Emergence of the verification phase procedure for confirming 'true' VO2max

Traditional VO2max criteria are typically based on attainment of a VO2 plateau, and threshold values for the respiratory exchange ratio, heart rate and blood lactate concentration. Despite long-standing criticisms directed at these criteria, their use remains widespread. This article discusses an alternative procedure, termed the verification phase, for confirming the attainment of true VO2max. Following a continuous incremental exercise test to the limit of tolerance and appropriate recovery period, the verification phase is performed and is characterized by a supramaximal square wave exercise bout. Consistent peak VO2 values in the incremental and verification phases, confirms that a true VO2max has been attained. Six recent studies investigated the utility of the verification phase for evaluating true VO2max. These studies consistently found small insignificant mean differences between the maximal VO2 attained in the incremental and verification phases. However, this group mean approach does not identify individual subjects who may not have attained a true VO2max. Notably, only one of the six studies reported a criterion threshold to verify the VO2max of individual subjects. Further research is required to investigate the utility of different verification phase procedures and to establish a suitable verification criterion threshold for confirming true VO2max.