The effect of acute plasma volume expansion on venous capacitance

The purpose of this study was to examine the effect of plasma volume (PV) expansion, induced by 1 single bout of high intensity exercise, on venous capacitance.

Fourteen active but untrained healthy young males were randomly assigned to an exercise (n=7) or control group (n=7). The exercise protocol consisted of 8 4-min bouts of exercise at 70-85% of maximal oxygen consumption (VO(2)max) with 5-min recovery periods between bouts. Resting and exercise HR and venous capacitance were assessed before and 24 hours after one bout of cycle exercise. Exercise HR was assessed during cycle exercise at 30, 45, and 60% of VO(2)max, whereas forearm and leg venous capacitance were examined by determining limb volume change after 2 min of venous occlusion at 50 mmHg. PV, plasma albumin, and sodium and potassium concentration were analysed pre and 24 hours post exercise.

Twenty-four hours after one single bout of exercise, PV was increased by 7.7%. The increase in PV was accompanied by a decrease in exercise HR of 5.8% at the 2 higher intensities (45 and 60% of VO(2)max) but no change in venous capacitance was found. No significant changes in plasma albumin and sodium concentration occurred, although potassium concentration was significantly increased by 29%.

An acute exercise-induced increase in plasma volume appears to be able to reduce exercise HR but has no effect on venous capacitance.