The classic research of Hill and Lupton (1923) revealed a linear increase in the steady and non-steady state rate of whole-body oxygen consumption (wbVO₂) while running on a grass track at exercise intensities ranging from low to exhausting. Since this time, we have now come to know that oxygen-uptake (VO₂) exhibits considerable variability above the ventilation threshold (VT), and contrary to previous expectations, does not represent a system with first-order linear dynamics. The exact slope of the VO₂ gain (ΔVO₂/ΔWR) above the VT remains controversial with some studies reporting steeper "excess VO₂", while others have documented "curvilinear responses", and even less steep increases in VO₂. Multiple physiological explanations for variable VO₂ gain during incremental exercise have been proposed but the involvement of changing motor unit recruitment and between-participant differences in muscle fibre types remain ambiguous due to contradictory results and methodological concerns. Therefore, the aim of this study was to investigate the within and between participants’ variability in the VO₂ gain that occurs during incremental exercise, and to improve understanding of these responses based on added data for VO₂max, muscle EMG activity, VT, and VO₂ kinetics.

Project Owner: Queensland University of Technology
Year commenced: 2021
Year completed: 2022
Status: Completed
Project ID: ID-230907-1059