The textbook outlines the basics of general biochemistry and biochemistry of muscular activity of the human body, describes the chemical structure and metabolic processes of the most important substances in the body, and reveals their role in ensuring muscular activity. The biochemical aspects of the processes of muscle contraction and the mechanisms of energy generation in muscles, the patterns of development of motor qualities, the processes of fatigue, recovery, adaptation, as well as rational nutrition and diagnostics of the functional state of athletes are considered. For students and teachers of higher and secondary educational institutions of physical education and sports, specialists in physical rehabilitation and recreation.

Book information:
Volkov N.I., Nesen E.N., Osipenko A.A., Korsun S.N. Biochemistry of muscle activity. 2000. - 503 p.

Part one. Biochemical foundations of the life of the human body
Chapter 1. Introduction to Biochemistry
1. Subject and methods of biochemistry research
2. History of the development of biochemistry and the formation of sports biochemistry
3. Chemical structure of the human body
4. Transformation of macromolecules
Control questions

Chapter 2. Metabolism in the body
1. Metabolism is a necessary condition for the existence of a living organism
2. Catabolic and anabolic reactions - two sides of metabolism
3. Types of metabolism
4. Stages of nutrient breakdown and energy extraction in cells
5. Cellular structures and their role in metabolism
6. Regulation of metabolism
Control questions

Chapter 3. Energy exchange in the body
1. Energy sources
2. ATP is a universal source of energy in the body
3. Biological oxidation is the main way of energy production in the cells of the body
4. Mitochondria - the “energy stations” of the cell
5. The citric acid cycle is the central pathway for aerobic nutrient oxidation
6. Respiratory chain
7. Oxidative phosphorylation is the main mechanism of ATP synthesis
8. Regulation of ATP metabolism
Control questions

Chapter 4. Exchange of water and minerals
1. Water and its role in the body
2. Water balance and its changes during muscle activity
3. Minerals and their role in the body
4. Metabolism of minerals during muscle activity
Control questions

Chapter 5. Acid-base state of the body
1. Mechanisms of transport of substances
2. Acid-base state of the internal environment of the body
3. Buffer systems and their role in maintaining a constant pH of the environment
Control questions

Chapter 6. Enzymes - biological catalysts
1. General understanding of enzymes
2. Structure of enzymes and coenzymes
3. Multiple Forms of Enzymes
4. Properties of enzymes
5. Mechanism of action of enzymes
6. Factors influencing the action of enzymes
7. Classification of enzymes
Control questions

Chapter 7. Vitamins
1. General idea of ​​vitamins
2. Classification of vitamins
3. Characteristics of fat-soluble vitamins
4. Characteristics of water-soluble vitamins
5. Vitamin-like substances
Control questions

Chapter 8. Hormones - metabolic regulators
1. General understanding of hormones
2. Properties of hormones
3. Chemical nature of hormones
4. Regulation of hormone biosynthesis
5. Mechanism of action of hormones
6. Biological role of hormones
7. The role of hormones in muscle activity
Control questions

Chapter 9. Biochemistry of carbohydrates
1. Chemical composition and biological role of carbohydrates
2. Characteristics of carbohydrate classes
3. Metabolism of carbohydrates in the human body
4. The breakdown of carbohydrates during digestion and their absorption into the blood
5. Blood glucose levels and its regulation
6. Intracellular carbohydrate metabolism
7. Carbohydrate metabolism during muscle activity
Control questions

Chapter 10. Biochemistry of lipids
1. Chemical composition and biological role of lipids
2. Characteristics of lipid classes
3. Metabolism of fats in the body
4. The breakdown of fats during digestion and their absorption
5. Intracellular fat metabolism
6. Regulation of lipid metabolism
7. Lipid metabolism disorders
8. Fat metabolism during muscle activity
Control questions

Chapter 11. Biochemistry of nucleic acids
1. Chemical structure of nucleic acids
2. Structure, properties and biological role of DNA
3. Structure, properties and biological role of RNA
4. Nucleic acid metabolism
Control questions

Chapter 12. Biochemistry of proteins
1. Chemical composition and biological role of proteins
2. Amino acids
3. Structural organization of proteins
4. Properties of proteins
5. Characteristics of individual proteins involved in providing muscle work
6. Free peptides and their role in the body
7. Protein metabolism in the body
8. Breakdown of proteins during digestion and absorption of amino acids
9. Protein biosynthesis and its regulation
10. Interstitial protein breakdown
11. Intracellular transformation of amino acids and urea synthesis
12. Protein metabolism during muscle activity
Control questions

Chapter 13. Integration and regulation of metabolism - the biochemical basis of adaptation processes
1. Interconversion of carbohydrates, fats and proteins
2. Regulatory systems of metabolism and their role in the body’s adaptation to physical activity
3. The role of individual tissues in the integration of intermediate metabolism
Control questions

Part two. Biochemistry of sports
Chapter 14. Biochemistry of muscles and muscle contraction
1. Types of muscles and muscle fibers
2. Structural organization of muscle fibers
3. Chemical composition of muscle tissue
4. Structural and biochemical changes in muscles during contraction and relaxation
5. Molecular mechanism of muscle contraction
Control questions

Chapter 15. Bioenergetics of muscle activity
1. General characteristics of energy generation mechanisms
2. Creatine phosphokinase mechanism of ATP resynthesis
3. Glycolytic mechanism of ATP resynthesis
4. Myokinase mechanism of ATP resynthesis
5. Aerobic mechanism of ATP resynthesis
6. Connection of energy systems during various physical activities and their adaptation during training
Control questions

Chapter 16. Biochemical changes in the body when performing exercises of varying intensity and duration
1. General direction of changes in biochemical processes during muscle activity
2. Transport of oxygen to working muscles and its consumption during muscle activity
3. Biochemical changes in individual organs and tissues during muscular work
4. Classification of physical exercises according to the nature of biochemical changes during muscle work
Control questions

Chapter 17. Biochemical factors of fatigue
1. Biochemical factors of fatigue during short-term exercises of maximum and submaximal power
2. Biochemical factors of fatigue during long-term exercise of high and moderate power
Control questions

Chapter 18. Biochemical characteristics of recovery processes during muscle activity
1. Dynamics of biochemical processes of recovery after muscle work
2. The sequence of restoring energy reserves after muscular work
3. Elimination of breakdown products during the rest period after muscular work
4. Using the peculiarities of recovery processes when building sports training
Control questions

Chapter 19. Biochemical factors of sports performance
1. Factors limiting human physical performance
2. Indicators of aerobic and anaerobic performance of an athlete
3. The influence of training on the performance of athletes
4. Age and athletic performance
Control questions

Chapter 20. Biochemical foundations of an athlete’s speed-strength qualities and methods of their development
1. Biochemical characteristics of speed and strength qualities
2. Biochemical foundations of speed-strength training methods for athletes
Control questions

Chapter 21. Biochemical basis of athletes' endurance
1. Biochemical factors of endurance
2. Training methods to promote endurance
Control questions

Chapter 22. Patterns of biochemical adaptation during sports training
1. Physical activity, adaptation and training effect
2. Patterns of development of biochemical adaptation and principles of training
3. Specificity of adaptive changes in the body during training
4. Reversibility of adaptive changes during training
5. Sequence of adaptive changes during training
6. Interaction of training effects during training
7. Cyclical development of adaptation during training
Control questions

Chapter 23. Biochemical foundations of rational nutrition for athletes
1. Principles of rational nutrition for athletes
2. Energy consumption of the body and its dependence on the work performed
3. Balance of nutrients in the athlete’s diet
4. The role of individual chemical components of food in ensuring muscle activity
5. Nutritional supplements and weight management
Control questions

Chapter 24. Biochemical control in sports
1. Objectives, types and organization of biochemical control
2. Objects of study and main biochemical parameters
3. Basic biochemical indicators of blood and urine composition, their changes during muscle activity
4. Biochemical control of the development of energy supply systems for the body during muscle activity
5. Biochemical control over the level of training, fatigue and recovery of the athlete’s body
6. Control over doping in sports
Control questions

Glossary of terms
Units
Literature

Additional information about the book: format: pdf, file size: 37.13 MB.

How does an athlete’s body adapt to intense muscular activity?

The physiology of sports studies deep functional changes in the body that arose in the process of adapting it to increased muscular activity. However, they are based on biochemical changes in the metabolism of tissues and organs and, ultimately, the body as a whole. However, we will consider in the most general form the main changes that occur under the influence of training only in the muscles.

The biochemical restructuring of muscles under the influence of training is based on the interdependence of the processes of expenditure and restoration of functional and energy reserves of muscles. As you already understand from the previous one, during muscle activity intensive breakdown of ATP occurs and, accordingly, other substances are intensively consumed. In the muscles, these are creatine phosphate, glycogen, lipids; in the liver, glycogen is broken down to form sugar, which is transported through the blood to the working muscles, heart, and brain; fats are intensively broken down and fatty acids are oxidized. At the same time, metabolic products accumulate in the body - phosphoric and lactic acids, ketone bodies, carbon dioxide. They are partially lost by the body, and partially used again, being involved in metabolism. Muscular activity is accompanied by an increase in the activity of many enzymes, and thanks to this, the synthesis of spent substances begins. Resynthesis of ATP, creatine phosphate and glycogen is already possible during work, but along with this there is also an intensive breakdown of these substances. Therefore, their content in the muscles during work never reaches the original level.

During the rest period, when the intensive breakdown of energy sources stops, the resynthesis processes acquire a clear advantage and not only restoration of what was expended (compensation) occurs, but also super-restoration (supercompensation), exceeding the initial level. This pattern is called the “law of supercompensation.”

The essence of the phenomenon of supercompensation.

In the biochemistry of sports, the patterns of this process have been studied. It has been established, for example, that if the substance is intensively consumed in the muscles, liver and other organs, the faster the resynthesis occurs and the more pronounced the phenomenon of super-recovery is. For example, after short-term intense work, an increase in the level of glycogen in muscles above the initial level occurs after 1 hour of rest, and after 12 hours it returns to the original, pre-working level. After long-term work, supercompensation occurs only after 12 hours, but the increased level of glycogen in the muscles persists for more than three days. This is possible only due to the high activity of enzymes and their enhanced synthesis.

Thus, one of the biochemical bases for changes in the body under the influence of training is an increase in the activity of enzyme systems and supercompensation of energy sources expended during work. Why is it very important to take into account the laws of supercompensation in the practice of sports training?

Knowledge of the patterns of supercompensation makes it possible to scientifically substantiate the intensity of loads and rest intervals during normal physical exercises and sports training.

Since supercompensation persists for some time after completion of work, subsequent work can be performed under more favorable biochemical conditions, and, in turn, lead to a further increase in the functional level (Fig...). If subsequent work is performed under conditions of incomplete recovery, then this leads to a decrease in the functional level (Fig...).

Under the influence of training, an active adaptation occurs in the body, but not to work “in general,” but to specific types of it. When studying various types of sports activities, the principle of specificity of biochemical adaptation was established and the biochemical foundations of the qualities of motor activity - speed, strength, endurance - were established. This means scientifically based recommendations for a targeted training system.

Let's give just one example. Remember how, after intense speed exercise (running), increased breathing (“shortness of breath”) occurs. What is this connected with? During work (running), due to lack of oxygen, under-oxidized products (lactic acid, etc.), as well as carbon dioxide, accumulate in the blood, which leads to a change in the degree of acidity of the blood. Accordingly, this causes excitation of the respiratory center in the medulla oblongata and increased breathing. As a result of intense oxidation, blood acidity is normalized. And this is only possible with high activity of aerobic oxidation enzymes. Consequently, after intensive work, aerobic oxidation enzymes actively function during the rest period. At the same time, the endurance of athletes performing long-term work directly depends on the activity of aerobic oxidation. On this basis, it was biochemists who recommended including short-term, high-intensity loads in the training of many sports, which is now generally accepted.

What are the biochemical characteristics of a trained organism?

In the muscles of a trained body:

The myosin content increases and the number of free HS groups in it increases, i.e. the ability of muscles to break down ATP;

The reserves of energy sources necessary for ATP resynthesis increase (the content of creatine phosphate, glycogen, lipids, etc.)

The activity of enzymes that catalyze both anaerobic and aerobic oxidative processes increases significantly;

The myoglobin content in the muscles increases, which creates an oxygen reserve in the muscles.

The protein content of the muscle stroma, which provides the mechanics of muscle relaxation, increases. Observations on athletes show that the ability to relax muscles increases under the influence of training.

Adaptation to one factor increases resistance to other factors (for example, stress, etc.);

The training of a modern athlete requires high intensity physical activity and a large volume of it, which can have a one-sided effect on the body. Therefore, it requires constant monitoring by doctors and sports medicine specialists, based on the biochemistry and physiology of sports.

And physical education, like sports activities, allows you to develop the reserve capabilities of the human body and ensure full health, high performance and longevity. Physical health is an integral part of the harmonious development of a person’s personality, it forms character, stability of mental processes, volitional qualities, etc.

The founder of the scientific system of physical education and medical-pedagogical control in physical culture is the remarkable domestic scientist, outstanding teacher, anatomist and doctor Pyotr Frantsevich Lesgaft. His theory is based on the principle of the unity of physical and mental, moral and aesthetic development of man. He considered the theory of physical education as a “branch of biological science.”

Biochemistry plays a huge role in the system of biological sciences that study the fundamentals of physical education and sports.

Already in the 40s of the last century, targeted scientific research in the field of sports biochemistry was begun in the laboratory of the Leningrad scientist Nikolai Nikolaevich Yakovlev. They made it possible to find out the essence and specific features of the body’s adaptation to various types of muscular activity, to substantiate the principles of sports training, factors affecting the athlete’s performance, states of fatigue, overtraining, and much more. etc. Subsequently, the development of sports biochemistry formed the basis for training astronauts for space flights.

What questions does sports biochemistry solve?

Biochemistry of sports is the basis of sports physiology and sports medicine. Biochemical studies of working muscles have established:

Patterns of biochemical changes as active adaptation to increased muscle activity;

Justification of the principles of sports training (repetition, regularity, work-rest ratio, etc.)

Biochemical characteristics of the qualities of motor activity (speed, strength, endurance)

Ways to speed up the recovery of an athlete’s body and many others. etc.

Questions and assignments.

Why do high-speed loads have a more versatile effect on the body?

Try to give a physiological and biochemical justification for Aristotle’s statement “Nothing depletes and destroys a person so much as prolonged physical inactivity.” Why is it so relevant for modern people?

Muscular activity - contraction and relaxation occur with the obligatory use of energy, which is released during the hydrolysis of ATP ATP + H 2 0 ADP + H 3 P0 4 + energy at rest, the concentration of ATP in muscles is about 5 mmol/l and, accordingly, 1 mmol of ATP corresponds to physiological conditions approximately 12 cal or 50 J (1 cal = 4.18 J)

Muscle mass in an adult is about 40% of body weight. In athletes building muscle, muscle mass can reach 60% or more of body weight. The muscles of an adult at rest consume about 10% of the total oxygen entering the body. During intense work, muscle oxygen consumption can increase to 90% of the total oxygen consumed.

Energy sources for aerobic resynthesis of ATP are carbohydrates, fats and amino acids, the breakdown of which is completed by the Krebs cycle. The Krebs cycle is the final stage of catabolism, during which acetyl coenzyme A is oxidized to CO2 and H20. During this process, 4 pairs of hydrogen atoms are removed from acids (isocitric, α-ketoglutaric, succinic and malic acid) and therefore 12 ATP molecules are formed from the oxidation of one molecule of acetyl coenzyme A.

ANAEROBIC PATHWAYS OF ATP RESINTHESIS Anaerobic pathways of ATP resynthesis (Creatine phosphate, glycolytic) are additional methods of ATP formation in cases where the main pathway for ATP production - aerobic - cannot provide muscle activity with the necessary amount of energy. This happens in the first minutes of any work, when tissue respiration has not yet fully developed, as well as when performing high-power physical activity.

Glycolytic pathway of ATP resynthesis This resynthesis pathway, like Creatine phosphate, belongs to the anaerobic methods of ATP formation. The source of energy necessary for ATP resynthesis in this case is muscle glycogen, the concentration of which in the sarcoplasm ranges from 0.2-3%. During the anaerobic breakdown of glycogen, the terminal glucose residues in the form of glucose-1-phosphate are alternately cleaved from its molecule under the influence of the enzyme phosphorylase. Next, glucose-1-phosphate molecules through a series of successive stages (there are 10 in total) are converted into lactic acid (lactate)

Adenylate kinase (myokinase) reaction Adenylate kinase (or myokinase) reaction occurs in muscle cells under conditions of significant accumulation of ADP in them, which is usually observed with the onset of fatigue. The adenylate kinase reaction is accelerated by the enzyme adenylate kinase (myokinase), which is located in the sarcoplasm of myocytes. During this reaction, one ADP molecule transfers its phosphate group to another ADP, resulting in the formation of ATP and AMP: ADP + ADP ATP + AMP

Work in the maximum power zone Continue for s. The main source of ATP under these conditions is creatine phosphate. Only at the end of the work is the creatine phosphate reaction replaced by glycolysis. Examples of physical exercises performed in the maximum power zone include sprinting, long and high jumps, some gymnastic exercises, and lifting weights.

Work in the submaximal power zone Duration up to 5 minutes. The leading mechanism of ATP resynthesis is glycolytic. At the beginning of work, until glycolysis has reached its maximum speed, the formation of ATP occurs due to creatine phosphate, and at the end of work, glycolysis begins to be replaced by tissue respiration. Work in the submaximal power zone is characterized by the highest oxygen debt - up to 20 liters. Examples of physical activities in this power zone include middle distance running, sprint swimming, track cycling, and sprint speed skating.

Work in a high power zone Duration up to 30 minutes. Work in this zone is characterized by approximately equal contributions from glycolysis and tissue respiration. The creatine phosphate pathway for ATP resynthesis functions only at the very beginning of work, and therefore its share in the total energy supply of this work is small. Examples of exercises in this power zone include the 5,000 m race, distance skating, cross-country skiing, and middle- and long-distance swimming.

Operation in a moderate power zone Continues for more than 30 minutes. Energy supply to muscle activity occurs predominantly aerobically. An example of such power is marathon running, track and field cross-country, race walking, road cycling, and long-distance cross-country skiing.

Useful Information In the International System of Units (SI), the basic unit of energy is the joule (J) and the unit of power is the watt (W). 1 joule (J) = 0.24 calories (cal). 1 kilojoule (kJ) = 1000 J. 1 calorie (cal) = 4.184 J. 1 kilocalorie (kcal) = 1000 cal = 4184 J. 1 watt (W) = 1 J-s"1 = 0.24 cal-s -1. 1 kilowatt (kW) = 1000 W. 1 kg-m-s"1 = 9.8 W. 1 horsepower (hp) = 735 watts. To express the power of ATP resynthesis pathways in J/min-kg, it is necessary to multiply the value of this criterion in cal/min-kg by 4.18, and to obtain the power value in W/kg, multiply by 0.07.

CONCLUSION

The study of biochemical processes during muscle activity is significant not only for sports biochemistry, biology, physiology, but also for medicine, because preventing fatigue, increasing the body's capabilities, as well as accelerating recovery processes are important aspects of preserving and strengthening the health of the population.

In-depth biochemical research at the molecular level contributes to improving training methods, finding the most effective ways to improve performance, developing ways to rehabilitate athletes, as well as assessing their fitness and rationalizing nutrition.

During muscular activity of varying power, the processes of hormone metabolism change to one degree or another, which in turn regulate the development of biochemical changes in the body in response to physical activity. An important role belongs to cyclic nucleotides as second messengers of hormones and neurotransmitters in the regulation of intracellular metabolism, as well as the regulation of the functional activity of muscles.

Based on literature data, we are convinced that the degree of change in biochemical processes in the body depends on the type of exercise performed, its power and duration.

Analysis of specialized literature made it possible to study biochemical changes in the athlete’s body during muscular work. First of all, these changes concern the mechanisms of aerobic and anaerobic energy production, which depend on the type of muscular work performed, its power and duration, as well as on the athlete’s training. Biochemical changes during muscle activity are observed in all organs and tissues of the body, which indicates the high impact of physical exercise on the body.

According to the literature, anaerobic (oxygen-free) and aerobic (with the participation of oxygen) mechanisms of energy supply to muscle activity are shown. The anaerobic mechanism provides energy to a greater extent during maximum and submaximal exercise power, since it has a fairly high deployment rate. The aerobic mechanism is the main one during long-term work of high and moderate power; it is the biochemical basis of general endurance, since its metabolic capacity is almost limitless.

Biochemical changes in the body when performing exercises of varying intensity are determined by the content of muscle metabolic products in the blood, urine, exhaled air, as well as directly in the muscles.

LIST OF REFERENCES USED

1. Brinzak V.P. Study of changes in acid-base balance in the development of arterial hypoxemia during muscle activity: Abstract...candidate of biological sciences. - Tartu, 1979. - 18 p.

2. Viru A. A., Kyrge P. K. Hormones and sports performance - M; Physical education and sport, 1983 - 159 p.

3. Volkov N. I. Adaptation of energy metabolism in humans to the effects of physical activity during systematic sports // Physiol.problems of adaptation: Abstract. - Tartu, 1984 - 94 p.

4. Volkov N.I., Nesen E.N., Osipenko A.A., Korsun S.N. Biochemistry of muscle activity: textbook for IFK-Olymp.lit-ra, 2000.- 503 p.

5. Gorokhov A. L. The content of catecholamines in the blood and muscles and their relationship with biochemicals. changes in the body during muscle activity//Ukr.biokhim.zhur. - 1971- T.43, No. 2 - 189 p.

6. Gusev N. B. Phosphorylation of myofibrillar proteins and regulation of contractile activity // Advances in biological chemistry. - 1984. - T.25 - 27 p.

7. Kalinsky M.I. State of the adenylate cyclase system of skeletal muscles during physical training: Tr. Tartu University. - Tartu, 1982. - 49 p.

8. Kalinsky M.I., Kononenko V.Ya. Features of catecholamine metabolism during muscle activity in a trained body: Materials of the Soviet-Amer. Symp. On the biochemistry of sports. - L., - 1974.- 203 p.

9. Kalinsky M.I., Kursky M.D., Osipenko A.A. Biochemical mechanisms of adaptation during muscle activity. - K.: Vishcha school. Head publishing house, 1986. - 183 p.

10. Kalinsky M.I., Rogozkin V.A. Biochemistry of muscle activity. - K.:Health, 1989. - 144 p.

11. Kursky M.D. Calcium transport and the role of cAMP-dependent phosphorylation in its regulation // Ukr. biochem. magazine - 1981. - T.53, No. 2. - 86 s.

12. Matlina E. Sh., Kassil G.N. Metabolism of catecholamines during physical activity in humans and animals // Advances in fiziol.nauk. - 1976. - T.7, No. 2. - 42 s.

13. Meerson F. Z. Adaptation of the heart to heavy load and heart failure. - M: Nauka, 1975. - 263 p.

14. Menshikov V.V. and others. Endocrine function of the pancreas during physical activity//Uch. zap. Tartu University. - 1981. - Issue 562. - 146 p.

15. Panin L. E. Biochemical mechanisms of stress. - Novosibirsk: Nauka, 1984. - 233 p.

16. Rogozkin V. A. On the regulation of skeletal muscle metabolism during their systematic function // Metabolism and biochemistry. assessment of an athlete's fitness: Materials of Sov. - Amer. symp. - L., 1974. - 90 p.

17. Saene T.P. Actomyosin ATPase activity of cardiac and skeletal muscles during physical exercise. training//Account. Tartu University. - 1980. - Issue 543. - 94 s.

18. Thomson K.E. The influence of muscle activity on the thyroid homeostasis of the body//Uch.zap. Tartu University. - 1980. - Issue 543. -116 s.

19. Haydarliu S.Kh. Functional biochemistry of adaptation. - Chisinau: Shtiintsa, 1984. - 265 p.

20. Hochachka P., Somero D. Biochemical adaptation strategy. - M: Mir, 1977. - 398 p.

21. Chernov V.D. Iodine exchange in the tissues of rats during physical exercise//Ukr. biochem. magazine - 1981. - T.53№6. - 86 s.

22. Shmalgauzen I.I. Regulation of shape formation in individual development. - M: Science. 1964. - 156 p.

23. Eller A.K. The importance of glucocorticoids in the regulation of protein metabolism and the mechanism of their action in the myocardium during muscle activity: Abstract of thesis. Sci. - Tartu, 1982. - 24 s.

24. Yakovlev N.N. Biochemistry of sports. - M: Physical culture and sport, 1974. - 288 p.

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A few words about this article:
Firstly, as I said in the public, this article was translated from another language (albeit, in principle, close to Russian, but still translation is quite a difficult job). The funny thing is that after I translated everything, I found on the Internet a small part of this article, already translated into Russian. Sorry for the wasted time. Anyway..

Secondly, this is an article about biochemistry! From here we must conclude that it will be difficult to understand, and no matter how hard you try to simplify it, it is still impossible to explain everything in simple terms, so I did not explain the vast majority of the described mechanisms in simple language, so as not to confuse the readers even more. If you read carefully and thoughtfully, you will be able to figure everything out. And thirdly, the article contains a sufficient number of terms (some are briefly explained in parentheses, some are not, because they cannot be explained in two or three words, and if you start describing them, the article may become too long and completely incomprehensible ). Therefore, I would advise using Internet search engines for those words whose meaning you do not know.

A question like: “Why post such complex articles if it’s difficult to understand them?” Such articles are needed in order to understand what processes occur in the body in a given period of time. I believe that only after knowing this kind of material can you begin to create methodological training systems for yourself. If you don’t know this, then many of the ways to change the body will probably be of the “pointing your finger at the sky” category, i.e. It’s clear what they’re based on. This is just my opinion.

And one more request: if there is something in the article that, in your opinion, is incorrect, or some inaccuracy, then please write about it in the comments (or PM me).

Go..

The human body, and even more so an athlete, never works in a “linear” (unchanging) mode. Very often the training process can force him to go to the maximum “speed” possible for him. In order to withstand the load, the body begins to optimize its work under this type of stress. If we consider strength training specifically (bodybuilding, powerlifting, weightlifting, etc.), then the first one to send a signal in the human body about the necessary temporary changes (adaptation) are our muscles.

Muscular activity causes changes not only in the working fiber, but also leads to biochemical changes throughout the body. An increase in muscle energy metabolism is preceded by a significant increase in the activity of the nervous and humoral systems.

In the pre-launch state, the action of the pituitary gland, adrenal cortex, and pancreas is activated. The combined action of adrenaline and the sympathetic nervous system leads to: an increase in heart rate, an increase in the volume of circulating blood, the formation in the muscles and penetration into the blood of energy metabolism metabolites (CO2, CH3-CH (OH)-COOH, AMP). A redistribution of potassium ions occurs, which leads to dilation of muscle blood vessels and constriction of blood vessels in internal organs. The above factors lead to a redistribution of the general blood flow of the body, improving the delivery of oxygen to working muscles.

Since the intracellular reserves of macroergs are sufficient for a short time, the body’s energy resources are mobilized in the pre-launch state. Under the influence of adrenaline (adrenal hormone) and glucagon (pancreatic hormone), the breakdown of liver glycogen into glucose increases, which is transported by the bloodstream to working muscles. Intramuscular and hepatic glycogen is a substrate for ATP resynthesis in creatine phosphate and glycolytic processes.

With an increase in work duration (stage of aerobic ATP resynthesis), fat breakdown products (fatty acids and ketone bodies) begin to play a major role in the energy supply of muscle contraction. Lipolysis (the process of fat breakdown) is activated by adrenaline and somatotropin (also known as “growth hormone”). At the same time, hepatic “uptake” and oxidation of blood lipids increases. As a result, the liver releases significant amounts of ketone bodies into the bloodstream, which are oxidized to carbon dioxide and water in working muscles. The processes of oxidation of lipids and carbohydrates occur in parallel, and the functional activity of the brain and heart depends on the amount of the latter. Therefore, during the period of aerobic resynthesis of ATP, the processes of gluconeogenesis occur - the synthesis of carbohydrates from substances of hydrocarbon nature. This process is regulated by the adrenal hormone cortisol. The main substrate of gluconeogenesis is amino acids. In small quantities, glycogen is also formed from fatty acids (liver).

Moving from a state of rest to active muscular work, the need for oxygen increases significantly, since the latter is the final acceptor of electrons and hydrogen protons of the mitochondrial respiratory chain system in cells, providing the processes of aerobic resynthesis of ATP.

The quality of oxygen supply to working muscles is affected by the “acidification” of the blood by metabolites of biological oxidation processes (lactic acid, carbon dioxide). The latter affect the chemoreceptors of the walls of blood vessels, which transmit signals to the central nervous system, increasing the activity of the respiratory center of the medulla oblongata (the transition area between the brain and the spinal cord).

Oxygen from the air spreads into the blood through the walls of the pulmonary alveoli (see figure) and blood capillaries due to the difference in its partial pressures:

1) Partial pressure in alveolar air is 100-105 mm. Hg st
2) Partial pressure in the blood at rest is 70-80 mm. Hg st
3) Partial pressure in the blood during active work is 40-50 mm. Hg st

Only a small percentage of the oxygen entering the blood dissolves in the plasma (0.3 ml per 100 ml of blood). The main part is bound in erythrocytes by hemoglobin:

Hb + O2 -> HbO2​

Hemoglobin- a protein multimolecule consisting of four completely independent subunits. Each subunit is associated with heme (heme is an iron-containing prosthetic group).

The addition of oxygen to the iron-containing group of hemoglobin is explained by the concept of kinship. The affinity for oxygen in different proteins is different and depends on the structure of the protein molecule.

A hemoglobin molecule can attach 4 oxygen molecules. The ability of hemoglobin to bind oxygen is influenced by the following factors: blood temperature (the lower it is, the better it binds oxygen, and its increase promotes the breakdown of oxy-hemoglobin); alkaline blood reaction.

After the attachment of the first oxygen molecules, the oxygen affinity of hemoglobin increases as a result of conformational changes in the polypeptide chains of globin.
Blood enriched with oxygen in the lungs enters the systemic circulation (the heart at rest pumps 5-6 liters of blood every minute, while transporting 250 - 300 ml of O2). During intensive work, in one minute the pumping speed increases to 30-40 liters, and the amount of oxygen carried by the blood is 5-6 liters.

Once in the working muscles (due to the presence of high concentrations of CO2 and elevated temperature), an accelerated breakdown of oxyhemoglobin occurs:

H-Hb-O2 -> H-Hb + O2​

Since the pressure of carbon dioxide in the tissue is greater than in the blood, hemoglobin freed from oxygen reversibly binds CO2, forming carbaminohemoglobin:

H-Hb + CO2 -> H-Hb-CO2​

which breaks down in the lungs to carbon dioxide and hydrogen protons:

H-Hb-CO2 -> H + + Hb-+ CO2​

Hydrogen protons are neutralized by negatively charged hemoglobin molecules, and carbon dioxide is released into the environment:

H + + Hb -> H-Hb​

Despite a certain activation of biochemical processes and functional systems in the pre-start state, during the transition from a resting state to intensive work, a certain imbalance is observed between the need for oxygen and its delivery. The amount of oxygen that is necessary to satisfy the body when performing muscular work is called the oxygen demand of the body. However, the increased need for oxygen cannot be satisfied for some time, so it takes some time to strengthen the activity of the respiratory and circulatory systems. Therefore, the beginning of any intensive work occurs in conditions of insufficient oxygen - oxygen deficiency.

If work is carried out at maximum power in a short period of time, then the demand for oxygen is so great that it cannot be satisfied even by the maximum possible absorption of oxygen. For example, when running 100 m, the body is supplied with oxygen by 5-10%, and 90-95% of oxygen arrives after the finish. The excess oxygen consumed after work is done is called oxygen debt.

The first part of the oxygen, which goes to the resynthesis of creatine phosphate (disintegrated during work), is called alactic oxygen debt; the second part of the oxygen, which goes to eliminate lactic acid and resynthesize glycogen, is called lactate oxygen debt.

Drawing. Oxygen influx, oxygen deficiency and oxygen debt during long-term operation at different powers. A - for light work, B - for heavy work, and C - for exhausting work; I - run-in period; II - stable (A, B) and false stable (C) state during operation; III - recovery period after performing the exercise; 1 - alactic, 2 - glycolytic components of oxygen debt (according to Volkov N.I., 1986).

Alactate oxygen debt compensates relatively quickly (30 sec. - 1 min.). Characterizes the contribution of creatine phosphate to the energy supply of muscle activity.

Lactate oxygen debt fully compensated within 1.5-2 hours upon completion of work. Indicates the share of glycolytic processes in energy supply. During prolonged intensive work, a significant proportion of other processes are present in the formation of lactate oxygen debt.

Performing intense muscular work is impossible without intensifying metabolic processes in the nervous tissue and tissues of the heart muscle. The best energy supply to the heart muscle is determined by a number of biochemical and anatomical and physiological features:
1. The heart muscle is penetrated by an extremely large number of blood capillaries through which blood flows with a high concentration of oxygen.
2. The most active enzymes are aerobic oxidation.
3. At rest, fatty acids, ketone bodies, and glucose are used as energy substrates. During intense muscular work, the main energy substrate is lactic acid.

The intensification of metabolic processes in nervous tissue is expressed in the following:
1. The consumption of glucose and oxygen in the blood increases.
2. The rate of restoration of glycogen and phospholipids increases.
3. The breakdown of proteins and the formation of ammonia increases.
4. The total amount of high-energy phosphate reserves decreases.

Since biochemical changes occur in living tissues, it is quite problematic to directly observe and study them. Therefore, knowing the basic patterns of metabolic processes, the main conclusions about their course are made based on the results of blood, urine, and exhaled air tests. For example, the contribution of the creatine phosphate reaction to the energy supply of muscles is assessed by the concentration of breakdown products (creatine and creatinine) in the blood. The most accurate indicator of the intensity and capacity of aerobic energy supply mechanisms is the amount of oxygen consumed. The level of development of glycolytic processes is assessed by the content of lactic acid in the blood both during work and in the first minutes of rest. Changes in acid balance indicators allow us to draw a conclusion about the body’s ability to resist acidic metabolites of anaerobic metabolism.

Changes in the rate of metabolic processes during muscle activity depend on:
- The total number of muscles that are involved in the work;
- Mode of muscle work (static or dynamic);
- Intensity and duration of work;
- Number of repetitions and rest breaks between exercises.

Depending on the number of muscles involved in the work, the latter is divided into local (less than 1/4 of all muscles are involved in the performance), regional and global (more than 3/4 of the muscles are involved).
Local work(chess, shooting) - causes changes in the working muscle without causing biochemical changes in the body as a whole.
Global work(walking, running, swimming, skiing, hockey, etc..) - causes large biochemical changes in all organs and tissues of the body, most strongly activates the activity of the respiratory and cardiovascular systems. The percentage of aerobic reactions in the energy supply of working muscles is extremely high.
Static mode muscle contraction leads to pinching of the capillaries, which means a worse supply of oxygen and energy substrates to the working muscles. Anaerobic processes act as energy supply for activity. Rest after performing static work should be dynamic low-intensity work.
Dynamic mode work provides oxygen to the working muscles much better, therefore the alternating contraction of the muscles acts as a kind of pump, pushing blood through the capillaries.

The dependence of biochemical processes on the power of the work performed and its duration is expressed as follows:
- The higher the power (high rate of ATP decay), the higher the proportion of anaerobic ATP resynthesis;
- The power (intensity) at which the highest degree of glycolytic energy supply processes is achieved is called depletion power.

The maximum possible power is defined as the maximum anaerobic power. The power of work is inversely related to the duration of work: the higher the power, the faster the biochemical changes occur, leading to fatigue.

From all that has been said, several simple conclusions can be drawn:
1) During the training process, there is an intensive consumption of various resources (oxygen, fatty acids, ketones, proteins, hormones and much more). That is why the athlete’s body constantly needs to provide itself with useful substances (nutrition, vitamins, nutritional supplements). Without such support, there is a high probability of harm to health.
2) When switching to “combat” mode, the human body needs some time to adapt to the load. This is why you shouldn’t put too much stress on yourself from the first minute of training - your body is simply not ready for this.
3) At the end of the workout, you also need to remember that, again, it takes time for the body to move from an excited state to a calm one. A good option to solve this issue is a cool-down (reducing training intensity).
4) The human body has its own limits (heart rate, pressure, amount of nutrients in the blood, rate of synthesis of substances). Based on this, you need to select the optimal training for yourself in terms of intensity and duration, i.e. find the middle at which you can get the maximum positive and the minimum negative.
5) Both static and dynamic must be used!
6) Not everything is as complicated as it first seems..

Let's finish here.​

P.S. Regarding fatigue, there is another article (which I also wrote about yesterday in a public post - “Biochemical changes during fatigue and during rest.” It is half as long and 3 times simpler than this one, but I don’t know if it’s worth posting here. Just the gist its point is that it summarizes the article posted here about supercompensation and “fatigue toxins.” For the sake of the collection (the completeness of the whole picture), I can also present it. Write in the comments whether it is necessary or not.