International Union for Circumpolar Health Ministry of Public Health and Social Development of RF Russian Academy of Medical Sciences Siberian Branch of Russian Academy of Medical Sciences Siberian Branch of Russian Academy of Sciences Medical Polar Fund “Science” The Northern Forum

Abstracts

Performance and Health in Cold Climate

Physiological mechanisms of thermal homeostasis maintenance at muscle work in the cold and at adaptation to cold were studied the in the laboratories of the Institute of Physiology.

It is known that new thermal state - working hyperthermia is achieved at long-term muscle work. At the beginning of work the temperature of working skeletal muscles rises, while deep (tympanic) body temperature may even decline. The downstrokes of timpanic temperature are registered only at low air temperatures and they remain when humidified and body temperature air is used for respiration. It points out the participation of the cooled blood of the upper layers of the body in the initial dropping of the deep body temperature. The muscle work energy consumption in the cold rises and the preliminary local warming of skeletal muscles substantially reduces it.

The adaptive changes were studied at the animal and human artificial acclimation with various regimes of cold exposures and by testing of groups of people selected by profession and considering the time of their cold exposure.

Young volunteers passed a 10-day's course of experimental acclimation to cold by LeBlanc’s (1978) scheme. Naked examinees were exposed to 13 C temperature 2 hours a day. The results revealed two groups of persons by body temperature dynamics in the cold - with predominance of "euthermic" and "hypothermic" response types. Intergroup differences were provided by the specific character of cold thermogenesis and vascular responses in the body surface.

In the selected by profession group of people, who had to spend 6-8 hours a day in the cold and with limited motion activity, the decrease of muscle work efficiency and optimal working load were shown. Among those cold adapted persons the rise of physical work energy consumption showed itself in augmentation of oxygen debt. Physiological mechanisms of this energy consumption rise are linked to sympathetic nervous system activation and change of tissue sensitivity to its mediator – noradrenalin, which, through beta-adrenoreceptors, increased the share of free oxidation processes at ATP resynthesis.

Note. Abstracts are published in author's edition

© 1996-2005, Siberian Branch of Russian Academy of Sciences, Novosibirsk
Last update: 06-Jul-2012 (11:52:05)