Temperature homeostatis and work efficiency in the cold.

The data concerning thermal homeostasis maintenance and energy cost of muscle work in a cold environment and at cold adaptation are presented. It was shown that 10 days' experimental acclimatizing to cold at daily two hour +13 degrees C sessions result in different individual adaptive forms, "euthermic" and "hypothermic", which have specific thermogenesis and body shell vascular reactions in a cold environment. Complex investigations were made on selected groups of people on the basis of professional work with the count of cold exposure time and level of muscular activity in cold. It was shown that daily repeated cold exposure lasting many hours at a circumscribed moving activity results in a reduction of performance efficiency and optimum muscular work power. On the other hand, the power of optimum load and efficiency of performance increases with regular physical exercises in a warm environment. Repeating muscular work in a cold environment does not change performance efficiency, rather it increases the power of optimum load. After acclimatization to cold, additional energy costs of muscular work come to light in the augmentation of the oxygenous debt. Physiological mechanisms of this energy consumption rise are linked to sympathetic nervous system activation and change of tissue sensitivity to its mediator--noradrenalinum.

[Systemic reactions and the central mechanisms of respiratory regulation in adaptation to cold and hypoxia]. / Sistemnye reaktsii i tsentral'nye mekhanizmy reguliatsii dykhaniia pri adaptatsii k kholodu i gipoksii.

Respiratory and circulatory changes in response to various physiological stimuli (hypoxia, cold, etc.) were studied. The respiratory center was found to play the leading role in the developing a response. Upon repeated exposures to cold and hypoxia, the central regulatory mechanisms include nonspecific compensatory mechanisms by changing the sensitivity of the respiratory center and its thresholds. Various regulatory strategies were found at different stages of adaptive processes. There was a correlation between the changes in the respiratory center and thermoregulatory shifts. The respiratory center was demonstrated to play a system-forming role. It is suggested that determination of the sensitivity of the respiratory center may serve for prognostic and diagnostic purposes.

[Individual typological characteristics of the cardiovascular reaction to partial body cooling in workers on field-watch assignments]. / Individual'no-tipologicheskie osobennosti reaktsii serdechno-sosudistoi sistemy na lokal'noe okhlazhdenie u rabotnikov po ékspeditsionno-vakhtovomu metodu.

Due to the use of a cluster analysis 5 types of the individual cardiovascular response to hand local cooling and of cold thermosensitivity were identified. The following groups were determined: I. non-cold-adapted group with elevated cold thermosensitivity and vascular response to local cooling, young age and short-term length of service on watch; 2. the group with different levels of thermal adaptation on the verge of the 3-year period of work, the age being similar; 3. the group with extremely low cold thermosensitivity and moderate vascular response to local cold. The group is characterized by long-term length of service and positive forecast as to individual work under subextreme conditions of being on dispatch watch.