It turns out that exercising to blow off steam when you’re upset might not be good for your heart.

A large, international study led by researchers at McMaster University in Hamilton ties heavy exertion while stressed or angry to triple the risk of having a heart attack within an hour.

“Extreme physical exertion especially when accompanied by extreme anger, those two things together triple the risk for someone to have a heart attack, especially if you’re middle aged and you have cardiac risk factors, people need to be careful,” warns Springfield, Pennsylvania psychologist Barry Jacobs.

Regular exercise is a healthy antidote to stress and can help prevent heart disease.

But the new research suggests there may be better or worse times to exercise, and that extremes can trigger harm.

The risk was greatest between 6 pm and midnight, and was independent of other factors such as smoking, high blood pressure or obesity.

You can read about the study in the Heart Association journal Circulation.