Does body position (sitting vs supine) affect hemodynamics at rest and during exercise in healthy adult males?
Body position significantly alters hemodynamics, with the sitting position resulting in lower cardiac output and stroke volume compared to the supine position at rest and during exercise.
Abstract In 10 healthy, adult, male subjects the hemodynamics have been studied by the aid of heart catheterization at rest and during work both in supine and sitting positions. The cardiac output was on the average 2.2 1/min less in the sitting than in the supine position, both at rest and during exercise. In the supine position, the stroke volume was constant at rest and during exercise. In the sitting position, the stroke volume at rest was 40 per cent smaller than in the supine. It increased considerably with mild work, but not significantly with an even heavier work load. It never reached the values obtained in the supine position, even during heavy work. The arterio‐venous oxygen difference was larger in the sitting than in the supine position, both at rest and during work. During heavy work, the oxygen transport per heart beat was the same in the supine and the sitting positions, and the physical working capacity (work performed per heart beat) was also of the same order.
Bevegård et al. (1960) studied this question.