A Brief Review of Exercise as a Treatment for Depression

A Brief Review of Exercise as a Treatment for Depression

1.  Introduction

In this chapter, we will review the evidence base for the effectiveness of different forms of exercise as treatments for clinical depression and related conditions.

The standard care approach for clinical depression is psychotherapy or antidepressant medication, either alone or in combination. Every year, an estimated 30 million Americans are prescribed antidepressant medication, often for prolonged periods. However, antidepressants, like all medicines, have costs and potential undesirable side effects, making the search for cost-effective and tolerable alternatives important for patient care.

There is a strong and growing scientific evidence base for exercise in the treatment of depression itself, and for prevention of depression, reducing anxiety and improving overall well being. Unsurprisingly, inactivity is associated with worse mental health.

2.  Exercise for depression: the evidence

At the time of writing, several thousand research studies have been published on physical activity, exercise, and depression. These studies are of variable quality and therefore importance. Where possible, we have selected articles of the highest quality – i.e., randomized trials — and where not, we have chosen the best from what was available in the published literature, including country guidelines which have undergone extensive peer review.

Highlights from a selection of the most relevant studies and guidelines have demonstrated that exercise is 1–5:

• Proven to prevent and treat depression
• Effective as a standalone treatment for mild to moderate depression
• Effective as an add-on strategy for both therapy and antidepressant medication treatment for depression
• As effective as psychotherapy or antidepressant medication
• Even at lower levels, physical activity is enough for improving mood
• Associated with higher patient satisfaction and lower numbers of dropouts compared to standard treatments.

How much exercise is enough? The UK’s National Institute for Health and Care Excellence (NICE) recommends that people with mild to moderate depression take part in about 3 sessions a week, lasting about 45 minutes to 1 hour, over 10 to 14 weeks.

How long before the effects are apparent? These same guidelines further suggest exercising for a minimum of 9 -12 weeks, although the optimal time period is unknown. It is also unclear how long it may take for the mental health benefits of exercise to become evident.

Does exercise work for everyone? Naturally, some people may respond positively, others may find it doesn’t improve their mood much, and some may experience only a modest benefit in the short term.

What about side effects? No treatment, including exercise, is without adverse effects and risks. The main adverse effects are physical: muscle soreness, injury, and fatigue. Studies suggest that exercise has far fewer side effects than medication.

Nonetheless, on balance, guidelines and researchers continue to advise that the beneficial effects of exercise on physical and mental health outweigh the risks.

3.  Cardio/AEROBIC EXERCISE for depression

“Cardio” exercise is a broad term referring to any form of exercise increasing the heart rate. Aerobic exercise is any form of exercise that uses oxygen. However, while “aerobic” and “cardio” are used interchangeably, they are technically different while are occurring simultaneously.

Cardiorespiratory fitness is a known protective factor against depression and cardiovascular mortality 6. For example, a large 5-year study in the Netherlands found a strong link between higher preexisting cardiorespiratory fitness and lower levels of depressive symptoms: moderate or high fitness halved the risk of developing depressive symptoms. In this study even lower intensity exercise was protective against depressive symptoms 7.

Cardio exercise has a strong evidence base for the effective treatment of depression, including in a Cochrane review 8 and meta-analysis 2. The Cochrane review included 39 trials of exercise in 2,326 people with depression. Overall, the authors found that exercise was beneficial for depression compared with no treatment or other control intervention. However, differences between the studies meant the results were not necessarily robust.

The more recent Morres et al. systematic review and meta-analysis (2019) included 11 high-quality trials of 455 adults with depression, who were both inpatients and outpatients. They found that aerobic exercise had a moderate-to-large effect on depressi