PhD, Associate Professor N.S. Bakhareva¹
S.N. Arkhipenko¹
A.S. Chumakova^1
1Kuban State Medical University, Krasnodar

Key words: anthropometric characteristics, body surface area.

Introduction. Fluctuations in the current number of heart contractions relative to its normal level often serve as a mandatory indicator of various pathological (cerebral palsy, hypothyroidism, infectious diseases, blood loss hypothermia), physiological (pregnancy, sleep, hypnosis, biorhythms, athletic heart), and pharmacodynamic conditions (anesthesia, smoking, alcohol or drug intoxication). Determining the proper number of heart contractions taking into account anthropometric indicators is very relevant.
Research objective - to determine the proper number of heart contractions (PNC) in children of "early childhood" belonging to the North Caucasus ethnic group of Russia, taking into account anthropometric indicators.
Research methods and organization. The experiment used height and weight data from 100 children (50 girls and 50 boys) aged 6.01±0.45 years (Kabardinian and Balkarian). The study was conducted at the kindergarten No. 1 in Chegem, KBR. Calculation of PNC was carried out using the formula of Yu.R. Sheikh-Zade (certificate № 2187247). Determination of body surface area taking into account height and weight indicators was carried out using the formula of Yu.R. Sheikh-Zade, 2000 [1].
Results of the study and their discussion. The statistical analysis revealed no significant differences in the values of morphometric parameters: in indicators of body surface area in boys (9178.9±168.7 cm2) and girls (8798±138.3 cm2); in PNC values between the groups of boys (77.4±0.5 min-1) and girls (78.2±0.6 min-1). An inverse significant relationship was revealed between PNC and body surface area (r=-0.90). In this case, deviation of the current number of heart contractions (CNC) from PNC in the group of boys did not exceed 10% - in 7 individuals, while in others, this deviation was more noticeable, reaching, respectively, 20% - in 8, 30% and more - in 29. In the group of girls, deviation of CNC from PNC did not exceed 10% - in 10 individuals, in others this deviation reached 20% - in 13, 30% and more - in 23 children. When studying CNC in children, it is necessary to focus not on the age of the child, but on his height and weight, directly determining the level of PNC, which is especially important when studying children in different regions, as well as in connection with the phenomenon of children's growth acceleration in the present era of human existence [2]. In children of both genders aged 4-7 years, the vertical dimensions of the body are most susceptible to growth processes, by the end of this age period, the first signs of gender-specific features in body sizes appear [2, 3].
Conclusions. An inverse relationship between body surface area and the proper number of heart contractions has been established. Gender differences in the indicators of the proper number of heart contractions and body surface area were not identified in children of the "neutral childhood" of the North Caucasus region of Russia (more than half of the examined children have the current number of heart contractions deviated from the proper number of heart contractions by 10-30%).

References
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2. Mandrikov V.B. Nikolenko I.N.,Krayushkin A.I. Faces of pre-conscription age (morpho-functional profile and physical development): monograph, Volgograd: VolgGMU Publishing House, 2014. 168 p.
3. Nikolenko V.N., Nikityuk D.B, Klochkova S.I. Somatic constitution and clinical medicine. Moscow: Practical Medicine, 2017. 256 p.