Faster oxygen uptake kinetics at the onset of submaximal cycling exercise following 4 weeks recombinant human erythropoietin (r-HuEPO) treatment

We tested the hypothesis that prolonged administration of moderate doses of recombinant human erythropoietin (r-HuEPO) accelerates the initial rate of rise in pulmonary O-2 uptake (V.O-2) in response to submaximal exercise and increases the maximal rate of O-2 uptake (V.O-2,O-max). Sixteen endurance-trained athletes were divided into two groups: r-HuEPO- (n=9) or placebo-treated (n=7). r-HuEPO or placebo (saline) injections were given s.c. 3 times a week for 4 weeks. Exercise testing, before and after the 4 weeks, comprised incremental maximal tests and several transitions from rest to 10-min cycling exercise at 65% V.O-2,O-max. V.O-2 was measured breath-by-breath during all tests. In the r-HuEPO group, resting haemoglobin concentration (+9.6%) and haematocrit (+8.3%), as well as V.O-2,O-max (+7.0%) and power output (+7.2%) increased significantly (P<0.05) after the 4 weeks, whereas no change was observed in the control group. The time constant of the primary V.O-2 response was significantly faster (+18%) after the 4 weeks r-HuEPO treatment than before (mean+/-SD; 29.3+/-4.5 vs. 35.7+/-7.4 s, respectively, P<0.05) but was unaffected in the placebo group (34.5+/-7.3 vs. 33.4+/-7.9 s). Collectively, our findings suggest that r-HuEPO contributes both to an acceleration of the dynamic response of V.O-2 to submaximal exercise and to an increase in maximal exercise capacity.