Objective: the main topics of the doctors’ questions were the preparation of medical documents for a TUE application, the determination of the anti­doping status of various substances and methods, as well as the use of dietary supplements in sports.
Materials and methods: an analysis was carried out of more than 400 appeals of doctors providing medical assistance to athletes of various levels on the issues of countering doping in sports. The aim of the work was to identify ways to improve educational and informational activities aimed at improving the quality of medical documents for TUE applications.
Results: the need for continuous work to improve the level of doctors’ knowledge in countering doping in sports was confirmed, including clarification of the procedure for using documents from anti­doping organizations, the need to use TUE guidelines for physicians and the specifics of prescribing substances prohibited only during the competitive period.

The article presents the results of an echocardiographic study of 64 male playing sports athletes (basketball and football). The results of the study showed that up to the age of 19 in playing sports athletes, only normal geometry of the left ventricle is observed. With age and, accordingly, with an increase in the experience of playing sports, the number of eccentric and concentric remodeling and eccentric and concentric myocardial hypertrophy increases statistically. The percentage of concentric myocardial hypertrophy (pathological remodeling) was 6.5 %, 12.5 % and 7.7 % in the groups 19–25 years old, 26–30 years old and 31 and older, respectively, which must be taken into account when taking measures to prevent overtraining and sudden cardiac death in sports.

Organization of medical support for major international events is one of the major challenges for organizers. There is no single supranational detailed normative act yet.

Objective: to analyze the existing national and international regulatory framework for the regulation of medical support for competitions with the subsequent formation of a general algorithm and uniform requirements.

Materials and methods: analysis of literature data and personal experience.

Results: The authors set out the general principles of organizing medical support for sports events based on an analysis of their own experience and recommendations of international organizations. The basic principles have been tested at a number of major sporting events and are practice-oriented. The preparation of the regulations should be based on the normative act of the international federation for the sport, adjusted taking into account national legislation and the scale of the sporting event being held and our own experience in holding such events. The practical significance of the work is the proposed scheme for organizing medical care at a sports facility. The number of medical teams and medical centers at each sports facility is determined by the organizers of the sports event in accordance with the approved national and international rules; the equipment of medical services is determined by the regulations of the Ministry of Health.

Conclusion: Medical regulations should contain general provisions, principles of health protection of athletes, implementation of anti-doping rules, compliance with safety measures at the facility. Requirements for the medical service of the competition for the personnel, facility, medical center of the arena, special conditions for ensuring the competition, interaction with the doping control services; maintenance of accounting and reporting documentation are allocated in a separate detailed chapter. A special place and training in practical skills should be given to the algorithm of actions in case of emergencies.

Professional athletes often have to participate in competitions in climatic conditions that differ from the optimal or habitual ones for their place of residence. In this regard, it seems relevant to the question of how borderline and extreme external conditions (low and high ambient temperatures, changes in atmospheric pressure, altitude) affect sports performance and endurance. The review presents the biochemical mechanisms underlying the adaptation of athletes to environmental conditions. The human body maintains a fairly constant internal temperature (in some articles — the core) of the body at a level of 37 ± 10C throughout its life, despite a wide range of environmental parameters. The intensity of the processes providing for the release of heat is reflexively regulated. The neurons responsible for heat exchange are located in the center of thermoregulation of the hypothalamus. In the course of evolution, mammals have developed a variety of mechanisms for regulating body temperature, including nervous and humoral, that affect energy metabolism and behavioral responses. There are two ways of heat generation: contractile thermogenesis, due to contractions of skeletal muscles (a special case — cold muscle tremors), and non-contractile — when the processes of cellular metabolism are activated: lipolysis (in particular, brown adipose tissue) and glycolysis. When exposed to extreme ambient temperatures, the thermoregulatory system adjusts to maintain a stable core body temperature by preventing heat loss and increasing heat production in cold conditions, or increasing heat dissipation if the ambient temperature rises. The ambient temperature corresponding to 20–25 ºС on land and 30–35 ºС in water is considered thermoneutral for humans in a state of relative rest. However, any deviations from these conditions, especially against the background of intense physical exercise, can lead to functional overstrain, decreased endurance and sports performance.

The review shows that the molecular mechanisms initiated by physical exertion underlie the multifactorial influence of the latter on the function of the cardiovascular system and the course of cardiac diseases. Exercise is an important component of the therapeutic treatment in patients with cardiovascular diseases, which is confirmed by the results of a meta­analysis that included 63 studies that were associated with various forms of aerobic exercise of different intensity (from 50 to 95 % VO₂) for 1 to 47 months, which showed that exercise-based CR improves cardiovascular function. Knowledge of the molecular basis of the impact of physical activity makes it possible to use biochemical markers to assess the effectiveness of rehabilitation programs.

The aim of the research was a clinical assessment of the effectiveness of the developed specialized sports nutrition product for regulating the level of hemoglobin in adolescent girls professionally involved in sports.
Materials and methods: 23 girls — athletes of various sports specialization were researched during a training camp. The athletes were determined by the clinical parameters of blood, its general analysis and biochemical parameters, then the physical endurance and performance were assessed.
Results: the developed product “Hemosport” demonstrated efficiency in most of the researched parameters in the main group compared with the control. The positive dynamics of most of the researched indicators revealed a general tendency to improve the state of vital organs and systems of the body of athletes of the main group, to increase their adaptive capabilities and vegetative balance.
Conclusions: clinical studies of the specialized product “Hemosport” allow it to be recommended in the practice of sports nutrition for adolescent girls of 12–17 years old who are professionally involved in sports to compensate for iron deficiency nutritional deficiencies specific for this group of athletes, as well as to increase the efficiency and effectiveness of their training.

T

The most important factor limiting sports performance is insufficient fluid intake by athletes and dehydration of the body, while a significant decrease in performance and sports endurance begins with a dehydration level of 2 % and above.
Objective: to study the effectiveness and safety of rehydration of the body of athletes­skiers of children and youth using isotonic drinks «Izonok» and «Izonok+».
Materials and methods: the main group (n = 12, 16.2 ± 1.4 years) took isotonic drinks for 30 days to compensate for fluid losses, the comparison group (n = 8, 15.7 ± 1.1 years) — drinking water. Bioimpedance body composition analysis was carried out on a KM-AR-01-”Diamant” device (RF, St.Petersburg), and central hemodynamic analysis was carried out on a «SIMONA 111» (LLC “Okulyus 2000”, RF). The content of secretory immunoglobulin A (sIgA) and lysozyme in saliva samples of athletes was carried out by the enzyme immunoassay on an ANTHOS 2010 analyzer (Austria). Statistical data processing was carried out using the Statistica 6.0 software package from Stat Soft @ Ink USA.
Results: The intake of an isotonic drink is accompanied by the stimulation of the production of secretory immunoglobulin (sIgA) and lysozyme compared to the consumption of drinking water. The total volume of fluid and the volume of extracellular fluid tended to increase; the volume of intracellular fluid remained practically unchanged; the amount of total water when taking isotonic increased.
Conclusion: The investigated isotonic drinks “Izonok” and “Izonok+” are effective sports drinks for maintaining optimal water-salt balance and local immunity

The aim of the review is to inform doctors and trainers of sports teams about technologies that prevent complications of sport brain injuries (SBI). Low levels of visibility of clinical manifestations, specific characteristics of individual reactions to injury, anti-aggravation behavior among sportsmen, absence of unbiased methods of diagnostics of SBI are the main reasons behind underestimation of the severity of trauma. Treatment and rehabilitation procedures of mild SBI do not currently consider specific characteristics of trauma, associated with the increase in body and brain temperature and reduced cerebral perfusion during the traumatizing intervention. Injury of the brain causes an increase in cerebral temperature, which, in turn, can aggravate the consequences of traumatization. The control of the temperature of the brain can be achieved with non-invasive method of microwave radiometry, while the technology of craniocerebral hypothermia (CCH), which has evident neuroprotective properties, can aid in the prevention of complications of SBI.

Lateral epicondylitis is a common pathology of the musculoskeletal system resulting from repeated microtrauma of the extensor muscles of the forearm and their tendons. Lateral epicondylitis was previously thought to be tendinitis, which is an inflammatory reaction in the tendon. However, histopathologically, it has been shown to be low in inflammatory elements: macrophages and neutrophils. Thus, it is now believed that this pathology is a tendinosis, which is defined as a degenerative rather than an inflammatory process.

The opinion that COVID-19 is a greater threat only to the elderly people has changed over the past year. Experience has been accumulated in the development of complications of varying severity in young patients who had optimal health indicators before infection. The consequences of myocarditis are most dangerous, especially in athletes and military personnel. We present a series of clinical cases of spontaneous mitral valve chordae rupture in highly trained middle-aged men in the early post-COVID period. In all cases, the infection proceeded subclinically; SARS-CoV-2 was verified only by analysis for IgM. 1–2 weeks after infection, against the background of a routine training process, patients felt pain in the heart area, which was underestimated. Patients presented for help at 2 and 10 weeks with complaints of reduced endurance and shortness of breath. Echocardiography revealed rupture of one of the chords of the anterior part of the mitral valve against the background of signs of myocarditis with the development of valvular insufficiency of the 1st degree. By the time of treatment, the pathology of other laboratory data and ECG was not observed. The control after 6 months showed in 1 patient a focus of myocardial fibrosis according to MRI, a minimal increase in NT-proBNP, a decrease in exercise tolerance, in 2 patients there was no visible fibrosis, normal NT-proBNP and complete restoration of exercise tolerance, but a decrease in local myocardial deformation according to echocardiography.

It is known that in children at rest, BP values depend on height, but this aspect is not taken into account when analyzing the maximum BP during exercise.
Objective: to determine the maximum value of BP in young elite athletes, depending on height and gender.
Materials and methods: 2313 (age 15.5 ± 1.4 years, 45% of young men) young elite athletes, members of national teams of the Russian Federation in 40 sports, were examined. All subjects underwent bicycle ergometry according to the PWC170 protocol, blood pressure was measured manually at each stage of the load, and its maximum values were determined during the entire test.
Results: The maximum BP values in boys were higher than in girls: systolic blood pressure (SBP) 195 ± 25 vs 175 ± 20 mmHg, p < 0.001, diastolic blood pressure (DBP) 80 ± 11 vs 80 ± 10 mm Hg, p < 0.05. A relationship was found between the maximum value of blood pressure on load and growth (r = 0.55; p < 0.001). Normative tables are proposed for assessing the maximum values of SBP and load, depending on growth.
Conclusion: In young elite athletes, the maximum BP value during VEM according to the PWC170 protocol depends not only on gender, but also on height. The maximum values of SBP during exercise in tall young elite athletes can reach 250 mm Hg in boys and 210 mm Hg in girls.

Objective: To investigate the nature of the relationship between the indicators of heart rate variability (HRV), reflecting the state of autonomous balance and the parameters of the component composition of the body of football players.
Materials and methods: We studied n = 80 football players living in the north­western region of the Russian Federation. Group data: 16.9 ± 0.8 years; weight 73.1 ± 4.7 kg; height 181.1 ± 4.9 cm. Monitoring of heart rate variability was carried out by the hardware and software complex “Omega-Sport, St.Petersburg”. The bioelectric activity of the heart was recorded in the II standard lead from the sitting position in the morning (9:00–10:00). The assessment of the body composition of football players was carried out four times (January, April, August, November) using the Inbody 770 analyzer, Japan.
Results: SI has a strong direct correlation with the indicators: “total fat content” (r = 0.994, P = 0.011); “total water content” (r = 0.811, P = 0.013). A direct strong correlation was established between SDNN and “total fat content” (r = 0.933, P = 0.009) and an inverse strong correlation with “total muscle mass” (r = -0.877, P = 0.006). pNN50 has a strong direct correlation with “total fat content” (r = 0.889, P = 0.011), in addition, there is a strong inverse correlation with “total muscle mass” (r = ­0.767, P = 0.012). HF and “total fat content” (r = 0.733, P = 0.008) have a strong direct correlation; and with the indicator “total water content” of skeletal muscle mass (r = -0.874, P = 0.011) a strong inverse. A strong inverse relationship is shown between LF and “total fat content” (r = –0.766, P = 0.011), as well as a strong direct correlation with “total muscle mass” (r = 0.951, P = 0.013), “total water content” (r = 0.917, P = 0.008).
Conclusions: There is a close correlation of the indicators “total muscle mass”, “total fat content”, “total water content” with a limited number of HRV parameters: SI, SDNN, pNN50, HF, LF. The study showed a significant (p < 0.05) predominance of: the activity of the parasympathetic ANS department — the competitive period, in which there was a significant (p < 0.05) increase in “total muscle mass”, a decrease in “total fat content” in the 1st, 2^nd and 3rd diagnostics; the activity of the sympathetic ANS department — the recovery period, which significantly (p < 0.05) affected: a decrease in “total muscle mass”, “total water content”; an increase in “total fat content” in the 4th diagnosis.