Relative Risk of Sudden Cardiac Death During Marathon Running

C a 6-fold increase in the absolute incidence of exercise-related sudden cardiac death in middle-aged men compared with younger men, Thompson's¹conclusion that vigorous physical activity transiently increases the risk of acute cardiac events agrees with relative risk analysis for a triggering effect of myocardial infarction during exercise.² ³Expressed as sudden cardiac death risk per person-hour, the reported rate of 1 per 50 000 marathon runners⁴represents a 5-fold increase over the average hourly incidence per person-hour. This translates into 1 death per 200 000 person-hours of competition compared with 1 sudden cardiac death per million person-hours among middle-aged men.⁵ The data are finally coming in on the issue of how much exercise might be too much. The cardiovascular benefit of training for middle-aged male marathon runners may be offset by a 5-fold increase in the odds ratio for acute cardiac events during competition. At