LET’S BE PERFECTLY clear from the start: Exercise is one of the best ways to boost your mental health. Countless studies have proved this beyond any reasonable doubt. Case closed.
However, a recent study revealed that, for some people, there can be too much of a good thing. Researchers from Yale University looked at data sourced from 1.2 million people in the U.S. to try to find out how much and which types of exercise are best for mental health. In the process, they found something a bit surprising.
The study, published in The Lancet, concludes that physical exercise was “significantly and meaningfully” associated with improved mental health, but that, “More exercise was not always better.”
Those who exercised for 30 to 60 minutes three to five times per week saw the most benefit, the researchers found. People who were physically active for more than 90 minutes every day also saw their mental health improve, though less so. But subjects who exercised for more than 90 minutes a day or more than 23 times a month actually had worse mental health than those who did not exercise at all.
This finding was “a little bit surprising,” says the study’s lead author, Dr. Adam Chekroud, an adjunct assistant professor of psychiatry at Yale. Previous studies have typically compared how different intensities of exercise affect mental health, but none have looked closely at different volumes of exercise, he says.
The Exercise Sweet Spot
Chekroud stresses that people should not read this the wrong way. “The take-home is, we showed that no exercise is worse than exercise, and that those who exercise too much had the worst mental health. There is a sweet spot, for sure,” he says.
He admits it’s hard to know if excessive exercise leads to mental illness, or the other way around. People who exercise so frequently or so long may be doing so because they are exhibiting obsessive or other poor psychological and emotional behaviors, including body dysmorphia or eating and weight disorders. On the other hand, overexercising to this degree can cause physical and emotional stress, fatigue and inflammation, all of which can have a deleterious impact on mental health. This chicken-or-egg question still needs to be resolved, he says.
For most of us, this issue is not really a problem. “Overexercising is rare, it is not common,” says Dr. Ronald L. Kamm, a psychiatrist who subspecializes in sports psychiatry. Those who are at risk, he says, include people with bipolar disorder, which can include mania. Also at risk are those with addictive personalities because “They overdo exercise, like with any addiction, and neglect other things in their life,” Kamm says. Then there is what he calls secondary exercise addiction, in which exercise is part of an eating disorder. “You see that in athletes more than in those with anorexia nervosa, athletes who compulsively exercise to the point of muscle damage and destruction to lose weight and control body fat,” he says. This is most common in sports that value aesthetics like skating or gymnastics or have weight limits like boxing, wrestling or crew. “Some call it athletica nervosa,” Kamm says.
Sometimes, the sport drives the disorder. Athletes in team sports may overtrain if they are trying to make a team or keep up with others on the team. “Doing that can bring on depression, fatigue and physiological problems like sleep disruption,” says Kamm, director of Sport Psychiatry Associates in Oakhurst, New Jersey, and past president of the International Society for Sport Psychiatry. “Parents and coaches need to sit these athletes down and say, ‘Take some time off.’ Usually, the depression and fatigue go away.”
However, Kamm believes that, for the most part, mental illness drives overexercising, not the other way around, and it needs to be treated as such. “Those with anorexia nervosa must be prevented from overexercising,” he says. “Many times, people don’t see it. They are athletes, so of course they are training very seriously, and it isn’t realized that they are compulsively exercising to control body weight. You treat the mental illness with intensive inpatient care, so they can control exercising.”
Exercise as Effective as Zoloft
Both Chekroud and Kamm continue to point out that exercise is, by and large, a good thing. “It is highly unlikely anyone reading this is exercising too much,” Chekroud says. Some people have taken his research and inferred they don’t need to exercise; “That is definitely not what we are messaging,” he says.
The bigger message from his study is that, on average, those who exercised had 1.5 fewer days of poor mental health per month than those who did no exercise at all. The difference was even greater in people with a previous diagnosis of depression: Those who exercised had 3.75 fewer bad days per month than nonexercisers. Overall, exercise was equated with a 43.2 percent reduction in instances of poor mental health, greater than the association between mental health and other modifiable factors.
That jibes with a landmark 1999 study out of Duke University that showed how a brisk 30-minute walk or jog three times a week was as effective as the antidepressant Zoloft in treating major depression. “That has become the gold standard,” Kamm says. He believes that 30 to 45 minutes of exercise per session is plenty. “I don’t see the benefit of going over 45 minutes,” he says. Exercising more than that starts to put unnecessary strain on the body. “You can run into physical problems, like damaging knees and ankles,” he says, and the risk increases as you get older.
