Erythropoietin (rHuEPO) doping: effects of exercise on anaerobic metabolism in rats

The purpose of this study was to investigate the effects of recombinant human erythropoietin (rHuEPO) administration on energy metabolism during exercise. Specifically, the contribution of anaerobic (glycogen) metabolism during exercise was evaluated. Sprague-Dawley rats were randomly assigned to an experimental [rHuEPO] (600 U x kg(-1) of Eprex, every 3 days) or control (equivalent volume of saline) group. After 15 days of treatment, animals from both groups were randomly subjected to either a 30-minute exercise (swimming with 5% body weight added) or resting period. They were sacrificed at the end of the exercise period. Their liver and muscles were quickly removed and frozen in liquid nitrogen. Blood was also sampled. rHuEPO administration resulted in a significant (P < 0.05) increase of hematocrit (from 42 +/- 2 to 54 +/- 7 L/L). In the rHuEPO group, both muscle glycogen and free fatty acids were higher whereas lactate was lower at the conclusion of the exercise period (P < 0.05). These results suggest that energy substrate utilization during exercise is affected by enhanced oxygen availability. Finally, a lower overall contribution to energy production from anaerobic metabolism during exercise followed rHuEPO administration.