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˙O 2 on‐kinetics trials pre BD and post BD. Visit one (0 hour), pre BD established hematological levels, V˙O 2max and Gas Exchange Threshold (GET). Subsequent visits comprised two 6‐minute moderate (∆ 50% rest‐GET) and 1 heavy (∆ 20% GET‐V˙O 2max ) trial. Post BD 0 hour the participants donated blood post hematological testing only. Results Despite non‐significances for V˙O 2 amplitude, time constant‐2 (tau 2 ) for V˙O 2 showed significant decreases at 24 and 48 hours, and tau 3 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˙O 2 amplitude, but time‐based components show sensitivity to reduced circulating O 2 ; with a decreased PO 2 a slower O 2 exchange across the blood myocyte barrier could result in altering O 2 kinetics.