Arnold2021_Article_IndependentAndCombinedImpactOf.pdf (1.1 MB)
Download fileIndependent and combined impact of hypoxia and acute inorganic nitrate ingestion on thermoregulatory responses to the cold
journal contribution
posted on 2021-02-09, 11:55 authored by Josh Arnold, Stephen BaileyStephen Bailey, Simon HodderSimon Hodder, Naoto Fujii, Alex LloydAlex LloydPurpose: This study assessed the impact of normobaric hypoxia and acute nitrate ingestion on shivering thermogenesis, cutaneous vascular control and thermometrics in response to cold stress. Method: Eleven male volunteers underwent passive cooling at 10°C air temperature across four conditions: 1) normoxia with placebo ingestion, 2) hypoxia (0.130 FiO2) with placebo ingestion, 3) normoxia with 13 mmol nitrate ingestion, 4) hypoxia with nitrate ingestion. Physiological metrics were assessed as a rate of change over 45-mins to determine heat loss, and at the point of shivering onset to determine thermogenic thermoeffector threshold. Result: Independently, hypoxia expedited shivering onset time (p = 0.05) due to a faster cooling rate as opposed to a change in central thermoeffector thresholds. Specifically, compared to normoxia, hypoxia increased skin blood flow (p = 0.02), leading to an increased core-cooling rate (p = 0.04) and delta change in rectal temperature (p = 0.03) over 45-mins, yet the same rectal temperature at shivering onset (p = 0.9). Independently, nitrate ingestion delayed shivering onset time (p = 0.01), mediated by a change in central thermoeffector thresholds, independent of changes in peripheral heat exchange. Specifically, compared to placebo ingestion, no difference was observed in skin blood flow (p = 0.5), core-cooling rate (p = 0.5) or delta change in rectal temperature (p = 0.7) over 45-mins, while nitrate reduced rectal temperature at shivering onset (p = 0.04). No interaction was observed between hypoxia and nitrate ingestion. Conclusion: This data improves our understanding of how hypoxia and nitric oxide modulate cold thermoregulation.
History
School
- Sport, Exercise and Health Sciences
Published in
European Journal of Applied PhysiologyVolume
121Issue
4Pages
1207-1218Publisher
Springer VerlagVersion
- VoR (Version of Record)
Rights holder
© The AuthorsPublisher statement
This is an Open Access Article. It is published by Springer under the Creative Commons Attribution 4.0 Unported Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/Acceptance date
2021-01-10Publication date
2021-02-09Copyright date
2021ISSN
1439-6319eISSN
1439-6327Publisher version
Language
- en