The athlete's heart.

Exercise training has an effect on myocardial metabolism and the coronary vasculature. Alterations in the autonomic nervous system tone appear to account for the bradycardia often seen in athletes. Cardiomyopathy is the main threat to health and life in the young competitive athlete. For the older jogger or marathoner, coronary disease is the most common cause of a sudden cardiac catastrophe. A thorough medical history and physical examination is the least expensive and the most effective means of screening athletes for underlying cardiovascular disease. This can be supplemented with additional studies such as the chest X-ray, resting and exercise ECG, ambulatory monitoring, radionuclear stress scanning, echocardiography, and electrophysiologic evaluations. The main therapeutic dilemmas occur in the symptomatic athlete who has variations from normal on physical examination and laboratory study. Prudence is advised when the examining physician cannot exclude a situation that could potentially result in an exercise-related death.