Chances are that someone you love has experienced depression. Approximately 8 percent of U.S. adults – some 21 million people – have a major depressive disorder each year. For people under age 18, depression is the most common cause of hospitalization.

For decades, researchers have been exploring interventions to prevent and treat depression, including medications, talk therapy, and exercise — which many studies have found is equally as effective in treating depression as medications and psychotherapy.

A new systematic review compiled by a team of global researchers adds more evidence to how exercise helps treat depression. The review was published in the British Medical Journal and includes 218 studies with more than 14,000 participants.

The review examined specific types and intensities of exercise to determine the best treatments for individuals. Here are some of its findings:

• Dance, exercise combined with medication, and walking or jogging were most effective for relieving symptoms of depression.
• Yoga, strength training, mixed aerobic exercises, and tai chi or qigong were moderately effective when performed regularly.
• Although light exercise, such as walking or hatha yoga, was still clinically meaningful, more vigorous exercise such as running or interval training was more effective at alleviating depression symptoms.
• The age and gender of the participants mattered. Walking and jogging were equally effective for men and women. Strength training was more effective for women, and yoga or qigong was more effective for men. For older adults, yoga was more effective. For younger people, strength training was more effective.
• Study participants were more likely to stick with exercise programs that included yoga or strength training. This is important when considering whether patients can adhere to a treatment program.

The researchers also discussed the limitations of the available data. Many studies only focused on a specific group, such as one gender or age group. Others included participants with many comorbidities, which makes it difficult to single out the benefits of a single treatment.

The researchers also highlighted the ancillary benefits exercise provides. For example, a group exercise class offers social interaction, running outside means access to nature, and yoga or tai chi promotes mindfulness. There is clear evidence that all of these “side benefits” also improve depressive symptoms, which makes it difficult to tease out the specific mechanisms at work.

Despite lingering questions, the take-home message is clear: Exercise is an effective treatment for depression. The authors of this review suggest that healthcare practitioners should prescribe exercise to patients experiencing depression, including specific advice on what types of exercises and intensities may work best for them.