Abstract
Maximal oxygen consumption (˙VO2max) shows a non-linear fall with altitude that is a mirror
image of the oxygen equilibrium curve. Di Prampero and Ferretti were the first to associate the non-linear behaviour of
the respiratory system to the oxygen equilibrium curve. On the other hand, Wagner constructed his convective curve
accounting for the effects of the oxygen equilibrium curve. The decrease is more accentuated in athletic subjects with
elevated ˙VO2max compared to those who are non-athletic, so that the large differences in ˙VO2max that are observed at sea
level disappear at altitude. Such consequences are due to the effect of ventilatory and pulmonary resistances to oxygen
flow in limiting ˙VO2max, which becomes progressively greater while moving toward higher altitudes compared to that of
the cardiovascular resistance. On top of Everest, the pulmonary resistances provide most of the ˙VO2max limitation and
the respiratory system provides linear responses.