Effect of an acute blood donation on oxygen uptake kinetics in moderate and heavy domains over a period of 96 hours

BACKGROUND: Studies determining the effects of blood donation (BD) on oxygen uptake kinetics are limited. This study aims to ascertain the effects of BD (~470 mL) over a period of 96 hours on oxygen uptake kinetics in moderate and heavy exercise domains. STUDY DESIGN AND METHODS: Twelve participants (nine males and three females; 31.1 ± 11.7 years, mass 79.9 ± 12.8 kg, height 175.5 ± 7.5 cm) completed four consecutive days (24-96 hours) of moderate and heavy V˙O2 on-kinetics trials pre BD and post BD. Visit one (0 hour), pre BD established hematological levels, V˙O2max and Gas Exchange Threshold (GET). Subsequent visits comprised two 6-minute moderate (∆ 50% rest-GET) and 1 heavy (∆ 20% GET-V˙O2max ) trial. Post BD 0 hour the participants donated blood post hematological testing only. RESULTS: Despite non-significances for V˙O2 amplitude, time constant-2 (tau2 ) for V˙O2 showed significant decreases at 24 and 48 hours, and tau3 showed significant increases at 72 and 96 hours pre to post BD (P < .05). Hemoglobin (Hb) values reduced (P < .05) pre (14.48 ± 0.16 g·dL-1 ) to post BD (13.47 ± 0.66 g·dL- 1). Hb significantly decreased at 24, 48, 72, and 96 hours compared to 0 hour post BD (P < .05). CONCLUSION: BD has no effect on V˙O2 amplitude, but time-based components show sensitivity to reduced circulating O2 ; with a decreased PO2 a slower O2 exchange across the blood myocyte barrier could result in altering O2 kinetics.