This review presents current summarized knowledge on definition, causes, symptoms and evidence of overtraining syndrome in athletes. Analysis of biochemical, physiological, endocrine, neuronal and mycological parameters, each of which is potentially involved in understanding of the metabolic aspects of overtraining syndrome, is required to study the latter. The development of overtraining syndrome is explained by numerous hypotheses with their own strengths and weaknesses. Each theory is centered around a key parameter, disbalance of which can lead to overtraining during the execution of long-term high intensity training loads. Obviously none of isolated markers can be used for diagnostic purposes. A comprehensive approach to explain overtraining syndrome development is provided by a theory of cytokines.

Objective: to study the effect of transmeridian air movements in contrasting geosocial conditions of competition on the direction and duration of stabilization of the chrono-resistance of athletes during periods of desynchronosis. Materials and methods: the study involved 103 highly skilled athletes – men of various specialties (age 22.6 ± 4.2 years). On the model of air movements across 7 time zones, the frequency, structure, and focus of reducing or increasing medical circulation reflecting the body's resistance during chronoadaptation were analyzed. Results: before the flight, athletes' visits to the doctor were rare exceptions. After air travel, pathological manifestations in health status were detected in more than 40% of migrants. Over 50% of the medical treatment accounted for well-compensated foci of chronic infection, relapses of erased diseases and injuries. The maximum frequency of medical treatment was observed at the 2-3rd week after the flight, at the 5th week - sporadic, but higher than in the "home" conditions. Conclusions: for the relative stabilization of the body's resistance in athletes in contrasting geo-modern regions, more than a month of acclimatization is required. The minimal decrease in the chrono-resistance direction is manifested at 2-3 weeks after the flight in the stage of transition of «acute» desynchronosis to hidden.

Objective: to evaluate the data of cardiac screening to identify cardiac pathology and determine sports participation among in athletes of Youth Sports Schools in five districts of St. Petersburg. Materials and methods: 9847 young athletes (average age 13.8 ± 4.9 years, 6127 men) were included in the study during 8 months. Clinical protocol uncluded the collection of complaints, anamnesis, family anamnesis, physical examination, ECG in 12 leads. If necessary, Holter monitoring, echocardiography, and an exercise test were performed. Results: typical ECG changes were registered in 60.4% of athletes, borderline in 0.05% and pathological in 3.69%. All athletes with pathological changes were excluded from the training and competitive process for the period of in-depth medical examination. In the end, two athletes were not allowed to continue participation in sport (2 with stressful ventricular arrhythmias). There was not any lethal outcomes for the entire period of the study. Conclusions: cardiological screening using the routine ECG method remains the main tool for identifying a possible pathological substrate and assessing the risk of sudden cardiac death. Early detection of cardiac arrhythmias and conduction disturbances allow to take measures to prevent sudden cardiac death.

Objective: to assess the impact of physical activity of different orientation and intensity on the physical performance and maximum oxygen consumption (MOC) in qualified athletes, depending on the period of the training process. Materials and methods: 136 male athletes were examined, 116 of them were qualified athletes (age 22.1±4.1 years). I group – wrestling (n=30), II – cross-country skiing, biathlon (n=27), III – powerlifting (n=33), IV – volleyball (n=26). V – control (n=20), sports training less than 3 years. Bicycle ergometry (VEM) with the assessment of physical performance on the PWC170 test in the preparatory and competitive periods of training was conducted. STATISTICA 10.0 program was used for statistical processing. Data were presented as: median (Me), lower and upper quartiles (25% and 75%). Results: the highest rates of PWC₁₇₀ – 1508.0 KGM/min and IPC – 65.37 ml/min/kg in the preparatory period and, respectively, PWC₁₇₀ – 1560.0 KGM/min and IPC – 68.00 ml/min/kg in the competitive period were achieved by athletes in group II. Athletes in group III had the lowest rates of PWC₁₇₀ – 1100.0 KGM/min and IPC – 40.60 ml/min/kg in both the preparatory and competitive periods – 1120.0 KGM/min and 42.04 ml/min/kg. Conclusions: high level of physical performance and MOC indicated the effectiveness of the cardiovascular system in athletes of highly dynamic sports, training for endurance (crosscountry skiing, biathlon). In powerlifters with high intensity of static loads, physical performance and MOC remained at a low level. The results can be used to make timely adjustments to the training and competitive process of athletes.

Objective: assessment of the actual nutrition of athletes involved in cyclic sports. Materials and methods: actual nutrition was investigated using 24-hour (daily) nutritional reproduction. Anthropometric study was conducted by height (cm) and body weight (kg) measuring with subsequent calculation of body mass index (BMI, kg/m²). Body composition was determined by the method of bioimpedansometry. Biochemical markers of nutritional status were determined using the «400 ABXPENTRA» Analyzer in unattended mode. Results: assessment of the actual nutrition of athletes revealed its imbalance-excess consumption of animal fat, cholesterol, sodium and added sugars (including confectionery). In the diet of athletes a vitamin deficiency of Group B, magnesium, calcium was detected, that was due to the insufficient consumption of dairy products, fish, vegetables and fruits. Conclusions: nutritional disorders caused adverse changes of the nutritional status in some of athletes surveyed that manifested by changes in the body composition, dyslipidemia against the background of insufficient efficiency of recovery processes and the risk of overwork.

Objective: comparative estimation of anthropometric parameters and body composition of elite athletes, specialized in some non-playing sports – bobsleigh, biathlon, bullet shooting and snowboarding. Materials ant methods: anthropometric measurements and bioimpedance analysis of body composition of 180 women and men elite athletes at precompetitive period were held. Average age of surveyed men (n=107) was 21,7±0,8; women (n=73) – 23,1±1,5. Results: anthropometric data analysis indicated that athletes who engaged in bobsleigh, had the highest mass-height indicators (men: height – 183,4±5,27 cm, body mass – 89,5±8,17 kg; women: height – 172±4,71 cm, body mass – 70,3±7,19). Percent of athletes with exceed waist/ hip index (WHR) was higher among bobsledders. It was indicated, that athlete’s body composition differed from average non-athletes population standards. Average indicators of absolute muscle body mass (MBM) among studied men and women athletes who engaged in all four sports exceeded the average reference population values. What is more, it was finding that significant increase of this indicator was detected among men (48,5±5,14 kg) and women (36,9±6,67 kg) bobsledders that was typical for individuals with increased physical activity. The highest indicators of %MBM were registered in bobsleigh athletes of both sexes (men – 54,18%, women – 52,62%). Average values of absolute and relative amount of fat body mass (FBM) of shooters, bobsledders and snowboarders of both sexes were in limits of population standards; but men (7.91±1.5 kg; 11.51%) and women (9.0±1.77 kg; 15.83%) biathlonists had values below average due to specificity of this sport. Conclusions: significant differences in height-weight indicators and body mass index (BMI) of athletes involved in various non-playing sports were found. Also, features of the body component composition of athletes of various specializations were revealed: the lowest absolute indicators of fat body mass were found in biathlonists; the most pronounced muscle body mass indicators were observed in representatives of the bobsleigh. A pronounced correlation between some body composition indicators and anthropometric indexes of physical development was revealed: correlation of WHR, BMI and %FBM, mainly among shooters and bobsleighists; MBM indicator with extracellular liquid (Extra.F) and intracellular liquid (Intra.F) indicators. Also the prevailing majority of athletes had excess Intra.F: 1.03-1.63 times higher relative to the reference values of the population standard.

Objective: to study emotional and characterological features of hockey players with different stress resistance. Materials and methods: 120 hockey players of the Junior Hockey League (JHL) aged from 16 to 21 years were involved in the study. Interviewing, evaluation of medical records, test of differential self-assessment of the functional state (SAN) and method of personality research using the questionnaire FPI (modified form B) were conducted. Results: according to the results of the study, it was found that hockey players with high stress resistance had significantly lower rates on the scales of neuroticism, depression, irritability, emotional lability, as well as significantly higher rates on the scales of sociability, openness, well-being and mood (p<0.05). On the contrary, hockey players with low stress resistance had opposite features. Also, hockey players with high stress resistance had a higher sports experience, as well as better health. Conclusions: stress-resistance of players has significantly high connection with neurotism and irritability, as well as significant moderate negative association with age and sports experience. It is established that with increasing of neuroticism and irritability, as well as reducing of the age and sports experience stress resistance of hockey players decreases. Taking into account the results of the study, in order to maintain health, prolong professional longevity and maintain the proper level of performance of hockey players, it is important to use an integrated approach that provides a whole group of activities: rationalization of work and rest, improvement of working conditions, optimization of microclimate in the team.

In recent years, progress has been observed in the field of psychological support for both the training and education of the younger generation and sports training. Directly psychological training of athletes plays a big role in achieving sports results. Athletes with high psychological preparation should participate in the competition. This condition is determined by the real assessment of their capabilities, the optimal level of emotional arousal, the lack of fear and the struggle for the best result with a rival. The organization of optimal psychological support and also psychological preparation of athletes leads to a deliberately effective psychological selection of athletes. At the same time, in our republic, attention was paid to psychological training, psychological selection and individual typological properties of athletes, that today occupy an important place in physical education and training of athletes. A psychologically prepared athlete can control his actions, exercise maximum thinking in difficult situations in the sports arena. And, as you know, an insufficient level of psychological readiness often leads to poor results and defeats at competitions.The article reveals some of the main aspects and problems of studying the psychological properties and characteristics of the personality of athletes, presents the psychomotor factors that determine the process of developing of special sports abilities and the effectiveness of activities in any sport.

Objective: evaluation of the hemodynamic characteristics of blood flow in athletes of youth age, engaged in cyclical and team sports. Materials and methods: a survey was conducted with the participation of athletes of the junior level (97 people), who were divided into 2 groups: 47 young men (age 12 [12; 13] years, min – 11 years; max – 14 years), who were professionally involved in ski racing (1st group) and a group of athletes involved in game sports (football players) (2nd group, n=50) (age was 12 [11; 13] years,min – 11 years; max – 14 years). The study evaluated the hemodynamic characteristics of the blood flow (systolic blood pressure, diastolic blood pressure, heart rate, minute volume of blood flow, cardiac index) and echocardioscopy. Results: the differences between the groups of skiers and football players have been proved: AD syst. (102 [88; 111] and 109 [94; 122], p <0.05 by the MannWhitney test), BP. Diast.(68 [59; 69] and 77 [64; 82], p <0.05 for the Mann-Whitney test), as well as the IOC (5.71 [4.38; 8.83] and 5.09 [3, 84; 7.84], p <0.05 by the Mann-Whitney test). In an echocardioscopic study, the analysis showed the following differences: the diameter of the pulmonary artery in skiers was 1.87 [1.78, 1.9] cm and 1.94 [1.9, 1.97] cm in football players. At the same time, the maximum pressure gradient in the descending aorta (PGf.) was 9.88 [9.24; 10.22] mm Hg. and 8.9 [8.16; 9.25] mm Hg. accordingly (p <0.05 by the Mann-Whitney test). Conclusions: as a result, athletes involved in cyclic sports have a high degree of adaptation of the cardiovascular system to physical stress compared to athletes involved in game sports.

Objective: study of the effect of Siberian stag velvet antlers powder on the state of hemopoesis and biochemical indicators of overtraining in winter cycling sports athletes. Materials and methods: the study was carried out in 86 athletes of high qualification of winter sports (cross-country skiing, biathlon) aged from 18 to 30 years, men. Sportsmen were divided into 3 groups: the main group I (n=30) received the velvet antlers powder in a dose of 2 g/day. Main group II (n=30) received the velvet antlers powder in the dose of 4 g/day. Control group III (n=26) received placebo (sugar-sand in similar capsules). The effectiveness of the antlers powder was evaluated on the basis of analysis of hematological (content of red blood cells, hemoglobin and hematocrit) and biochemical indicators (iron content, total serum iron-binding capacity, ferritin, erythropoietin, cortisol, testosterone, lactate, glucose, urea, uric acid, c-reactive protein and indicators of lipid peroxidation). Results: the use of the velvet antlers powder helps stimulate the synthesis of erythropoietin within reference values, preserve iron reserves and prevent the development of iron deficiency anemia, glucose correction, lactate, urea and other laboratory overtraining. These effects are most pronounced at a dose of antlers powder per 4 g/day in athletes from groups I and II. Correction of glucose, lactate, urea and other laboratory indicators of overtraining, as well as an increase in the anabolism index was observed only in group II of athletes taking antlers powder at a dose of 4 g/day. In the control group, endocrine-biochemical signs of overtraining were detected against the background of intense training loads. Conclusions: the internal use of Siberian stag velvet antlers powder has a hemostimulating effect, as well as helps to correct biochemical indicators of overtraining in athletes of winter cyclical sports during the training period of the year cycle training.

Objective: to evaluate the long-term results of treatment of athletes with osteo-chondral knee defects. Damage of the hyaline cartilage of the knee joint is quite common, and in 5-10% of cases requires surgical treatment. In the absence of proper treatment, such damage can lead to the osteoarthritis. According to some data in the structure of knee injuries of athletes contains about 36% cases of full-layer damage of hyaline cartilage. The most popular methods of treatment are microfracture and mosaic autochondroplasty. Materials and methods: the study was carried out from 2015 to 2018. We examined 56 patients with full-layer damage of hyaline cartilage of the knee joint, among them: 32-soccer players, 12-volleyball players, 7-kickboxers/ wrestlers, 5-field athletes. All patients were divided into 2 representative groups. The first group included 42 patients who underwent microfracturing, in the second group involved 14 patients with mosaic autochondroplasty. KOOS and Lysholm Knee Scoring Scale used to evaluate the results. The results statistically processed using the Mann-Whitney U-test. The level of evidence defined as p≤0.05. Results: the average follow-up period was 2.3 years (from 1.5 to 2.8 years). Comparing the results obtained in both groups, we registered a prevailing of mosaic autochondroplasty per 1.5 points by the Lysholm Knee scale (95% confidence interval) and 2.7 points by the Knee injury and osteoarthritis outcome scale (95% confidence interval). Conclusions: long-term results of treatment of patients with osteo-chondral injuries of the knee joint showed no significant difference between microfracturing and mosaic autochondroplasty. In both groups, a high level of functional state of knee joint was obtained on the scales of Knee injury and osteoarthritis outcome and Lysholm Knee in comparison with preoperative evaluation. We believe that microfracturing is less aggressive and quite effective method of treatment of patients with osteo-chondral defects of large joints, especially at young age. However, it should be noted that the implementation of the mosaic autochondroplasty allows to get the best long-term results at the expense of a stable and full replacement of the defect.