Exercise should be the primary treatment for depression and other common mental health conditions, according to University of South Australia (UniSA) researchers.

The most comprehensive review of research to date shows that mild to moderate symptoms of depression, anxiety, and psychological distress can be alleviated with physical activity. According to their investigation, exercise is 1.5 times more effective than counseling and top medications.

The study found that 12-week or shorter exercise interventions reduced mental health symptoms the most.

"Importantly, the research shows that it doesn't take much for exercise to make a positive change to your mental health," says lead author, clinical exercise physiologist Ben Singh from UniSA.

Mental health disorders are a leading cause of health problems around the world. Costly for individuals and for society as a whole, poor mental health affected 1 in 8 people in 2019, and recent studies show up to 1 in 5 people experience higher levels of psychological distress during middle age.

Previous studies have found that patients suffering from depression, anxiety, or other forms of psychological distress may benefit from physical activity just as much as they would from psychotherapy or pharmaceutical treatment.

"Physical activity is known to help improve mental health," says Singh, "Yet despite the evidence, it has not been widely adopted as a first-choice treatment."

Because individual studies have looked at such a wide variety of physical activity types, intensities, population subgroups, and comparison groups, it may be difficult for clinicians to make sense of evidence suggesting physical activity is beneficial in the treatment of mental health disorders.

So Singh and his colleagues at UniSA conducted a broader type of study called an umbrella review, to evaluate how all kinds of physical activity affect depression, anxiety, and psychological distress in adults.

An umbrella review examines a collection of reviews rather than individual studies to provide an overall picture of what existing research says about a specific subject. Put simply, it provides 'umbrella' coverage of all the evidence on a topic.

The research team extracted all the eligible studies published prior to 2022 from 12 electronic databases. Overall, they analyzed 97 reviews that included 1039 trials with more than 128,119 participants.

When comparing the effects of exercise to those of usual care across all populations, they found that exercise improved symptoms of depression, anxiety, and psychological distress 1.5 times better than talk therapy or medication.

"We also found that all types of physical activity and exercise were beneficial, including aerobic exercise such as walking, resistance training, Pilates, and yoga," says Singh.

Some types of exercise seemed to help in different ways. For example, yoga and other mind-body exercises helped reduce anxiety the most, while resistance exercise helped the most with depression.

"Higher intensity exercise had greater improvements for depression and anxiety, while longer durations had smaller effects when compared to short and mid-duration bursts," Singh explains.

The fact that longer interventions were less effective than shorter ones may seem to go against common sense. The authors suggest it is possible that this finding shows that people may find it burdensome to stick with longer exercise programs that may impact the psychological benefits.

Women who were pregnant or had recently given birth, people with depression, HIV, and kidney disease, and healthy people benefited most.

The researchers say this may be reflecting populations that are more likely to have higher symptoms of depression and anxiety and lower levels of physical activity, and as a result, have more room for improvement than non-clinical populations.

It should be noted that the majority of the evidence available described mild to moderate depression, with fewer reviews on anxiety and psychological distress. More research in diverse areas of mental health could lead to more solid conclusions.

Of course, the findings don't rule out that medication and therapy are important treatments for many mental health conditions; rather they suggest that exercise is also an important treatment, and one that deserves renewed focus.

"Physical activity is highly beneficial for improving symptoms of depression, anxiety, and distress across a wide range of adult populations, including the general population, people with diagnosed mental health disorders and people with chronic disease," the authors conclude.

The review has been published in the British Journal of Sports Medicine.