Attempting to "blow off steam" through vigorous exercise could triple the risk of a heart attack within the hour.
And being very upset or angry more than doubles the risk of a heart attack within an hour, while heavy physical exertion does the same, a worldwide study has suggested.
But combining the two - such as using extreme exercise as a way of calming down - increases the risk even further.
Experts said the study, the biggest of its kind, provides evidence of a "crucial link" between mind and body.
Dr Andrew Smyth, lead author of the study from the Population Health Research Institute at McMaster University in Canada, said: "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."