Open this publication in new window or tab >>2025 (English)In: American Journal of Physiology. Regulatory Integrative and Comparative Physiology, ISSN 0363-6119, E-ISSN 1522-1490, Vol. 328, no 4, p. 433-446Article in journal (Refereed) Published
Abstract [en]
Previous studies have suggested that, during prolonged cold exposure, shivering thermogenesis may gradually be attenuated, supposedly reflecting a state of central fatigue (aka ‘thermoregulatory fatigue’) provoked by extended shivering activity, that precipitates hypothermia. The purpose of this study was to revisit the validity of this notion. Twelve noncold-acclimatized men participated in three ∼10-h sessions, during which they performed repeatedly three 120-min cold-water immersions. To induce discrete amounts of heat-producing thermoeffector output, presumptively leading to distinct levels of fatigue during each session, subjects were submersed, within each session, in either severely (15°C), moderately (20°C), or slightly (28°C) cold water. The cold-induced elevation in thermogenic rate was similar across the three repeated immersions performed within the 15°C (∼130 W·m2) and 20°C (∼100 W·m2) sessions (P ≥ 0.43). In the 28°C-session, the metabolic heat production was augmented by ∼7% in the second and third immersions compared with the first immersion (P = 0.01). No intrasession differences were noted with regards to the body-core cooling rate, the cold-induced drop in skin temperature and forearm cutaneous vascular conductance, or the stress-hormone (salivary α-amylase and cortisol concentrations) and thermoperceptual responses (P > 0.05). The present findings, therefore, demonstrate that the ability to generate heat remains intact during prolonged iterative exposure to a high-heat loss environment in a single day, regardless of the severity of cold stressor. The intermittent application of slight cold stress (i.e., 28°C water) appears to mediate metabolic sensitization, reflecting either the circadian rhythmicity of heat-producing thermoeffector activity, or perhaps the rapid induction of metabolic adaptation.
Place, publisher, year, edition, pages
American Physiological Society, 2025
Keywords
cold adaptation, habituation, hypothermia, immersion, shivering
National Category
Physiology and Anatomy
Identifiers
urn:nbn:se:kth:diva-361776 (URN)10.1152/ajpregu.00310.2024 (DOI)39982218 (PubMedID)2-s2.0-86000485132 (Scopus ID)
Note
QC 20250331
2025-03-272025-03-272025-03-31Bibliographically approved