Khankeldiev Sh. Kh. Regional features of the physical status of youth students fergana 2022 Reviewer

1.9. FEATURES OF THE BODY'S REACTIONS TO PHYSICAL
EXERCISES PERFORMED UNDER CONDITIONS OF HYPERTHERMIA
It is known that an increase in internal body temperature during exercise is one of the main factors that prevent the increase of athletic achievements, and is associated with such dangers as the possibility of overheating of the body, the onset of heat stroke, etc. Especially these dangers increase when performing physical exercises in conditions of high ambient temperature. Therefore, the issues of thermoregulation during exercise have long been the subject of close attention of researchers working in the field of scientific foundations of physical culture and sports.
It has been repeatedly noted in the literature that different people have different individual resistance to performing physical exercises at high ambient temperatures. In the light of the objectives of this work, we will be interested in features of this kind observed in children and students.
The first thorough studies, according to literary sources, in which physiological reactions were compared when performing strenuous muscle work in conditions of high external temperature were performed at the turn of the 60-70 years. It followed from them that women demonstrate less resistance to performing physical exercises in conditions of high ambient temperature than men.
However, it was subsequently shown that physically trained women have lower pulse rates and core body temperature (this was recorded using rectal temperature) than poorly trained men. Since it is known that both the heart rate and rectal temperature during exercise are proportional to the relative values of the maximum oxygen consumption with which this physical exercise is performed. The higher values of heart rate and rectal temperature in women, which were found in the first studies, could be explained by non-sexual characteristics and a lower level of physical fitness of the women studied.
Several studies compared the reactions of men and women who had approximately equal aerobic capabilities. In these studies, it was shown that there are no differences between the sexes in relation to heat load during exercise.
Although, on average, women have less height, less weight and a smaller body surface than men, their body surface to weight ratio is somewhat larger. So, if we take the average data as a basis, then the ratio of body surface to weight in women is 278.4 cm kg, and in men on average 264 cm2 kg. Therefore, when performing physical exercises, when the air temperature exceeds the skin temperature, heat will flow from the external environment due to radiation and convection more quickly in those persons whose body surface to body weight ratio is large. This corresponds to cases when the ambient temperature exceeds 36°.
In addition, some of the heat will come due to solar radiation and at lower temperatures if physical exercises are performed outdoors.
Since the vast majority of studies comparing the physiological responses of men and women to physical activity at different external temperatures were performed indoors, the influence of solar radiation was usually ignored in these studies.
When the skin temperature begins to exceed the ambient temperature, smaller people release heat to the environment through the skin (radiation + convection + evaporation) more quickly than people with large total body sizes, since people with smaller total body sizes have a larger body surface to weight ratio. Therefore, women will have advantages in values at a temperature that does not exceed 36 °.
This is especially true for performing exercises in conditions of high humidity. If the humidity of the air is low, then the main source of heat transfer is evaporation.
In this case, it can be thought that women are in a less advantageous position, since the total water content in their body, as you know, is somewhat less. This is due to the fact that women, as a rule, weigh less and, in addition, have a higher percentage of fat content, as a result of which both the absolute and relative water content in the body of women is somewhat lower than that of men.
If men and women have equal sweating (that is, if the amount of sweat released per unit of time is approximately the same), women may lose in this case a greater percentage of the water that is contained in the body. A high degree of dehydration in women reduces the volume of circulating blood, increases its viscosity, and creates additional stress on the cardiovascular system of women.
Since water has a significantly higher heat capacity (1.98 kcal /g deg.) than fat (0.4 kcal / g deg.) in women, body temperature will rise at a higher rate with the same relative power of work (on I sq. of surface or per kg of body weight), since they have a higher percentage fat content.
This is not, however, the leading limitation in such types of movements as running, since on average women produce less heat when performing physical exercises, due to smaller body sizes and lower running speed (although the strongest female athletes, as is known, show results far exceeding the achievements of average men).
Based on the theoretical differences in the reactions of men and women discussed above, it could be hypothesized that men have an advantage over women when exercises are performed in conditions of high ambient temperature and low humidity.
Indeed, when men and women perform physical exercises at the same values of oxygen consumption per I kg of body weight, at low humidity and high ambient temperature, the core temperature of the body and the skin temperature are also higher in women's heart rate.
However, in this case, women work at higher relative values of oxygen consumption (in comparison with their levels of maximum oxygen consumption), since, as a rule, women have a lower value of maximum oxygen consumption than men. A large relative intensity of physical exercise in women, in this case, increases blood volume to a greater extent than in men, and therefore leads to a higher heart rate.
However, if physical activity is equalized by the relative values of maximum oxygen consumption, that is, for example, if men and women perform an exercise with an intensity equal to, say, 60-70% of their maximum oxygen consumption, then in this case there are no significant differences in the physical reactions of men and women to physical activity.
The core temperature of the body during exercise is proportional to the relative oxygen consumption (in% to their maximum values). When men and women work at the same relative values of maximum oxygen consumption in conditions of high temperature and low humidity, there are no significant differences in rectal temperature indicators between men and women. From the works, significantly large values of rectal temperature in women, which, however, took place only in the period preceding acclimatization.
As for the surface, skin temperature, here the data of various researchers differ. It was found that the skin temperature of women during physical exercises performed in desert conditions is higher than that of men, however, other researchers who conducted studies in the climate chamber did not find significant differences in skin temperature in men and women who performed physical exercises in similar conditions.
When performing exercises in conditions of high temperature and low humidity of the environment, non-clematises men had a higher rate of sweating than women. It was shown that there are no statistically significant differences in the rate of sweating between men and women if both have passed the necessary period of acclimatization. It was found that the rate of sweating in men after acclimatization is greater than in women, however, in this study, men worked at a higher intensity of load than women. An increase in the intensity of energy metabolism in men leads to a greater increase in their heat, which results in the need for greater heat transfer through evaporation in order to maintain thermal balance. The rate of sweating during exercise is highly correlated with heat production. Frey and Kimono found no significant differences in heat tolerance between men and women who had passed the acclimatization period. Before the start of acclimatization, the tolerance of women, estimated by the time limit of work, was lower.
Tolerance in women after acclimatization was higher than in men, however, this is probably due to the fact that men performed exercises with greater intensity of load. The reverse situation was observed in the work of Shapiro et al. who, in the conclusions of their article, reported that even after acclimatization, women had a higher rectal temperature and skin temperature. However, in their experiments, the intensity of the load in women (expressed in % of MPC) was lower than in men.
The above theoretical considerations gave reason to assume that when performing physical exercises in conditions of high temperature and humidity of the environment, women have some advantages over men due to the fact that their ratio of body surface to weight reaches large values. In addition, under these conditions, the amount of sweating is not a limiting factor, since the heat transfer due to the evaporation of the tea is relatively small, which means that the rate of sweating in men when performing physical exercises in conditions of high humidity and ambient temperature is higher than in women.
However, under these conditions, the sweating efficiency is relatively low due to low evaporation values. When performing exercises in conditions of high humidity for a long time, there is a decrease in the intensity of sweating.
The decrease in the activity of sweat glands is apparently related to humidity, where significant differences between men and women in the threshold intensity of physical exercise, causing the onset of sweating, were found.


Table 1
Comparative differences in morphological characteristics of men and women (data by V.V.Bunak)

Morphological specifications	Men	Women
Weight, kg	70,0	58,2
Body length, cm	175,3	162,6
Body surface area, m	1,85	1,62
The ratio of body surface area to weight, m/kg	264,3	278,4

If we equalize men and women in relation to the surface of the body to its weight, then in this case there are no significant differences between men and women both in terms of body core temperature and heart rate. It follows from this that the advantages of women when performing physical exercises in humid hot air are primarily due to the fact that they have a greater ratio of body surface to weight. This facilitates the return of heat through radiation and convection, since the amount of heat production is the same for both men and women.

A cclimatization to exercise in conditions of high temperature and humidity of the environment leads to the fact that both the heart rate and rectal temperature are equally reduced in both men and women. (fig. 1)
Fig. 3 Changes in rectal temperature, heart rate and blood sugar content during exercise in conditions of high external temperature.

Zatsiorsky V.M. et al. found that both men and women working with an intensity equal to about 30% of their maximum oxygen consumption values were approximately the same during the first 90 minutes of exercise. both heart rate and rectal temperature. However, at 3 hours of work, both of these indicators were higher in men than in women. In the same work, it was shown that after acclimatization, the intensity of sweating increases more in men than in women.

Since, when working at high ambient temperatures, heat transfer due to sweat evaporation is limited, a significant part of the released sweat does not evaporate, and in a sense, it is wasted, without contributing to a decrease in body temperature. A higher heart rate in men after acclimatization is quite possibly caused by a greater degree of dehydration of the body, which reduces the volume of circulating blood, increases hematocrit and blood viscosity, imposes additional difficulties on the cardiovascular system.
The facts currently available indicate that women with a low level of physical fitness are much less tolerant of exercises performed in conditions of high ambient temperature than those women who have a high level of aerobic capabilities.
The first signs of acclimatization are observed after the very first classes. It was shown that trained female athletes maintained minute blood volume to a better extent during exercises in conditions of high temperature and humidity of the surrounding air than poorly trained subjects. In these experiments, the intensity of the exercises was selected in such a way that the subjects performed the load in approximately the same percentage of relative intensity from their maximum oxygen consumption. And although there were no significant differences in rectal temperature, heart rate and sweating rate between trained and untrained women, the shock systolic blood volume in non-athletes was lower. The inability to maintain a high level of minute blood volume explains the lower tolerance of low-skilled athletes when performing exercises in heat conditions. This inability to maintain high values of systolic blood volume, quite possibly, may be associated with the loss of blood plasma during exercise, due to increased sweating. The decrease in blood plasma volume in women training in long-distance running was 50% less than in non-athletes.
The authors attribute the differences in the decrease in plasma volume to a large increase in the protein content in plasma in highly qualified athletes compared with untrained individuals. A number of authors found no differences in the decrease in plasma volume as a result of physical exercise in high ambient temperatures as a result of four weeks of training for women who had not previously engaged in systematic physical exercise. However, at the same time, they found a significant increase in plasma volume at rest and the total protein content in plasma after exercise.
As for the training methods, it was found that the use of interval training methods in running increases the length of time during which the subjects can exercise in conditions of high ambient temperature. It has been shown that acclimatization to exercise in conditions of high air temperature is faster in trained than in untrained athletes in the case when all subjects perform exercises at the same level relative to the intensity of physical activity (in% of their individual MPC).
Training approximately equally reduces the threshold value of the load that leads to sweating in both men and women. However, trained women begin to sweat with greater intensity than untrained women. The earlier onset of sweating and its higher intensity in trained athletes are probably associated with increased secretory activity and with the sensitivity of sweat glands, which increases as a result of training.
Summing up, we can say that when men and women perform exercises with the same relative intensity (in % of their level of maximum oxygen consumption), the differences between them in their response to physical exercises performed in conditions of high temperature and low humidity of the surrounding air are negligible. Naturally, if men perform physical exercises with a higher relative intensity (in% of the values of maximum oxygen consumption), they have a higher core body temperature and heart rate than women.
From the above data, it follows that women are more able to withstand high air temperature when it is combined with high humidity. The greater tolerance of women to exercise in conditions of high temperature and high humidity is obviously associated with a more favorable ratio of their surface and body weight, which facilitates heat transfer through radiation and convection. The threshold of sweating as a result of training is also reduced in cases when the exercise takes place in conditions of high ambient humidity and evaporation turns out to be an ineffective heat transfer mechanism. As a result of training, there is an earlier suppression of excessive sweating in trained athletes compared to untrained ones. This protects the body from excessive moisture loss.