Indices of the first derivative and of the normalized first derivative of the left apexcardiogram were used to evaluate the contractile state of the left ventricle of cyclists in the competitive season compared to their resting season and of cardiac patients before and after a physical training program. In both groups exercise capacity increased after training (P less than 0.001). The normalized first derivative of the upstroke of the systolic wave and the time from the onset of electrical depolarization to the peak value of the first derivative of the upstroke of the systolic wave were unchanged after training in both groups. Also in both groups training did not alter the height of the A-wave in percentage of the amplitude of the systolic wave nor the normalized first derivative of the A-wave. These indices suggest that the compliance of the left ventricle was not decreased despite thickened left ventricular walls as reported in both groups. Thus physical training does not seem to alter the intrinsic myocardial contractile state, as far as reflected by these indices of the left apexcardiogram.