Exercise and Sudden Cardiac Death

IN this issue of the Journal, Siscovick and co-workers1 report that vigorous physical exercise both protects against and provokes sudden cardiac death. The risk of cardiac arrest during vigorous physical activity was transiently increased, especially in men who habitually engaged only in low levels of physical activity. Despite this short-term danger associated with exercise, however, the total risk for men who regularly exercised vigorously was only 40 per cent of that for the less active subjects. These results suggest that vigorous exercise is both protector from and provoker of sudden cardiac death but that any short-term risk of exercise . . .