Factors determining muscle activity. Muscle activity and cardiac activity, their relationship. Electrical activity of muscles: the best exercises for each muscle group, research results

Welcome, welcome, is anyone there? The ABCs of Bodybuilding are in touch! And on this Friday we will examine an unusual topic called electrical activity of muscles.

After reading, you will learn what EMG is as a phenomenon, what and for what purposes this process is used, why most studies on the “better” exercises operate specifically on electrical activity data.

So, make yourself comfortable, it will be interesting.

Electrical activity of muscles: questions and answers

This is the second article in the “Muscle inside” series, in the first we talked about, but in general the cycle is dedicated to the phenomena and events that take place (may leak) inside the muscles. These notes will allow you to better understand the pumping processes and make faster progress in improving your physique. Why did we actually decide to talk specifically about the electrical activity of muscles? Everything is very simple. In our technical (and not only) articles, we constantly provide lists of the best exercises, which are formed precisely on the basis of EMG research data.

For almost five years now, we have been providing you with this information, but not once during this time have we revealed the very essence of the phenomenon. Well, today we will fill this gap.

Note:
All further narration on the topic of electrical activity of muscles will be divided into subchapters.

What is electromyography? Muscle activity measurement

EMG is an electrodiagnostic medicine technique for assessing and recording electrical activity produced by skeletal muscles. The EMG procedure is performed using a device called an electromyograph to create a recording called an electromyogram. The electromyograph detects the electrical potential generated by muscle cells when they are electrically or neurologically activated. To understand the essence of the EMG phenomenon, it is necessary to have an idea of ​​the structure of the muscles and the processes occurring within them.

A muscle is an organized “collection” of muscle fibers (MF), which in turn are made up of groups of components known as myofibrils. In the skeletal system, nerve fibers initiate electrical impulses in the m.v., known as muscle action potentials. They create chemical interactions that activate myofibril contraction. The more activated fibers in a muscle part, the stronger the contraction that the muscle can produce. Muscles can only create force when they contract/shorten. Pull and push forces in the musculoskeletal system are generated by the coupling of muscles that act in an antagonistic pattern: one muscle contracts and the other relaxes. For example, when lifting a dumbbell for the biceps, the biceps brachii muscle contracts/shortens when lifting the apparatus, and the triceps (antagonist) is in a relaxed state.

EMG in various sports

The method of assessing the basic muscle activity that occurs during physical movement has become widespread in many sports, especially fitness and bodybuilding. By measuring the number and magnitude of impulses generated during muscle activation, it is possible to assess how much a muscle unit is stimulated to produce a particular force. An electromyogram is a visual illustration of the signals generated during muscle activity. And further in the text we will look at some “portraits” of EMG.

EMG procedure. What does it consist of and where is it carried out?

For the most part, it is possible to measure the electrical activity of muscles only in special sports research laboratories, i.e. specialized institutions. Modern fitness clubs do not provide such an opportunity due to the lack of qualified specialists and low demand from the club’s audience.

The procedure itself consists of:

• placement on the human body in a certain area (on or near the muscle group being studied) special electrodes connected to a unit that measures electrical impulses;
• recording and transmission of signals to a computer through a wireless transmission unit for EMG data from located surface electrodes for subsequent display and analysis.

In the picture version, the EMG procedure looks like this.

Muscle tissue at rest is electrically inactive. When a muscle voluntarily contracts, action potentials begin to appear. As the force of muscle contraction increases, more and more muscle fibers fire action potentials. When the muscle contracts fully, a random group of action potentials with varying speeds and amplitudes should appear. (full set and interference pattern).

Thus, the process of obtaining a picture comes down to the fact that the subject performs a specific exercise according to a specific scheme (sets/reps/rest), and the devices record electrical impulses generated by the muscles. Ultimately, the results are displayed on the PC screen in the form of a specific pulse graph.

Purity of EMG results and the concept of MVC

As you probably remember from our technical notes, sometimes we gave different values ​​for muscle electrical activity even for the same exercise. This is due to the intricacies of the procedure itself. In general, the final results are influenced by a number of factors:

• choosing a specific muscle;
• the size of the muscle itself (men and women have different volumes);
• correct electrode placement (in a specific place of the superficial muscle - muscle belly, longitudinal midline);
• human body fat percentage (the more fat, the weaker the EMG signal);
• thickness - how strongly the central nervous system generates the signal, how quickly it enters the muscle;
• training experience - how well developed a person is.

Thus, due to these initial conditions, different studies may produce different results.

Note:

More accurate results of muscle activity in a specific movement are provided by the intramuscular assessment method. This is when a needle electrode is inserted through the skin into the muscle tissue. The needle is then moved to several points in the relaxed muscle to assess both insertion and resting activity in the muscle. By assessing resting and insertion activity, the electromyograph evaluates muscle activity during voluntary contraction. The shape, size and frequency of the resulting electrical signals indicate the degree of activity of a particular muscle.

In the electromyography procedure, one of its main functions is how well the muscle can be activated. The most common method is to perform a maximum voluntary contraction (MVC) of the muscle being tested. It is MVC, in most studies, that is accepted as the most reliable means of analyzing peak force and force produced by muscles.

However, the most complete picture of muscle activity can be provided by providing both sets of data. (MVC and ARV - average) EMG values.

Actually, we’ve dealt with the theoretical part of the note, now let’s dive into practice.

Electrical activity of muscles: the best exercises for each muscle group, research results

Now we will begin to collect cones :) from our dear audience, and all because we will engage in a thankless task - proving that a specific exercise is the best for a specific muscle group.

And why it is ungrateful, you will understand as the story progresses.

So, by taking EMG readings during various exercises, we can paint an illustrative picture of the level of activity and arousal within the muscle. This can indicate how effective a particular exercise is at stimulating a particular muscle.

I. Research results (Professor Tudor Bompa, Mauro Di Pasquale, Italy 2014)

The data is presented according to the template, muscle group-exercise-percentage of activation m.v.:

Note:

The percentage value indicates the proportion of fibers activated; a value of 100% indicates complete activation.

No. 1. Latissimus dorsi muscles:

• – 91 ;
• – 89 ;
• – 86 ;
• – 83 .

No. 2. Pectoral muscles (greater pectoral):

• – 93 ;
• – 87 ;
• – 85 ;
• – 84 .

No. 3. Front deltoid:

• standing dumbbell press – 79 ;
• – 73 .

No. 4. Middle/side delta:

• straight arm raises through the sides with dumbbells - 63 ;
• raises straight arms through the sides on the upper block of the crossover - 47 .

No. 5. Rear deltoid:

• standing bent over raise with dumbbells - 85 ;
• Bent-over arms raise while standing from the lower block of the crossover – 77 .

No. 6. Biceps (long head):

• curling arms on a Scott bench with dumbbells - 90 ;
• curling arms with dumbbells while sitting on a bench at an upward angle - 88 ;
• (narrow grip) – 86 ;
• – 84 ;
• – 80 .

No. 7. Quadriceps (rectus femoris muscle):

• – 88 ;
• – 86 ;
• – 78 ;
• – 76 .

No. 8. Back surface (biceps) of the thigh:

• – 82 ;
• – 56 .

No. 9. Rear surface (semitendinosus muscle) hips:

• – 88 ;
• deadlift on straight legs - 63 .

With respect and gratitude, Dmitry Protasov.

Without muscles, life would be impossible. Heartbeat, blood circulation, digestion, bowel movements, sweating, chewing food, vision, movement - all these processes are controlled by different types of muscles.

There are three main types of muscles in the body:

1. skeletal muscles, which contract voluntarily1 and are attached to various bones of the musculoskeletal system;
2. smooth muscles, or involuntary2 contractions. These include the muscles of the stomach, intestines, blood vessels, etc.;
3. cardiac muscles.

Skeletal muscles have an extremely complex structure. The smallest elements of muscle tissue are thin filaments called filaments; they are combined protein chains of actin and myosin. From these threads are formed sarcomeres(sarcos - “flesh”, mere - “part”). Those, in turn, bind into myofibrils (myos - “muscles”, fibrillae - “tiny fibers”), of which muscle fibers are composed. And the latter are combined into bundles that form the muscles of the skeleton.

So, the sequence is as follows: protein chains - filaments - sarcomeres - myofibrils - muscle fibers - bundles of muscle fibers - skeletal muscles.

Energy requirement

One of the main characteristics of muscles is that they have an extensive network of blood vessels that provide our muscles with nutrients and oxygen, as well as eliminate waste products.

Muscle contraction is an active process that requires energy.

The length of the muscle decreases due to interweaving protein sarcomeres(actin and myosin), which connect to each other like the teeth of two combs. The resulting tension causes the bones, to the surface of which the muscle ligaments are attached, to move.

Any muscle always has active fibers - at any time, even when it is inactive. The contractions of these muscle fibers are not sufficient to move the bone, but they maintain the muscles under constant tension. This residual tension in the skeletal muscles is called muscle tone. Due to lack of muscle tone, muscles may look flabby and loose, but even slight tension causes them to become more active. It is thanks to muscle tone that the biceps of strong people look so impressive even in a relaxed state. Muscle tone maintains muscle shape when most of the muscle fibers are relaxed. While a person is at rest, muscle tone contributes to the stable position of bones and joints, whereas in its absence the joints are deprived of such support. For example, people who have lost sensation in one of their arms due to a stroke experience the fact that the shoulder constantly comes out of the socket under the weight of the arm. The deltoid (located around the shoulder joint) muscle becomes so weak that it is no longer able to support the numerous bones in the joint capsule.

Muscle tone also acts as a shock absorber, absorbing some of the energy during a sharp blow or jolt. Good muscle tone is a necessary condition for sports and physical education, which often involve sudden movements. Exercise, in turn, helps increase muscle tone.

Muscle contraction

There are two types of muscle contractions - isotonic and isometric.

At isotonic contractions external and internal loads on the muscle remain constant, but its length and cross-section change. When you lift a weight from the floor, walk or run, the muscles in your body perform isotonic contractions.

At isometric contractions the geometry of the muscle does not change, since it is already contracted to its maximum. Such contractions are observed, for example, when a person tries to move a stationary object (say, a wall), tries unsuccessfully to lift something very heavy from the floor, or performs resistance exercises.

Providing muscles with energy

Muscle contraction requires a huge amount of energy. Therefore, it is not surprising that a special process of obtaining energy takes place in muscle tissue, which is not represented anywhere else in our body. Active muscle cells contain myoglobin, which in its structure resembles hemoglobin in the blood and is also able to absorb oxygen and store it for later use. It is for this reason that the most active skeletal muscles are bright red.

In addition, muscle tissue cells contain large numbers of mitochondria (microscopic energy production factories), which produce energy molecules - they are also ATP molecules (adenosine triphosphoric acid) - in the process of aerobic, that is, absorbing oxygen, transformation of glucose molecules. However, even despite this, we sometimes do not have enough energy to satisfy the needs of the muscles. So Mother Nature awarded the muscles with two most useful physiological characteristics:

• the ability to store glucose in the form of glycogen, which can be broken down at any time to meet increased energy needs;
• the ability to carry out anaerobic (without the participation of oxygen) transformation of glucose into energy molecules and lactic acid.

As you can see, nature has endowed skeletal muscles with an amazing ability: they can produce energy on their own, without waiting for help from the liver or other internal organs. So, skeletal muscles:

• contain a special protein that can capture oxygen molecules (myoglobin);
• can carry out both aerobic and anaerobic breakdown of glucose to produce energy;
• store glycogen reserves (a glucose-based compound);
• have an extensive network of blood vessels that supply glucose and calcium, which are vital for muscle tissue proteins (muscles cannot contract without these two substances). Blood vessels also help remove waste products such as carbon dioxide (carbon dioxide) from the body.

When muscles contract, the need for oxygen in the whole body increases, and it takes most of it from the blood. To meet the increased need for oxygen, breathing and heart rate increase. This is why during intense exercise your heart rate jumps and your breathing speeds up. Even after cessation of physical activity, the respiratory rate and heart rate remain elevated for some time, continuing to provide the body with additional portions of life-giving oxygen.

Thus, physical exercise is the only natural way to:

• improve blood circulation;
• make the heart pump blood harder, thereby increasing the tone of the heart muscle;
• increase energy reserves in the body;
• burn excess body fat and accumulated sugar in the body;
• give additional tone to the muscles of the body, thereby improving overall well-being.

Excessive energy consumption

The only undesirable consequence of excessive muscle contraction during exercise is the accumulation of lactic acid in muscle tissue.

Under normal conditions, glucose in the cell's mitochondria is converted to carbon dioxide and water using oxygen molecules (see page 31).

When muscles become too active, mitochondria do not have time to produce enough energy, resulting in additional ATP molecules being formed during the anaerobic (without the participation of oxygen) conversion of glucose into lactic acid.

If the increased need for energy persists for a long time, and the mitochondria cannot fully satisfy it due to lack of oxygen, then the level of lactic acid increases. This results in a change in the chemical structure of the muscle fibers, which stop contracting until the mitochondria receive enough oxygen to quickly convert lactic acid into carbon dioxide and water.

In general, this byproduct of incomplete combustion of glucose - lactic acid - harms the body, especially the heart muscle.

Excess lactic acid is not only accompanied by muscle spasms and pain, but also reduces the overall performance of muscle tissue because it causes a feeling of fatigue.

Athletes regularly have their lactic acid levels checked during training to see how efficiently their muscles are working.

Fatigue

Muscle fatigue is a condition in which muscles can no longer contract. The main reason is the accumulation of lactic acid, which interferes with normal muscle function. This is exactly the way nature created to prevent a person from endlessly straining his muscles. Because of this, marathon runners, especially those who are undertrained, often give up halfway, and not everyone makes it to the finish line. Muscle fatigue provides the muscles with an opportunity to restore energy reserves and get rid of waste products.

Any physical activity leads to varying degrees of fatigue. The smallest muscles, such as those in the eyes or hands, tire much faster than larger ones.

Those who have had to write with their hands for a long time are very familiar with the feeling when the brush gets so tired that they can no longer write a word. Children during tests or exams often try to write very quickly, which is why their hands get tired, start to hurt, and they have no choice but to interrupt this activity.

Need for rest

Thus, it is necessary to alternate periods of exercise and rest. To achieve this, nature has endowed us with a sleep mechanism that allows muscles to replenish energy reserves daily, repair any damage associated with physical wear and tear, and get rid of waste products, including lactic acid. When a person does not get enough sleep and works hard, using up the time allotted for rest, the muscles lose the ability to function normally and sooner or later exhaustion occurs.

No matter how much we want it, we cannot force our muscles to work with constant efficiency for a long period. That is why athletes are recommended to have proper rest or healthy sleep after competitions.

Muscle activity

Muscular activity is characterized by such parameters as force- the maximum tension that an individual muscle or group of muscles can create, and endurance- the period of time during which a person is able to continue an activity related to physical activity.

Muscle activity is determined by two main factors: the type of muscle fibers involved, and the level of physical fitness of the person.

Types of muscle fibers

Myologists distinguish three main types of skeletal muscle fibers in the human body: fast, slow and intermediate.

Fast muscle fibers

Most of the skeletal muscle consists of them. These muscle fibers owe their name to the fact that they are capable of instantly contracting after external stimulation (after approximately one hundredth of a second).

These fibers are large in diameter, composed of densely packed myofibrils, have significant reserves of glycogen (the form in which glucose is stored in the body), and contain relatively little myoglobin and mitochondria. They cope well with fast and sudden movements.

These muscle fibers have no time to wait for slow blood to reach them, so they have very few capillaries. Such muscles contract rapidly and with enormous force, and therefore they have neither the time nor the ability to use oxygen for energy production (therefore, they have low blood circulation, few mitochondria and myoglobin). They use a quick and convenient anaerobic method of processing glucose, during which the notorious lactic acid is formed as a by-product. This is why fast-twitch muscle fibers tire very quickly. They cope with the task - and then lose their strength.

Sprinters push themselves so hard in the 100-meter race that they almost collapse at the finish line - for several minutes after that they can hardly even stand. If you ask them to do another run soon, you will be surprised how much worse the result will be. Poorly trained runners often experience colic, a painful cramp in the side.

When it comes to endurance, fast muscles are inferior to other types of muscle fibers. Due to the small number of blood vessels and low myoglobin content, they are very pale in color.

Slow muscle fibers

Their diameter is half that of fast fibers, and they take almost three times longer to contract, but at the same time they can work much longer. Muscles made from these fibers contain a fair amount of myoglobin, have an extensive network of capillaries and many mitochondria, but their glycogen reserves are minimal (which is why they are not so voluminous).

Slow muscle fibers also use other sources for energy: carbohydrates, amino acids and fatty acids.

Such muscles are not very strong, but they are very resilient: to meet their moderate energy needs, they use the aerobic process of converting glucose, due to which they do not get tired so quickly. Thanks to the abundant blood supply, they receive enough oxygen, and breakdown products are constantly removed in the blood, so that slow muscle fibers are able to work normally for a long time.

Slow-twitch muscle fibers are responsible for maintaining posture; they can remain contracted for a long time without getting tired. Due to the high myoglobin content and the extensive network of capillaries, muscles consisting of slow fibers have a dark red color.

Intermediate muscle fibers

In terms of their properties, they are in the middle between fast and slow muscle fibers. They are more resilient than fast fibers, but at the same time stronger than slow ones..

During training, long-distance runners try to develop these types of muscle fibers, as they have an amazing combination of strength and endurance.

Muscle exercises

With the help of a properly designed training program, you can easily change the type of muscle fibers. Weightlifters and bodybuilders achieve the formation of intermediate muscle fibers by rapidly contracting the biceps and other muscles.

The proportion of different types of muscle fibers in a muscle can vary depending on the chosen training program.

The ratio of fast and slow muscle fibers is determined by genetic parameters, but the relative number of intermediate fibers (relative to fast) can be increased.

Regular exercise promotes the formation of additional mitochondria, the accumulation of glycogen reserves and an increase in the concentration of proteins and enzymes in muscle tissue. Thanks to all these factors, muscles increase in volume.

The number of muscle fibers, determined genetically, does not change over time, but their composition (content of proteins, glycogen, enzymes, mitochondria) may change.

Most human muscles contain all types of muscle fibers, which is why such muscles appear pink. However, the back muscles (as well as the calf muscles) consist mainly of slow-twitch fibers, so they are red in color and are able to maintain posture. The muscles of the eyes and hands, which are responsible for rapid movements, are white because they have fewer blood vessels and myoglobin.

Some people stay thin no matter how much they eat or exercise at the gym. They can only gain minimal muscle mass. This is their genetic constitution. Sumo wrestlers, through a high-calorie diet and constant training, build up huge reserves of muscle and fat tissue.

Previously, Soviet athletes drank kefir in large quantities, since along with it the body received chains of amino acids necessary for the formation of proteins in the muscles. They also took ginseng (especially in Siberia) to increase muscle strength and endurance. Therefore, Soviet athletes were invincible in weightlifting and other disciplines at the Olympic Games.

To gain muscle mass, some athletes use steroids or testosterone. But even in such cases, muscles increase in volume only with regular grueling training: there is no simple way to “pump up”.

There is no convincing evidence that taking steroids and testosterone is useful for “artificially” gaining muscle mass, while the harm they cause to the body has long been well known to everyone.

Muscles can not only grow, but also atrophy, especially if they are hardly used in everyday life. They lose mass. This can be easily seen from the broken leg, which was in a cast for a long time, making it impossible to move. Some diseases, such as polio, affect the nerves, leading to paralysis and atrophy of certain muscles.

Conclusion

So, scientists have established the following facts regarding muscles.

1. There are three types of muscles in the human body: skeletal, smooth and cardiac.
2. Skeletal muscles, as a rule, contract voluntarily - we can control them at will.
3. Smooth muscles contract involuntarily and are not subject to control by our consciousness (walls of blood vessels, bladder, intestines, etc.).
4. The fibers that make up skeletal muscles are, in turn, divided into three types:
   • fast muscle fibers. They contain few blood vessels and myoglobin, are characterized by a pale color, and are responsible for performing fast and sudden movements. Get tired quickly;
   • slow muscle fibers. They contain many blood vessels, mitochondria and myoglobin, are red in color, and are responsible for slow and sustained activities such as maintaining posture. They don’t get tired so quickly;
   • intermediate muscle fibers. According to their characteristics, they are between fast and slow. They get tired more slowly than fast-twitch muscle fibers (in this regard, they are closer to the muscles responsible for maintaining posture).
5. There are two types of muscle contractions:
   • isometric - the length of the muscle remains unchanged;
   • isotonic - the load on the muscle does not change, but its length and cross-section change (this happens when performing various movements).
6. When contracting, muscles consume a huge amount of energy, and therefore are forced to produce it independently. To do this, they use one of two mechanisms:
   • aerobic process in slow muscle fibers. They have access to a lot of oxygen in the blood, and myoglobin helps them use it;
   • anaerobic process in fast muscle fibers. Energy is produced in the process of incomplete combustion of glucose without the participation of oxygen. Additionally, lactic acid is formed, which causes muscles to become tired.
7. Muscles contract due to the excitation of fibers by motor neurons. Contraction is based on a complex biomechanical reaction that occurs with the participation of calcium and as a result of which protein chains fit into each other. Thus, muscle function should be considered not only from a mechanical, but also from a neurological point of view. Muscles, tensing, make a visible effort, while simultaneously passing electrical impulses through themselves.

Chapter 16. Muscle activity.
from Linus Pauling's book "How to Live Longer and Feel Better"

The functions of muscles in the human body are the production of work and energy using substances obtained from food, primarily carbohydrates and fats.
Good health requires good muscle activity. It is not surprising that ascorbic acid is a necessary participant in this process. Muscles are composed of approximately 30% actomycin protein, which in turn consists of two types of fibrous proteins - actin and myosin. Muscles are able to perform their work only under certain conditions - energy is needed. Energy is obtained through the oxidation of nutrients, primarily fats.
Each cell of muscle tissue contains energy structures - mitochondria, within which the process of oxidation occurs with the formation of high-energy molecules ATP and ADP. These molecules are used in a variety of biochemical reactions as sources of energy.
CARNITINE is an essential component for muscle activity and energy production. It is one of the many orthomolecular substances of the human body - normally present and necessary for life. This substance was discovered in 1905 by Russian scientists Gulevich and Krinberg, who studied muscle function. They found this substance in an amount of 1% in red meat and in smaller amounts in white meat and called it "carnis", lat. - "meat".
It was found that carnitine is necessary so that fat molecules can penetrate into the mitochondria, where the oxidation process occurs to produce energy. The carnitine molecule interacts with a fat molecule and a coenzyme A molecule - only this complex is able to penetrate the mitochondrial membrane. Carnitine is released inside the mitochondria, and it safely returns back to the intercellular space. Thus, carnitine serves as a “shuttle” for carrying fat molecules into the mitochondria.
The level of fat that can be burned is determined by the level of carnitine in the muscles, i.e. – carnitine is a very important substance!
We get some carnitine from food, especially red meat. This explains why red meat increases muscle strength. We are also able to synthesize our own carnitine from the essential amino acid lysine, which is present in many proteins obtained from food, mainly meat.
The synthesis of your own carnitine is possible only with the participation of ascorbic acid. Optimal intake of vitamin C can increase the synthesis of carnitine from lysine. The amount of carnitine in the body depends on the amount of vitamin C. This explains the fact that among those sailors who developed scurvy, the first signal of the disease was muscle weakness.
Dr. Evan Cameron, who treated cancer patients, quotes his patient as saying: “Doctor, I feel strong now,” a few days after starting to take 10 g of ascorbic acid per day.
The human body is made up of muscles. The heart is a muscle. The immune system is able to perform its functions of “patrol” and destroy “strangers” thanks to actin-myosin fibers, which allow leukocytes to actively move.
Thus, the role of vitamin C in maintaining and improving health is beyond doubt.

Bed rest has significant adverse effects on healthy people (as it does on astronauts in zero gravity), which may exceed the therapeutic effect of bed rest in patients.

For example, as a result of 3 weeks of bed rest in young healthy people, stroke volume and heart rate, even without exercise in the supine position, changed unfavorably. Heart rate increased, and myocardial contractility decreased.

This should be considered an uneconomical type of response to physical inactivity. In a standing position, these changes were aggravated. The use of submaximal exercise led to even greater changes in circulatory parameters, and the exercise performed while standing was accompanied by an inadequate decrease in mean arterial pressure (BP), which increased with maximum exercise.

The noted changes indicate a decrease in the reserve capacity of blood circulation under the influence of physical inactivity, which may be associated both with a decrease in myocardial mass and with a weakening of the functional capabilities of the regulatory apparatus.

Recent reviews of data from randomized controlled trials on the effects of bed rest have shown no improvement in patients who adhered to prescribed long-term bed rest. In many cases, on the contrary, if an early start of physical activity was not ensured, the functional state of the body worsened.

The negative effects of prolonged bed rest and local immobilization become most pronounced after 50 years. Not only older people, but also patients with chronic diseases and people with disabilities are especially susceptible to the negative effects of immobilization.

For example, in healthy people, as a result of prolonged bed rest, shortening of the muscles of the back and legs, especially the muscles involved in the movements of the knee and ankle joints, develops.

In patients with impaired motor control, accompanied by limb weakness and muscle spasticity, the same complications can be expected, but they develop much more quickly.

A healthy person may respond to prolonged inactivity in the supine position with muscle atrophy, weakness or stiffness, and discomfort. In a patient with neurological impairment, independent functioning will be significantly reduced as a result of prolonged bed rest, so prevention of such complications should be one of the main principles of recovery.

Physiology of muscle activity

Not a single act of life is carried out without muscle contraction, be it contraction of the heart muscle, the walls of blood vessels, or the movement of the eyeball. Muscles are a reliable bioengine. Their work is not only the simplest reflex, but also a combination of hundreds of spatial movements that are extremely complex in terms of coordination.

A person has more than 600 muscles, which can be called a universal, subtle instrument. With their help, a person has an almost unlimited influence on the world around him and realizes himself in a variety of activities. For example, we would not have learned to write if the muscles of the hand and fingers had not been developed, and we would not have been able to make various objects. The fingers of a virtuoso musician work wonders. A person can lift a barbell weighing 265 kg with straight arms. Acrobats and gymnasts manage to perform a triple somersault in one jump. No less amazing is the ability of the muscles to perform long-term hard work - endurance: even women now run the marathon distance (42 km 195 m) faster than in 2 hours 30 minutes.

In the form of feedback, muscles influence the tone and level of activity of the central nervous system, which has been improved over hundreds of thousands of years along with the evolutionary complication of behavioral reactions.

The capabilities of the muscular system are enormous. One of its main features is that its work can be controlled arbitrarily, that is, by an effort of will. And through muscles you can ultimately influence energy supply processes. After all, physical work is performed using internal energy resources, the source of which is carbohydrates, proteins and fats supplied with food.

The energy contained in the consumed products is transferred as a result of a cycle of biochemical reactions into internal bioenergy, and then spent, for example, on the work of the muscular system, mental activity, and also on the formation of heat. The chemical reactions that support the life of the cells of our body due to the constant consumption of energy do not stop for a moment.

Thinking and intellectual work are also associated with movement, but not directly physical. In the brain cells there is a movement (at the metabolic level) of energy carriers: the bioelectric “action potential” is excited, the blood delivers substances rich in energy to the brain, and then removes their decay products. “Movement” in brain cells represents a change in the bioelectric potential and its maintenance due to continuously occurring biochemical reactions - metabolic reactions that constantly require the delivery of “energy raw materials”. This is why increased blood flow is so important for productive intellectual work.

The existence of living organisms is based on the continuity of metabolic processes - a kind of circulation of life support elements occurs. Therefore, the role of muscle activity is so important - a natural factor that accelerates the intensity of metabolic processes.

What is muscle activity and how does it affect metabolism?

The muscle is a bundle of very thin longitudinal fibers - myofibrils, which include the contractile protein actomyosin. Muscle contraction occurs due to electromagnetic forces, causing thin and thick threads to move towards each other in the same way as a metal core is drawn into the coil of an electromagnet. Excitation transmitted by bioelectric impulses along nerve fibers at a speed of about 5 m/s causes a total shortening of myofibrils and an increase in the transverse size of the muscle.

The mechanism of muscle work from the point of view of bioenergy is shown schematically in Fig. 1.

Rice. 1. Bioenergetic mechanism of muscle work

The more muscle fibers are shortened and the more powerful the contraction, the higher the level of consumption of energy stored in muscle cells in vice adenosine triphosphoric acid (ATP). ATP is synthesized in cellular “energy stations” - mitochondria by breaking down carbohydrates, fats and proteins delivered by the blood through capillaries.

No less important is the amount of mechanical resistance overcome by the muscle. This resistance determines the intensity of the neuromuscular impulse and also ensures uniform stretching of the muscle tissue (as it contracts) from its original length to its final size. This means that the higher the level of neuromuscular excitation, the more biochemical energy is consumed. The greatest physiological efficiency is achieved if, when moving bone levers overcoming external resistance, the same muscle tension is maintained (working in an isotonic mode).

The intensity of muscle work is also important, that is, its quantity in units of time, and its duration, which are determined by the energy capabilities of the body.

Movement is one of the main conditions for human existence in the environment, and it is possible only due to the activity of the muscular system, which means that muscles must be constantly trained. The physiological activity of any organism depends on its biological power, and this, in turn, on the performance of the muscles that “submit” to volitional control. Figuratively speaking, health is a mirror of stress. The parable of Milo of Croton tells about a young man who carried a bull on his shoulders, and with its growth Milo’s strength also grew.

By loading the muscles, you can effectively regulate not only energy exchange, but also the overall metabolism in the body. This is the most natural way to “manage” biopotential, causing positive changes in all organs and systems. And their condition determines the level of our health.

The psyche as a system for controlling behavior, in particular the most complex movements of skeletal units, is closely connected with the body (somatics), primarily with muscles, which have the ability to transform internal energy resources contained in ATP. It is not without reason that in recent decades there has been an emphasis on studying the body from the point of view of psychosomatics. Therefore, often in people who are physically inactive, whose muscles, including the heart, are not trained and developed, not only energy exchange processes are disrupted, but also the work of the central nervous system, “responsible” for the normal functioning of the body, since the size of the nervous -muscle tension depends on the intensity of biochemical reactions in nerve cells, which also constantly need energy supply. In other words, the activity of the central nervous system also depends on the work of the muscles. That is why movement and physical activity make it possible not only to maintain, but also to increase the functional capabilities of the body, which determine the level of health. Therefore, if you exercise regularly, tangible results will appear quite quickly. What to choose is up to you to decide. Try to master athletic gymnastics without apparatus - maybe this is what you need?

From the book Guide to Spearfishing while holding your breath by Bardi Marco

Physiology of breathing Breathing consists of two phases: inhalation and exhalation. During inhalation, the muscles of the diaphragm and intercostal muscles contract. The diaphragm bends down, pressing on the abdominal organs and increasing the volume of the chest; as a result of contraction of the intercostal muscles

From the book From the very beginning (the coach's path) author Golovikhin Evgeniy Vasilievich

Part I. Physiology of cardiopulmonary activity Oxygen is the “fuel” necessary for the implementation of all energy processes of the human body. Its importance for maintaining life was noted back in 1777 by Antoine Lavoisier, who,

From the book Theory and methodology of pull-ups (parts 1-3) author Kozhurkin A. N.

Chapter 5. Adaptation of muscle tissue Dear colleagues, how nice it is to have worked for 5–6 years with a group of athletes to receive excellent quality material for elite sports. Each athlete represents the end result of many years of coaching work. Competently

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Chapter 6. Basics of energy supply to muscle activity in contact styles of martial arts You are watching a fight. You mark the beginning, the athletes perform feints, constantly move, prepare attacks, and defend themselves. Suddenly, one of the athletes explodes and inflicts

From the book The Comprehensive Guide to Strength Development author Hatfield Frederick

2.3.2 Energy supply for muscle activity. Thus, there are several ways to supply energy to muscle activity. The question is what is the relationship between the pathways of ATP resynthesis during specific muscle activity. It turns out it depends

From the book Psychology of Sports author Ilyin Evgeniy Pavlovich

Muscle Physiology Surely many of you may doubt the need to thoroughly study all the material presented below. Having examined in the previous chapter the functions, names and general concept of muscles in general, you can already understand how important knowledge of all these points is for

From the book Success or Positive Way of Thinking author Bogachev Philip Olegovich

In training to increase muscle size, variation is the key to achieving maximum muscle gain. Use all the given techniques, changing them both during the approach and between approaches. For triathletes, increasing muscle size due to muscular

From the book Aerobics for the chest author Gatkin Evgeniy Yakovlevich

CHAPTER 1 Psychology of athlete activity Sport is a specific type of human activity and at the same time a social phenomenon that helps raise the prestige of not only individuals, but also entire communities, including the state. Currently

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From the book Ready for Battle! Stress resistance in hand-to-hand combat author Kadochnikov Alexey Alekseevich

From the book Equilibrium in Motion. Rider's seat author Dietze Susanne von

From the book All About Horses [Complete guide to proper care, feeding, maintenance, dressage] author Skripnik Igor

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Chapter 1 Conditions of activity in hand-to-hand combat The psychology of hand-to-hand combat is designed to study the patterns of manifestation and development of the human psyche, the formation of the psychology of individual activity in the specific conditions of applied military activity. To activities in

From the author's book

2. Physiology of movement 2.1. Joints: structure, functions and biomechanics A joint is a movable connection between two bones. The structure of the joints ensures the execution of movements, their direction and amplitude. Rice. 2.1. Joint diagram: 1 - head of the joint; 2 - cartilage; 3 -