Athlete’s Heart: What Is Still “Normal”?

There is overwhelming evidence that the heart of competitive athletes may differ from that of nonathletes, matched for age, gender and body size. Enlargement of the left ventricular internal diameter is most pronounced and reaches about 10% in athletes performing predominantly dynamic sports; mainly strength training athletes have a lesser increase of the internal dimension, which is limited to a mere 2.5%. Also the left ventricular wall appears to be thickened in all types of athletes compared with controls. In sports with high dynamic and low static demands, wall thickness is proportionate or slightly disproportionate to the size of the internal diameter so that relative wall thickness is not different from control or slightly increased (predominantly eccentric hypertrophy). In strength athletes the disproportionate increase of wall thickness averages about 12% (predominantly concentric hyper trophy). In sports with high dynamic and high static demands and requiring prolonged training, such as cycling, the increases of absolute and relative wall thickness reach 29% and 19%, respectively, and are more pronounced than in runners (mixed hypertrophy). A plausible interpretation of these results is that the development of so-called eccentric or concentric left ventricular hypertrophy according to the type of sports cannot be regarded as an absolute or dichotomous concept, because training regimens on the one hand and sports activities on the other are not exclusively dynamic or static and because the load on the heart is not purely of the volume or the pressure type. Most studies agree that left ventricular systolic and diastolic function is normal in the athlete at rest, whereas diastolic function seems to be enhanced in the exercising endurance athlete. The largest differences from control subjects have been observed in cyclists and rowers. Left ventricular wall thickness may increase up to 16 mm, and is usually associated with an increased LV internal diameter and normal systolic and diastolic LV function.