Effects of erythropoietin administration on cerebral metabolism and exercise capacity in men

Recombinant human erythropoietin (EPO) increases exercise capacity by stimulating erythropoiesis and subsequently enhancing oxygen delivery to the working muscles. In a large dose, EPO cross the blood brain barrier and may reduce central fatigue and improve cognition. In turn, this would augment exercise capacity independent of erythropoiesis. To test this hypothesis, 15 healthy young males (18-34 yo., 74 +/- 7 kg) received either 3 days of high dose (30,000 IU day(-1), N=7) double-blinded placebo controlled or 3 months of low dose (5,000 IU week(-1), N=8) counter-balanced open but controlled administration of EPO. We recorded exercise capacity, transcranial ultrasonography-derived middle cerebral artery blood velocity, and arterial-internal jugular venous concentration differences of glucose and lactate. In addition, cognitive function, ratings of perceived exertion, ventilation and voluntary activation by transcranial magnetic stimulation-induced twitch force were evaluated. Although EPO in a high dose increased cerebrospinal fluid EPO concentration ~20-fold and affected ventilation and cerebral glucose and lactate metabolism (P<0.05), 3 days high dose EPO administration had no effect on cognition, voluntary activation or exercise capacity but ratings of perceived exertion increased (P<0.05). We confirmed that 3 month's administration of EPO increases exercise capacity, but the improvement could not be accounted for by other mechanisms than enhanced oxygen delivery. In conclusion, EPO does not attenuate central fatigue or changes cognitive performance strategy suggesting that EPO enhances exercise capacity exclusively by increased oxygen delivery to the working muscles.