The Benefits of Exercise for Mental Health

Recent research on the link between physical activity and depression risk in adults has suggested that exercise may offset the genetic tendency toward depression. Adults with genetic risks who exercised regularly were no more likely to develop depression than those without the genetic propensity.

There is good evidence that this same association holds in adolescents, a group with a generally high risk of depression and with concerningly high suicide rates.

A study published in the March issue of the journal The Lancet Psychiatry found that even light activity — and a corresponding decrease in the amount of time that kids spent being sedentary — was linked to better mental health as they got older.

The researchers looked at the activity of adolescents at the ages of 12, 14 and 16, who were then assessed for depression at around 18 and found that the activity levels when kids were younger were linked to their mental health later on; the depression scores at 18 were lower for every additional 60 minutes per day of light activity at ages 12, 14 and 16, and higher for every additional sedentary hour.

Xihe Zhu, an associate professor of human movement science at Old Dominion University in Norfolk, Va., said that research shows that “some exercise is going to be much better than no exercise at all.” Dr. Zhu was the first author on a 2019 study of 35,000 children and adolescents from 6 to 17 in the United States, which found that those who reported no exercise were twice as likely to have mental health problems, particularly related to anxiety and depression, compared with those who met the exercise guidelines.

Even if children exercised only one to three days a week, he said, there was a strong correlation with lower rates of anxiety and depression — and there was no significant difference between them and those who exercised four to six days a week.

Good sleep duration and extracurricular activities were also associated with better mental health. In fact, physical activity may improve sleep quality, which is closely linked to mental health.

In addition, on a 2017 study on European adolescents, it was found that there was a clear association between more frequent physical activity and lower levels of depression and anxiety, but the most significant difference was between the least active group (active for 60 minutes or more on zero to three of the past 14 days) and the somewhat active group (four to seven of the past 14 days). The most active group (eight to 14 of the past 14 days) had the highest levels of well-being and the lowest levels of depression and anxiety, though within that group, daily activity conferred no special benefit.

The cross-sectional studies that show an association between exercise and better mental health cannot actually show causality, and being depressed or otherwise affected by mental health problems might stop a person from exercising. 

“When you look at populations with mental health issues, they typically have low physical activity or exercise,” Dr. Zhu said. In adults, those populations also typically have high levels of obesity and cardiovascular health problems, he said.

A 2019 review cited a number of possible ways exercise may affect depression, including biological mechanisms like stimulation of neurological pathways and processes, and reducing inflammation, but also that “exercise promotes self-esteem, social support and self-efficacy.”

“Moderate activity of any kind, getting out and doing something, is associated with improvements, lower levels of depressive symptoms, lower levels of anxiety, better well-being,” Dr. McMahon, a research fellow at the National Suicide Research Foundation and the School of Public Health, University College Cork in Ireland, said.