The Oxygen Uptake Plateau—A Critical Review of the Frequently Misunderstood Phenomenon

Abstract

A flattening of the oxygen uptake–work rate relationship at severe exercise indicates the achievement of maximum oxygen uptake (VO 2 max). Unfortunately, a distinct plateau (VO 2pl) at VO 2 maxis not found in all participants. The aim of this investigation was to critically review the influence of research methods and physiological factors on the VO 2pl incidence. It is shown that many studies used inappropriate definitions or methodical approaches to check for the occurrence of a VO 2pl. In contrast to the widespread assumptions it is unclear whether there is higher VO 2pl incidence in (uphill) running compared to cycling exercise or in discontinuous compared to continuous incremental exercise tests. Furthermore, most studies that evaluated the validity of supramaximal verification phases, reported verification bout durations, which are too short to ensure that VO 2 max have been achieved by all participants. As a result, there is little evidence for a higher VO 2pl incidence and a corresponding advantage for the diagnoses of VO 2 max when incremental tests are supplemented by supramaximal verification bouts. Preliminary evidence suggests that the occurrence of a VO 2pl in continuous incremental tests is determined by physiological factors like anaerobic capacity, VO 2-kinetics and accumulation of metabolites in the submaximal intensity domain. Subsequent studies should take more attention to the use of valid VO 2pl definitions, which require a cut-off at ~ 50% of the submaximal VO 2 increase and rather large sampling intervals. Furthermore, if verification bouts are used to verify the achievement of VO 2 peak/VO 2 max, it should be ensured that they can be sustained for sufficient durations.