Haemodynamic changes during continuous exercise.

Abstract
In 6 symptom -free young subjects an alteration in posture from supine to erect resulted in a 25% fall on cardiac output and a 33% fall in stroke volume. On exercise at 300 kpm/min. there was an Initial rise in aortic and pulmonary pressure, but these then fell progressively to approach the erect resting level after 30 min. of continuous exercise. The heart rate increased slowly throughout the period of exercise, but the cardiac output and O2 uptake remained almost unchanged once the steady state was reached. Cardiac work and tension time index decreased as exercise was prolonged.