The article examines the effect on heart rate variability (HRV) indices in athletes depending on training status, different types of physical exertion, gender and age, presented in both cross-sectional and longitudinal studies. Also included is the predictability of HRV during overtraining, athletic condition, and athletic performance. Heart rate variability (HRV) has long been used as a diagnostic marker of overexertion and overtraining. A large body of evidence shows that in athletes of all ages, regular aerobic training usually results in significant improvements in total and instantaneous HRV. These changes, which are accompanied by a significant decrease in heart rate both at rest and during submaximal exercise, reflect an increase in autonomic efferent activity and a shift in favor of enhanced vagal modulation of heart rate. At present, the available data do not allow us to draw definitive conclusions about the usefulness of traditional HRV indices for evaluating the performance of physical exercises and monitoring the training load. The discrepancies in the results published so far are due to several factors, including insufficient study size and design, and different HRV methods. It also remains to be seen whether traditional HRV indices will be useful for diagnosing overexertion and overtraining.

Aim: The non-functional overreaching requires a deeper study because its diagnosing is not based on conventional methods. Orthostatic and clinostatic tests make it easy and quick to detect health problems. The purpose of this research is defining orthostatic reactions among 68 athletes with and without signs of non-functional overreaching. Materials and Methods: Our research comprises 2 groups of 68 athletes subdivided by presence of non-functional overreaching. The first group includes 27 persons with vegetative disorder signs. The second group covers 41 individuals without non-functional overreaching. For all of them, we conducted orthostatic tests to record blood pressure and heart rate horizontally and vertically. Results: The research showed that 9 athletes (33.3% of the O+ group) had unsatisfactory results after body tests in horizontal and vertical positions. All athletes revealed the orthostatic tolerance disorder. For 5 sportsmen, the latter was accompanied by the clinostatic overreaction. Resting heart rate did not vary considerably between both groups (р=0.412). However, orthostatic tests reflected the sharp index rise among 9 individuals. For non-functional overreaching athletes, the mean value (р<0.001) exceeded the corresponding one in the O- group more than twofold. Conclusions: Although today it is possible to differentiate orthostatic-clinostatic tolerance from vegetative dysfunction, further research must be conducted to clarify this syndrome types and to improve physical recovery for non-functional overreaching athletes.

The article examines indicators of autonomic dysfunction and features of autonomic regulation of heart rhythm in athletes. The study was conducted on the basis of the sports medicine center of Sumy State University. Two groups of athletes took part in the study. The first group of athletes included those who had signs of a non-functional state and autonomic dysfunction (in the survey according to Wayne, or it was diagnosed with an unsatisfactory ortho/clinostatic reaction) - 27 people. The second group consisted of 40 people without signs of functional overstrain (overtraining). In the course of the study, highly qualified track and field athletes were examined using the method of heart rate variability (HRV), orthostatic and clinostatic tests, and Wayne's questionnaire. The main temporal, spectral and indicators of heart rate variability were studied, and the predominant type of autonomic regulation of heart activity was established. The study of indicators of vegetative regulation of the heart showed a statistical difference between indicators of heart rate variability in athletes. Thus, the study of the features of heart rate variability makes it possible to assess the state of the mechanisms of regulation of physiological functions in the human body, as well as the general activity of regulatory mechanisms, neurohumoral regulation of the heart, the relationship between sympathetic and parasympathetic links of the autonomic nervous system. It is also quite important that the obtained data on the athlete's functional state can be used in the future to evaluate the athlete's training process and ways to optimize it.

Aim: To form an idea about the necessity of introduction in sport training of sportsmen of modern physiotherapy and rehabilitation technologies on the example of work of university clinic. Materials and Methods: Theoretical analysis and systematization of data of scientific-methodical literature, data of Internet network, as well as research of experience of activity of university clinic and center of sports preparation of highly skilled sportsmen. Conclusions: The work of the multidisciplinary rehabilitation team plays an important role in the restoration of athletes, so their choice should be more individualized with the aim of more effective restoration of functional capabilities of athletes’ performance. The influence of training and competitive loads on the athlete’s body is quite diverse and can cause various appropriate reactions, which are largely determined by the functional state of his body. The effectiveness of the restorative effects is closely related to the initial functional state, and the same procedures, can both accelerate recovery processes and be an additional burden on the body. That is why the development and implementation of scientifically based recommendations on the methodology of training of high-qualified sportsmen on the basis of analysis of modern achievements of medical science and results of own scientific researches is one of the main tasks of this team.