Independent and combined impact of hypoxia and acute inorganic nitrate ingestion on thermoregulatory responses to the cold
journal contributionposted on 2021-02-09, 11:55 authored by Josh Arnold, Stephen BaileyStephen Bailey, Simon HodderSimon Hodder, Naoto Fujii, Alex LloydAlex Lloyd
Purpose: 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.
- Sport, Exercise and Health Sciences
Published inEuropean Journal of Applied Physiology
- VoR (Version of Record)
Rights holder© The Authors
Publisher statementThis 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/