Indigenous ethnic groups of the North have lost some adaptive characteristics because of recent changes in the traditional lifestyle, the giving up of traditional food, and new occupations [1][2][3]. In Yakutia (Sakha), urbanization has most strongly affected university and college students, who are characterized by decreased motor activity and an increased intellectual load. Therefore, the changes in the adaptation potential of this social group are of special theoretical and practical interest.The resistance of the human body to adverse environmental factors is largely determined by constitutional characteristics [4].The morphological and functional characteristics of the indigenous populations of northern Asia have been the subject of numerous studies [5,6]. However, the relationships between the morphological and functional constitutions in different ethnic groups require further analysis.In our opinion, a relationship between body height and hemodynamic parameters is physiologically obvious. A taller body places more stringent requirements on the cardiovascular system (CVS) because the blood supply to the upper body, especially, the brain, requires a more active functioning of the heart and blood vessels [7].It remains largely unknown how exercise performance is related with body size, autonomic regulation type, and hemodynamic type in northern Asian populations.I studied the relationships between exercise performance and morphological and functional characteristics in representatives of different ethnic groups of Yakutia with different body heights. METHODSExercise performance and morphological and functional characteristics were studied in 83 male students of the Yakutian State University, who were aged 17-23 years. The sample comprised 45 Yakuts and 38 Caucasoids who were born in Yakutia (first-or second-generation residents of Yakutia).To study cardiodynamic and hemodynamic parameters, I used tetrapolar thoracic rheography [8]. Initially, the rheograms of subjects sitting on a bicycle ergometer at rest were recorded by means of an R4-02 rheograph. The rheograms were used to calculate the stroke index (SI, ml/m 2 ), cardiac index (CI, l/m 2 ), and heart rate (HR, bpm). An EK 2T-02 electrocardiograph was used. Blood pressure (BP) was measured by the method of Korotkoff.The exercise performance was estimated by the work performed by the subjects at the last stage of a continuous two-stage load on a VE 05 Ritm bicycle ergometer. The loads at the first stage (5 min) and the second stage (until failure, i.e., for as long as the subject was able to perform the exercise) were 100 and 200 W, respectively. The pedaling rate was 60 rpm. All subjects performed the first stage of the load successfully. Therefore, the quantitative parameters of exercise performance were estimated on the basis of the work ( A , kJ) performed at the second (last) stage of the ergometer load: A = Wt /1000 , where W = 200 W is the power of the second stage of the load; t is the time (in seconds) of performing the work with this power at t...

Analysis of spectral power and EEG rhythm index in Yakut students (n=38) was carried out. Higher spectral power values of base alpha rhythm were noted, relatively slow wave teta-and delta-activity. Regardless of the lateralization of the dominant hand, the decreasing occipital-frontal gradient of the alpha-rhythm index was clearly expressed. For the delta rhythm index, the decreasing gradient was directed in the opposite, frontally occipital direction. A similar organization of the bioelectric activity of the brain is characteristic of the tendency to become a "mature" EEG pattern in youth. The formation of brain functional maturity in right-handed and left-handed women is reflected in certain differences in the wave structure of the EEG pattern. A large degree of dominance and great heterogeneity of the alpha rhythm was revealed in the right-handed, while in the left-handeda greater decrease in the power of slow-wave tetaand delta-rhythms. The obtained results of the study of background EEG in young Yakut men indicated the ongoing process of bioelectric activity of the brain. Some lag in the formation of mature EEG in Yakut students may be based on a slowdown in the connections between regulatory subcortical structures (diencephalic synchronizing and stem desynchronizing) and the cerebral cortex, which in turn is specific to the age development of the body in the complex climatic and social conditions of the North.

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Introduction. Since the end of the last century, changes in society have reflected on the morphophysiological status of the indigenous population of Yakutia. The work investigated the dynamics of the physical constitution and functional indicators of the circulatory system in young Yakuts, students of the North-Eastern Federal University, over the past two decades. Material and methods. The study involved young men 18-21 years old: 54 born - in 1998-99 and 63 in 2019, anthropometric studies were conducted, and physical development and body type were assessed. Hemodynamic parameters heart rate and blood pressure were determined: Results. The determination of body mass index (BMI) revealed a high degree of discrepancy between bodyweight and height in students of this century. In 1998-99, the normal BMI value was found in 85.2%, above the norm - in 7.4% of the examined. While in 2019, normal BMI values are observed in 58.7%, in 36.5% - above the norm, including 9.5% - 1-2 degree obesity. In 2019, the distribution of students by somatotype changed: along with a decrease in normosthenics by 14.5% and asthenics by 13.2%, the number of hypersthenics increased by 36.5%. Analysis of hemodynamic parameters depending on the type of constitution revealed significantly higher blood pressure (BP.) values in hypersthenics compared to normostenics and asthenics. Over the 20-year period of observation, students had a significant increase in the values of systolic blood pressure, pulse pressure, and the greatest increase was noted in students with hypersthenic constitution. Conclusions. The revealed shifts of anthropometric indices in modern Yakut students, compared with the young men of 1998-99, indicate an increase in the prevalence of overweight and the development of a constitution according to the hypersthenic type. Against the background of body hypersthenization, the adaptive capabilities of the circulatory system decrease.

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