Sudden death during exercise: how real a hazard?

The literature dealing with sudden cardiac death in relation to exercise, particularly sport, is reviewed. The exact incidence of unexpected sudden cardiac death during physical activity in persons previously presumed healthy is difficult to determine due to the wide variation in reporting methods; by all indications, it is extremely low. The most common cardiac condition underlying sudden cardiac death in persons over age 30 years is, overwhelmingly, coronary artery disease. In younger athletes it is much less common and is usually due to hypertrophic cardiomyopathy, congenital anomalies or inherent abnormalities of the conducting system. The PAR-Q (Preparation for Activity Readiness Questionnaire) appears to be an adequate pre-exercise screening tool for recreational and middle-aged athletes. A (cost) effective pre-exercise screening strategy for the younger and highly competitive athlete remains elusive. Extensive and costly screening methods (eg, ECG, echocardiography, treadmill studies) do not seem warranted for any asymptomatic, presumed healthy groups. Although the risk of sudden cardiac death is measurably higher during exercise than during sedentary activity, the overall risk is demonstrably lower in habitually active and physically fit persons. The resolution of this paradox is that even the most active persons rarely spend more than an hour or two a day at vigorous exercise, while the protective effects against sudden cardiac death operate for the remainder of the day.