Effect of blood donation on maximal oxygen consumption

This study determined the effect of donating one unit of blood on various physiological parameters associated with a VO2(max) test.

Ten healthy, male subjects (23+/-4 years, 178+/-7.6 cm, 74.4+/-12.3 kg) completed a VO2(max) test 24 h before donating one unit of blood (~500 mL) and 24 h after donating blood. The Bruce protocol was used to determine the subjects' VO2(max). Physiological responses were measured at the end of the VO2(max) test. A repeated measures ANOVA was used to determine if there were significant (P<0.05) differences in the subjects' physiological responses between the VO2(max) before and after blood donation.

Significant differences were found in VO2(max) (mean+/-SD, 3.18+/-0.74 vs 2.87+/-0.53 L.min(-1)), cardiac output (Q, 25+/-5 vs 22.5+/-3.3 L.min(-1)), stroke volume (SV, 134+/-37 vs 121+/-22 mL.beat(-1)), delivery of oxygen (DO(2), 5+/-.87 vs 3.97+/-.68 L.min(-1)), and hemoglobin concentration (Hb, 153+/-12 vs 135+/-16 gm.L(-1)). No significant changes were observed for heart rate (HR); arteriovenous oxygen difference (a-vO(2) diff), systolic blood pressure (SBP), and diastolic blood pressure (DBP).

These findings indicate that donating one unit of blood decreased VO2(max) due to the decrease in Q, which resulted from the decrease in SV since HR was unchanged. The lower VO2(max) along with the decrease in DO(2) would be expected to have a negative effect on athletic performance.