Today we will talk about energy supply of muscle activity... As you know, energy is needed for the work of any systems of our body, let's take a closer look at the mechanism of energy supply to muscles.
The source of energy in our body is the ATP molecule (adenosine triphosphate). The number of ATP molecules is limited, so their constant resynthesis is required.
Energy supply of muscles in practice
Enough theory, let's look at the energy supply of muscles using the example of a sport.
Breakdown of creatine phosphate
This is the very first source of recovery of the ATP molecule. You will be able to do the work for about 10 seconds, after 30 seconds, the reserves of creatine phosphate will drop to 50%. With a little thought, it is safe to say that this method of energy supply works in powerlifting or weightlifting, where the task is to lift as much weight as possible.
Anaerobic glycolysis
Glycolysis starts working about 30 seconds after the start of the set and can resynthesize energy for several minutes. This oxygen-free way of supplying energy is more prominent in bodybuilding. Just fast muscle fibers work at this moment. Fast muscle fibers are large, which explains why bodybuilders train in this manner.
Oxidation
Oxidation is an aerobic (oxygen) way of obtaining energy, it is the cheapest, but it takes a lot of time, since oxygen must still be obtained and, besides, it must be assimilated. This mode of energy can be seen in marathon runners. Oxidation provides work slow muscle fibers, marathon runners do not show power, they run at an easy pace for a long time, which is typical for slow fibers.
P.S.
I think today's information will be enough. You have understood how the energy supply system of muscle activity works. Of course, many questions will arise, but these are other topics that were touched upon here. Wait for new articles.
Table 2 - Classification of overweight and obesity by body fat content
Low 6-10% 14-18%
Normal 11-17% 19-22%
Excess 18-20% 23-30%
Obesity More than 20% More than 30%
In addition to the percentage of body fat, it is important to note its distribution on the body. For these purposes, there is an indicator of the ratio of the waist circumference to the hip circumference (OT / OB). For men, this coefficient should be less than 0.95, and for women less than 0.85. The value of OT / OB for men is more than 1.0 and women are more than 0.85
It has been proven that RT equal to 100 cm indirectly indicates such a volume of visceral adipose tissue, in which, as a rule, metabolic disorders develop and the risk of developing type 2 diabetes mellitus increases significantly.
BIBLIOGRAPHIC LIST
1. Shutova, V. I. Obesity, or overweight syndrome / V. I. Shutova, L. I. Danilova // Medical news. - Minsk, 2004. - No. 7. - S. 41-47.
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3. Verbovaya, N. Ye. Obesity and growth hormone: causal relationships / N. E. Verbovaya, S. V. Bulgakova // Problems of endocrinology. - M .: Media Sfera, 2001. - No. 3. - P. 44-47.
4. Glucose-induced thermogenesis in obese persons / NT Starkova [et al.] // Probl. endocrinology. - 2004. - T. 50, No. 4. - S. 16-18.
5. Milewicz, A. Perimenopausal obesity / A. Milewicz, B. Bidz-inska, A Sidorowicz // Gynecol Endocrinol. - 1996. - No. 10 (4). - R. 285-291. Review PMID: 8908531 (Problems of Endocrinology 1998. - No. 1. - pp. 52-53).
indicates an abdominal type of obesity. Waist circumference is also an indicator of the clinical risk of developing obesity metabolic complications. Studies have confirmed a strong correlation between the degree of development of visceral adipose tissue and the size of the waist circumference (table 3).
6. Krasnov, V. V. Body weight of a patient with ischemic heart disease: controversial and unresolved issues / V. V. Krasnov // Cardiology. - 2002. - No. 9. - S. 69-71.
7. Ametov, AS Principles of nutrition for obese patients / AS Ametov // Diabetes. Lifestyle. - M., 1997. - No. 7. - S. 28-30.
8. Voznesenskaya, T. G. Obesity and metabolism / T. G. Voznesenskaya // Eating disorders in obesity and their correction. - 2004. - No. 2. - S. 25-29.
9. Handbook of clinical pharmacology / Е.А. Kholodova [and others]; ed. E. A. Kholodovoy. - Minsk: Belarus, 1998 .-- S. 259-277.
10. Okorokov, A. N. Treatment of diseases of internal organs / A. N. Okorokov. - Minsk: Vysh. shk., 1996. - T. 2. - S. 455-472.
11. Balabolkin, MI Differential diagnosis and treatment of endocrine diseases / MI Balabolkin, EM Klebanova, VM Kreminskaya. - M .: Medicine, 2002 .-- 751 p.
12. Kliorin, A. I. Obesity in childhood / A. I. Klio-rin. - L .: Medicine, 1989 .-- 256 p.
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14. Lavin, N. Manual of Endocrinology and Metabolism / N. Lavin. - 2-nd. ed. - Boston: Little, Brown and Company, 1994. - P. 38, 66, 138, 154, 357, 384, 387.
15. Danilova, LI Metabolic syndrome: diagnostic criteria, treatment protocols: study guide. allowance / L. I. Danilova, N. V. Murashko. - Minsk: BelMAPO, 2005 .-- 26 p.
Received 05/15/2014
Table 3 - Correlation between visceral adipose tissue and waist circumference
Increased risk High risk
More than or equal to 94 cm More than or equal to 102
More than or equal to 80 cm More than or equal to 88 cm
UDC: 612.017.2: 612.013.7: 611.73]: 612.766.1
INTERACTION AND ADAPTATION OF THE ENERGY SUPPLY SYSTEMS OF THE SKELETAL MUSCLES DURING PHYSICAL EXERCISE
Yu. I. Brel
Gomel State Medical University
Currently, interest in the study of changes in the processes of energy supply during physical activity is associated with the use of modern methods for studying aerobic and anaerobic metabolism of skeletal muscles, as well as with the high practical significance of assessing energy exchange in sports medicine for the development of criteria for correcting the training process and diagnosing overtraining.
This review sheds light on modern ideas about the interaction and adaptation of energy supply systems during physical exertion of varying intensity and duration.
Key words: physical activity, energy metabolism, aerobic metabolism, anaerobic metabolism.
INTERACTION AND ADAPTATION OF ENERGY SYSTEMS OF SKELETAL MUSCLES DURING PHYSICAL EXERCISE
Yu. I. Brel Gomel State Medical University
Nowadays, the interest to study of changes in processes of energy supply in physical exercise is associated with the use of modern methods of study of aerobic and anaerobic metabolism in skeletal muscles, and also assessment of energy interchange in sport medicine for correction of training process and diagnostics of overtraining syndrome with high practical significance. This review covers contemporary notions on interaction and adaptation of energy systems in skeletal muscles during physical exercises of different intensity and duration.
Key words: physical exercise, energy exchange, aerobic metabolism, anaerobic metabolism.
Introduction
The study of the interaction of the main energy supply systems and mechanisms that ensure an increase in the efficiency of their work during intense physical exertion is of great theoretical and practical interest, since it serves as the basis for the development of evaluation criteria functional state athletes and correction of the training process. At present, the relevance of studying changes in the processes of energy supply during physical activity is associated with the possibility of using modern methods of studying aerobic and anaerobic metabolism of skeletal muscles. Anaerobic mechanisms of energy supply of muscle work, their relative contribution to energy production during various physical loads are being actively studied. There is an increasing interest in the study of the mechanisms of the influence of the deficiency of energy substrates in the development of the overtraining syndrome and other disorders of the functional state of the body of athletes. This review sheds light on modern ideas about the interaction of the main systems of energy supply and adaptation of energy metabolism during physical exertion of various intensity and duration.
Sources of energy for muscle activity
Energy for muscle contraction is provided by the breakdown of adenosine triphosphate (ATP). Since the reserves of ATP in the muscles are small and sufficient to provide high-intensity work for 1-2 s, ATP resynthesis is required to continue muscle contraction. ATP reduction occurs through three different but closely interconnected energy systems: phosphagenic, glycolytic and oxidative. Depending on the intensity and duration of the
the contribution to the energy supply of the above mechanisms of energy production differs significantly from the controlled physical activity.
Phosphagenic energy system (ATP-creatine phosphate system) uses the energy released during the breakdown of creatine phosphate (CP) for the re-synthesis of ATP. This pathway of energy production provides a rapid recovery of ATP, however, the reserves of CP are limited and sufficient to meet the energy needs of the muscles only during 315 s of intense physical activity. The phosphagenic system largely determines sports performance in sports with short-term single or limited number of repeated intense muscle contractions (in particular, weightlifting, throwing, jumping, etc.). Earlier it was assumed that at the initial stage of high-intensity muscle work, ATP resynthesis occurs exclusively due to the breakdown of CP. It has now been proven that during intense physical exertion, glycolysis is activated rather quickly and it is believed that at maximum loads the ATP-creatine phosphate system dominates in the share of total ATP production for 5-6 s, and maximum speed decay of CF is observed for 1.3 s with a subsequent gradual decrease.
Since the energy power of the phosphagenic system depends on the concentration of CP, the ability of athletes to quickly restore CP reserves is important for sports performance. Studies using the 31P-magnetic resonance spectroscopy method have shown that almost complete replenishment of CF reserves takes 5-15 minutes, depending on the degree of decrease in its amount, the severity of metabolic acidosis and the type of muscle fibers. ...
The lactate (glycolytic) system provides a slow reduction of ATP under anaerobic conditions due to the energy of the breakdown of glucose (released from glycogen) by the glycolysis reaction with the formation of lactic acid (lactate). This path of energy formation is of particular importance with prolonged physical activity of high intensity, lasting up to 1-2 minutes (for example, when running at medium distances), as well as with a sharp increase in the power of longer and less strenuous work (acceleration when running long distances) and if there is a lack of oxygen during static work. The lactate system is less efficient in comparison with the aerobic mechanism in terms of the amount of generated energy, moreover, the release of energy during glycolysis is limited due to inhibition of glycolytic enzymes during the accumulation of lactic acid and a decrease in pH, leading to a decrease in ATP resynthesis. It was previously believed that glycolysis begins after the depletion of CF reserves. Currently, the results of many studies have shown that ATP resynthesis through glycolysis during intense muscular work begins almost immediately after the start of the load and reaches a maximum for 10-15 s of the load.
The oxidative system provides energy for the work of muscles in aerobic conditions through the reactions of oxidation of fats and carbohydrates. For long-term physical activity (long-distance running, cross-country skiing, cycling, etc.) this source of energy supply is the leading one. The main substrates for aerobic metabolism are muscle glycogen (although the contribution of plasma glucose increases with duration of exercise) and free fatty acids derived from triglyceride stores in muscle and adipose tissue. The relative contribution of these two sources depends on the intensity and duration of the load and on the fitness level of the athlete. During a submaximal load, carbohydrates are the first to be included in the process of energy supply, the current reserves of which are limited (in trained athletes, there are enough carbohydrate reserves to perform continuous physical activity for 60-90 minutes), and then fats. The greatest contribution of fatty acids to aerobic ATP production is observed at an exercise intensity of 60% of the maximum oxygen consumption.
It was assumed that the participation of proteins in the formation of energy during muscle work is insignificant. However, the results of recent studies show that during physical activity of duration
how many hours the contribution of proteins to the total energy metabolism can be up to 10-15%, which is accompanied by the destruction of protein structures, mainly of skeletal muscles and necessitates daily replenishment of protein loss during regular sports.
Traditionally, it was believed that the aerobic energy system plays an insignificant role in ensuring performance during high-intensity short-term physical exertion and is included in the process of energy formation at 2-3 minutes from the beginning of the load. Recent studies have shown that all energy supply systems are involved to one degree or another in all types of muscular work and the aerobic system reacts quickly enough to energy needs during intense exercise, although it is not able to provide them at the initial stages of exercise. Having analyzed the results of more than 30 studies evaluating the contribution of the anaerobic system during maximum exercise, Gastin showed that the duration of maximum physical activity, at which there is an equal contribution to the energy production of aerobic and anaerobic energy systems, is in the interval between 1 and 2 minutes, and is an average of about 75 s.
Methods for assessing energy supply systems and energy consumption
The aerobic energy release pathway from carbohydrate and fat oxidation can be quantified as there is a direct correlation between O2 intake and total aerobic ATP production. The use of the method of indirect calorimetry and the determination of the respiratory coefficient (the ratio of the released CO2 to the absorbed O2), which characterizes the type of oxidized substrate (carbohydrates, fats, or proteins), with the subsequent determination of energy expenditure, provides a fairly accurate assessment of aerobic energy production. The limitations of using this method are associated with the fact that when performing physical exercise of high intensity, the amount of CO2 released by the lungs may not correspond to that produced in the tissues, and thus it can be considered sufficiently reliable only when performing exercises of moderate intensity. In addition, due to the fact that proteins in the body are not completely oxidized, it is impossible to accurately determine the amount of protein utilization based on the respiratory coefficient.
An important indicator of the power of aerobic processes is the maximum oxygen consumption (MOC) - the limiting value of oxygen intake into the body in 1 min.
MIC is expressed in liters per minute and can be determined using submaximal samples (indirect method) and maximum samples (direct method). During the load at the level of the VO2 max, the body is supplied with energy by both aerobic and anaerobic routes. Since anaerobic energy supply is limited, the intensity of the load at the VO2 max level cannot be maintained for a long time (no more than 5 minutes). To determine the MPC by a direct method, a bicycle ergometer and gas analyzers are most often used, however, the subject is required to have a desire to perform work to failure, which is not always achievable. Indirect methods for determining the IPC are based on the linear dependence of the IPC and heart rate at a certain power. According to many researchers, the VO2 max allows a fairly accurate assessment of cardiorespiratory endurance and aerobic fitness, but it is not a characteristic indicator of the functional capabilities of athletes during endurance training.
Methods for quantifying the anaerobic energy supply pathway are less accurate than those for aerobic metabolism. Numerous methods have been proposed, however, since anaerobic ATP production is an intracellular process, this makes it difficult to directly assess the reliability of existing methods. Traditionally used methods for assessing anaerobic energy supply include determining the value of oxygen debt, measuring the concentration of blood lactate and ergometry.
Oxygen debt is the increased oxygen consumption compared to rest and continues for some time after exercise. The use of the oxygen debt value to assess the anaerobic energy supply pathway was based on the assumption that the amount of oxygen consumed after exercise is associated with lactate metabolism during the recovery period. BaSho et al. found that the use of this method led to a significant overestimation of the contribution of the anaerobic system to the energy supply of intense muscle work. A discrepancy was revealed between the amount of oxygen consumed during the recovery period and the accumulation and metabolism of lactate. It has been demonstrated that the classical explanation for excess oxygen consumption is oversimplified and a combination of a number of factors not directly related to anaerobic energy release results in increased oxygen demand after physical activity. These factors include inflammation
reduction of oxygen reserves contained in myoglobin and hemoglobin and expended during physical activity, an increase in hormonal activity (in particular, the concentration of adrenaline and norepinephrine), an increase in body temperature, increased respiration and a general increase in energy consumption associated with the restoration of homeostasis ..
The concentration of lactate in the blood is often used as a criterion for assessing the intensity of physical activity and as an indicator reflecting the anaerobic pathway of energy release during muscle work. At rest in a healthy person, the lactate concentration is 12 mmol / l. In well-trained athletes for endurance, under long-term low-intensity loads, lactate values \u200b\u200bdo not exceed the aerobic threshold (2 mmol / l). At a given load intensity, energy supply occurs completely aerobic way. With an increase in the intensity of the load, the anaerobic system is connected to the load, however, if the body maintains an equilibrium between the production and elimination of lactic acid, the concentration of lactate is in the range of 2-4 mmol / l. This range of intensity is called the aerobic-anaerobic transit zone. A sharp increase in blood lactate concentration indicates that the athlete is working in the anaerobic zone. The boundary between the aerobic-anaerobic transit zone and the anaerobic zone is called the anaerobic threshold. Typically, the lactate concentration at the anaerobic threshold is 4 mmol / L. The lactate test for determining the anaerobic threshold of an athlete, based on the relationship between the level of lactate in the blood and the intensity of the load, is used to assess the functional state of the athlete and correct the training process.
However, at present, the hypothesis of the lactate threshold is being criticized due to many contradictions and inaccuracy of non-invasive methods for determining the value of the anaerobic threshold. It has been demonstrated that although blood lactate reflects the intensity of glycolysis, it cannot be used to accurately quantify muscle lactate production. In particular, it was shown that the concentration of lactate in the blood during physical exertion is significantly lower than the concentration of lactate in the muscles, and measuring the concentration of lactate in the blood does not provide information on the rate of its formation, but only reflects the balance between the release of lactate into the blood and its elimination from the blood. At present, the hypothesis of the lactate threshold continues to be defended, since it has practical value, allowing
performance and level physical fitness athletes.
Ergometric measurements are often used as non-invasive indirect methods for measuring the power of all three power supply systems and are based on the fact that the contribution of power supply systems depends on the intensity and duration of operation, and in these tests the load duration is chosen that maximizes the contribution of one power supply system while minimizing the participation of others. systems. However, the peculiarities of activation and contribution of each power system make it difficult to accurately assess the energy exchange. In particular, the fact that the glycolytic process leading to the formation of lactate is initiated during the first few seconds of intense physical activity makes it impossible to distinguish between the alactan and lactan components of anaerobic metabolism. ... It should also be borne in mind that the aerobic path makes a significant contribution to energy supply even with a maximum load of 30 seconds.
The application of the muscle tissue biopsy technique made it possible to directly measure the decrease in the amount of ATP and CP and the accumulation of lactate in the muscle under study and, therefore, to assess the total anaerobic energy production of the body, taking into account the active muscle mass involved in a certain physical activity. Difficulties in using the method are associated with the issues of the representativeness of the muscle sample and the possible underestimation of the participation of the anaerobic pathway due to metabolic changes that occur in the time interval between the end of the load and the taking of the biopsy material.
Features of adaptation of energy supply and metabolism systems to aerobic and anaerobic loads
Systematic aerobic training leads to an increase in glycogen stores in trained muscles, which is associated with the active use of muscle glycogen during each training session and with the stimulation of mechanisms that ensure its resynthesis, as well as an increase in the amount of triglycerides. The mechanisms providing an increased content of energy sources in an athlete trained to develop endurance have not been studied enough. Nevertheless, it was found that after 8 weeks of exercise, the content of triglycerides in the muscle increases 1.8 times, and there is a redistribution of vacuoles containing triglycerides along the muscle fiber closer to the mitochondria, which makes it easier to use them as an energy source during physical activity.
Endurance training increases the activity of many muscle enzymes involved in fat oxidation and increases the amount of free fatty acids in the blood, thereby conserving muscle glycogen stores and delaying fatigue. Thus, the increase in muscle aerobic endurance is due to an increase in energy generation capacity with a greater emphasis on the use of fats for ATP synthesis.
Training of anaerobic orientation increases the level of anaerobic activity due to an increase in strength qualities to a greater extent than an increase in the efficiency of functioning of anaerobic energy production systems. There is a small number of studies devoted to the study of the adaptive responses of the ATP-creatine phosphate system to short-term maximum exercise. It has been demonstrated that the maximum physical activity of the sprint type (lasting 6 s) contributes to an increase in strength qualities, but practically does not affect the efficiency of the energy generation process due to the breakdown of ATP and CP. At the same time, in another study, an increase in the activity of enzymes of the phosphagenic system was observed due to cycles of training loads lasting 5 s.
Anaerobic training with load cycles of 30 seconds increases the activity of a number of key glycolytic and oxidative enzymes. It has been shown that the activity of such glycolytic enzymes as phosphorylase, phosphofructokinase and lactate dehydrogenase increases by 10-25% as a result of 30-second exercise cycles and practically does not change due to short-term (6-second) cycles, mainly affecting the ATP- KF. However, both types of loads to the same extent influenced the work capacity and the intensity of fatigue, which indicates a predominant increase in strength qualities than an increase in anaerobic ATP production.
Since a certain amount of energy required to perform short-term loads of at least 30 s duration is provided by oxidative metabolism, short-term physical exercises of the sprint type also increase the aerobic capabilities of the mouse. Thus, in addition to increasing strength, an increase in the efficiency of muscle activity and a delay in the onset of fatigue during training loads of an anaerobic orientation may be due to an improvement in the aerobic capabilities of the muscles.
Of particular importance is the study of changes in metabolism and energy supply in the event of overtraining syndrome in athletes. This is due to the fact that overtraining not only leads to a decrease in physical performance, but also to a negative effect on other body systems, in particular, a decrease in immunity and susceptibility to infectious diseases of the upper respiratory tract, as well as the fact that in order to eliminate overtraining, it is necessary to stop training for a period from several weeks to several months.
At present, the only diagnostic criterion for the development of overtraining is a decrease in an athlete's physical working capacity, and it is urgent to develop sufficiently informative indicators to predict the occurrence of this syndrome and its diagnosis at the initial stages of development. Among the currently existing hypotheses of the development of overtraining, aspects of changes in metabolism and energy exchange occupy an important place. In particular, the carbohydrate hypothesis explains the development of overtraining by the fact that with fatigue occurs transient hypoglycemia associated with depletion of muscle and liver glycogen stores, which is aggravated in the case of insufficient intake of carbohydrates from food. It was revealed that hypoglycemia during exercise is more pronounced in overtrained athletes, while the increase in lactate may be low, which indicates an insignificant participation of glycolysis in the metabolism of skeletal muscles in such athletes. However, while overtraining athletes have a greater decrease in glycogen stores with prolonged exercise, there is a sufficient recovery of glycogen stores in the period between loads. It is assumed that repeated depletion of glycogen stores can lead to changes in other metabolic pathways involved in the energy supply of muscle load, in particular, to an increase in the oxidation of branched-chain amino acids (leucine, isoleucine, valine), the change in metabolism of which is associated with the occurrence of fatigue processes in the central nervous system. system.
Currently, in addition to determining an increase in blood lactate, it is proposed to use the following parameters as biochemical markers for diagnosing overtraining syndrome and assessing changes in energy supply systems: an increase in blood urea concentration, a decrease in glucose and glutamine, and a decrease in the ratio of the concentration of free
tryptophan to the concentration of branched-chain amino acids. However, none of the above parameters can serve as a diagnostic standard, which dictates the need for further study of metabolic changes in the development of overtraining syndrome.
Conclusion
During intense physical exertion, ATP re-synthesis in muscles occurs under anaerobic conditions due to the breakdown of CP and glycolysis, and under aerobic conditions due to oxidation reactions of carbohydrates, fats and proteins. Analysis of literature data demonstrates that all three energy supply systems are activated to one degree or another in all types of muscular work, but the relative contribution of each of the systems depends on the intensity and duration of the physical activity performed. It has been shown that although anaerobic mechanisms to a large extent ensure the resynthesis of ATP during high-intensity and short-term physical exertion, the aerobic energy system also plays a significant role in ensuring performance under such loads. Existing methods for assessing energy supply systems (indirect calorimetry, determination of maximum oxygen consumption) allow a fairly accurate assessment of the aerobic pathway of energy release. At the same time, the traditionally used methods for assessing anaerobic energy supply (determining the value of oxygen debt, measuring the concentration of blood lactate and ergometry) are less accurate. When adapting to aerobic loads in trained muscles, there is an increase in glycogen and triglyceride stores and an increase in fat oxidation processes. Anaerobic training improves physical performance mainly due to the development of strength qualities. With the development of overtraining in athletes, hypoglycemia is observed with a slight increase in blood lactate, as well as an increase in the oxidation of branched-chain amino acids and the subsequent development of central fatigue.
Further study of the interaction of the main energy supply systems and their role in the development of changes in the functional state of athletes will allow developing universal criteria for assessing the effectiveness of the training process, substantiating the need for prescribing pharmacological support, as well as identifying informative biochemical markers for diagnosing pathological changes in the body during intense physical activity.
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Received May 16, 2014
UDC 616-018.2-007.17: 612.014.2
ANATOMICAL FEATURES OF THE VENOUS CHANNEL OF THE SHIN
(literature review)
S. A. Semenyago, V. N. Zhdanovich Gomel State Medical University
In the course of a detailed analysis of domestic and foreign literary sources, the structuring of the venous system of the lower leg was carried out with a description of the options for the structure of some departments. Also given are the concepts of communicating and perforating veins, venous sinuses of the lower leg with an indication of their meaning for clinicians. The most significant communicants and perforators are described and data on their localization are given.
Key words: venous system, perforators, communicants, varicose veins.
ANATOMIC FEATURES OF VENOUS SYSTEM OF THE LOWER LEG
(literature review)
S. A. Semeniago, V. N. Zhdanovich Gomel State Medical University
The review gives a detailed analysis of national and foreign publications and describes the structure and variations of the venous system of the lower leg. It also gives notions and clinical importance of communicating and perforating veins and venous sinuses of the lower leg. The most significant communicating and perforating veins and their localization were described.
Key words: venous system, perforating veins, communicating veins, varicose veins.
The supply of the contracting muscles with energy occurs during chemical transformations that take place without the participation of oxygen - anaerobic glycolysis - and with its participation - oxidative (aerobic) phosphorylation. Oxygen is required not only for aerobic phosphorylation, but also for the partial oxidation of lactic acid (lactate), the end product of the anaerobic breakdown of glycogen.
The most important is oxidative phosphorylation, since it allows more efficient use of the energy of chemical transformations in muscles and tissues. Anaerobic processes of energy production are included in the absence of oxygen as an auxiliary mechanism. Thus, the function of oxygen metabolism is to generate energy necessary for various kinds of physiological processes, including the contractile activity of muscles.
The main chemical reactions of energy processes take place in a special part of cells (mitochondria), where oxygen is supplied. In the mitochondria of cells, adenosine triphosphoric acid (ATP) is formed, which is a universal form of energy storage in its phosphorus bonds. The transformation of chemical reactions with the participation of ATP into mechanical work is carried out by the contractile protein material of the muscles - actin and myosin. The complex protein structure of actomyosin under the influence of ATP is able to contract, while the latter decomposes to ADP and AMP (adenosine-diphosphoric and adenosine monophosphoric acids). ATP reserves in muscle tissue are limited, so a constant replenishment of this compound is required to perform significant muscle work.
Recovery (resynthesis) of ATP occurs both due to the high-energy compounds contained in the muscle (creatine phosphate) and due to the high-energy compounds formed in it during muscle activity.
Creatine phosphate is of great importance in the processes of muscle contraction, playing the role of an energy depot. Moreover, its energy storage capacity is higher than that of ATP. However, creatine phosphate does not react with the muscle contractile substance (actomyosin), but reacts only with ADP.
The creatine kinase reaction is extremely fast, and it is characteristic of short-term intense physical activity
ATP resynthesis due to high-energy phosphorus compounds formed during muscle activity can be carried out by glycolytic and respiratory phosphorylation.
Glycolytic phosphorylation, like the creatine kinase reaction, is an anaerobic pathway for ATP resynthesis. Due to the fact that carbohydrate reserves of the body, especially in riding horses, are large enough, glycolysis can provide ATP resynthesis for a long time.
Resynthesis of ATP by glycolytic phosphorylation is predominant during muscular loads of maximum intensity, when there is a sharp discrepancy between the greatly increased demand of the body for oxygen and disabilities her satisfaction. The end product of anaerobic breakdown of carbohydrates is lactic acid.
At maximum muscle activity, an excess of lactic acid is formed, which diffuses into the blood. After maximum work, for example after a quick jump or running, there is a rapid breathing and increased oxygen consumption compared to the state of rest. The increased amount of oxygen consumed during the recovery period is called oxygen debt and is spent on oxidation in the liver and heart tissues of some of the excess lactic acid (up to 1/4), formed during the period of maximum muscle activity. The rest of the excess lactic acid accumulated in the blood during a brisk run is converted back into glycogen in the liver.
An important role in muscle energy is played by the oxidation processes of pyruvic acid, which is a precursor of lactic acid during anaerobic phosphorylation. Most pyro-tartaric acid is the basis for aerobic breakdown of carbohydrates and other oxidative reactions.
A prerequisite for aerobic oxidation is a good supply of oxygen to the body. This pathway of ATP resynthesis is typical for loads of medium and moderate intensity, when the body's demand for oxygen can be fully satisfied.
Most of the aerobic oxidative transformations are used to support motor activity. During muscular work, the level of oxygen consumption by the body increases many times. Skeletal muscle during strenuous work can increase oxygen consumption up to 100 times. Therefore, the delivery of the required amount of oxygen for metabolic processes in the muscles is a decisive condition for the motor activity of the horse's body.
In the process of energy metabolism, oxygen is consumed by the body and carbon dioxide is released. Of great importance is the ratio of the released carbon dioxide: consumed oxygen - the so-called respiratory coefficient, which in a certain way reflects the nature of metabolism. Respiratory coefficient has complex dynamics and undergoes changes during work. In horses, when moving with a step, it fluctuates within unity, and with more intense movement it decreases due to the depletion of carbohydrates and the gradual involvement in the metabolism of proteins and fats. Thus, the respiratory quotient indicates which energetic substance is being oxidized. When oxidizing carbohydrates, it is equal to one, when oxidizing proteins - 0.8, fats - 0.7.
By the amount of oxygen consumed at a certain respiratory coefficient, it is possible to calculate the expenditure of calories required to ensure a particular job.
The minimum metabolic rate during complete muscle rest is called basal metabolism. In horses, basal metabolism is not the same and depends on age, weight, breed and other factors. Knowing the data on the basal metabolic rate and expenditures during movement, it is possible to determine the total amount of energy expended by a horse at different gaits when covering a particular distance (Table 1).
Table 1. Energy consumption of riding horses in kilocalories when working under the saddle with a rider weighing 80 kg * (according to G.G. Carlsen)
* (Taking into account the oxygen debt; 1 kcal contains 4.18 kJ.)
The energy consumption when moving with a step in horses is 0.58-0.71 kcal per 1 kg / km. When switching to a trot, the energy consumption per unit of time increases by about 2 times, that is, in proportion to the increase in the speed of movement. At the same time, these changes are insignificant when calculated per unit path.
It should be noted that the amount of oxygen consumption characterizes the level of oxidation-reduction processes in the body, and the oxygen debt is a measure of the participation of the processes of anaerobic energy production during muscle activity. The sum of these values, that is, oxygen consumption during work and oxygen debt, is the level of oxygen demand and is an indicator of the body's energy consumption
Chapter 6. Basics of energy supply of muscular activity in contact styles of martial arts
You are watching the fight. You mark the beginning, athletes perform false attacks, constantly move, prepare attacks, defend themselves. Suddenly, one of the athletes explodes and delivers a series of blows at different levels. He hits, develops success, picks up the pace and suddenly gets up. At the end of the fight, he significantly lost his lightness, his breathing was quickened and the beginning of the attacks became noticeable. What's happening? What energy processes have taken place, and why does the body react in such a way to a competitive load. The answer is in the energy supply of muscle activity.
The training effect on the muscular system entails changes in the energy supply of movements. It is undeniable that there are generally accepted model characteristics of competitive technique. Specialists, coaches, athletes, scientists have their own idea of \u200b\u200bthe educational and training process and use knowledge, skills and experience in practice. In general, the model parameters of a martial artist are clear to everyone. Each coach has his own stereotype of thinking. And everyone tries to adjust the process of training an athlete to fit their stereotype. In most cases, preference is given to speed-strength parameters, some develop special endurance, someone focuses on technique and tactics. The goal is one - sports performance.
This chapter describes in detail the mechanisms of energy supply of muscle activity in relation to contact percussion martial arts.
A taekwondo match lasts six minutes and consists of three rounds of two minutes with a minute of rest between rounds. In karate, the fight lasts three minutes and if the winner has not been determined, then after the decision of the judges, another two minutes are added. In kickboxing, there are three rounds of two minutes with a minute of rest between rounds. From this we can conclude that the fight is supported anaerobicenergy processes.
To perform physical activity of varying intensity, energy is needed to provide the process of muscle contraction. There are several energy synthesis systems in the body that are used to provide a particular type of physical activity. All these systems are united by the fact that the final energy substrate is adenosine triphosphoric acid (ATP). There are several mechanisms for the synthesis of ATP: with the use of oxygen (aerobic pathway), without the use of oxygen (anaerobic pathway), and with or without the formation of lactic acid (lactate).
Let's consider the mechanisms of energy supply of muscle activity.
The firstThe basis of the evaluative action, the quality impact is made up of BS fibers. It's no secret that a blow or a series of blows is carried out in a short period of time. The biomechanics of movement plays an important role, but the essence of the impact is strength, speed and accuracy. It is necessary to develop maximum power in a minimum period of time.
The starting movement in general, whether it be a jump, hit, or lifting weights, is carried out due to creatine energy. And it is called the anaerobic alactate system (ATP - creatine). This system is typical for short-term efforts and is the main one at maximum loads of a speed-power nature. Energy exchange is carried out along this path when performing work of very high intensity (sprint, high jumps, lifting weights, etc.). And also in all cases when we start suddenly from a state of rest and our muscles begin to consume a small amount of ATP accumulated in muscle fibers, and then ATP is formed thanks to creatine phosphate (CrP), which contains one creatine molecule and one phosphate molecule, which are connected by an energy-generating bond (- * -): Creatine - * -P
When this bond is broken, energy is released, which is used for the resynthesis of ATP from ADP and phosphate.
This system is called anaerobic, since oxygen does not participate in resynthesis, and alactic, since lactic acid is not formed. The amount of ATP that can be formed in this case (about four times the ATP supply) is limited, since the stores of creatine phosphate in muscle fibers are small. They are depleted in 6-9 seconds.
Optimal training for the creatine phosphate system
The main goal of the development of the creatine phosphate system is to increase the content of creatine phosphate in the muscles. This is achieved by performing high-intensity training work at 80–90% of the maximum. The duration of the exercises performed is very short, from 5-10 to 20 seconds, and the intervals between repetitions of the load should be sufficiently long (from 1 minute or more). Since such types of training are carried out with a high heart rate, they can be recommended only to athletes with a sufficient degree of training of the cardiovascular system, and, accordingly, it is undesirable to use them in athletes of older age groups.
SecondShort-term muscle work, in contact styles of martial arts: taekwondo, karate and kickboxing, up to 3 minutesanaerobic lactate system. It is the training of the anaerobic lactate system that contributes to the high-quality execution of explosive powerful punches and kicks in a duel, which lasts up to three minutes with short rest pauses.
Energy metabolism during prolonged exercise is mainly the lot of aerobic reactions, but anaerobic processes also play a significant role. For example, the transition from a state of rest to action (movement) is always associated with an increase in oxygen demand. But the organs of oxygen supply are "heavy on the rise", they cannot quickly engage in work with maximum intensity. This is where the ability to work in conditions of oxygen debt helps out, since it is possible to accumulate little oxygen in the body: only 400–500 ml in the lungs, 900–1000 in the blood, 300–400 in muscles and interstitial fluid. Alas, these reserves are only enough for a few seconds of exercise. (The body also has a mechanism for the accumulation of oxygen in the form of superoxides or peroxide compounds. This mechanism is most likely used by yogis).
During physical work, when exposed to pathogenic factors, the body needs to spend some additional energy to maintain homeostasis. The aerobic process, as already noted, is the most economical (compared with creatine phosphate, 38 times), however, it is slow enough and cannot provide enough energy. In such cases, the role of carbohydrates in the energy supply of the body increases. They are split first when there is an urgent need for energy generation. For example, when operating at maximum and submaximal power, about 70–90% of all consumed energy is provided by glycolysis. In other words, to obtain energy more quickly, the body enhances the glycolytic type of energy exchange, since it is faster than oxygen and much longer than creatine phosphate.
It is also called the anaerobic glycolytic system, since sugar molecules are broken down without oxygen. Sugar molecules, more precisely glucose molecules, are not completely broken down, but only to the formation of lactic acid. The muscle actually does not contain lactic acid molecules, but a negatively charged lactate ion (LA-) and a positively charged hydrogen ion (H +), as well as the energy necessary for the formation of ATP from ADP and phosphate: Glucose \u003d LA- + H + + energy
Both of these ions can be viewed as unnecessary, interfering with the muscles. They can also get from the muscle into the bloodstream even during muscle work, if this work is long enough.
It is generally accepted that a muscle resorts to the anaerobic lactate system when the intensity of the work performed is such that the ATP demand per minute will exceed the amount of ATP generated by the aerobic system.
Figure: oneFactors providing anaerobic performance of the body.
The anaerobic lactate system is important in running at a distance of 400 m, 800 m and even a longer distance of 1500 m. In the future we will see that not all muscle is usually involved here, but only part of its fibers.
The dependence of the anaerobic capacity of the body (anaerobic performance) on a number of factors is reflected in fig. one
ThirdLactic acid, or lactate, is always present in the body. Under certain types of exercise, lactate is absorbed by the fibers of a particular muscle. Individual fitness levels are able to absorb and use varying amounts of lactate. Only narrowly focused training on the formation of the activity of enzyme systems that catalyze anaerobic reactions lead to an increase in the body's resistance to a high concentration of lactate in the blood.
In practice, this is a high tempo, biting, strong and accurate strikes, quick recovery.
Many people do not know that our body produces very small amounts of lactic acid even at rest. These small amounts of lactic acid can be easily removed from the body, but they explain why there are always traces of lactate in the blood of a person.
We can say that the amount of lactic acid formed per second by the muscles and released into the blood increases when we increase the intensity of the load, for example, the speed or weight of a load. Up to a certain intensity of load, the body can release all lactic acid into the blood. It is usually absorbed by other muscles or other muscle fibers of the same muscle that produces this substance, as well as by the heart, liver or kidneys. Thus, the level of lactate in the blood always remains close to the basal value.
People trained for long-term stress produce a fairly large amount of lactate, but their body is able to absorb most of it.
Lactic acid is produced by muscles and then released into the blood, where its concentration can be measured. It is present both in muscle fibers and in the blood as two ions, respectively, one molecule and one electrically charged atom. The first ion is the negatively charged lactate ion (LA-). The level of this substance in the blood can, in particular, be measured. The second ion is the positively charged hydrogen ion (H-). It is the second ion that causes great discomfort, since it increases the level of lactic acid in the muscles. What's more, it can even disrupt proper muscle function. We feel a decrease in muscle performance after running at high speed. It is mostly caused by an increase in lactic acid levels. When this level exceeds a certain value, various changes occur in muscle fibers (for example, a change in mitochondria), which can persist for several hours (even days in individuals who are not used to performing loads associated with the formation of lactic acid). The recovery mechanisms of the human body gradually reconstruct the state before the load, in some cases the state that allows the individual to tolerate high levels of lactic acid in the blood.
Note that hydrogen ions interfere not only with muscles, but also with the brain, as soon as they enter the bloodstream, they reach the cerebrospinal fluid (the fluid surrounding the brain) .That is why the formation of large amounts of lactic acid negatively affects mental clarity, coordination and reflex reactions. All of these effects can be partly caused by ammonia, which is also produced in muscles. That is, lactic acid is, in many ways, an unnecessary substance that interferes with the body. However, its molecules contain energy, so it is important that the working muscles learn to use this energy source.
Blood lactate level
Commonly used blood lactate levels are listed below. Note that when using different measurement methods, there may be slight differences in the values \u200b\u200bobtained.
About 1 mmol / L: at rest and when running at a slow pace;
About 2 mmol / L: during a marathon run at a constant pace or at a speed at the level of the aerobic threshold;
About 4 mmol / L: For most runners, this will be measured when running at a speed at the anaerobic threshold or when running at a speed that the athlete can maintain for one hour while running at a constant pace on a level surface;
About 18–20 mmol / L: in high-class athletes after achieving the best personal result at a distance of 400 m or 800 m; for elite athletes, this indicator can be more than 25 mmol / l;
Another reliable test of the body's anaerobic performance is maximum oxygen demand. One of the first to determine this figure, equal to 18.7 liters, the English physiologist Hill. Subsequent investigations made it possible to obtain an even greater value - 20–23 liters. Just as in the case of the IPC, this oxygen debt is observed only in high-class athletes. For those who do not go in for sports or active physical education, it does not exceed 4-7 liters or 60-100 mg per 1 kg of weight.
Fourthnegative manifestations of an increase in lactate levels, indicates the inability of aerobic energy supply systems to ensure overcoming high-intensity physical activity. High concentrations of lactate in the blood are a reflection of the development of acidosis (acidification) both within the muscle cells themselves (intracellular acidosis) and in the intercellular spaces surrounding them (extracellular acidosis). Acidification of muscle cells leads to serious metabolic disorders. The amount of lactate more than 7 mmol / l is contraindicated for the development of technical elements.
In training practice, a monotonous high-speed impact is often used. Where the heart rate is more than 90% of the maximum. There are not enough breaks for rest and recovery. The athlete is fully loaded, overstrained, not recovered.
The functioning of many enzyme systems, including aerobic energy supply, is sharply disrupted during the development of acidosis, which, in particular, has a negative effect on aerobic capacity. Moreover, these changes can persist for a long time. For example, it may take several days to fully restore aerobic capacity after overcoming physical activity, accompanied by a significant accumulation of lactate. Frequent uncontrolled repetition of such a load in the absence of complete recovery of aerobic systems leads to the development of overtraining. Long-term preservation of intra- and extracellular acidosis is accompanied by damage to the cell walls of the skeletal muscles. This is accompanied by an increase in the concentration of intracellular substances in the blood, the content of which in the blood is minimal in the absence of damage to muscle cells. These substances include creatine phosphokinase (CPK) and urea. An increase in the concentration of these substances is a clear sign of damage to muscle cells. While it takes 24–96 hours to reduce the concentration of these substances in the blood, a much longer period is required to completely restore the normal structure of muscle cells. During this period, it is possible to carry out a training load only of a recovery nature.
An increase in lactate levels is accompanied by a simultaneous loss of coordination of movements, which is clearly manifested in high-tech sports. With a lactate level of 6–8 mmol / l, it is considered inappropriate to carry out trainings for practicing techniques, since with impaired coordination of movements it is difficult to achieve technically competent performance of the required exercises.
With acidosis associated with the accumulation of lactate, the risk of injury to athletes increases dramatically. Violation of the integrity of the cell walls of skeletal muscles leads to their microfractures. Abrupt and uncoordinated movements can also lead to more serious traumatic injuries (tears or tears of muscles, tendons, joint damage).
Resynthesis (re-formation) of creatine phosphate slows down in "acidified" muscles. This should be taken into account when training the striking technique of arms and legs, especially when leading up to a competition. During this time, intense physical activity, accompanied by the accumulation of lactate and depletion of creatine phosphate reserves, should be avoided.
Special methods have been developed for training the lactate system, aimed at increasing the body's resistance to increased formation and accumulation of lactic acid. The main task of such training comes down to the adaptation of the athlete's body to overcome the competitive load in conditions of increased education and accumulation of lactic acid.
Types of lactate system training:
1. Repeated training.
Physical activity of high intensity and lasting from 20 to 180 seconds alternates with rest intervals from 30 to 60 seconds. Rest intervals should not be too long, otherwise lactate levels will decrease. The number of episodes is from 2 to 10. Rest pauses between episodes are from 5 to 7 minutes. Usually, these are training sessions that are quite tough in their intensity, requiring careful monitoring of the athlete's condition and the correct choice of the volume and duration of the load. The coach must control the heart rate during training. This text is an introductory fragment.
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Heading "Biochemistry". Aerobic and anaerobic factors of sports performance. Bioenergetic criteria for physical performance. Biochemical indicators of the level of development of aerobic and anaerobic components of sports performance. Correlation in the levels of development of aerobic and anaerobic components of sports performance among representatives different types sports. Features of biochemical changes in the body under critical conditions of muscle activity.
Among the leading biochemical factors that determine sports performance, the most important are bioenergetic (aerobic and anaerobic) capabilities of the body. Depending on the intensity and nature of the provision, it is proposed to divide the work into several categories:
- anaerobic (alactate) zone of load power;
- anaerobic (glycolytic) zone;
- zone of mixed anaerobic-aerobic supply (anaerobic processes prevail);
- zone of mixed aerobic-anaerobic provision (aerobic processes prevail);
- zone of aerobic energy supply.
Anaerobic work of maximum power (10-20 sec.) Is performed mainly on the intracellular reserves of phosphagen (creatine phosphate + ATP). The oxygen debt is small, has an alactic character and should cover the resynthesis of consumed macroergs. A significant accumulation of lactate does not occur, although glycolysis may be involved in providing such short-term loads and the lactate content in working muscles increases.
Operation of submaximal capacities depending on the rate and duration, it lies in the zones of anaerobic (glycolytic) and anaerobic-aerobic energy supply. The leading contribution is the contribution of anaerobic glycolysis, which leads to the accumulation of high intracellular concentrations of lactate, acidification of the environment, the development of NAD deficiency and autoinhibition of the process. Lactate has a good, but final rate of penetration through membranes and the equilibrium between its content in muscles and plasma is established only after 5-10 minutes. from the beginning of work.
At work high power prevails aerobic way of energy supply (75-98%). Work of moderate power is characterized by almost complete aerobic energy supply and the possibility of long-term performance from 1 hour. up to many hours depending on the specific power. There are a significant number of indicators used to identify the level of development, aerobic and anaerobic energy conversion mechanisms.
One of them provides an integral assessment of these mechanisms, others allow one to characterize their various aspects (deployment speed, power, capacity, efficiency) or the state of any individual link or stage. The most informative are the indicators recorded during the performance of testing loads, causing close to the limiting activation of the corresponding energy conversion processes. It should be borne in mind that anaerobic processes are highly specific and to the greatest extent are included in the energy supply of only the type of activity in which the athlete has undergone special training. This means that bicycle ergometric tests are most suitable for cyclists to assess the possibilities of using anaerobic processes of energy supply for work, and for runners, running, etc.
The power, duration and nature of the exercise performed by the test are of great importance for identifying the possibilities of using various energy supply processes. For example, to assess the level of development of the alactate anaerobic mechanism, short-term (20-30 sec.) Exercises performed with maximum intensity are most suitable. The greatest shifts associated with the participation of the glycolytic anaerobic mechanism of energy supply of work are found when performing exercises with a duration of 1-3 minutes. with a maximum intensity for this duration. An example would be work consisting of 2-4 repetitive exercises, about 1 minute in duration, performed at equal or decreasing rest intervals. Each repetition exercise should be done at the highest possible intensity. The state of aerobic and anaerobic processes of energy supply to muscle work can be characterized using a test with a stepwise increase in load to "failure".
The indicators characterizing the level of anaerobic systems are the values \u200b\u200bof alactate and lactate oxygen debt, the nature of which was considered earlier. Informative indicators of the depth of glycolytic anaerobic shifts are the maximum concentration of lactic acid in the blood, indicators of active blood reaction (pH) and shift of buffer bases (BE).
To assess the level of development of aerobic mechanisms of energy production, the determination of the maximum oxygen consumption (MOC) is used - the highest oxygen consumption per unit of time that can be achieved under conditions of intense muscular work.
IPC characterizes the maximum power of the aerobic process and is of an integral (generalized) nature, since the ability to generate energy in aerobic processes is determined by the combined activity of many organs and systems of the body responsible for the utilization, transport and use of oxygen. In sports where the main source of energy is aerobic process, along with power, its capacity is of great importance. The holding time of the maximum oxygen consumption is used as a measure of the capacity. For this, together with the value of the VO2 max, the value of the "critical power" is determined - the lowest power of the exercise at which the VO2 max is achieved. For these purposes, the most convenient test with a stepwise increase in load. Then (usually the next day) the athletes are asked to perform the work at the critical power level. The time during which the “critical power” can be maintained and oxygen consumption changes is recorded. The time of work at the “critical power” and the time of retention of the VO2 max correlate with each other and are informative in relation to the capacity of the aerobic pathway of ATP resynthesis.
As known, initial stages any sufficiently intense muscular work is provided with energy due to anaerobic processes. The main reason for this is the inertia of the aerobic energy supply systems. After the deployment of the aerobic process to a level corresponding to the power of the performed exercise, two situations may arise:
- aerobic processes fully cope with the energy supply of the body;
- along with the aerobic process, anaerobic glycolysis is involved in energy supply.
Studies have shown that in exercises, the power of which has not yet reached "critical", and, therefore, the aerobic processes have not developed to the maximum level, anaerobic glycolysis can participate in the energy supply of work throughout its entire course. The lowest power, starting from which glycolysis participates in energy production throughout the work, along with aerobic processes, is called the "threshold of anaerobic metabolism" (ANSP)... The power of the TANM is usually expressed in relative units - the level of oxygen consumption (as a percentage of the IPC) achieved during operation. An improvement in fitness for aerobic loadings is accompanied by an increase in TANM. The value of TANM depends primarily on the characteristics of aerobic mechanisms of energy production, in particular, on their effectiveness. Since the efficiency of the aerobic process can undergo changes, for example, due to a change in the conjugation of oxidation with phosphorylation, it is of interest to assess this side of the body's functional readiness. The most important within individual changes in this indicator at different stages training cycle... You can also assess the efficiency of the aerobic process in the test with a stepwise increase in load when determining the level of oxygen consumption at each step.
So, the participation of anaerobic and aerobic processes in the energy supply of muscle activity is determined, on the one hand, by the power and other features of the exercise performed, and on the other, by the kinetic characteristics (maximum power, maximum power retention time, maximum capacity and efficiency) of the energy production processes.
The considered kinetic characteristics depend on the combined action of many tissues and organs and change in different ways under the influence training exercises... This feature of the response of bioenergetic processes to training loads must be taken into account when drawing up training programs.