Abstract des Autors

The effects on the cardiovascular system of various patterns of physical activity are analyzed. Several studies have suggested that an increase in left ventricular mass may be seen in trained athletes (not related solely to body size); the increased left ventricular mass observed in athletes is due in large part to an increased transverse end-diastolic dimension of the left ventricle (approximately 10% over that in matched sedentary control group). The most impressive increases in cavity dimension are most consistently identified in endurance athletes. Left ventricular end-systolic dimension is usually increased in athletes compared with control subjects although this difference is usually mild and has achieved statistical significance in only some investigations. Ventricular wall thickness (with little or no increase in the cavity dimension) is often increased in athletes participating in sports involving isometric exertion (specially compared with values in sedentary control subjects); in absolute terms these reported wall thicknesses are not substantially increased and rarely greater than 12 mm (the maximal reported thickness is 16 mm). The increase in ventricular mass induced by long-term conditioning may often include the right ventricle; many athletes also have enlargement of left atrium. The percent fractional shortening (or the derived ejection fraction) is within normal limits in most athletes (relatively mild deviations from normal left ventricular contractility have been reported in only two studies, both involving competitive cyclists). Diastolic function too is within normal limits under basal conditions. A training dependent vagotonic and compensatory decrease in heart rate at rest and during exercise is another adaptation process that is found in many athletes; sinus bradycardia is found in the great majority of athletes trained for isotonic exercise and is correlated with the training level. Sinus pauses lasting more than 2 seconds are found in more than one third of athletes. The incidence of first degree and second degree Wenckeback atrio-ventricular block (observed only at rest) occurred approximately in 25% of trained endurance athletes. In competitive athletes the incidence of atrial fibrillation, fascicular tachycardia and accelerated idioventricular rhythm is rare but increased compared with control subjects. Primary prevention studies have identified the beneficial effect of regular physical exercise on coronary risk factors and the protective effect in patients with coronary artery disease; exercise training favorably alters lipid and carbohydrate metabolism and blood pressure. Verf.-Referat