Maximal aerobic performance progressively decreases with increasing levels of hypoxia, because of a reduction in arterial oxygen content (CaO2) due to both hypoxia and exercise (4, 15, 16). Hypoxia limits the oxygen transfer between the lung alveoli and the capillary which results in a drop in CaO2. The successive steps of oxygen transport from the ambient air to the tissues are greatly affected by this drop. Moreover, at and above 4000 m the O2 peak reduction is larger than expected only from the reduction in CaO2 (6). Although this drop has been widely studied in the past (1, 16), far less attention has been paid to tissue oxygenation because of technical difficulties to monitor this variable. Recent studies have used Near Infra Red Spectroscopy (NIRS) to measure changes in oxy (O2Hb) and deoxy (HHb) hemoglobin in the tissues (12, 13).
© Copyright 2008 International symposium of altitude training. All rights reserved.