Maximal oxygen uptake and erythropoietic responses after training at moderate altitude

Summary

Six well-trained male cross-country skiers trained for 7 days at 2700 m above sea level, their accommodation being at 1695 m. Blood samples for haemoglobin concentration [Hb], erythropoietin concentration [EPO] and reticulocyte count were collected before, during and after altitude exposure. Packed cell volume (PCV), red blood cell count (RBC), transferrin-iron saturation, mean red cell volume (MCV), mean corpuscular haemoglobin concentration (MCHC), maximal oxygen uptake, maximal achieved ventilation and heart rate were determined pre- and postaltitude exposure. The [EPO] increased significantly from prealtitude (mean 36 mU·ml⁻¹, SD 5) to maximal altitude values (mean 47 mU·ml⁻¹, SD 3). The [Hb] had increased significantly above pre-altitude values (mean 8.8 mmol·l⁻¹, SD 0.5) on day 2 (mean 9.1 mmol·l⁻¹, SD 0.4) and day 7 (mean 9.4 mmol·l⁻¹, SD 0.4) at altitude and on day 4 postaltitude (mean 9.2 mmol·l⁻¹, SD 0.4). The reticulocyte counts had increased significantly above pre-altitude values (mean 6‰, SD 3‰) on day 3 at altitude (mean 12‰, SD 8‰) and day 4 postaltitude (mean 10‰, SD 5‰). The RBC counts had increased on the 4th postaltitude day. The transferrin-iron saturation had decreased below pre-altitude values (mean 23%, SD 4%) on day 4 postaltitude (mean 14%, SD 5%) and had increased on day 11 postaltitude (mean 22%, SD 7%). There were no significant changes in MCV, MCHC, PCV, maximal oxygen uptake and maximal achieved ventilation, and heart rate pre- to postaltitude. These observations demonstrated an erythropoietic response to the altitude training which was not sufficient to increase the postaltitude maximal oxygen uptake.