Additive Effect of EPO and Altitude on Hemoglobin Mass But Not Peak Oxygen Uptake.

PURPOSE: This study evaluated whether recombinant human erythropoietin (rhEpo) treatment combined with hypoxia provided an additive effect on hemoglobin mass (Hb_mass) and peak oxygen uptake (V̇O_2peak) compared with altitude or rhEpo alone. METHODS: Thirty-nine participants underwent two interventions, each containing 4-wk baseline (PRE 1–4), 4-wk exposure at sea level or 2320 m of altitude (INT 1–4), and 4-wk follow-up (POST 1–4). Participants were randomly assigned to 20 IU·kg⁻¹ rhEpo or placebo injections every second day for 3 wk during the exposure period at sea level (SL-EPO, n = 25; SL-PLA, n = 9) or at altitude (ALT-EPO, n = 12; ALT-PLA, n = 27). RESULTS: Hb_mass displayed a significant time–treatment effect (P < 0.001) when comparing ALT-EPO and ALT-PLA. Specifically, the increase in Hb_mass was higher (P < 0.05 to P < 0.001) for ALT-EPO from INT 2 to POST 3 except for POST 2. Similarly, a significant time–treatment effect (P < 0.001) existed for changes in Hb_mass when comparing ALT-EPO with SL-EPO, with the increase in Hb_mass being higher (P < 0.01 to P < 0.001) for ALT-EPO from INT 2 to POST 4. A significant time–treatment effect was present when SL-PLA was compared with ALT-PLA (P < 0.05) and SL-EPO (P < 0.05). For V̇O_2peak, the time–treatment interaction was not significant when comparing ALT-EPO to ALT-PLA. However, when ALT-EPO was compared with SL-EPO, a significant time–treatment interaction existed (P < 0.001) due to a decrease in V̇O_2peak during altitude. CONCLUSIONS: The combined treatment of microdoses of rhEpo and altitude exposure results in an additive increase in Hb_mass but does not significantly enhance V̇O_2peak compared with each treatment alone.