“WORK-TO-WORK” EXERCISE SLOWS PULMONARY OXYGEN UPTAKE KINETICS, DECREASES CRITICAL POWER, AND INCREASES W’ DURING SUPINE CYCLING

Goulding, Richie P and Roche, Denise and Marwood, Simon (2018) “WORK-TO-WORK” EXERCISE SLOWS PULMONARY OXYGEN UPTAKE KINETICS, DECREASES CRITICAL POWER, AND INCREASES W’ DURING SUPINE CYCLING. Physiological Reports, 6 (21). ISSN 2051-817X

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Abstract

We have previously demonstrated that the phase II time constant of pulmonary oxygen uptake kinetics (τ_V ̇ O2) is an independent determinant of critical power (CP) when O2 availability is not limiting, i.e. during upright cycle exercise in young, healthy individuals. Whether this causative relationship remains when O2 availability is impaired remains unknown. During supine exercise, which causes an O2 availability limitation during the exercise transition, we therefore determined the impact of a raised baseline work rate on τ_V ̇ O2 and CP. CP, τ_V ̇ O2, and muscle oxygenation status (the latter via near-infrared spectroscopy) were determined via four severe-intensity constant-power exercise tests completed in two conditions: 1) with exercise initiated from an unloaded cycling baseline (U→S), and 2) with exercise initiated from a moderate-intensity baseline work rate of 90% of the gas exchange threshold (M→S). In M→S, critical power was lower (U→S = 146 ± 39 W, vs. M→S = 132 ± 33 W, P = 0.023) and τ_V ̇ O2 was greater (U→S = 45 ± 16 s, vs. M→S = 69 ± 129 s, P = 0.001) when compared to U→S. There was no difference in tissue oxyhaemoglobin concentration ([HbO2 + MbO2]) at baseline or during exercise. The concomitant increase in τ_V ̇ O2 and reduction in CP during M→S compared to U→S shows for the first time that τ_V ̇ O2 is an independent determinant of CP in conditions where O2 availability is limiting.

Item Type: Article
Additional Information and Comments: © 2018 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
Keywords: critical power, exercise tolerance, oxidative metabolism, oxygen uptake kinetics, power-duration relationship, work-to-work exercise.
Faculty / Department: Faculty of Science > School of Health Sciences
Depositing User: Simon Marwood
Date Deposited: 19 Nov 2018 15:58
Last Modified: 19 Nov 2018 15:58
URI: http://hira.hope.ac.uk/id/eprint/2670

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