Comparison of supine and sitting body position during a triangular exercise test. I. Experiences in healthy subjects.

A comparison of haemodynamic parameters is performed during a triangular exercise test on bicycle ergometer in respect of studying the influence of supine and sitting body position. At the maximal symptom-limited work load reached the heart rate is on the average 9.2% higher, the arterial systolic pressure 16.1% and the cardiac output 17.2% less in the sitting body position (P less than 0.001). On the opposite the pulmonary artery pressure during work is of slightly but not significantly higher level in the sitting position than in the supine. This phenomenon is explained by a prevailing of the beta-adrenergic tonus in our untrained subjects, while total sympathetic stimulation seems to be comparable in both body positions.