This was one of the primary questions addressed by the 1981 expedition to Everest. As mentioned earlier, VO2 max decreases with altitude due to the lower barometric pressure, which causes a lower PO2 and a desaturation of hemoglobin. In effect, the VO2 max at the summit of
Everest was predicated on the observed rate of decrease in VO2 max at the summit of Everest was predicated on the observed rate of decrease in VO2 max at lower altitudes and then extrapolated to the barometric pressure at the top of the mountain. One of the first major findings of the 1981 expediton was that the barometric pressure at the summit was 17 mm Hg higher than previously