ИСТИНА

Availability of methods for evaluation of cardiac performance, heart rhythm (HR) variability, and blood pressure (BP) variability is of crucial importance in child training in elite sports and in physical training at school. We performed simultaneous recording of HR and systolic and diastolic BP variability parameters. The following standard parameters were recorded in each case: mean, maximum, and minimum values of HR and BP, and spectral power in standard ranges (very-low-frequencies VLF, low-frequencies LF, and high-frequencies HF). Additionally, stress-index, baroreflex sensitivity (BRS), and parameters of cardiac performance such as stroke volume (SV) and cardiac output (CO) were evaluated. The following exercise tests were used: warm-up running at the physical education class at school, Martinet test, and performance of a short program consisting of the same elements in young figure skaters (2min 30sec ± 10sec; submaximal exercise). For evaluation of the physiological parameters during exercise test, they were measured for 2-min in the sitting position before and immediately after the exercise. We also used the data of functional monitoring (2010-2013; 7 control points) for 35 young figure skaters (22 girls and 13 boys at the age of 8-14 years), and for 14 pupils of Moscow general education school (control group; 9 boys and 5 girls at the age of 9-10 years). Stereotyped variations of cardiovascular system parameters were recorded during the first minute after physical exercise (Martinet test): decrease in HR and increase in SV and BRS. On minutes 2-3 after physical exercise of different intensity, the restoration processes in children have individual dynamics. In nonathletic schoolchildren, an increase in HR by 20-30%, and a decrease in SV (by 7-11%) and BRS (by 10-40%) were observed after moderate physical exercise in comparison with the baseline values; stress-index increased by 4-7 times. In the majority of young figure skaters after submaximal exercise, HR increased by 30-50%, SV decreased by 10%, stress-index decreased by 20-30%, and BRS increased by 30-50%. In contrast, under conditions of overtraining, stress-index in young athletes increased by 3-10 times and BRS decreased by 2-3 times. Analysis of the dynamics of the test parameters over 36 months revealed only age-related regularities of changes in the cardiovascular system parameters in young athletes at rest. Variations in training regimens and participation in competitions affected only post-load parameters. These findings suggest that evaluation of parameters characterizing autonomic regulation and cardiac performance in addition to standard parameters (HR, BP, spectral variability parameters, and stress-index) are highly informative for monitoring of the functional status of children with different level of physical fitness. Evaluation of the physiological parameters before and after training of the appropriate intensity provides objective information for the schoolteacher, coach, and physician that can help in planning both physical education classes and elite sport training process