[Individual-typological evaluation of cardiorespiratory responses to hypoxia and hypercapnia in young healthy men].

The aim of the study was the approaches development to a substantiation of recommendations on the persons selection for different types of physical exercise on the basis of individual chemoreflex reactivity of cardiorespiratory system. That's for the ventilatory and cardial responses in tests with increasing inhalation hypoxia and hypercapnia on the group of young healthy man was performed. It was shown that hypoxia induce predominantly cardial response, but hypercapnia--ventilatory response. On that predominantly chemoreflex reactions (respiration system to hypercarbia and cardiac--to hypoxaemia) four types of in parts were defined: small reactions in both parts (type 1), small reaction of cardiac system and strong of respiratory system (type 2), strong for heart response and small for respiration (type 3), and strong for both parts (type 4). Statistical analysis has shown that each type of reactions is specific to certain kind of sports training: 1 type for swimmers, 2 and 3 types for skiers, 4 type for boxers, weight lifters and wrestlers. For skiers group the inverse regression dependence between the growth of heart reactivity to hypoxaemia and depression of the pulmonary ventilation reactivity to hypercarbia is revealed at joint rising of the oxygen consumption per unit body weight. High quality skiers are distinguished by relative balance of chemoreflex responses of respiration and heart. It was found that physically untrained persons have pronounced individual variability of cardiorespiratory system chemoreflex reactions, what can be used for personal recommendations for choosing the kind of sports to employment.

[Comparative analysis of gas exchange and cardiorespiratory systems reactions to increasing normobaric hypoxia and physical load of swimmers and skiers].

Qualification comparable groups of young men engaged in cyclic kinds of sports were tested with stepwise accruing loads on bicycle ergometer and 25-minute exponential increasing normobaric hypoxia to final concentration of 10% oxygen. Group of skiers, having the greatest values of the maximal oxygen consumption at muscular work, show the relaxed cardiorespiratory reactions and more falling of blood oxygen in the hypoxia. The swimmers, having restrictions of ventilatory function in the course of trainings, form preadaptation to hypoxia with changes of external respiration and gas exchange functions that allows at hypoxia to better oxygen sate the blood in lungs. The joint assessment of aerobic capacity at physical work and physiological reactions to hypoxia shows the direct relation between individual maximal oxygen consumption and the descent rate of blood oxygen saturation at accruing hypoxia that can be useful at an assessment of a sportsman functional state and its correction at training processes.

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.

Baseline values of cardiovascular and respiratory parameters predict response to acute hypoxia in young healthy men.

The majority of the available works have studied distinct hypoxic responses of respiratory and cardiovascular systems. This study examines how these systems interact while responding to hypoxia and whether baseline metrics moderate reactions to a hypoxic challenge. Central hemodynamic, aortic wave reflection, and gas exchange parameters were measured in 27 trained young men before and after 10-min normobaric isocapnic hypoxia (10 % O2). Associations were assessed by correlation and multiple regression analyses. Hypoxic changes in the parameters of pulse wave analysis such as augmentation index (-114 %, p=0.007), pulse pressure amplification (+6 %, p=0.020), time to aortic reflection wave (+21 %, p<0.001) report on the increase in arterial distensibility. Specifically, initially compliant arteries blunt the positive cardiac chronotropic response to hypoxia and facilitate the myocardial workload. The degree of blood oxygen desaturation is directly correlated with both baseline values and hypoxic responses of aortic and peripheral blood pressures. The hypoxia-induced gain in ventilation (VE), while controlling for basal VE and heart rate (HR), is inversely associated with deltaHR and deltasystolic blood pressure. The study suggests that cardiovascular and respiratory systems mutually supplement each other when responding to hypoxic challenge.

Body thermal state influence on local skin thermosensitivity.

Three series of experiments (I-III) on 33 volunteers aged 20-23 years old were carried out using the climatic chamber. The thermal thresholds were measured on the forearm of men dressed only in swimming trunks. The Peltier thermode was used. Inspection I was carried out in a thermoneutral environment (27 degrees C) with 1 degree C step modification of the initial thermode temperature ("i) within 29-38 degrees C temperature span. In an alternative experiments (II) the "i was supported at 33 degrees C, while the men were exposed to 20, 27 and 38 degrees C. In the last series (III) "i was maintained close to natural cutaneous temperature and the environmental temperatures were 27, 20 and 14 degrees C. It is shown that selected changes of local cutaneous temperature (I series) or the medium temperature (II series) render the a sharply expressed and opposite influence on local thermal thresholds. Common body cooling (III series) also reduces local thermal sensitivity. The equations and three-dimensional graphs linking thresholds of local thermal sensitivity, local skin temperature and average weighted full coverlet temperature (or deep body, or environmental temperature) on obtained data were computed. They allow taking into account the influence of body thermal state in practice of a quantitative cutaneous thermal sensitivity definition.

[Thermoregulatory effect of beta-adrenoreceptor block in the cold-adapted rat at rest and during exertion]. / Termoreguliatsionnyi éffekt blokady beta-adrenoretseptorov u adaptirovannykh k kholodu krys v pokoe i pri rabote.

Inderal does not affect the thermoregulatory system in thermoneutral conditions. Blockade of beta-adrenoreceptors at 6 degrees C decreases the oxygen consumption in cold-acclimated rats and reduces it down to the level of control animals. Cold-acclimated rats have the same level of work hyperthermia at different ambient temperatures (26 degrees C, 6 degrees C) and under inderal injection. Control animals can only the same in warm environment.

[Effect of adaptation to cold and physical training on heat emission during muscle work]. / Vliianie adaptatsii k kholodu i fizicheskoi trenirovki na teplootdachu pri vypolnenii myshechnoi raboty.

People, for a long time exposed to cold and physical training or cold only, exhibit strengthening of thermal regulatory reactions aimed at the preservation of heat in the body in the state of rest, as well as during muscular tension. Adaptation of the organism to cold in the situation of limited motor activity lead to the increase of the thickness of the body "cover" under the conditions of rest in the cold due to the decrease of the temperature of skeletal muscles, while physical training in the cold facilitates stabilization of muscular temperature and, correspondingly, lessening of the thickness of the "cover". At the initial stage of muscular activity thermal regulatory reactions of the organism are aimed at the decrease in heat emission, which promotes accelerated heating of the muscles.