CARDIAC EFFECTS OF A COMPETITIVE ROAD RACE IN TRAINED CHILD RUNNERS

Background Animal studies and investigations of adult endurance athlet es indicate a transient depression of myocardial function after prolon ged high-intensity exercise. Purpose. To determine whether a similar d ecrease is observed in child distance runners after a 4-km competitive road race. Methods. Anthropometric measures, resting M-mode echocardi ograms, maximal cycle exercise tests with estimation of cardiac output , and electrocardiograms were performed before a 4-km road race in nin e run-trained boys (mean age, 12.2 years). Weight and resting echocard iogram and electrocardiogram were assessed immediately after the race. The entire test battery was repeated 24 hours later. Results. Small b ut significant decreases in mean body weight and left ventricular end- diastolic dimension were observed immediately after the race, but ther e were no changes in shortening fraction. These findings are consisten t with the effects of dehydration. Measurements returned to prerace va lues by 24 hours of recovery. Peak work capacity, maximal stroke volum e, and maximal cardiac output were similar on prerace and 24-hour-post race testing. No electrocardiographic abnormalities were observed. Con clusions. No adverse cardiac effects were observed from a competitive 4-km road race in male child distance runners.