Key messages
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Exercise may be moderately effective compared to no therapy for reducing symptoms of depression.
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The evidence suggests there is little to no difference in the reduction of symptoms of depression provided by exercise compared to those provided by psychological therapies or antidepressants, but this conclusion is based on a few small studies.
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The studies measured the outcomes at the end of treatment, and most of them did not follow up participants in the longer term.
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Unwanted effects from exercise were not common, affecting only a small number of participants.
What is depression?
Depression is a common illness, affecting over 100 million people worldwide. Depression can have a significant impact on people’s physical health, as well as reducing their quality of life.
How is depression treated?
Research has shown that both pharmacological treatment (antidepressant medication) and psychological therapies (i.e. talking treatments aimed at changing people's thoughts, emotions, or behaviours) can be effective for treating depression. However, many people prefer to try alternative approaches. Some health guidelines suggest that exercise could be used as an alternative treatment.
What did we want to find out?
We wanted to find out if exercise reduces the symptoms of depression and improves quality of life in people with depression, and we wanted to find out how exercise compares to medication, psychological therapy and alternative treatments. We also wanted to find out if exercise is associated with any unwanted effects and if it provides good value for money. This review updates one last published in 2013.
What did we do?
We searched for randomised controlled trials (RCTs) (i.e. studies where people are assigned to a treatment group randomly) that assessed the effectiveness of exercise for treating depression in adults (18 years of age and over). Studies had to compare exercise with either another active treatment (e.g. medication or psychological therapy) or an inactive intervention (e.g. no treatment, being put on a waiting list, or being given a placebo treatment (i.e. an inactive treatment that seems like a real treatment)). All studies had to include adults with a diagnosis of depression, and the physical activity carried out had to fit our definition of 'exercise'.
We described, evaluated and summarised the results of the studies. We made a judgement about our confidence in the evidence based on factors such as the size of the studies and the methods used to conduct them. We searched medical databases for studies up to November 2023.
What did we find?
We found 73 studies that involved at least 4985 adults with depression. The risk of bias in some of the studies was high, which lowered our confidence in the findings.
Exercise may result in a reduction in depressive symptoms compared to no therapy, although the evidence about long-term effects is uncertain.
There is probably little to no difference in depressive symptoms between people undertaking exercise and those receiving psychological therapy. There may be little to no difference in depressive symptoms between people doing exercise and those taking antidepressants.
There does not seem to be a difference between the different interventions in terms of their acceptability as treatments, as measured by the number of participants completing the studies.
The benefits of exercise compared to no therapy, psychological therapy or pharmacological treatments on quality of life are inconsistent and uncertain.
Adverse events from exercise were not common. The small number of participants who experienced them usually reported muscle and joint problems or worsening of depression.
What are the limitations of the evidence?
Many of the studies included a relatively small number of people and had a high risk of bias in terms of the research methods they used. Also, most studies only assessed the effects of exercise over a short period of time. These factors limit our confidence in the findings of the review. Future research should focus on improving the quality of the studies, working out which characteristics of exercise are effective for different people, and ensuring different types of people are included in the studies so that health equity issues can be considered.
Read the full abstract
Depression is a common and important cause of morbidity and mortality worldwide. Depression is commonly treated with antidepressants and/or psychological therapy, but some people may prefer alternative approaches such as exercise. There are a number of theoretical reasons why exercise may improve depression. This is an update of an earlier review first published in 2009.
Objectives
To determine the effectiveness of exercise in the treatment of depression in adults compared with no intervention, waiting list control or placebo, or where exercise is used as an adjunct to an established treatment that is received by both exercising and non-exercising groups.
To determine the effectiveness of exercise compared with other active interventions for depression in adults (psychological therapies, pharmacological treatments or alternative interventions such as light therapy).
Search strategy
We searched the Cochrane Depression, Anxiety and Neurosis Review Group’s Controlled Trials Register (CCDANCTR) to November 2013. We searched MEDLINE, Embase, PsycINFO and the Cochrane Central Register of Controlled Trials (CENTRAL) from 2013 to November 2023. No date or language restrictions were applied.
Selection criteria
Randomised controlled trials in which exercise (defined according to American College of Sports Medicine criteria) was compared to standard treatment, no treatment or a placebo treatment, pharmacological treatment, psychological treatment or other active treatment in adults (aged 18 and over) with depression, as defined by trial authors. We included cluster trials and those that randomised individuals. We excluded trials of postnatal depression.
Data collection and analysis
Two review authors extracted data on primary and secondary outcomes at the end of the trial and end of follow-up (if available). We calculated effect sizes for each trial using Hedges' g method and a standardised mean difference (SMD) for the overall pooled effect, using a random-effects model risk ratio for dichotomous data. Where trials used a number of different tools to assess depression, we included the main outcome measure only in the meta-analysis. Where trials provided several 'doses' of exercise, we used data from the biggest 'dose' of exercise, and performed sensitivity analyses using the lower 'dose'. We performed subgroup analyses to explore the influence of method of diagnosis of depression (diagnostic interview or cut-off point on scale), intensity of exercise and the number of sessions of exercise on effect sizes. Two authors performed the 'Risk of bias' assessments. Our sensitivity analyses explored the influence of study quality on outcome.
Main results
Thirty-nine trials (2326 participants) fulfilled our inclusion criteria, of which 37 provided data for meta-analyses. There were multiple sources of bias in many of the trials; randomisation was adequately concealed in 14 studies, 15 used intention-to-treat analyses and 12 used blinded outcome assessors.
For the 35 trials (1356 participants) comparing exercise with no treatment or a control intervention, the pooled SMD for the primary outcome of depression at the end of treatment was -0.62 (95% confidence interval (CI) -0.81 to -0.42), indicating a moderate clinical effect. There was moderate heterogeneity (I² = 63%).
When we included only the six trials (464 participants) with adequate allocation concealment, intention-to-treat analysis and blinded outcome assessment, the pooled SMD for this outcome was not statistically significant (-0.18, 95% CI -0.47 to 0.11). Pooled data from the eight trials (377 participants) providing long-term follow-up data on mood found a small effect in favour of exercise (SMD -0.33, 95% CI -0.63 to -0.03).
Twenty-nine trials reported acceptability of treatment, three trials reported quality of life, none reported cost, and six reported adverse events.
For acceptability of treatment (assessed by number of drop-outs during the intervention), the risk ratio was 1.00 (95% CI 0.97 to 1.04).
Seven trials compared exercise with psychological therapy (189 participants), and found no significant difference (SMD -0.03, 95% CI -0.32 to 0.26). Four trials (n = 300) compared exercise with pharmacological treatment and found no significant difference (SMD -0.11, -0.34, 0.12). One trial (n = 18) reported that exercise was more effective than bright light therapy (MD -6.40, 95% CI -10.20 to -2.60).
For each trial that was included, two authors independently assessed for sources of bias in accordance with the Cochrane Collaboration 'Risk of bias' tool. In exercise trials, there are inherent difficulties in blinding both those receiving the intervention and those delivering the intervention. Many trials used participant self-report rating scales as a method for post-intervention analysis, which also has the potential to bias findings.
Authors' conclusions
Exercise may be moderately more effective than a control intervention for reducing symptoms of depression. Exercise appears to be no more or less effective than psychological or pharmacological treatments, though this conclusion is based on a few small trials. Long-term follow-up was rare.
The addition of 35 RCTs (at least 2526 participants) to this update has had very little effect on the estimate of the benefit of exercise on symptoms of depression. If further research is to take place, it should focus on improving trial quality, assessing which characteristics of exercise are effective for different people, and exploring health equity.
Funding
This review update had no grant funding. Review authors AC, JH, CH and CW were part-funded by the National Institute for Health and Care Research Applied Research Collaboration North West Coast (NIHR ARC NWC). The views expressed are those of the authors and not necessarily those of the NHS, NIHR or Department of Health and Social Care.
Registration
Protocols and previous versions: DOI 10.1002/14651858.CD004366; DOI 10.1002/14651858.CD4366.pub2; DOI 10.1002/14651858.CD4366.pub3; DOI 10.1002/14651858.CD4366.pub4; DOI 10.1002/14651858.CD4366.pub5; DOI 10.1002/14651858.CD4366.pub6
