Gender features of autonomic regulation of cardic activity in young athletes

Background. The success of sports activity is related to the level of the athlete's functional state. The analysis of heart rate variability will allow to determine the adaptive capabilities and the state of the reserves of the cardiac activity of the athlete’s body at the present time and to predict the sports result. The purpose of this work is to study the gender characteristics of the autonomic regulation of cardiac activity in child athletes. Materials and methods. The study involved 22 children aged 12 to 18 years. All study participants were divided into 2 groups: group 1 (n = 10) ‒ boys, group 2 (n = 12) ‒ girls. Heart rate, systolic and diastolic blood pressure, body weight, and height were measured noninvasively. We calculated the adaptive potential, body mass index, Kerdo index. For assessment of heart rate variability we calculated the vegetative balance index (VBI), vegetative rhythm index (VRI) and stress index (SI) of regulatory systems. Statistical analysis was performed using t-test, U-test and χ2-test. Results. In both groups, satisfactory adaptation of the cardiovascular system (CVS) to physical activity (AP < 2.6), however, the value of this indicator is higher among boys by 7.25 % (p < 0.001), which may indirectly indicate better functional reserves of the body of girls during adaptation to physical activity. When calculating the Kerdo index and studying heart rate variability (HRV), it was found that 50 % of boys are sympathicotonic and 10 % are parasympathicotonic. Among girls, an increase in the tone of the sympathetic division of the ANS is more common by 8.3 % (p < 0.001). The RRNN value in the boys group is 15 % higher than in the girls group (p < 0.001). The value of NN50 and pNN50 was also higher among boys by 44.87 % and 41.17 %, respectively (p < 0.05). SDNN and RMSSD in the group of girls are less by 25.5 % (p < 0.01) and 34.5 % (p < 0.05), respectively. The mean heart rate is higher among girls by 11.6 % (p < 0.01). IVR, VLOOKUP and IN were higher in the group of girls by 32.8 %, 32.9 % and 50.8 %, respectively (p < 0.01). Conclusions. In both gender groups, satisfactory adaptation of the cardiovascular system to physical activity was revealed. According to linear rhythmograms and columnar histograms, HRV is higher in the boys group, stress indices are higher in the girls group