POST-LOADING DYNAMICS OF HEART RATE VARIABILITY INDICES IN HIGHLY QUALIFIED ATHLETES IN THE FORMATION OF OVERSTRAINS BY SYMPATHETIC AND PARASYMPATHETIC TYPES
Authors: Guzii О. V. , Romanchuk A. Р. , Мahlovanyy A. V. 
Published: January 2021

Objective: to determine the HRV changes in highly qualified athletes that occur in the post-loading period, during the formation of overstrains by sympathetic and parasympathetic types.
Research methods. 202 highly qualified male athletes aged 22.6 ± 2.8 years, who are representatives of acyclic sports, were examined. All studies were performed in the pre-competition period using spiroarteriocardiorhythmography (SACR): in the morning, on an empty stomach, in a sitting position on the day of training (K1), immediately (first 5-7 minutes) after training (K2) and the next morning after training on an empty stomach (K3). Each registration lasted 2 minutes.
Results. At the initial stage, changes in HRV were identified, which testified to the development of overstrain of the sympathetic and parasympathetic types. The approach proposed by N. I. Shlyk was used for this purpose, when all athletes had the type of their cardiac rhythm regulation determined at K1, K2 and K3. With this in mind, 2 observation groups were formed – OG1 (with a stable central predominance of regulatory effects on heart rate) and OG2 (with a stable autonomous predominance of regulatory effects on heart rate). In OG1 at K2 and K3 the type II of cardiac rhythm regulation was noted, while in OG2 – at K2 types III and IV of regulation, and at K3 –type IV of regulation were detected. OG1 consisted of 10 athletes, OG2 – 9 athletes. The comparison group (CG) consisted of all 202 athletes.
The analysis of changes in absolute values of HRV indicators at K1, K2 and K3 in OG1 and OG2 in comparison with CG was carried out. The dynamics of changes in most indicators in OG1 at K3 indicates their under recovery compared to CG, except for the indicator LF (ms2), which returns to baseline values and indicates the predominance of the sympathetic circuit of cardiac rhythm regulation. The dynamics of changes in and OG2 indicated a significant recovery of parasympathetic effects at K2, which was characterized by an increase in HFn (n. u) and RMSSD (ms).
In general, the parameters of HRV, which characterize the overstrain of the cardiovascular system regulation, include RMSSD (ms), the values of which at K2 change in the opposite direction during the formation the parasympathetic type of overstrain compared to other athletes as well as its stable decrease at sympathetic overstrain at K2 and K3; the IAB index, which increasing at K2 remains at the same level at K3, at sympathetic overstrain, and at parasympathetic – changes little at K2 and decreases significantly at K3; the PAPR index, which after a pronounced increase at K2 remains moderately elevated at K3 compared to baseline in both variants of overstrain. Activation of VLF-effects in parasympathetic overstrain in K3 was indicative.
Conclusions. The study of post-load dynamics of HRV parameters in athletes with the formation of overstrain by sympathetic and parasympathetic types showed that the most significant are the dynamics of RMSSD, IAB, PAPR and VLF, which can contribute to the use of data for validation of overstrain by sympathetic and, especially, by parasympathetic types.