Alterations in VO2max and the VO2 plateau with manipulation of sampling interval

The most accepted criterion for confirming attainment of VO(2)max is a plateau in oxygen consumption (VO2) at VO(2)max, but its incidence varies. To compare VO(2)max and VO2 plateau incidence across various sampling intervals, and to examine predictors of the change in VO2 (Delta VO2) at VO(2)max. Sedentary, recreationally-active, and endurance-trained subjects (n = 108, age = 24.2 +/- 6.2 year) completed incremental exercise on the treadmill or cycle ergometer. Gas exchange data were obtained breath-by-breath and time-averaged every 15, 30, and 60 s. VO(2)max attainment was verified with the Taylor et al. (1955) criterion (Delta VO2 at VO(2)max <= 2.1 ml kg(-1) min(-1)). Multiple regression was used to examine predictors of Delta VO2 at VO(2)max. VO2 plateau incidence was higher using breath-by-breath (81%) and 15 (91%) and 30 s time averaging (89%) versus 60 s averaging (59%). Compared to 60 s averaging, VO(2)max was significantly higher (P < 0.05) when data were obtained breath-by-breath and with 15 and 30 s time-averaging compared to 60 s sampling. VO(2)max was not related to VO2 plateau incidence. Respiratory rate was a significant predictor of Delta VO2 at VO(2)max in endurance-trained subjects. More frequent data acquisition revealed higher VO(2)max and incidence of the VO2 plateau compared to 60 s time averaging. Secondary criteria to verify VO(2)max attainment should not be used, as they do not discern between subjects who do and do not reveal a plateau in VO2 at VO(2)max.