Left ventricular dynamics during exercise in elite marathon runners

AbstractTo assess left ventricular structure and function at rest and during exercise in endurance athletes, 10 elite marathon runners, aged 28 to 37 years, and 10 matched nonathletes were studied by echocardiography and supine bicycle ergometry. Each athlete's best marathon time was <2 h 16 min. Echocardiography was performed at rest, at a 60 W work load and at an individually adjusted work load, at which heart rate was 110 beats/min (physical working capacity 110 [PWC110]). Oxygen uptake at PWC110averaged (±SD) 1.14 ± 0.2 liters/min in the nonathletes and 2.0 ± 0.2 liters/min in the runners (p < 0.001).The left ventricular internal diameter at end-diastole was similar at the three activity levels in the control subjects but increased significantly from rest to exercise in the runners (p < 0.001). Left ventricular systolic meridional wall stress remained unchanged during exercise in the nonathletes but was significantly higher at PWC110in the athletes (p < 0.05). Both the systolic peak velocity of posterior wall endocardial displacement and fractional shortening of the left ventricular internal diameter increased with exercise; at [PWC110]). the endocardial peak velocity was higher in the runners than in the control subjects (p < 0.01). The endocardial peak velocity during relaxation was comparable in athletes and control subjects at rest, increased similarly at a 60 W work load, but was higher in the runners at [PWC110]). (p < 0.05).In conclusion, left ventricular dynamics during supine bicycle exercise differ between elite marathon runners and nonathletes; ventricular dilation, with preserved fractional shortening, and a faster relaxation may contribute to the development of a high stroke volume in the exercising athlete