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CARDIAC
Child athletes have superior cardiac functional capacity compared with nonathletes. Nonetheless, there is some cause for caution. Data obtained from studies using animals and humans indicate that myocardial function can be depressed, at least transiently, after intense exercise. Echocardiographic studies have indicated a transient decrease in left ventricular contractility after extremes of athletic competition (ie, 24-hour ultramarathon runs).3

A limited number of studies have failed to identify an adverse effect of intense endurance training on the heart of the child athlete. In these investigations, no differences in resting echocardiograms or electrocardiograms have been observed between trained prepubertal runners and nonathletes.4,5 Rost studied a group of young swimmers longitudinally with echocardiograms over a 10-year period. Cardiac volume and chamber size exceeded those of nonathletic children.6 The effects of sustained submaximal exercise on cardiac function are similar in children and adults.7 Evaluation of cardiac function before and immediately after a 4-km road race by echocardiograms in run-trained boys ages 9 to 14 years showed no evidence of change in left ventricular contractility.8

Based on these limited data, currently there is no indication that intense athletic training of the child athlete results in injury to the heart. However, closer study of the cardiac characteristics of children training at elite levels is necessary before this conclusion can be verified. Careful assessment of cardiovascular status (heart murmurs, abnormal rhythms) remains important in ongoing medical care of the child athlete.

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