(Reuters) - Sudden bursts of moderate to intense physical activity -- such as jogging or having sex -- significantly increase the risk of having a heart attack, especially in people who do not get regular exercise, U.S. researchers said on Tuesday. Doctors have long known that physical activity can cause serious heart problems, but the new study helps to quantify that risk, Dr. Issa Dahabreh of Tufts Medical Center in Boston, whose study appears in the Journal of the American Medical Association.
