The Effect of Body Position on the Circulation at Rest and During Exercise, with Special Reference to the Influence on the Stroke Volume

Abstract

B E V E G~, S., A. HOLMGREN and B. JONSSON. The eJect of body position on the circulation at rest and during exercise, with special reference to the inzuence on the stroke volume. Acta physiol. scand. 1960. 49. 279-298.-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 l/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. I n the sitting position, the stroke volume at rest was 40 per cent smaller than in the supine. I t increased considerably with mild work, but not significantly with a n 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.

Cardiovascular Adjustments to Gravitational Stress

“…Cardiac output is 1-2 liters/min higher in the supine than in the sitting position at rest and during dynamic exercise involving large muscle groups, e.g., bicycle exercise (21)(22)(23)(24)85,328,329). Body position does not affect the slope of the normal linear relationship between oxygen uptake and cardiac output.…”

“…The systemic arteriovenous oxygen difference also increases. A change from the supine to standing position causes qualitatively similar but slightly larger hemodynamic adjustments than a change from the supine to sitting position (23,24). Matalon and Farhi (224) demonstrated an inverse linear relationship between cardiac output and the sine of the tilting angle during passive head-up tilt.…”

Position as a variable for cardiovascular responses during exercise

“…In studies comparing full upright sitting and supine bicycle ergometry (without torso stabilization), peak workloads have been reported to be significantly greater in the full upright position (36), in the supine position (6), or not significantly different (1,14). In addition to undergoing multigated radionuclide angiography in both 70" tilt and supine positions, all 21 of our subjects also underwent full upright (90") bicycle ergometry with respiratory gas analysis to establish the level of maximal exercise capacity (plateau O2 consumption).…”

“…The distribution of blood and the hydrostatic forces acting between the cardiac pump and the peripheral vasculature are altered when a subject assumes different positions. Position-related differences in the hernodynamic and cardiac functional responses to exercise have been noted in normal subjects (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)37) and in patients with various types of heart disease (4,7, 12, 16-19); the specific results have, however, varied somewhat from study to study.…”

Left ventricular performance in normal subjects: a comparison of the responses to exercise in the upright and supine positions.

“…Hemodynamic studies have generally, but not unanimously, shown that stroke volume increases with transition from rest to exercise in both the upright and supine positions. ", 4,[8][9][10][40][41][42] LV end-diastolic volume during supine exercise has been shown to decrease in studies in which metallic epicardial markers" and angiography were used.14 Using angiography, Gorlin et al12 found no substantial change in LV enddiastolic volume. Crawford et al6 demonstrated echocardiographically that diastolic diameter does not change during moderate supine and upright bicycle exercise.…”