Exercise prescription and the risk of sudden death.

Sudden and unaccustomed physical activity may precipitate ventricular fibrillation, myocardial infarction, and sudden death. Evidence supporting this contention is drawn from a review of physiopathology, reported antecedents of infarction and death, and the experience of exercise test centres and gymnasia. The risk of precipitating ventricular fibrillation in a coronary-prone population may be as high as two episodes per 1,000 man hours of physical activity. Such an incidence has important medico-legal implications for fitness test centres and gymnasia. Despite the challenge of devising an exercise prescription that will avoid these hazards, current evidence suggests the long term effects of increased physical activity improve the prognosis of the coronary-prone individual.