VO2 linear-onset kinetics spanning steady- and non-steady-state exercise

Robert Robergs; Bridgette O'Malley; Anais Dewilde; Shaun D’Auria; Ales Krouzecky

doi:10.3389/fphys.2025.1547662

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VO2 linear-onset kinetics spanning steady- and non-steady-state exercise

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VO2 linear-onset kinetics spanning steady- and non-steady-state exercise

Robert Robergs, Bridgette O'Malley, Anais Dewilde, Shaun D’Auria and Ales Krouzecky

Frontiers in Physiology, Vol.16, pp.1-16

2025

DOI: https://doi.org/10.3389/fphys.2025.1547662

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Abstract

cycling

endurance exercise

training

plateau

critical power

oxygen consumption

Introduction: The traditional method for quantifying the kinetics of the increase in the body’s consumption of oxygen (VO2) during exercise transitions to steady state involves application of a mono-exponential function. Anomalies exist to question the validity of this method, as they show the initial (∼1 min) of this VO2 response is linear. Methods: Fourteen highly endurance trained subjects (12 males, 2 females) completed a ramp incremental cycling protocol, as well as 8 different constant load trials at 43 to 148 % of their critical power (CP). Results: For the initial five exercise bouts, the linear fit of the initial segment was significantly more accurate (lower standard error of estimates; SE) compared to the mono-exponential fit (p < 0.001). There were two different systematic profiles of the linear onset (LO) VO2 slope from different bouts of increasing exercise intensities; 1) a sustained increase (increased kinetics) (n = 7), and 2) a plateau or decrease (impaired kinetics) (n = 7). Both sub-groups were similar in all measures of cardio-respiratory and muscular endurance. Discussion: The LO VO2 kinetics method is superior to the traditional approach as it was a more valid representation of the initial VO2 response, can be applied to both steady and non-steady state exercise intensities, requires less than 2 min of exercise, but across multiple bouts, and identifies more complex physiology than the mono-exponential method. Added research is needed to discern the most valid methods to measure LO VO2 kinetics, and to learn more about its physiological determinants compared to the traditional mono-exponential method.

Details

Title: VO2 linear-onset kinetics spanning steady- and non-steady-state exercise
Authors: Robert Robergs (Corresponding Author) - Queensland University of Technology
Bridgette O'Malley - Queensland University of Technology
Anais Dewilde - Queensland University of Technology
Shaun D’Auria - Queensland Academy of Sport
Ales Krouzecky - Charles University
Publication details: Frontiers in Physiology, Vol.16, pp.1-16
Publisher: Frontiers Research Foundation
Date published: 2025
DOI: 10.3389/fphys.2025.1547662
ISSN: 1664-042X
Copyright note: © 2025 Robergs, O’Malley, Dewilde, D’Auria and Krouzecky. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Data Availability: The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.
Organisation Unit: School of Health - Biomedicine; School of Health - Sports & Exercise Science
Language: English
Record Identifier: 991156940002621
Output Type: Journal article

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