Hemodynamic response to treadmill exercise in normal subjects.

Abstract

Cardiac output, stroke volume, heart rate, arteriovenous O2 difference, and mean pulmonary artery pressure were determined in 24 normal male volunteer subjects using the direct Fick method. A change in body posture from supine rest to standing rest is accompanied by a fall in cardiac output and stroke volume and an increase in O2 consumption, heart rate, and A-V O2 difference. No change in mean pulmonary artery pressure occurred. With initiation of mild treadmill exercise, stroke volume increased to supine resting values or slightly higher. Increasing the workload to submaximal levels resulted in further smaller increases in stroke volume. However, heart rate now was predominant in increasing cardiac output. Mean pulmonary artery pressures during treadmill exercise exceeded normal supine and standing resting values.