Effect of blood donation on maximal oxygen consumption

Aim. This study determined the effect of donating one unit of blood on various physiological parameters associated with a (V)over dotO(2max) test. Methods. Ten healthy, male subjects (23 +/- 4 years, 178 +/- 7.6 cm, 74.4 +/- 12.3 kg) completed a (V)over dotO(2max) test 24 h before donating one unit of blood (similar to 500 mL) and 24 h after donating blood. The Bruce protocol was used to determine the subjects' (V)over dotO(2max). Physiological responses were measured at the end of the (V)oveer dotO(2max) test. A repeated measures ANOVA was used to determine if there were significant (P<0.05) differences in the subjects' physiological responses between the (V)over dotO(2max) before and after blood donation. Results. Significant differences were found in (V)ovr dotO(2max) (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 (DO2, 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). Conclusions. These findings indicate that donating one unit of blood decreased (V)over dotO(2max) due to the decrease in Q, which resulted from the decrease in SV since HR was unchanged. The lower (V)over dotO(2max) along with the decrease in DO2 would be expected to have a negative effect on athletic performance.