ABSTRACT
Adaptation to high altitude involves a complex series of events that optimize oxygen delivery from the air to the mitochondria both quickly and over longer periods of time from weeks to months to generations. Because of the lower amount of oxygen available from ambient air at high altitude, exercise capacity decreases predictably upon ascent, but with time for at least partial acclimatization, maximum and sustainable work improves, albeit not to sea-level values. This chapter summarizes each of these steps as they are understood now and applies this knowledge to a wide array of people from normal folks to athletes to patients who sojourn or live at high altitude. Adaptations of respiration, cardiac response, gas exchange, blood, perfusion, and cells will be briefly reviewed. Exercise testing at modest, moderate, and very high altitudes will be related to relevant clinical markers of the effect of higher altitudes on subjects. Interpretation of CPET done at higher altitude laboratories also needs to be done in the context of the altitude of the testing site. Additionally, the topic and controversy of training at high altitude for both low- and high-altitude competition will be addressed.
