Gender differences in plasma volume changes in response to arm & leg ergometer exercise

Abstract

Plasma volume shift (PVS) in response to exercise is a well‐understood phenomenon that has not been investigated for gender differences. Ten healthy young subjects ‐ 5 men (mean age 24.8) and 5 women (mean age 24.4) ‐ each pedaled a cycle ergometer at 50 rpm starting at 0.5 kp and increasing by 0.5 kp every 2 min until heart rate (HR) reached 170. They continued for 8 min with work load adjusted to keep HR at 170±5 bpm. On a separate day, subjects turned an arm ergometer at 50 rpm starting at 0.25 kp and increasing by 0.25 kp every minute until HR reached 170, then continued for 8 min as above. Sessions were counterbalanced. Two‐mL blood samples (in EDTA) were drawn immediately before and after each exercise bout. Hematocrit (Hct) was measured using a microhematocrit reader. Hemoglobin (Hb) was measured using the cyanmethemoglobin method. PVS was calculated using the Dill & Costill equations. One‐way ANOVA revealed significant (p<0.05) pre‐ to post‐exercise increases in Hct and Hb and decreases in PV within both groups. Change in Hb was significant (p<0.05; F=18.366) between groups for arm ergometry. PVS was not significantly different between groups for either type of ergometry. Data suggest that, for a moderately high level of cardiovascular stress, upper and lower body aerobic exercise elicits similar PVS regardless of gender.This research was supported by the Department of Kinesiology and Health Studies, SLU.