Cardiovascular adjustments induced by training evaluated during semisupine isotonic exercise and recovery period: an echocardiographic study.

Two groups of subjects were examined: trained athletes (group A) and a sedentary control group (group B). The subjects performed submaximal bicycle exercise in the semisupine position to evaluate the differences between the two groups with regard to cardiovascular response during exercise and recovery and to point out all the changes due to training. During the first part of exercise, cardiac output increased contemporary with heart rate and myocardial contractility as shown by the trend of the ejection fraction, higher in group A, under the same level of total vascular peripheral resistances. Later there was an increase of cardiac output for a further increase of heart rate and cardiac inotropism due to the homeometric mechanism. During recovery the heart rate and peripheral vascular resistance reduction led to an increase of venous return which set up the Frank-Starling mechanism via an increase of left ventricular dimensions. These adjustments were more efficient in group A. During exercise and recovery the heart rate-pressure product was constantly lower in group A with a significant difference to group B. Therefore, trained athletes' myocardium is more efficient than that of the sedentary group because it performs an external work load with a lower oxygen consumption.