- Exercise as an evidence-based treatment for depression is a recent phenomenon, having only emerged in the last two decades.
- Science in the form of randomized clinical trials and laboratory neuroscience have converged to show mood benefits from exercise.
- Because exercise is relatively cheaper than standard depression treatments and carries less stigma, it would be more accessible to many.
Believe it or not, exercise as an evidence-based treatment for depression is only a recent phenomenon. For many years, anecdotal testimony and data from observational studies suggested that people who exercised regularly were less likely to suffer from depression. Mental health experts at the time, however, generally downplayed this evidence as spurious. Poor energy and low levels of physical activity, after all, were symptoms of depression; therefore, it made more sense to many experts that exercise habits were the result of depression rather than exercise being a remedy for depression. According to these expert opinions, the studies had it backward: What we needed was to treat depression with conventional medicines and therapies that would help people engage in regular exercise.
Then came the last two decades of clinical trials and laboratory exercise science. In the case of clinical trials, there first emerged a growing number of studies indicating that participating in a variety of exercise regimens reduced symptoms among people entering the study with depression diagnoses. These individual studies were subsequently followed by systematic reviews and meta-analyses that combined results from independent clinical trials, with the majority again indicating that exercise was effective (1). Most recently, there are now even systematic reviews of the numerous meta-analyses of clinical trials (e.g., 2), once again favoring the conclusion that exercise, for the average person, produces a moderate depression reduction benefit.
Importantly, most of these trials and reviews compared exercise to usual care or no treatment for depression. Although the number of studies is currently still small, however, the clinical trials that have compared exercise as a treatment against conventional antidepressants and psychotherapies generally found no difference, suggesting that exercise may be about as effective as more widely used depression treatments.
Laboratory exercise science may offer an even more convincing recommendation for using exercise as a first-line depression treatment by revealing how exercise works to improve emotional well-being. For example:
- Exercise improves mitochondrial functioning, resulting in greater energy levels and increased functional capacity. Instead of needing energy to exercise, it is more accurate to consider that we need exercise to have energy.
- Among many brain benefits, exercise reduces inflammation in brain tissue (3). Chronic inflammation contributes to every major metabolic disease (e.g., heart disease, diabetes, Alzheimer’s Disease, stroke); fewer know, however, that inflammation also impacts emotional functioning, particularly causing “somatic” symptoms of depression such as fatigue, sleep impairment, appetite and sex drive reductions, and loss of interest in activities, among others.
- Exercise helps your brain convert tryptophan into serotonin (the important mood-regulating neurotransmitter). You can’t eat serotonin or take it in a pill; instead, your brain has to make it, using an amino acid called tryptophan. However, tryptophan—even if you’re eating enough of it (many do not)—doesn’t automatically convert to serotonin. Without adequate nutrition and exercise, tryptophan can convert into a neurotoxic substance called quinolinic acid. From this perspective, exercise and diet work together for emotional health. Exercise, specifically, optimizes the way that your brain uses nutrients.
- One of the most potent ways neuroscience shows that exercise helps depression is by improving sleep. Regular exercisers don’t necessarily sleep more, but they reliably sleep better (e.g., they experience higher quality deep (slow-wave) sleep (3).
- Finally, exercise counters and helps prevent depression by moderating our stress response. Exercise is among the most effective forms of stress management for many reasons, including the combination of acute and chronic benefits exercise has for improving blood flow, reducing muscle tension, and altering hormones and neurotransmitters levels to increase focus, energy, and reduce pain.
In the span of two decades, science has brought exercise into the mainstream as a treatment for depression. Not only do we know that exercise works, but we also now have a greatly improved understanding of how it works based on advancing neuroscience.
Because exercise does not have the barriers of conventional depression treatments such as stigma, high costs, and access, the hope is that exercise could become a first-line treatment for depression available to a larger population. Similarly, the absence of data suggesting that any specific form or intensity of exercise is required—they all seem to work, leaving it more up to personal preference and options available to the individual—indicates that exercise could be a flexible, patient-centered treatment option for depression.
If you are among the growing number considering exercise as an option for improving your mental health, keep in mind that exercise doesn’t work for everyone and that exercise may work even better if combined with conventional treatments and other improvements in your health habits.