Fig. 1.

Oxygen delivery (A) and consumption (VO₂) (B) during sprint exercise in men. Oxygen delivery and VO₂ were measured by the direct Fick method during 30-s all out sprints in normoxia (red circles) and severe acute hypoxia equivalent an altitude of 5300 m above sea level (light blue circles; P_IO₂ = 73 mmHg). The symbol (*) indicates significant differences between normoxia and hypoxia. Leg VO₂ was similar in both conditions despite large differences in O₂ delivery, indicating that at least during the first 15 s O₂ delivery was not limiting mitochondrial respiration when the exercise was carried out in normoxia (modified from Calbet et al. [16]). (For interpretation of the references to colour in this figure legend, the reader is referred to the Web version of this article.)