Repeated serial determination of cardiac output during 30 min exercise

Abstract

Cardiac output was determined with the dye-dilution technique at rest supine, sitting, and during 30 min. exercise at 600 or 900 kpm/mln. on a bicycle ergometer. Cardiac output and stroke volume were lower at rest in the sitting than in the supine position and increased considerably during the first 2 min. of exercise. Cardiac output continued to increase during the first 7 min. and was then fairly stable at both work loads, with a mean variation coefficient of 6.2%. The stroke volume fell ? slightly after 7 min. of work. Bandaging the legs increased the stroke volume at rest and during exercise in the sitting position. The effect of previous exercise was analyzed at two work tests 2 hr. apart. The heart rate was significantly higher at rest and during exercise at the second examination but the cardiac output did not change significantly.