It may feel good to vent frustrations on a punching bag or pour outrage into weight-lifting session, but researchers warn engaging in heavy physical exertion while angry or upset could trigger a heart attack.

Researchers at the Population Health Research Institute at McMaster University in Canada and at the HRB Clinical Research Facility in Galway, Ireland, examined data from 12,461 patients from 52 countries and found the risk for a heart attack within an hour doubled if a patient was angry or emotionally upset. The same was true for heavy physical exertion. The risk more than tripled if someone was upset or angry and engaged in heavy physical exertion.

The research was published Monday in the American Heart Association journal Circulation.

The triggers appeared to be independent of an increased heart attack risk from other factors, including age, smoking, obesity or high blood pressure.

Lead author Dr. Andrew Smyth said extreme emotion and physical triggers may have similar effects on the body.

"Both can raise blood pressure and heart rate, changing the flow of blood through blood vessels and reducing blood supply to the heart," Smyth said in a press release. "This is particularly important in blood vessels already narrowed by plaque, which could block the flow of blood leading to a heart attack.

"Regular physical activity has many health benefits, including the prevention of heart disease, so we want that to continue. However, we would recommend that a person who is angry or upset who wants to exercise to blow off steam not go beyond their normal routine to extremes of activity."

Psychologist Barry Jacobs of the American Heart Association said excess anger, under the wrong conditions, can cause heart attacks.

"People who are at risk for a heart attack would do best to avoid extreme emotional situations," Jacobs said. He suggested talking with others facing similar challenges to manage emotions.

“One of the weaknesses of the study is that it doesn’t define what an extreme physical exertion experience would be or an extreme anger experience,” Jacobs told Reuters Health by phone.