VO2 Steady State at and Just Above Maximum Lactate Steady State Intensity

Abstract

Over recent decades the association between metabolic and gas exchange parameters during exercise has become evident. Different "thresholds" (such as lactate thresholds, critical power, EMG thresholds) and intensity domains appear to be linked to an upper limit of oxygen uptake steady state (V̇O_2SS). The aim of this study was to investigate whether MLSS is associated with the upper limit for a V̇O_2SS. Forty-five subjects underwent one incremental test and 4-6 30-minute MLSS tests on a cycle ergometer. A three-component model was used to describe V̇O₂ response at P_MLSS and just above P_MLSS+1. To evaluate the results, breath-by-breath V̇O₂ and lactate (LA) values were analyzed using the intraclass correlation coefficient (ICC), increasing (k-) values and the Wilcoxon test. According to the calculated k-values of LA and VO₂ at P_MLSS and P_MLSS+1, no significant increase of VO₂ occurred during both intensities (P_MLSS and P_MLSS+1) from minute 10 to minute 30, confirming the existence of a V̇O_2SS. Additionally, the ICC of 0.94 confirmed high accordance of the VO₂ kinetics at both intensities (P_MLSS and P_MLSS+1). This study shows that power output at MLSS workload does not represent an accurate cut for an upper limit of V̇O_2SS.