Cold Adaptations

Abstract

Nowdays, occupational and recreational activities in cold environments are common. Exposure to cold induces thermoregulatory responses like changes of behaviour and physiological adjustments to maintain thermal balance either by increasing metabolic heat production by shivering and/or by decreasing heat losses consecutive to peripheral cutaneous vasoconstriction. Those physiological responses present a great variability among individuals and depend mainly on biometrical characteristics, age, and general cold adaptation. During severe cold exposure, medical disorders may occur such as accidental hypothermia and/or freezing or non-freezing cold injuries. General cold adaptations have been qualitatively classified by Hammel and quantitatively by Savourey. This last classification takes into account the quantitative changes of the main cold reactions: higher or lower metabolic heat production, higher or lesser heat losses and finally the level of the core temperature observed at the end of a standardized exposure to cold. General cold adaptations observed previously in natives could also be developed in laboratory conditions by continuous or intermittent cold exposures. Beside general cold adaptation, local cold adaptation exists and is characterized by a lesser decrease of skin temperature, a more pronounced cold induced vasodilation, less pain and a higher manual dexterity. Adaptations to cold may reduce the occurrence of accidents and improve human performance as surviving in the cold. The present review describes both general and local cold adaptations in humans and how they are of interest for cold workers.

Ecological Genetics of Thyroid Hormone Physiology in Humans and Wild Animals

“…Similar cases were also found for indigenous Nenets and nonindigenous Russians: both showed significant increases in total T4 levels during winter, but the magnitude of the increase was significantly greater in the Nenets than in the Russians [27]. Because thyroid hormones play important roles in regulating metabolic rate and adaptation to cold environments [28,29], human populations inhabiting colder environments may acquire genetic basis for more efficient thyroid hormone-induced thermogenesis and may therefore be genetically adapted to cold environments [30].…”

XP-Antarctik Expedition: The Effect of a Month-Long Expedition in Antarctica on Physiological Performance

“…At the same time, these thermal sensation and pain decreases induce a greater risk of cold injuries, such as frost bite (Leppäluoto, Korhonen, & Hassi, 2001;Mäkinen, 2010). Despite this risk, cold adaptations represent one of the means for the prevention of pathophysiology effects from exposure to cold environments according to Launay and Savourey (2009). The authors explain that adaptation to cold induces less discomfort, preserves dexterity, prevents general and local cold illnesses and injuries, and improves survival in a cold environment.…”

“…Launay and Savourey(2009) describe the term adaptation as the changes that reduce the physiological strain produced by the cold, unlike the term acclimation where the changes are in response to an experimentally and specific condition (e.g., wind or temperature) or the term acclimatization where the changes occur as a response to a natural climate, as is the case in the present study. The last term defined by Launay and Savourey (2009) was habituation used to elicit new physiological responses or more pronounced physiological reactions induced by an acclimatization or acclimation. Thus, the mechanisms that occur under conditions of acclimatization and habituation can help one to propose more efficient physiological preparation for Polar explorers before an expedition.…”

Thermal stress, human performance, and physical employment standards

“…Finally, with prolonged cold exposure, there is some evidence of elevated nonshivering thermogenesis through metabolic or muscular changes. The evidence for physiological adaptations from longitudinal cold exposure is equivocal (Launay and Savourey 2009), with the dominant adaptation a perceptual habituation and desensitization to cold stress rather than large-scale systemic physiological changes as seen with heat acclimatization. Despite population and longitudinal evidence of cold adaptation in the extremities through greater local blood flow and digit skin temperatures, this has largely not been observed in laboratory acclimation studies (Cheung and Daanen 2012).…”