Metabolic and Thermal Responses to Short-Term, Intense Cold Water Acclimation Protocol
Non-compensable cold exposure represents a potentially deadly threat to humans, as we lack highly specialized organs and mechanisms necessary to maintain our optimal core temperature of ~37°C. Repeated exposures to cold have been shown to induce protective physiological changes in cold responses th...
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| Format: | Others |
| Language: | en |
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Université d'Ottawa / University of Ottawa
2019
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| Online Access: | http://hdl.handle.net/10393/39532 http://dx.doi.org/10.20381/ruor-23775 |
| Summary: | Non-compensable cold exposure represents a potentially deadly threat to humans, as we lack highly specialized organs and mechanisms necessary to maintain our optimal core temperature of ~37°C. Repeated exposures to cold have been shown to induce protective physiological changes in cold responses through a process known as cold acclimatization (natural) or acclimation (in laboratory). The purpose of this thesis was to determine what physiological changes occur following an intense 7 day, 14°C cold water immersion acclimation protocol, during both non-compensable (Chapter 2) and compensable cold exposures (Chapter 3). This includes identifying changes in the contributions of the shivering (ST) and non-shivering (NST) thermogenic pathways to overall heat production. ST and NST changes were quantified via electromyography and indirect calorimetry, respectively.
This 7 day cold water acclimation protocol resulted in a decrease in cooling rate, a significant increase in mean esophageal core temperature, a decrease in peak heart rate following immersion, and increased thermal comfort from day 1 to day 7 of the 1h 14°C cold water immersions. Further to these findings, changes in ST and NST were measured pre- and post-acclimation with a standardized compensable cold protocol using a liquid conditioned suit (LCS) which lowered Tskin to 26°C for 2.5h. The cold acclimation protocol resulted in a ~38% decrease in mean shivering over the 2.5h without any change in thermogenic rate from pre- to post-cold acclimation. In addition, no significant difference in fuel selection was observed. These results indicate that the short, intense cold acclimation protocol did result in a substantial change in the contribution of ST and NST to total heat production which could increase cold tolerance by reducing involuntary muscle contractions during ST. |
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