Exercise and Arterial Pressure during Simulated Increase of Gravity

Heart rate and arterial pressure were continuously recorded in eight healthy young adults in the sitting position at 3 G, acting in the head‐seat direction, before and during leg exercise at 600 kpm/min for 6 min. In spite of the threefold increase of the hydrostatic pressure gradient along the head‐trunk line the arterial mean pressure at the level of the heart was higher at 3 G than at normal gravity, both at rest and during exercise. Exercise at 3 G resulted in a more rapid rise in the arterial mean and pulse pressures, the final increments being similar or somewhat greater than they were at normal gravity. The results emphasize the importance of the leg muscle pump as a booster of the cardiac pump in situations where large hydrostatic pressures in the lower portion of the body would otherwise tend to curtail the effective circulating blood volume.