The Effect of Hypoxia and Cold at Rest on Human Thermoregulation.
NAVAL HEALTH RESEARCH CENTER SAN DIEGO CA
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Cold is associated with altitude, and the higher the altitude, the lower the temperature. As the ambient temperature decreases, oxygen consumption VO2 in humans at rest increases Feith, Hesslink, Reading, Kincaid, Pozos, 1993 LeBlanc, 1986 Reading, Kincaid, Roberts, Hesslink, Pozos, 1994 Robinson Haymes, 1990 Tikuisis, Bell, Jacobs, 1991. As cold stress increases, VO2 and heat production rise. This rise is primarily due to shivering Kleinebeckel KIussmann, 1990. When hypoxia is added to cold at rest, less shivering and a lower VO2 can occur. Controversy exists as to the threshold altitude or oxygen O2 percentage at which shivering is reduced. A threshold level of 12 oxygen simulating an altitude of 4160 m has been proposed for reduction in shivering and VO2 Kottke, Phalen, Taylor, Visscher, Evans, 1948 Blatteis, 1971. Resting thermogenesis, or the ability of the body to create heat in order to maintain homeostasis, occurs in part by shivering. If shivering is limited, decreased, or stopped, core temperature will decline, and the person will become hypothermic and eventually die if core temperature is not restored to normal. In a military environment, hypothermia will impede combat performance by rendering the hypothermic person ineffective to carry out hisher mission, and it will increase manpower demands by requiring attention from at least one other person. Therefore, maintenance of a stable core temperature during cold exposure is of paramount importance if troops are to be battle ready.
- Medicine and Medical Research
- Stress Physiology