Intermittent hypobaric hypoxia stimulates erythropoiesis and improves aerobic capacity

Purpose: The purpose of the study was to examine the effect of a very short intermittent exposure to moderate hypoxia in a hypobaric chamber on aerobic performance capacity at sea level and the erythropoietic response. The effects of hypobaric hypoxia alone and combined with low-intensity exercise were also compared. Methods: Seventeen members of three high-altitude expeditions were exposed to intermittent hypoxia in a hypobaric chamber over 9 d at simulated altitude, which was progressively increased from 4000 to 5500 m in sessions ranging from 3 to 5 h.d(-1). One group (N = 7; HE group) combined passive exposure to hypoxia with low-intensity exercise on a cycle ergometer. Another group CN = 10; H group)was only exposed to passive hypoxia. Before and after the exposure to hypoxia, medical status, performance capacity, and complete hematological and hemorheological profile of subjects were evaluated. Results: No significant differences were observed between the two groups (IIE vs PI) in any of the parameters studied, indicating that hypoxia alone was responsible for the changes. After the acclimation period, a significant increase in exercise time (mean difference: +3.9%; P < 0.01), and maximal pulmonary ventilation (+5.5%; P < 0.05) was observed during file maximal incremental test at sea level. Individual lactate-velocity curves significantly shifted to the right (P < 0.05), thus revealing an improvement of aerobic endurance. A significant increase was found in PCV (42.1-45.1%; P < 0.0001), RBC count (5.16 to 5.79.10(6).mm(-3); P < 0.0001), reticulocytes (0.5 to 1.1%; P < 0.0001) and hemoglobin (Hb) concentration (14.2 to 16.7 g.dL(-1); P < 0.002). Conclusions: It was concluded that short-term hypobaric hypoxia can activate the erythropoietic response and improve the aerobic performance capacity in healthy subjects.