Objective: to study the dynamics of performance and its regulatory neurovegetative support in professional football players under various anaerobic energy supply regimes at the stages of the preparatory period.

Materials and methods: in a prospective study, 16 male athletes aged 18–20 years, first sports category, the main squad of the Smolensk State University of Sports football team at a special preparatory stage of the training and competition cycle were examined. Athletes performed anaerobic tests lasting 6, 15, and 45 seconds to assess, respectively, speed-strength abilities, maximum alactic power and glycolytic endurance on a modernized version of the Ergomedic 894E “Monark” bicycle ergometer. The functional state of athletes in the dynamics of the tests was assessed by diagnosing heart rate variability indicators using the “Varicard 2.6” device.

Results: the initial values of anaerobic performance in qualified football players were high during all three tests and corresponded to their qualification. Intensive training factors of the preparatory period were reflected in the potentiation of their special performance. At the same time, the least “trainable” in the dynamics of the preparatory period, but the most stable and less “costly” in the neurovegetative provision of muscle activity were speed-strength abilities. With the transition to the test assessment of the dynamics of maximum alactic power (MAP) and glycolytic endurance in football players, more significant increases in the values of the corresponding indicators were noted, most pronounced by the end of the special preparatory period. However, such progress in anaerobic performance indicators was accompanied by negative dynamics in HRV indicators (a significant decrease in HF values, the most pronounced increase in LF, LF / HF, VLF), which can be assessed as an overstrain of autonomic regulation, initial signs of overtraining.

Conclusion: the most difficult in terms of the tension of autonomous regulation is recognized as a 45-second anaerobic test, during which the metabolism switches to glycolysis. The obtained results prove the validity of modifications of training regimes of football players at the preparatory stage, aimed at optimizing/reducing the loads of alactate and glycolytic orientation in favor of aerobic training, in order to “bring out” athletes to the best test sports results while maintaining an adequate functional state.

The ability to perform steady-state submaximal exercise at a certain intensity (exercise tolerance) predicts endurance performance in athletes, but also the quality of life and the capability to perform daily living activities in older people and patients suffering from chronic diseases. Improvements in exercise tolerance following exercise training are well established but may also occur or be enhanced as a consequence of adaptations to other stimuli, e.g., repeated exposures to real or simulated altitude. Adaptive responses (i.e., beneficially impacting exercise tolerance) depend on the type and extent of hypoxia stimuli, in particular, whether they are applied during exercise (intermittent hypoxia training, IHT) or at rest (intermittent hypoxia exposure, IHE).

This brief review summarizes the evidence showing that IHT seems to elicit more pronounced effects on exercise tolerance than IHE. The most relevant adaptations to IHT are primarily provoked within the working skeletal muscles, whereas the rather small effects of IHE may include improved autonomic regulatory processes, endothelial function, cardioprotection, and increasing antioxidant capacity, all of which can probably be enhanced by combination with exercise (IHT). While IHE seems particularly suited for sedentary and elderly people or those suffering from chronic diseases, IHT will be more appropriate for young and already trained people. Thus, IHE is recommended for those with low exercise tolerance and can be followed up with exercise training in normoxia and finally with IHT.

Objective: to evaluate the interactions and dynamics of hematological parameters before and after exercise testing in high performance sprint swimmers.

Materials and methods: 16 male (n = 8) and female (n = 8) high‑performance swimmers (19.31 ± 1.08 years) were studied. Venous blood samples were taken before and after exercise. Erythrocyte, leukocyte and platelet indices were assessed. Physical activity was a stepwise incremental test on an ergometer until failure.

Results: a significant variation in hematological blood parameters was found in the swimmers both at rest and after exercise. In both men and women an increase in haematocrit was observed with an increase in erythrocyte count. The increase in erythrocyte indices was accompanied by a decrease in platelet indices in female athletes. In males, inverse relationships were mainly found only between the leukocyte blood indices. In female athletes, the number of direct and feedback correlations after exercise remained at the same level as at rest, whereas in men the number of direct correlations decreased after exercise.

Conclusion: the training effect in females was manifested by the formation of several interdependencies between blood parameters, indicating a better adaptation of the blood system to the training load. In men, on the other hand, the pattern of relationships indicates the presence of tension in the regulatory mechanisms.

Purpose: to assess the functional-metabolic state and intestinal microbiota of athletes of cyclic sports with high and low levels of performance.

Materials and methods: the study involved 20 male athletes of cyclic sports aged 18–22 years. Based on the results of the athletes’ maximum performance — relative speed (V_rel.), shown in the ergometry test, the group was divided into two subgroups. To determine the presence or absence of intestinal dysbacteriosis, microbiological examination of feces was used.

Results: High performance athletes (HPA) had significantly higher values of the circulatory efficiency coefficient (CEC) and aspartate aminotransferase (AST). In the HPA group, a positive correlation was found between the level of liver enzyme activity and intestinal microflora, as well as the activity of the ALT enzyme and speed characteristics. In the group of low performance athletes (LPA), positive correlations were found between performance indicators and hemolytic E. coli. Opportunistic bacteria were found in 40 % of men in the LPA group.

Conclusion: In athletes with a high level of physical performance, the functional state was characterized by the activation of anabolic processes. Whereas in athletes with a low level of physical performance, catabolic processes prevailed, caused by the presence of opportunistic and pathogenic microorganisms in the intestine. It was concluded that athletes should regularly undergo ergometric testing with a study of the intestinal microbiome in order to prevent the development of dysbiosis.

Introduction: Despite the large number of classifications of muscle injuries proposed by different expert groups, there is still no classification that can fully satisfy the requirements of practitioners in terms of predicting the duration of treatment and minimising the risk of recurrence. At the same time, the diversity of classifications may lead to different interpretations of the severity of the same injury with subsequent variability in the choice of rehabilitation protocol and its duration.

Aim: to analyse the advantages and disadvantages of the most common classifications of muscle injuries in the practice of professionals working with athletes.

Materials and methods: The Pubmed and Google Scholar databases were searched for articles in English describing classifications of muscle injuries proposed since 2000. The following word combinations were used for the search: ‘classification of muscle injuries’, ‘grading of muscle injuries’, ‘muscle damage’ and ‘muscle injuries’. The study design was a narrative review.

Results: Eight classifications proposed by different expert groups since 2000 were found. The Munich Consensus and British Athletic Association classifications of muscle injuries and the MLG-R classification can be considered the most commonly used at present, based on various combinations of clinical symptomatology, mechanism of injury and localisation, and magnetic resonance imaging findings.

Conclusion: There are currently several of the most widely used classifications of muscle injuries, and communities of practice should appreciate this diversity when determining injury severity and predicting treatment time, and use the same classification.

Objective: To study the effect of the new coronavirus infection (COVID‑19) on the endocrine system and physical performance parameters of athletes.

Materials and methods: The results of an in‑depth medical examination (IME) of 7,509 elite athletes, members of the Moscow national teams, were analyzed for the period 2020 and 2021. The analysis took into account data on sports and infectious anamnesis, results of clinical and laboratory examination of athletes, and spiroergometry data.

Results: Among the 7.509 examined athletes, 2.937 (39 %) had a coronavirus infection 3–12 months before the examination, 4.572 people (61 %) did not have a history of COVID. No significant difference was found in the number of athletes who had recovered depending on the sport group, according to the Peliccia classification. A significantly higher prevalence of endocrine diseases and deviations in hormonal parameters was revealed in the group of athletes who had recovered from COVID‑19 (890 people — 30%), in contrast to 15 % (710 people) of uninfected athletes. Statistical analysis among athletes who had recovered from COVID‑19, divided into a group with hypothyroidism and a group without hypothyroidism, showed a significant difference in the results of spiroergometry. Athletes with hypothyroidism showed significantly higher heart rates at rest, at peak exercise, and at the fifth minute of recovery, as well as lower peak oxygen consumption and a decrease in heart rate at the anaerobic threshold.

Conclusion: The results of the study showed a significantly higher prevalence of endocrine diseases in the group of athletes who had recovered from COVID‑19, in contrast to uninfected athletes. Athletes with hypothyroidism who have had COVID‑19, according to spiroergometry data, demonstrated a slowdown in recovery processes and a decrease in physical performance, a decrease in aerobic and anaerobic reserves, which indicates a more significant negative impact of coronavirus infection on the physical performance of athletes with hypothyroidism and requires closer attention to this group of athletes to restore their health and competitive potential.

Takotsubo cardiomyopathy (TTC) has become more common in clinical practice, and with a wide variety of pathologies, which is apparently associated with an improvement in the diagnosis of this disease. At the same time, this diagnosis is still not always established, primarily due to the lack of doctors’ awareness about this disease. TTC has many synonyms: broken heart syndrome, stress-induced cardiomyopathy, apical ballooning syndrome. TTC is a form of acute and, as a rule, reversible heart failure, provoked in most patients by various stress factors, occurring with transient dysfunction primarily of the left ventricle, clinically and echocardiographically resembling acute coronary syndrome. Recently, TTC has become more common in athletes, during stress testing (bicycle ergometry, treadmill test). Taking into account the large amount of information about TTC and the many unresolved issues, it’s necessary to analyze the literature and share our own experience in TTC diagnosis. The article highlights aspects of the etiology, pathogenesis, epidemiology, diagnostics and treatment of stress-induced TTC, which occurs in response to physical or mental stress and characterized by transient left ventricular dysfunction. The clinical example is the authors’ own observation.