VO2max is one of the most studied metrics in exercise physiology&sports science, but its determinants are often presented and understood incompletely. We hope that our work encourages the application of the gold standard theoretical framework also when invasive approaches are not feasible.

Maximal oxygen uptake and maximal work rate decreased along with fractional inspired oxygen due to decreasing convective oxygen transport, whereas diffusive oxygen conductance was not altered by FIO2.

At submaximal intensities alterations to muscle oxygenation develop at lower work rates in hypoxia, but at maximal exercise, muscle oxygenation is altered to a similar extent in hypoxia and normoxia compared to resting levels. Crucially, similar values are reached at a lower work rate in hypoxia.

Central and peripheral compensatory mechanisms maintain oxygen uptake at submaximal intensities despite alterd fractional inspired oxygen.

We combined non-invasive methodology with the gold standard theoretical framework of the determinants of VO2max and characterized how the integrated interplay of the central and peripheral components of O2 pathway determine responses to acute whole-body exercise under conditions of varied FIO2.

We comment on the excellent Inglis et al. paper ”Changes in V̇O2max after 6 Weeks of Intensity Domain-Specific Training: Role of Central and Peripheral Adaptations”, and suggest that DO2 rather than a-vO2 difference should be to assess peripheral changes

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This also illustrates why I try to remind athletes that they shouldn’t be too concerned about their VO2max compared to others. It’s more important to look at how the different determinants of endurance performance interact in their particular situation.