Dr. Med., Professor A.L. Pokhachevsky^{1, 2}
O.V. Graf³
PhD, Associate Professor A.B. Petrov^{3, 4}
G.S. Marchitan²
Associate Professor G.A. Lebedinskaya^2
1I.M. Sechenov First Moscow State Medical University, Moscow
²I.P. Pavlov Ryazan State Medical University, Ryazan
³Lesgaft National State University of Physical Education, Sports and Health, St. Petersburg
⁴National Medical Research Center named after V.A. Almazov of the Ministry of Health of Russia, St. Petersburg

Keywords: circulatory disorders, neck muscles, cervical spine, neurohumoral regulation of the athlete's body.

Introduction and rationale. Under-recovery associated with underestimation of time for rest and its redistribution during the loading period, excessive load and overload can lead the muscles into a state of excessive readiness, which is manifested by an increase in tone. The deep muscles of the spine, increasing the tone, change the mobility of the vertebrae, and in the cervical region, disrupt the blood flow in the basin of the vertebral artery, which is the direct cause of impaired blood supply to the brain stem. A change in the mobility of the cervical spine, expressed in insufficiency and asymmetry of the angles of inclination and rotation of the head relative to the transverse, sagittal and central axes, caused by a violation of the tone of the deep muscles of the neck, is probably the cause of circulatory disorders in the basin of the vertebral artery. The consequence of this is a violation of the blood supply to the brain stem - one of the probable causes of a violation of the functional state of the athlete's body.
Objective. To reveal the relationship between circulatory disorders in the basin of the vertebral artery and the neurohumoral regulation of the athlete's body.
Materials and methods. A focus group of active athletes, polyathletes, track and field athletes (12 people, 17-22 years old), MS qualification, CMS, 1 sports category was studied. The study included: firstly, an anamnesis of pain, injuries, mobility disorders in the neck, functional tests for the volume and symmetry of movements in the cervical spine; secondly, ultrasound scanning of brachiocephalic vessels, the diameter and linear velocity of blood flow of the vertebral arteries were assessed in areas V1 (from the beginning to the transverse process of the 6th cervical vertebra (C-6)), 2 (from C-6 to C-2), 3 ( from C2 to the entrance to the spinal canal C1) on the left and right; thirdly, an active orthostatic test (AOT), during which the electrocardiogram was recorded for 5 minutes in the supine position (clinostasis), and then standing (orthostasis), including an active transition from the clinostasis position to orthostasis. Frequency analysis of HR was carried out in accordance with the standard. The current functional state was assessed by the TP indicator (total power of the spectrum), taking into account the contribution of fast oscillations (HF-component) - reflecting the activity of the parasympathetic division of the autonomic nervous system, slow oscillations (LF-component) - a marker of the activity of sympathetic influences and very slow oscillations (VLF -component) - reflective, humoral-metabolic and cerebral ergotropic effects on HR. The LF/HF ratio was regarded as sympathetic reactivity. The reactivity of the parasympathetic division was assessed by a ratio of 30:15 [1-3]. The results of the study were processed using the statistical package Statistica 10.0. Since the distribution of values differed from normal, the data are presented as median (Me) and 25.75 percentile (Pc).
Results. Complaints of pain and other disorders in the neck are absent. However, functional tests revealed asymmetry of mobility of the cervical spine. In order to objectify the identified violations, all athletes underwent ultrasound scanning of brachiocephalic vessels. In all cases of changes in the mobility of the cervical spine, a different degree of asymmetry of blood circulation in the basin of the vertebral artery was revealed. At the same time, a decrease in the diameter of the vertebral artery revealed in V1, 2, 3 areas corresponded to a decrease in the linear velocity of blood flow in them.
The revealed violation of blood supply is manifested by a low level of heart rate variability: a decrease in the total power of the spectrum, which is actually based on fast regulatory elements. At the same time, the core of regulation is humoral-metabolic waves both in clino- and orthostasis, and the depressive level of sympathetic supply is replaced by a minimum of parasympathetic reactivity.
Conclusions. Thus, the identified chain of relationships proves the likelihood of one of the reasons for the decrease in the functional state of the athlete's body: an independent change in the tone of the deep muscles of the neck, leading to displacements in the cervical spine, which in turn causes circulatory disorders in the basin of the vertebral artery. The latter circumstance is a probable cause of insufficient blood supply to the vegetative centers of the brain, which leads to a violation of the neurohumoral regulation of the athlete's body.

References

1. Mikhailov, V.M. Heart rate variability (a new look at the old paradigm) / V.M. Mikhailov. - Ivanovo: Neurosoft LLC, 2017. – 516 p.
2. Lapkin M.M., Trutneva E.A., Birchenko N.S., Petrov A.B., Shuliko Y.V., Kalinin A.V. Prognostic potential of time series markers in cardiac rhythmogram in stress testing. Human Physiology. 2019. Vol. 45. N 3. P. 271-282.
3. Lapkin M.M., Birchenko N.S., Pokhachevskiy D.A., Pozhimalin V.N., Petrov A.B. Prognostic potential of exercise cardiac rhythmogram during the early adaptation period. Human. Sport. Medicine. 2018. N 1 (18). P. 46-59