Condition of Heart Rate Variability in Adolescence under the Conditions of the Active Orthostatic Test as the Method of Autonomic Regulation Assessment

The objective of the research was to study the expediency of heart rate variability indices use in terms of active orthostasis as adaptative reserve assessment. Materials and methods. The study involved students at the age of 17-19 with different levels of physical fitness. The girls of the main group were engaged in physical exercises only during physical education classes. The girls of the control group had been engaged in aerobics and jogging for 2-3 years already. The heart rate variability under the conditions of active orthostatic test and exercise tolerance was evaluated. Results of the research. Moderate activation of sympathetic-adrenal system on the background of reduced exercise tolerance was observed in the girls of the main group. It was indicated by increase in index of strain by 22.7 %, LF and LF/HF indices on the background of cholinergic (HF) system tonus reduction. The changes indicated excessive cerebral ergotropic impact on lower regulatory structure under the conditions of active orthostasis in girls with low physical activity. Index of higher autonomic centers activity that is the index of centralization was 53.64 % higher than initial results under the conditions of active orthostasis in girls of the main group. Such fact was not observed in the girls of the control group indicating to the advantage of central boundary over the autonomous one. The results can serve as a marker of disadaptation syndrome in adolescence. Conclusions. Heart rate variability analysis in terms of orthostasis can be recommended to determine the condition of adaptation reserves in young people. ?