Exogenous Erythropoietin Improves Hematological Status And Physical Performance In Males Following Prolonged Strenuous Exercise Training.

PURPOSE: Negative hematological adaptations following prolonged periods of strenuous physical exertion contribute to declines in physical performance. Exogenous erythropoietin (EPO) is a potential intervention to stimulate hematological and non-hematological adaptations that sustain or enhance physical performance during periods of high physical activity. This study aimed to determine the effects of EPO administration during 28 days of strenuous training on hemoglobin (Hgb) concentrations and hematocrit (Hct), physical performance, substrate oxidation, and skeletal myofiber type. METHODS: Eight healthy active men completed this longitudinal study. EPO injections were given 3X/wk at 50 IU/kg body mass for 28 days. During this period, exercise-induced energy expenditure was 1334 ± 24 kcal 4X/wk, and all food and drinks were provided to maintain energy balance. Body mass, Hgb, Hct, and time trial (TT) performance were assessed on days 0, 7, 14, 21, and 27. V̇O2peak was assessed on days 0, 14, and 26. Rested fasted muscle biopsies were obtained on days 0 and 28, followed by assessment of substrate oxidation during 90-min of treadmill load carriage (LC; 30% body mass) at 55 ± 5% of V̇O2peak using indirect calorimetry and a 6-6-[2H2] glucose tracer. RESULTS: Body mass was maintained throughout the study. Hgb and Hct increased, and TT performance improved on days 21 and 27 (Hgb: 6.3 ± 5.1%, 10.6 ± 5.6%; Hct: 6.3 ± 5.3%, 10.5 ± 5.8%; TT: -6.8 ± 5.8%, -8.8 ± 7.4% respectively) relative to 0 (P < 0.05). V̇O2peak increased (P < 0.05) from day 0 to 14 and 26. Energy expenditure, fat oxidation, and glucose metabolic clearance rate increased (P < 0.05) during LC exercise from day 0 to 28. Myofiber type or capillarization did not change. CONCLUSION: EPO may be a viable intervention to enhance aerobic performance through hematological enhancements during 28 days of high physical activity. These data suggest improved performance with EPO resulting from enhanced whole-body fat oxidation and glucose clearance through greater oxygen carrying capacity, independent of changes to myofiber type and capillarization. Support: Defense Health Program/Military Operational Medicine Research Program. Views are those of the authors and not the official policy of the Department of Army, Department of Defense, or the U.S. Government. Defense Health Program/Military Operational Medicine Research Program.