Effect of exercise on cardiac performance in human subjects with minimal heart disease

1. 1. A study of myocardial performance at rest and during exercise was performed in 16 subjects: 7 with no demonstrable heart disease and 9 with mild heart disease. The interrelation of various indices of contractility and of cardiac energy need were analyzed. 2. 2. At a level of effort sufficient to more than double total body oxygen consumption, increases in pressure time and in minute work were greater than the increases in cardiac energy consumption, indicating an increased mechanical efficiency of the left ventricle on effort. 3. 3. The increase in mean ejection rate varied inversely with the increase in pressure time per beat in most subjects.