Hyperoxia speeds pulmonary oxygen uptake kinetics and increases critical power during supine cycling

Goulding, Richie P and Roche, Denise and Marwood, Simon (2019) Hyperoxia speeds pulmonary oxygen uptake kinetics and increases critical power during supine cycling. Experimental Physiology. ISSN 1469-445X (Accepted for Publication)

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The present study determined the impact of hyperoxia on the phase II time constant of pulmonary oxygen uptake kinetics (τ_V ̇ O2) and critical power (CP) during supine cycle exercise. 8 healthy males completed an incremental test to determine maximal oxygen uptake and the gas exchange threshold (GET). Eight separate visits followed, whereby CP, τ_V ̇ O2 and absolute concentrations of oxyhaemoglobin ([HbO2]; via near-infrared spectroscopy) were determined via four constant-power tests to exhaustion, each repeated once in normoxia and once in hyperoxia (FiO2 = 0.5). A 6-minute bout of moderate intensity exercise (70% GET) was also undertaken prior to each severe intensity bout, in both conditions. CP was greater (hyperoxia = 148 ± 29 W vs. normoxia = 134 ± 27 W, P = 0.006) and the τ_V ̇ O2 was reduced (hyperoxia = 33 ± 12 s vs. normoxia = 52 ± 22 s, P = 0.007) during severe exercise in hyperoxia when compared to normoxia. Furthermore, [HbO2] was enhanced in hyperoxia compared to normoxia (hyperoxia: 67 ± 10 versus normoxia: 63 ± 11 μM; P = 0.020). τ_V ̇ O2 was significantly related to CP in hyperoxia (r = 0.89, P < 0.001), however no relationship was observed in normoxia (r = 0.03, P = 0.68). Muscle oxygenation was increased, τ_V ̇ O2 was reduced and CP was increased in hyperoxia compared to normoxia, suggesting that τ_V ̇ O2 is an independent determinant of CP. That τ_V ̇ O2 was related to CP in hyperoxia but not normoxia further supports this notion.

Item Type: Article
Additional Information and Comments: This is the peer reviewed version of an article that has been accepted for publication in Experimental Physiology. The article will be published in its final form at https://doi.org/10.1113/EP087599 This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
Keywords: Critical power, oxygen uptake kinetics, hyperoxia, supine, exercise
Faculty / Department: Faculty of Science > School of Health Sciences
Depositing User: Simon Marwood
Date Deposited: 23 May 2019 13:16
Last Modified: 01 Jul 2020 00:15
URI: https://hira.hope.ac.uk/id/eprint/2863

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