V.A. Vishnevsky, professor, Ph.D.
K.S. Krivchenkova, postgraduate
Surgut state university of KhMAR-Yugra, Surgut

Key words: physical loads and adaptation to northern conditions, external respiratory system, school phases of ontogenesis.

Relevance. Winter sports are being actively developed in Yugra. The graduates of Surgut state university, such as Tour de Ski victor A.G. Legkov, World Universiade winner S.A. Turyshev, Olympic Games participant E.L. Turysheva and winner of the Biathlon World Cup stages A.A. Volkov, are well-known outside the region and Russia. Meanwhile, the natural climatic characteristics of the region seriously influence the mechanisms of adaptation to physical loads in these conditions. The ideas of stress-limiting body systems and the cross effects of adaptation to different stress factors can underlie their interpretation [7]. With the active warm-blooded life, the main factors limiting the body's tolerance to extreme environmental factors are matching oxygen and energy consumption by the body and the efficiency of performance of the systems that provide gas exchange. When a man breathes in cold environment, the cool-down of the nasopharyngeal and bronchial mucous activates the reflecting mechanisms of shallow and frequent breathing (“northern short breath”) [1], as well as the laryngospasm. This reflex is intended to decrease heat losses trough the respiratory tracts, as these losses even in a dormant state can reach 30-50% from the total heat production. However, during the long-term strenuous activity under low temperatures, that inevitably demands a significant increase in the respiratory minute volume, the defense reflex of bronchiospasm is removed, and a direct cold-induced injury of the lung tissues of the pneumopathy-type is developed: dehydration and thickening of mucous and submucous bronchial layers, smooth muscle hypertrophy, desquamation of the bronchial basal epithelium, hydropic dystrophy and destruction of alveolocytes, vascular hyperelastosis and endosclerosis. The damage of the mucous epithelium of alveoli serves as an additional way for the penetration of virus and bacterial agents.

Beside the cold, several other factors of the northern climate have a detrimental effect on the bronchopulmonary system: the B-group vitamin deficiency, abrupt and non-periodic weather changes accompanied by atmospheric pressure alterations, strong winds. V.N. Katyukhin et al. [6], the doctors from Surgut, revealed that the most cases of severe pneumonia have been registered at the conditions of low air temperatures and high oxygen content in the atmosphere. In the late February the correlation has reached 0,91 at p<0,001. The important pathogenetic role of the pneumotropic aerobic bacteria was assumed; those bacteria are supposed to enhance their activity at high oxygen concentrations. The high oxygen concentrations in the atmosphere and the hyperoxic state are known to cause the reduction of adaptation abilities and even promote a toxic effect. Under the northern conditions, a powerful increase of the free-radical groups occurs not only during the inflammation development, but at the adaptation disorders too.

Thus, winter sports training in Yugra is complicated during the cold season by low temperatures, and during the summer, when the aerobic background is formed, - by low oxygen content in the atmosphere.

The purpose of the study was to analyze the problems of adaptive-compensatory changes in the system of external respiration of Yugra schoolchildren.

Materials and methods. The study was carried out within the regional monitoring of health, physical development and fitness of Yugra schoolchildren [4, 5]. The characteristics of external respiration were estimated by a “Micro Medical” spirometer, using the best flow-volume loop test. The following parameters were calculated: chest circumference (CC); vital capacity (VC); forced expiratory volume in 0,75 s (FEV.75); forced expiratory volume in 1 s (FEV.1); forced vital capacity (FVC); peak expiratory flow (PEF); maximum voluntary ventilation (MVV); forced inspiratory volume in 1 s (FIV1); forced inspiratory vital capacity (FIVC); peak inspiratory flow (PIF); forced expiratory time (FET). The territory was divided into 5 climate zones, according to S.V. Sokolov’s procedure [8]: Northern, Trans-Ural, Western, Central, and Southern.

Results and discussion. The development of the external respiration system proceeds in accordance with the fundamentals of the P.K. Anokhin’s theory of system genesis: at each stage of child’s development the respiratory system is functionally fully formed for this age, corresponding to the environmental conditions; the age changes of the external respiration system occur irregularly and in a heterochronic way. In the primary school age boys have larger CC compared to girls. The earlier girls’ pubescence by 12-13 years eliminates this difference, and with the start of the boys’ adolescent period their CC becomes larger again (Table 1). The fastest growth of the CC occurs between 12 and 15 years for boys and from 9 to 13-14 years for girls. After 16 years the girls’ CC ceases to grow.

Table 1. Chest circumference of Yugra schoolchildren (regional monitoring)

Note: *** - significant differences relative to previous age group at p < 0.001.

The CC and vital capacity (VC) tend to increase from the south to the north of the region (Table 2).

Table 2. Percent of children with different CC values in different climate zones of Khanty-Mansi Autonomous Region (KhMAR-Yugra)

This phenomenon may be considered as a compensatory reaction to the cold air in the northern region. A.A. Vazhenin [3] showed that the aboriginal children of the northern Tyumen have smaller bodies, well-marked transverse sizes of their bodies and developed chest. Therefore, an evolutionary reasonable ecologic type is formed.

The study of the perspiration ease gives important information about the functional abilities of the external perspiration system at various stages of the ontogenesis. As a rule, the resistance of respiration paths is inversely proportional to the lung volume. However, this relationship can be broken when the lung volumes are not proportional to the volume of perspiration paths. For instance, O.A. Antsiferova and A.B. Gudkov [2] detected that children from European Northern Russia have a reduced passability of the perspiration paths. Nonetheless, those data were obtained for a narrow age range (11 – 14 years), and for the region different from KMAR-Yugra. In this regard, we give here the results of our studies performed by the best flow-volume loop method in the schools №39 and №26 of Surgut (Table 3).

Table 3. Forced expiratory volume dynamics in 0,75 s (FEV.75) and in 1 s (FEV.1) for schoolchildren of schools №39 and №26 of Surgut (l/s)

Notes: *** – significant differences relative to previous age group at p < 0,001; ** – at p < 0,01; * – at p < 0,05.

The forced lung volume is known to be restricted mainly by the increasing resistance in respiratory paths. The results of the FEV.75 and FEV.1 investigations stipulate for two conclusions. Firstly, the changes in these parameters are cyclic, with a period of 1-2 years, while the CC and VC values keep growing up to 16 years. This is explained by the fact that the elongation of the bronchial tree prevails over its transverse expansion during the body’s active growth. As a result, the reduction of the dynamic resistance of the perspiration paths slows down. Then active expansion of the bronchial tree occurs, and the relationship between the volume and the resistance restores. The second feature is related to the differences in the age dynamics of the parameters for boys and girls. The boys’ and young men’s FEV.75 and FEV.1 values increase up to 16 years and their changes correspond to the dynamics of the CC and VV. The most intense changes of these parameters occur at 13-14 years, when the development of the lung respiratory function is stimulated by significant hormonal alterations, metabolism acceleration and energy loss heightening. The girls’ and young women’s FEV.75 и FEV.1 values actively grow up to 13 years only. This cannot be attributed to the earlier pubescence and different hormonal state, as CC and VC continue to increase up to 16 years. This indicates the increase of the bronchial resistance to airflow for the 14-17 year old girls and young women from Yugra, that can create preconditions for obstructive disorders in the bronchial tree.

A comparative analysis of the external perspiration parameters of resident and migrant schoolchildren from Yugra is of particular interest. Such analysis shows that Yugra residents, as compared to migrant schoolchildren, have longer and heavier bodies, higher CC values and some other parameters of the external respiration (Table 4). It can be explained partly by the constitutional features of migrants who arrive to Surgut mainly from south republics of the former USSR. However, CC of migrant schoolchildren amounts to 96,4% of CC of their Surgut resident coevals, and FEV.75 and FEV.1 - 85,6 and 86,8% respectively; therefore, the bronchial resistance to airflow of migrant schoolchildren can be considered as more significantly heightened as compared to more adapted to the Yugra conditions resident schoolchildren.

Table 4. Comparative analysis of the external perspiration parameters of Yugra resident and migrant schoolchildren

An analysis of the age dynamics of the system development by the method of multidimensional phase spaces showed that a pronounced increase of the 7-dimensional parallelepiped volume, that contained the quasi-attractor of the external perspiration vector, started from 10 – 11 years and from 14 years for girls and boys, respectively, and so this increase coincided with the period of the most intense growth of the bronchial resistance (Fig. 1). The most significant spread in stochastic and chaotic parameters by the asymmetry factors was observed at the age of 12 and 15 years (Fig. 2).

Fig. 1. Dynamics of volume of quasi-attractor of the external perspiration vector of schoolchildren at stages of school ontogenesis (FEV.1, FVC, PEF, MVV, FIVI, FIVC, PIF, V value, c.u. – sub-space volume)

Fig. 2. Dynamics of index of skewness (c.u.) of the external perspiration vector at different stages of school ontogenesis.

Conclusion. The findings indicate the presence of the features of formation of the evolution conformable ecological type in schoolchildren of the northern areas of Yugra, which is expressed in the form of increased chest circumference and vital capacity in response to a decrease in temperature of the inhaled air. The identified age and gender-related features of the increase of the airways resistance to air flow, preconditioning obstructive disorders of the bronchial apparatus should be taken into account when organizing the training process in winter sports. This applies particularly to girls of middle and senior school ages and migrant children.

References

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Corresponding author: apokin_vv@mail.ru