[Capacity for regression of the athletic heart]

Dynamic exercise leads to an increase in heart size and to hypertrophy depending on the intensity and extent of training. The maximum of left ventricular muscle mass is reached at 3.5 g/kg, which is 70-80% higher compared to untrained subjects. The mass/volume ratio remains constant (left ventricle 1.0-1.2 g/ml). Systolic wall stress and ejection fraction of the enlarged left ventricle do not change. No heart hypertrophy can be found in athletes carrying out maximum static exercise. Heart size and heart hypertrophy regress when training stops completely. The velocity of regression is not exactly known, a maximum regression of 10-15% within three weeks is probable. Investigations of former athletes show a decrease of heart size and heart hypertrophy, especially when related to body weight. The degree of regression depends on the actual physical activity; another factor may be the duration of the competition activity. It is supposed that only a small degree of training prevents the decrease of heart enlargement, heart hypertrophy and higher performance ability. Damage to the cardiovascular system caused by maximum exercise training cannot be found.