Exercise is known to benefit people's mental health, but scientists recently discovered that too much exercise may have a negative effect on it.
Researchers from Yale University conducted the largest study of its kind on the association between mental health and exercise. Published in The Lancet Psychiatry on August, the study showed a link to exercise improving mental health—and a link to it negatively affecting mental health.
The researchers studied about 1.2 million people in the United States in 2011, 2013 and 2015. The participants, on average, experienced 3.4 days of poor mental health each month. Those who did exercise experienced 1.5 fewer days of poor mental health per month, compared to those who didn't exercise at all. The team found that people who exercised for 30 to 60 minutes three to five times a week had the best mental health, but those who exercised for more than three hours had worse mental health than those who didn't exercise at all.
The scientists think that people who exercise so much may experience poorer mental health because that much exercise can be a sign of obsessive behaviors that have been associated with poor emotional and psychological outcomes. However, the only mental health disorder that the researchers looked at was depression.
For those who had been diagnosed with depression, people who did exercise experienced 3.75 fewer negative mental health days than those who did not, showing an even greater difference. According to the Centers for Disease Control and Prevention, 7.6 percent of people in the U.S. age 12 and over have depression. While all types of exercise appeared to help with mental health, aerobic exercise, cycling, gym-based exercise and team sports were the most beneficial.
Other types of nontraditional exercise, like conducting chores, also helped with mental health. Overall, the scientists found that those who exercised experienced a 43.2 percent reduction in poor mental health than those who did not.
The team also looked at more specific factors, like education. People with a college education reported 17.8 percent fewer days of poor mental health than those without that level of education. Additionally, people in a healthy BMI range reported a 4 percent reduction in poor mental health days than those whose BMIs were high. Even salary was a factor: Compared to people with lower salaries, those with higher salaries experienced a 17 percent reduction in poor mental health days.
The study showed that exercise can help with mental health, but that in some cases, limiting it may be necessary.
