Haemoglobin-based oxygen carriers (HBOCs) such as Hemopure™ are touted as a tenable substitute for red blood cells and therefore potential doping agents, although the mechanisms of oxygen transport of HBOCs are incompletely understood. We investigated whether infusion of Hemopure™ increased maximal oxygen uptake (V·O2max) and endurance performance in healthy subjects. Twelve male subjects performed two 4-minute submaximal exercise bouts equivalent to 60 % and 75 % of V·O2max on a cycle ergometer, followed by a ramped incremental protocol to elicit V·O2max. A crossover design tested the effect of infusing either 30 g (6 subjects) or 45 g (6 subjects) of Hemopure™ versus a placebo. Under our study conditions, Hemopure™ did not increase V·O2max nor endurance performance. However, the infusion of Hemopure™ caused a decrease in heart rate of ~ 10 bpm (p = 0.009) and an average increase in mean (~ 7 mmHg) and diastolic blood pressure (~ 8 mmHg) (p = 0.046) at submaximal and maximal exercise intensities. Infusion of Hemopure™ did not bestow the same physiological advantages generally associated with infusion of red blood cells. It is conceivable that under exercise conditions, the hypertensive effects of Hemopure™ counter the performance-enhancing effect of improved blood oxygen carrying capacity.
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