlying cause of their depression, she says.
Still, the evidence to date consistently shows that exercise brings both mental and physical health benefits, says Stubbs. “Whether it be running, gym, pilates, yoga, these all have various beneficial effects – the most important thing is empowering people to do something they enjoy,” he says.
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