You probably already know that exercise makes you healthier and reduces your risk of heart disease. But new research has revealed a surprising reason for this result. And then it all comes back to stress.

People who exercise regularly may be better protected from heart disease, in part due to reduced stress-related brain activity, a new study published Monday in the Massachusetts General The discovery was made by hospital researchers. This may be one reason why people with depression, a stress-related mental health condition, often benefit greatly from physical activity.

“Physical activity was approximately twice as effective in reducing the risk of cardiovascular disease in patients with depression. Effects on stress-related activity in the brain may explain this new observation.” Dr. Ahmed Tawakol, senior author of the study and a cardiologist at MGH, said in a release.

In other words, people who exercise more have less stress, which has a positive effect on heart health.

In the study, published in the Journal of the American College of Cardiology, Tawakol and his colleagues analyzed medical records of 50,359 people who also completed a physical fitness survey. A portion of that group also underwent brain imaging scans and measurements of stress-related brain activity.

At an average follow-up of 10 years, nearly 13% of participants developed heart disease. However, those who exercised regularly had a 23% lower risk of developing cardiovascular disease than those who did not exercise. The cardiovascular effects were also greater among people with a history of depression, who would be expected to have higher levels of stress-related brain activity.

So, while everyone benefits from exercise, those who have been under a lot of stress may have even greater heart health.

The researchers noted that more research is needed in this area, but the results are very promising.

“Clinicians should inform patients that physical activity can have important effects on the brain, which can have significant cardiovascular benefits in patients with stress-related syndromes such as depression. “We will be able to do that,” Tawakol said.

This is not the first time that exercise has been shown to have significant positive effects on physical and mental health. Exercise has already been shown to reduce anxiety, depression, and moodiness by increasing self-esteem and improving cognitive function. And when it comes to mental health benefits, going for a brisk walk outside, cycling, doing a little yoga, or going for a swim are all important.

Studies have shown that physical activity can also reduce heart disease, the number one cause of death for Americans. Staying active can also reduce the incidence of diabetes and cancer.

The latest research points to a growing body of evidence highlighting the link between mental health and physical health, and the real impact that long-term stress has on people’s bodies.