Changes in performance at different periods of work are characterized by ergographic and electromyographic indicators presented in table. 6. The first Period, defined as the period of working out and assimilating the rhythm, is characterized by the fact that by the end of it there is a slight increase in the amplitude of the ergogram, a decrease in the variability of this value and an increase in work productivity. As a result of these processes, in the second period there is an increase in the amplitude of movement from 92 to 97 mm, a decrease in variability from 6.5 to 5.7%; the consumption of bioelectric energy, expressed in conventional units (in millivolts per 1 cm of lifting the load) per unit of work, decreases from 4.2 to 4 mV.

All these changes indicate that the second period is the period of the highest efficiency. Table data. 6 explain the physiological mechanism of increasing performance during this period. This is a decrease in the time interval during which nervous excitement has time to develop and come to an end, providing muscle contraction necessary for a single flexion of the finger lifting the load. About decreasing the interval nervous excitement can be judged by a decrease in the duration of volleys, or packs, the bioelectric activity of the flexor and extensor muscles of the fingers. A decrease in the interval of excitation, or the assimilation of a high rhythm of activity of the nerve centers, is obtained due to the summation of traces of excitement that remain after each next movement.

Table 6. Changes in various performance indicators by periods of work in boys aged 16-18

After the period of the highest working capacity, a period of decreasing working capacity begins, at this time processes occur in the body that partially compensate for the beginning fatigue (the third period of the dynamics of working capacity). In this case, on the ergogram, decreases in amplitudes are noted, alternating with their increase; the total bioelectrical activity of muscles and the amplitude of muscle biocurrents slightly increase. In the fourth period of work, despite the effect of physiological compensatory measures, fatigue continues to deepen, which is expressed in a further decrease in the amplitude of the ergogram, in an increase in the variability of amplitudes, in a decrease in the productivity of bioelectric processes and in deconcentration of muscle strength and nervous processes.

In children of different ages, indicators of the dynamics of working capacity differ in both biomechanical and bioelectrical processes. In children of primary school age, the peculiarities of work are observed, due to such quantitative indicators as the size and mass of muscles, as well as insufficiently developed mechanisms of mastering the rhythm and compensating for fatigue. Age characteristics of the dynamics of working capacity are presented in table. 7.

Table 7. Performance indicators in children of different ages (average values)

As can be seen from these data, various indicators of working capacity change regularly with age. Thus, the amount of work performed per minute increases unevenly with age. Age-related increases in the amount of work performed depend on physical development. This position is confirmed by the results of a statistical test: it turned out that the correlation coefficient between the values \u200b\u200bof hand force and the amount of work performed in one minute is 0.71. In young children, work took place with a relatively large variability of the duration of motor cycles, with some lag in the performance of work from the signals of the metronome setting the pace. For older children, a clear rhythm and less variability in the duration of motor cycles are characteristic. With increasing age of the subjects, the efficiency of work increases, the consumption of total bioelectric energy per unit of work (100 kgf · m) decreases. There was a close inverse correlation between the increase in work performed per minute and the amount of consumption of bioelectric activity, the correlation coefficient was 0.77.

The range of factors that have a negative impact on the neuromuscular apparatus of a person and his muscular performance is limited. The natural and strongest factor that has both negative and positive effects on human skeletal muscles and motor functions during all periods of life is the amount of load on the musculoskeletal system. The most significant "blow" to the muscular system (at any age) causes a decrease in physical activity on it. At all stages of human ontogenesis, a decrease in motor activity leads to a decrease in energy consumption, leading to inhibition of oxidative phosphorylation processes in muscle cells. At the same time, the rate of ATP resynthesis in muscles decreases and their physical performance decreases. In myocytes, the number of mitochondria, their size and content in their cristae decrease. The activity of phosphorylase A and B, NADH 2 -dehydrogenase, succinate dehydrogenase, enzymatic activity of ATP-ase of myofibrils decreases. The rate of breakdown and synthesis of energy-rich phosphorus compounds is slowed down and, therefore, muscle performance is reduced. This begins to manifest itself to the greatest extent in adulthood (after 35-40 years).

The lack of an optimal level of physical activity in a person (daily energy consumption is less than 2800-3000 kcal) reduces the tone of skeletal muscles, their excitability and contractile properties, impairs the ability to perform highly coordinated movements, reduces muscle performance both during dynamic and static work, practically of any intensity ... The main reason for the decrease in the performance of muscles, especially those that are not very active during the day, is a decrease in the content of contractile proteins in muscle cells due to a slowdown in the intensity of their synthesis. In conditions of weakening of physical activity and, consequently, a decrease in the intensity of disintegration of macroergs, the periodic stimulation of the genetic apparatus of the cell, which determines the synthesis of contractile proteins, weakens. Due to a decrease in the activity of phosphorylation processes in myocytes, protein synthesis slows down according to the DNA-RNA-protein scheme. With a decrease in physical activity, the production of hormones that stimulate the development of muscle tissue (androgens, insulin) slows down. This mechanism also leads to a slowdown in the rate of synthesis of Contracting proteins in skeletal muscle cells.

However, not only reduced physical activity, but also increasedis also one of the factors that reduce the functionality of the locomotor system and contribute to the development of pathology of the neuromuscular system. Here (due to the specifics of the tasks of the textbook) there is no need to touch upon the influence of high physical stresses (for example, in weightlifters) on the development of pathology of the musculoskeletal system. This is the subject of sports medicine. At the same time, it should be emphasized that the work of millions of people is associated with the need to perform a large number (per working day) of physical movements with a small amount (from 100-500 g to 10-15 kg and more). So, for example, assemblers of electric motors, controllers-sorters, operators-assemblers of automobile plants, shoe collectors, operators of computer keyboard machines, telegraph operators make from 40 to 130 thousand finger movements per working day. In this case, the total local work of small muscle groups often exceeds 100-120 thousand kgm per work shift. The degree of muscle fatigue that develops during such work, the subsequent overstrain of the neuromuscular apparatus and professional pathology of the neuromuscular apparatus are determined by the number of movements per shift and the magnitude of the effort developed by the muscles. If the value of the total load exceeds a certain threshold level (for example, 60-80 thousand finger movements per shift), then the result is a decrease in muscle performance and the development of occupational diseases of the neuromuscular system is possible.

At all stages of human ontogenesis, the optimal activity of his musculoskeletal system or disorders of muscle functions depend on the intake of the necessary chemical substrates in the body: proteins, carbohydrates, fats, vitamins and minerals, i.e. from the structure of food.

Protein make up about 15% of body weight, mainly located in skeletal muscles. Until the human body is completely devoid of its main energy substrates (carbohydrates and fats), the share of proteins in the energy supply of vital activity does not exceed 1-5%. The main purpose of protein consumption is to use them in the growth and maintenance of muscle and bone mass, building cellular structures, and enzyme synthesis. In a person who does not perform significant physical activity, daily protein losses are about 25-30 g. With hard physical work, this value increases by 7-10 g. The required daily protein intake is greatest during periods of growth of the body and when performing large physical activity... The minimum amount of protein consumed per day per 1 kg. body weight for children 4-7 years old is 3.5-4 g; 8-12 years old - 3 g and adolescents 2-2.5 g. After the completion of the growth of the body, it is necessary to consume about 1 g of protein per 1 kg of body weight. For persons performing heavy physical work, this value should be 20-30 % more. It must be remembered that even in the most protein-rich foods (meat, eggs), the protein content does not exceed 20-26 %. Therefore, in order to maintain a full-fledged protein balance, the amount of protein products consumed by a person in comparison with the above norms of protein intake must be increased by 4-5 times.

The main sources of energy for human muscular work are carbohydrates and fats. When I g of carbohydrates are "burned", 4.1 kcal of energy is released, air fats - 9.3 kcal. The percentage of the use of carbohydrates and fats during muscular activity of a person depends on the power of work. The higher it is, the more carbohydrates are spent, and the less - the more fats are oxidized. There are no special problems with the fat content in relation to the tasks of providing energy to the work of the musculoskeletal system at all stages of ontogenesis, since the existing fat depot in a person is able to provide the real needs of his body for energy during work of medium and moderate power for many hours. The situation is somewhat more complicated with carbohydrates.

The fact is that the performance of skeletal muscles is directly dependent on the content of carbohydrates (glycogen) in their fibers. Normally, 1 kg of muscle contains about 15-17 g of glycogen. At any age, the more glycogen muscle fibers contain, the more work they are able to do. The content of carbohydrates in the muscle depends on the intensity of the previous work (their expenditure), the intake of carbohydrates with food, the duration of the recovery period after exercise. To maintain a high working capacity of a person at all age periods, the general laws are: I) with any amount of carbohydrates in the daily diet in the absence of physical exercise, the glycogen content in the muscles changes slightly; 2) the concentration of glycogen in muscle fibers decreases almost completely with intensive work for 40-100 minutes; 3) complete restoration of muscle glycogen content requires 3-4 days; 4) the possibility of increasing the content of glycogen in muscles, and, consequently, their performance by 50-200%. To do this, it is necessary to perform muscle work of submaximal power (70-80% of the BMD) for 30-60 minutes (with such a load, glycogen will be mainly consumed) and then use a carbohydrate diet for 2-3 days (the carbohydrate content in food is up to 70-80% ).

ATP plays a leading role in ensuring muscle activity. At the same time, ATP resynthesis and, therefore, muscle performance largely depend on the content in the body vitamins. With a lack of B-complex vitamins, a person's aerobic endurance decreases. This is due to the fact that among the many different functions that are influenced by vitamins of this group, their role is especially great as cofactors in various enzyme systems associated with food oxidation and energy production. So, in particular, vitamin W (thiamine) is necessary for the transformation of pyruvic acid into acetyl-CoA. Vitamin Bp (riboflavin) is converted to FAD, which acts as a hydrogen acceptor during oxidation. Vitamin Bo (niacin) is a component of NADP - a co-enzyme of glycolysis. Vitamin Btr plays an important role in amino acid metabolism (changes in muscle mass during exercise) and is required for the formation of red blood cells, which transport oxygen to muscle cells for oxidation processes. The functions of the B-complex vitamins are so interrelated that a deficiency of one of them can disrupt the utilization of others. Lack of one or more B vitamins reduces muscle performance. Additional use of this group of vitamins increases efficiency only in cases where the subjects had a deficiency of these vitamins.

Insufficient intake of vitamin C (ascorbic acid) with food also reduces the muscle performance of a person. This vitamin is essential for the formation of collagen, a protein found in connective tissue. Therefore, it is important for ensuring normal function (especially under heavy loads) of the osteo-ligamentous apparatus and blood vessels. Vitamin C is involved in the metabolism of amino acids, the synthesis of certain hormones (catecholamines, anti-inflammatory corticoids), in ensuring the absorption of iron from the intestine. Additional intake of vitamin C increases muscle performance only in cases where there is a deficiency in the body. Vitamin E (alpha-tocopherol) helps increase the concentration of creatine in the muscles and develop more strength. It also has antioxidant properties. Information about the effect of other vitamins on muscle performance in untrained and athletes is very contradictory. However, there is no doubt that without taking the daily intake of a full complex of vitamins, muscle performance can be reduced.

The importance of minerals in maintaining high muscle performance is beyond doubt. However, their additional need was noted only for persons performing long and large physical activity in a hot and humid climate.

Reception has a negative effect on motor functions alcohol. The data on this "risk" factor in relation to the activity of the musculoskeletal system are rather ambiguous. They are even less definite in relation to the effect of alcohol on the muscular system in ontogenesis. However, some of the proven statements about the effects of alcohol on the neuromuscular system are as follows.

I. Alcohol intake leads to an increase in the processes of inhibition in the motor area of \u200b\u200bthe cerebral cortex, impairs the differentiation of inhibitory processes during motor reactions, reduces the speed of switching the processes of inhibition and excitation, reduces the strength of the processes of concentration of excitation and the rate of increase in the frequency of impulses in motor motor neurons. 2. When alcohol is consumed in a person, the strength and speed of contraction of skeletal muscles decrease, which leads to a decrease in their speed-strength qualities. The manifestations of human motor coordination are deteriorating. 4. All kinds of reactions to external stimuli (light, sound, etc.) are slowed down. 5. The vegetative reactions to the same muscle work as before the intake of alcohol increase, that is, the physiological "cost" of the work increases. 6. The concentration of glucose in the blood decreases, thereby causing a deterioration in the functions of the muscular system. 7. The content of glycogen in the muscles decreases (even after a single intake of alcohol), which leads to a decrease in muscle performance. 8. Long-term alcohol intake leads to a decrease in the contractile function of human skeletal muscles.

Extremely limited information about the impact tobacco smoking on the functions of the musculoskeletal system. It is only known for certain that nicotine, getting into the blood, impairs the processes of regulation of the force of contraction of skeletal muscles, impairs coordination of movements, reduces muscle performance. Smokers generally have lower BMD than nonsmokers. This is due to the more intense addition of carbon monoxide to hemoglobin in erythrocytes, which reduces oxygen transport to working muscles. Nicotine, reducing the content of vitamins in the human body, helps to reduce its muscle performance. With prolonged smoking, the elasticity of the connective tissue decreases, and the extensibility of the muscles decreases. This leads to painful reactions during intense contractions of human muscles.

Thus, along with many negative effects of tobacco smoking on the systems of the human body and their functions, nicotine also causes a decrease in muscle performance and the level of physical health of smokers.

One of the most widely used by people ergogenic means, that is, means of increasing efficiency, is caffeine... By acting on the central nervous system, caffeine increases its excitability; improves concentration of attention; cheers up; shortens the speed of sensorimotor reactions; reduces fatigue and delays the time of its manifestation; stimulates the release of catecholamines; enhances the mobilization of free fatty acids from the depot; increases the rate of utilization of muscle triglycerides. Through all of these reactions, caffeine produces a marked increase in aerobic performance (cycling, long distance running, swimming, etc.). Caffeine appears to also improve muscle performance in sprinters and strength athletes. This may be due to its ability to enhance calcium metabolism in the sarcospasmic reticulum and the work of the sodium-potassium pump in muscle cells.

Nevertheless, despite the indicated effect of caffeine on a person's performance, it can also cause negative consequences.In people who are not used to using caffeine, but are sensitive to it, as well as in those who use it in large doses, caffeine causes increased excitability, insomnia, anxiety, skeletal muscle tremors. Acting as a diuretic, caffeine increases dehydration by disrupting thermoregulation processes, and reduces muscle performance, especially in high temperature and humidity environments.

Some athletes use drugs to speed up the recovery process after heavy physical exertion. Sometimes even cocaine is used. The latter stimulates the activity of the central nervous system, is considered a sympathomimetic drug, and blocks the reuse of norepinephrine and dopamine (neurotransmitters) by neurons after their formation. By blocking their reuse, cocaine enhances the effects of these neurotransmitters throughout the body. Some athletes believe that cocaine improves performance. However, this omission is misleading. It is associated with the emerging feeling of euphoria, which increases motivation and self-confidence. Along with this, cocaine "masks" fatigue and pain and may contribute to the development of overstrain in the neuromuscular system. In general, cocaine has not been shown to have the ability to increase muscle performance,

To increase muscle performance, people involved in physical exercise and sports are often used hormonaldrugs. From the beginning of the 50s, the era of the use of anabolic steroids began, and from the second half of the 80s, of synthetic growth hormone. Due to the greatest prevalence and danger of use for the body, we will dwell only on androgens - anabolic steroids, almost identical to male sex hormones.

The use of anabolic hormones leads to a significant increase in: total body weight; the content of potassium and nitrogen in the urine, indicating an increase in lean body mass; the size of whole muscles and the cross-sectional area of \u200b\u200btheir constituent myocytes by increasing the number of myofibrils contained in them (that is, the number of contractile proteins); strength and performance of skeletal muscles.

Therefore, the main effect of using steroid hormones is to increase muscle mass (myofibrillar hypertrophy) and force of contraction. At the same time, these hormones are practically do not affect on the aerobic endurance of a person, the speed qualities of his muscles, the speed of the processes of restoration of working capacity after intense physical exertion.

However, the use of steroid hormones (this sometimes happens already from school age) is not only a matter of ethics, but also a problem of maintaining the health of a huge number of people. Due to the high degree of health risk, anabolic hormones and synthetic growth hormone are considered illegal drugs. The main negative health effects of those taking steroid hormones are as follows. The use of synthetic anabolic hormones suppresses the secretion of its own gonadotropic hormones, which control the development and function of the sex glands (testicles and ovaries). In men, decreased gonadotropin secretion can lead to testicular atrophy, decreased testosterone secretion and decreased sperm count. Gonadotropic hormones in women are necessary for the implementation of ovulation and the secretion of estrogens, therefore, a low blood level of these hormones as a result of the use of anabolic steroids leads to menstrual irregularities, as well as masculinization - a decrease in breast volume, a coarse voice, the appearance of facial hair.

A side effect of using anabolic steroids can be an enlarged prostate in men. There are also known cases of liver dysfunction due to the development of chemical hepatitis, which can turn into liver cancer.

In persons who have been using anabolic steroids for a long time, a decrease in myocardial contractile function is possible. They have a significant decrease in the concentration of high-density alpha-lipoproteins in the blood, which have antiatherogenic properties, that is, they prevent the development of atherosclerosis. Therefore, the use of steroid hormones is associated with a high risk of coronary heart disease.

The use of steroids leads to changes in a person's personality traits. The most pronounced of which is increased aggressiveness.

Physical fatigue

Prolonged and intense muscle activity leads to a temporary decrease in physical performance organism - fatigue. The process of fatigue initially affects the central nervous system, then the neuromuscular synapse and, last of all, the muscle. So, people who have recently lost an arm or leg feel their presence for a long time. While doing mental work with the missing limb, they soon announced their fatigue. This proves that fatigue processes develop in the central nervous system, since no muscle work was performed.

Fatigue is a normal physiological process developed to protect physiological systems from systematic overwork, which is a pathological process and leads to a breakdown in the activity of the nervous and other physiological systems of the body. Rational rest quickly helps to restore performance. After physical work, it is useful to change the type of activity, since complete rest is slower to restore strength.

Muscular system development

The child's muscular system undergoes significant structural and functional changes in the process of ontogenesis. The formation of muscle cells and the formation of muscles as structural units of the muscular system occurs heterochronously. The process of "rough" muscle formation ends by 7-8 weeks of prenatal development. At this stage, irritation of the skin receptors already causes the fetal motor responses, which indicates the establishment of a functional connection between tactile reception and the muscular system. In the following months, the functional maturation of muscle cells is intense, associated with an increase in the number of myofibrils and their thickness. After birth, maturation of muscle tissue continues. Muscle mass grows mainly due to an increase in the longitudinal and transverse dimensions of muscle fibers, and not the number of myofibrils, the total number of which increases slightly (about 10%). In particular, intensive fiber growth is observed up to 7 years of age and during puberty. Starting from the age of 14-15, the microstructure of muscle tissue practically does not differ from that of an adult. However, the thickening of muscle fibers can last up to 30-35 years.

First, those skeletal muscles that are necessary for the normal functioning of the child's body at this age stage develop. Muscle development upper limbs usually precedes muscle development lower limbs... Larger muscles are always formed before small ones. For example, the muscles of the shoulder and forearm develop faster than the small muscles of the hand. In a one-year-old baby, the muscles of the arms and shoulder girdle are better developed than the muscles of the pelvis and legs. The muscles of the arms develop especially intensively at the age of 6-7 years. The total muscle mass grows rapidly during puberty: in boys - at 13-14 years old, and in girls - at 11-12 years old.

Table 2.1 shows the data characterizing the mass of skeletal muscles in the process of postnatal development of children and adolescents.

Table 2.1

Increase in skeletal mouse mass with age

In the process of ontogenesis, the functional properties of muscles also change significantly. Excitability, lability, contractility and speed of excitation of muscle fibers increase, muscle tone changes. The newborn has an increased muscle tone, and the tone of the muscles that cause flexion of the limbs prevails over the tone of the extensor muscles. As a result, the arms and legs of infants are more often bent. The intensive development and increase in the tone of the extensors, characteristic of the adult body, occurs by the age of 5. Children have poor muscle relaxation ability, which increases with age. Stiffness of movement in children and adolescents is usually associated with this. Only after 15 years do the movements become more flexible.

In the process of development of the musculoskeletal system, the motor qualities of the muscles change: speed, strength, agility, flexibility and endurance. Their development occurs unevenly (hetero-chronically) and depends on the functional state of the body and training. For the development of each quality, there are certain sensitive (sensitive) periods of individual development, when the maximum increase can be obtained. Individual feature formation of motor qualities and their manifestation are largely determined by the genetic program. First of all, quickness and dexterity of movements are developed. The speed (speed) of movements is characterized by the number of movements that a person is able to make per unit of time. The speed is determined by three indicators: the speed of a single movement, the time of the motor reaction and the frequency of movements. From a physiological point of view, the development of speed is due to the following factors

rami: lability (functional mobility) of nerve centers and skeletal muscles, their energy supply and the ratio of fast and slow fibers. Lability is the limiting rhythm of impulses that the nerve centers are able to reproduce in a unit of time, which depends on the mutual transition of excitation and inhibition in the motor centers of the cortex and in the working muscles. The energy supply of movements is carried out due to the energy of anaerobic breakdown of muscle phosphagens (ATP and creatine phosphate), as the most rapid energy mechanism. The ratio of fast (white) muscle fibers, in which mainly anaerobic breakdown of phosphagens occurs, and slow (red) ones, in which aerobic oxidation of carbohydrates occurs, is genetically programmed to a certain extent, although it can vary depending on the nature of physical activity.

The speed of a single movement increases significantly in children from 4-5 years old and by 13-14 years old reaches the adult level. By the age of 13-14, the time of a simple motor reaction, which is due to the speed of physiological processes in the neuromuscular apparatus, also reaches the adult level. The maximum voluntary frequency of movements increases from 7 to 13 years, and in boys at 7-10 years old it is higher than in girls, and at 13-14 years old, the frequency of movements of girls exceeds this indicator in boys. Finally, the maximum frequency of movements in a given rhythm also increases sharply at 7-9 years of age. The greatest increase in speed as a result of training is observed in children from 9 to 12 years old.

Until the age of 13-14, the development of dexterity is completed, which is associated with the ability of children and adolescents to carry out accurate, coordinated and fast movements. Consequently, dexterity is associated, firstly, with the spatial accuracy of movements, secondly, with the temporal accuracy, and thirdly, with the speed of solving complex motional problems. The development of dexterity, starting from 3-4 years old, quickly improves in the first and second childhood, which is facilitated by the good elasticity of muscle fibers and ligaments in children of this age. The greatest increase in the accuracy of movements is observed from 4-5 to 7-8 years. Up to 6-7 years old, children are not able to make fine precise movements in the extremely a short time... Then the spatial accuracy of movements gradually develops, followed by temporal accuracy. Finally, the ability to quickly solve motor problems in various situations is improved last. Agility continues to improve until age 17. Interestingly, sports training has a significant impact on the development of dexterity, and in 15-16-year-old athletes, the accuracy of movements is two times higher than in untrained adolescents of the same age.

Flexibility is the degree of mobility of individual parts of the human body relative to each other, which is expressed in the amplitude (range) of movements. It depends on the anatomical features of the articular surfaces, the nature of their joints, the elasticity of the tissues surrounding the joints, as well as on the functional state of the central nervous system and the locomotor system. The ability to reproduce the amplitude of movements maximally increases at 7-10 years old and after 12 years practically does not change, and the accuracy of reproduction of small angular displacements (up to 10-15 °) increases to 13-14 years.

The formation of the skeletal and muscular system is of great importance for the development of strength. The strength of individual muscle groups develops unevenly, therefore in each age period there are different relationships between the strength of different muscles. In preschoolers, the strength of the muscles of the trunk is greater than the muscles of the limbs. Due to the increased muscle tone and the excess of the flexor muscles over the extensors in preschoolers and younger students, it is difficult to maintain erect postures, so they can maintain an upright posture without fatigue for no more than 2 minutes. In younger schoolchildren, the flexors of the trunk, hips and soles have the greatest strength. The strength of the extensor muscles of these parts of the body increases by the age of 9-11. Poor development of the "muscle corset" causes a curvature of the spine, poor posture if hygiene rules are not followed. Weak development of the muscles of the foot leads to flat feet. The greatest increase in strength is observed in middle and senior school age, especially intensively, strength increases from 10-12 to 16-17 years. In girls, the increase in strength occurs somewhat earlier, from 10-12 years old, and in boys - from 13-14. Nevertheless, boys are superior to girls in this indicator in all age groups, but a particularly clear difference appears from 13-14 years old.

Later than other physical qualities, endurance develops, characterized by the time during which a sufficient level of the body's performance is maintained without the development of fatigue. The factors for the development of endurance are the degree of formation of the oxygen transport system of the body - the respiratory, cardiovascular and blood systems. These systems ensure the supply of oxygen to the body and its transport to the working muscles, due to which the mechanisms of aerobic energy supply of the muscles are activated. There are age, sex and individual differences in endurance. Endurance (especially to static work) of children preschool age is at a low level. An intensive increase in endurance for dynamic work is observed from 11-12 years old. So, if we take the volume of dynamic work of 7-year-old schoolchildren as 100%, then for 10-year-olds it will be 150%, and for 14-15-year-olds - more than 400% (M.V. Antropova, 1968). Schoolchildren's endurance to static loads also increases intensively from 11-12 years old. In general, by the age of 17-19, students' endurance is about 85% of the adult level. A sensitive period of endurance development is adolescence, when the functions of the cardiorespiratory system mature in sufficient measure. It reaches its maximum level by the age of 22-25.

In general, by the age of 13-15, the formation of all parts of the motor analyzer ends, which occurs especially intensively at the age of 7-12 years.

With aging, muscle mass decreases and by the age of 70-90 it is approximately 50% of the level in adulthood. It does this by reducing the diameter of the muscle fibers and the amount of fluid in the tissue. At the same time, the strength and speed of muscle contraction, their excitability, elasticity, flexibility, accuracy, endurance also decrease, which is reflected in a decrease in the amplitude and smoothness of movements, an increase in rigidity, impaired coordination (awkward gait), a decrease in muscle tone, and a slowdown in movements. This is due to a lengthening of the action potential in myocytes, a slowdown in the rate of excitation, a decrease in the strength of nervous processes and a deterioration in energy metabolism in cells.

Characterizing physical performance, it should be noted that the methodology for determining it gives only an approximate idea of \u200b\u200bthis phenomenon, since a person consists not only of muscles and systems for ensuring their activity, but also has a mind and such psycho-emotional qualities as willpower, motivation, desire, ability to mobilization of efforts, etc. In this regard, working capacity, including physical, is a very multifaceted concept. An external manifestation of high performance can be high achievements in sports, in physical labor, achievement of the maximum amount of work that a person can perform to the emergence of significant physiological changes.

A rough estimate of the level can be obtained by climbing the stairs. It is necessary to go to the 4th floor at an average pace of walking without stopping. If a person easily overcame this rise and feels that there is still a reserve, the mark is "good". If a person suffocated, it means that the level of his health is reduced.

According to the recommendations of V.I. Bobritsky (2000), the level of physical performance oriented can be assessed by a test with 20 squats. To do this, you need to calculate a stable pulse while sitting for 10 seconds, then within 30 seconds you need to do 20 squats, raising your arms forward. After that, you need to sit down again and fix the recovery time of the pulse to its original values, counting it over time intervals of 10 s. If the heart rate has recovered faster than 1 minute. the mark is "excellent", up to 2 minutes. - "Good", slower than 3 minutes. - "Poorly". The same assessment can be made by conducting a breath hold test. You need to take 1-2 deep breaths - exhalation, and then take a deep breath (not the maximum!) And hold your breath as much as possible. If breathing is held for\u003e 60 s - "excellent", 40-59 s - "good",<39 с — «плохо» (для женщин на 10 с меньше).

It should be remembered that the quantitative characteristics of the working capacity of children and adolescents are not always objective, since their ability to volitional tension is not yet sufficiently developed. Children often quit work long before they reach the limit of strenuous activity.

Muscular performance in general depends on muscle strength and endurance, as well as on the state of the vegetative components of the body, then on the state of the cardiovascular system, respiration, thermoregulation, metabolism and the presence of movement patterns. There are certain relationships between these components. Therefore, for greater accuracy of the age characteristics of the physical performance of adolescents, A.A. Markosyan (1974) recommends taking into account four elements:

Strength development level (dynamometry indicators).

The level of development of various types of motor skills (assessed by the number or speed of certain movements in 1 minute);

The level of development of the functions of the cardiovascular and respiratory systems;

The level of development of endurance and the ability to short-term development of power (this is what characterizes the indicator

An indicator of fatigue is, first of all, a decrease in physical strength or performance, which can be caused both by changes in the muscle itself, and with changes in the central nervous system (in the nerve centers). An extreme case of fatigue of a particular muscle is its prolonged contraction and temporary inability to completely relax, which is called contracture.

The participation of the nervous system in the development of fatigue is associated mainly with the accumulation of decay products, or with the depletion of mediators in the nerve synapses. The restoration of working capacity is significantly facilitated by a change in the type of activity (active or passive rest), positive emotions and motivation, etc.

Fatigue processes at the muscle level are associated with the depletion of energy carriers and, above all, adenosine triphosphoric acid (ATP) and with the accumulation in the muscles of the products of anaerobic breakdown of glycogen, especially lactic acid, which takes a certain time to withdraw. By the way, the feeling of heaviness in the stomach, which worked hard, can take several days and is due, to a certain extent, to the accumulation of lactic acid. Restoring muscle performance is facilitated by rest (rest), moderate muscle warm-up, targeted massage, and protein-carbohydrate food.

Small children (up to 4 years old) get tired very quickly with muscle loads. From the age of five, the ability for physical work of children gradually begins to increase along with an increase in the energy capabilities of skeletal muscles and with structural and functional maturation.

But in children of preschool and primary school age, the final differentiation of skeletal muscles is not yet completed, therefore, in general, in children of 6-9 years old, physical performance is 2.5-3 times lower than in children of 15-16 years.

The turning point in the development of physical performance of children occurs at the age of 12-13, when significant changes are observed in the morphology of muscle fibers and in the energy of contractions: muscle endurance increases abruptly, and at the same time, the ability to carry out loads for a long time with a lower risk of fatigue.

It should also be noted that physical performance (as well as mental performance) of children has certain fluctuations during the day: its highest levels are observed from 10 to 14 hours, as well as from 17 to 19 hours. In the period from 7 to 10 o'clock in the morning and from 16 to 17 o'clock there are periods of increasing efficiency (calculation phases), and in the periods from 14 to 16 o'clock and from 19 o'clock in the evening, the efficiency decreases (phases "fatigue"). periods of optimal performance (Tuesday, Wednesday, Thursday), periods of increasing performance (Sunday, Monday) and periods of fatigue (Friday, Saturday). The least work capacity for most people is at night (from 23.00 to 6.00 in the morning) and on Friday. Physical performance also significantly decreases within 1-1.5 hours after eating. The dynamics of human performance is, to a certain extent, influenced by the individual biological rhythms of each person. The above dynamics of working capacity is inherent in the so-called normochronists. In people who belong to "larks" the highest working capacity is shifted by 1.5-2 hours at the beginning of the day, and for "owls" - for the same period of the second half of the day. The specified periodization of working capacity should be taken into account when organizing physical education and sports training.

Introduction

Physiology of sports is a section of human physiology that studies changes in body functions during sports activities and their mechanisms. Sports physiology is closely related to the theory and methodology of physical culture; it equips the athlete and the coach with knowledge about the physiological processes occurring in the athlete's body during training and competitive activities.

Age physiology is a science that studies the characteristics of an organism's vital activity at different stages of ontogenesis. Such sciences as gerontology and juvenology are closely related to it. Gerontology is the science of aging of living organisms, including humans, and of the prevention of aging processes.

Mature and old age are naturally coming stages of a person's individual development. The processes of maturation and aging occur continuously, unevenly and non-simultaneously. They affect not equally different tissues, organs and systems of the body.

The first period of mature age includes men and women from 21 to 35 years old, to the second period - women aged 36-55 years and men - 36-60 years old; the elderly are women aged 56-74 years, and men - 61-74 years old. The period from 75 to 90 years old belongs to old age, and people over 90 years old - to centenarians.

Age physiology as a special scientific discipline

Age physiology studies the characteristics of the vital activity of the organism at different periods of individual development or ontogenesis (Greek: ontos - an individual, genesis - development). The concept of ontogenesis includes all stages of the development of an organism from the moment of fertilization of an egg to the death of a person. There are prenatal (before birth) and postnatal (after birth) stages.

Development is understood as 3 main processes: 1) growth - an increase in the number of cells (in bones) or an increase in the size of cells (muscles); 2) differentiation of organs and tissues; 3) shaping. These processes are closely interrelated. For example, the accelerated growth of the body slows down the processes of shaping and differentiation of tissues.

The formation of various organs and systems, motor qualities and skills, their improvement in the process of physical education can be successful if scientifically grounded application of various means and methods of physical culture. It is necessary to take into account the age-sex and individual characteristics of children, adolescents, mature and elderly people, as well as the reserve capabilities of their body at different stages of individual development. Knowledge of such patterns will protect against the use of both insufficient and excessive muscle loads.

The entire life cycle (after birth) is divided into separate age periods. Age periodization is based on a set of signs: body size and individual organs, their mass, skeletal ossification (bone age), teething (dental age), development of endocrine glands, degree of puberty, development of muscle strength.

There are the following age periods:

1-10 days - newborn; 10days - 1 year - infancy; 1-3 years - early childhood; 4-7 years old - first childhood; 8-12 years old M and 8-11 years old D - second childhood; 13-16 years old M and 12-15 years old D - adolescents; 17-21 years old boys and 16-20 years old girls - youth; 22-35 years - the first mature age; 35-60 years for a man and 35-55 years for a woman - the second mature age; 60-74 - elderly; 75-90 - senile; over 90 are long-livers.

The period of puberty (puberty or transitional period) is especially noted. There is a significant hormonal change in the body, the development of secondary sexual characteristics, deterioration of conditioned reflex activity, motor skills, fatigue increases, speech becomes difficult, emotional reactions and behavior are unbalanced. Significant annual increase in body length.

The main patterns of age-related development are periodization and heterochronism (unevenness and different timing of growth and development).

In connection with the main patterns of age periodization, a program is being built for teaching children at school, rationing physical and mental stress, determining the size of furniture, shoes, clothes, etc. misconduct, receive a pension.

Aging processes and life expectancy

There are a number of theories on aging at the cellular, molecular, and organismal levels. Common to most of these theories is the recognition of the role of age-related mutations in the genetic apparatus of the cell. However, most researchers believe that aging at the cellular and molecular level occurs more slowly than in the whole organism.

The main theories of aging are as follows. According to the theory of “wear”, in the second half of a person’s life, under the sign of involution, “wear” of cells, tissues and body systems (like parts of a machine) and a weakening of regulatory processes occur. At the same time, with age, nervous regulation is disturbed somewhat earlier, and then humoral. The weak side of this theory is that in the process of life a person not only wears out, but heals himself and self-regulates.

The theory of waste of vital energy is close to the one described above. In accordance with the energy rule of M. Rubner, the energy fund of a person is predetermined genetically, and during life it is only spent. If we fully follow this theory, then we can assume that the lower the physical activity and the less energy consumption, the slower aging occurs and the longer life is.

The colloidal-chemical theory of aging postulates the proposition that cells and tissues have a colloidal structure, which is destroyed in the process of life, forming harmful chemicals. These toxic substances, poisoning the body, cause aging. In order to slow down the involutional processes, it is necessary to remove the destroyed colloids from the body and create new ones. But how to do this, the authors of the theory do not indicate.

At the end of the 19th and the beginning of the 20th centuries, the theory of autointoxication (self-poisoning), developed by the Nobel Prize laureate (1908) I.I. optimism ". Along with others and reasons that affect life expectancy (bad habits, unfavorable environmental factors, etc.), the author believed, in particular, that self-poisoning with intestinal poisons occurs due to the vital activity of colon microbes that cause the formation of toxic substances (phenol, indole, scotol), which lead to poisoning of the body and the onset of premature old age. In order to prevent old age, I.I. At the same time, the scientist made another extremely important conclusion: it is necessary to prolong life, not old age. In other words, he formulated the concept of active longevity, of that period of life when a person retains both physical and mental strength - when he is capable of creativity.

Some scientists adhere to the theory of somatic cell inferiority. The authors of this theory distinguish two groups of cells: a) reproductive - the most important, complete and active, which ensure the preservation of the species; b) somatic - they give their vital resources first, they are depleted and aging faster. This theory goes back to the position expressed by II Mechnikov (1903) about the development of disharmony in elderly people. The main reason for them is the contradiction between the long-lasting sexual instinct and the rather quickly disappearing ability to satisfy the sexual feeling, between the thirst for life and the opportunity to live. These disharmonies form a person's state of pessimism, which in turn intensifies these disharmonies. In this regard, II Mechnikov concludes that our desires are often incommensurate with our capabilities, and this shortens life!

Thus, there are a number of theories of aging, each of which, firstly, reflects the views of the authors on involutional changes, and secondly, considers these changes at certain levels of the organism. It can be assumed that this complex biological process has a polymorphic nature and it is not possible to explain its development by any one reason.

Naturally, the rate of aging, along with socio-economic and medical factors, determines the life expectancy of people. Life expectancy varies from country to country. So, in Holland, Sweden, USA and Japan the average life expectancy is about 80 years. In the Soviet Union (data for 1987), the average life expectancy was 72 for women and 64 for men. Life expectancy in Russia has been falling since 1990, and in 1996 it averaged 68 for women and 57 for men.

The maximum life expectancy, according to the calculations of V.V. Frolkis (1975), can reach 115-120 years. This makes the prospect of increasing active longevity and life expectancy by 40-50% reasonable. The English doctor-gerontologist Justin Glase in his book "Living 180 ... It is Possible" indicates that this requires: rational nutrition and proper breathing; movement and a healthy lifestyle; reduction of stress and motivation for a long life.

After 20-25 years (the end of the formation of the organism), the processes of involution begin, which affect all marks, tissues, organs, systems of the organism and their regulation. All age-related changes are reduced to three types: indicators and parameters that decrease with age; little changing and gradually increasing.

The first group of age-related changes includes the contractility of the myocardium and skeletal muscles, visual acuity, hearing and performance of nerve centers, the function of the digestive glands and internal secretion, the activity of enzymes and hormones. The second group of indicators is blood sugar level, acid-base balance, membrane potential, morphological composition of blood, etc. The indicators and parameters that gradually increase with age include the synthesis of hormones in the pituitary gland (ACTH, vasopressin), the sensitivity of cells to chemical and humoral substances, the level of cholesterol, lecithins and lipoproteins in the blood.

The most important physiological characteristic of young people is homeostasis (the relative constancy of the internal environment of the body), for mature and elderly people - homeoresis (age-related changes in the basic parameters of the body). The most significant age-related changes occur in people aged 50-60; at this time, various diseases develop more often.

Recent studies have shown that the body's ability to adapt to normal environmental factors changes with age, which ultimately leads to the development of chronic stress reactions in the elderly. Analyzing changes in the body during aging and stress, V.M. Dielman (1976) found that many of them are identical. The author proposed the so-called elevation theory of aging (elevation, lat., - rise, shift up), based on the fact that the activity of the hypothalamic part of the brain, which controls the regulation of the internal environment of the body, does not decrease with age, but, on the contrary, increases. This is expressed in an increase in the thresholds for homeostatic inhibition, metabolic disorders and the development of chronic stress. On the basis of this theory, some practical measures are proposed aimed at improving the adaptive capabilities of older people (active rest, optimal physical activity, biologically active substances).

An increase in the perception thresholds of various stimuli (hypothalamic threshold according to V.M.Dilman) is primarily due to a decrease in the reactivity of the body of the elderly. These age-related physiological characteristics lead to a change in homeostasis, the development of stress reactions, a deterioration in the functions of various organs and systems, and a decrease in mental and physical performance. Lowering the threshold of hypothalamus perception, L.Kh. Harkavi et al. (1990) established an improvement in body functions, an increase in the phagocytic activity of leukocytes, the level of sex hormones and performance in the elderly.

Physiological characteristics of the body of people of mature and old age

The processes of maturation and aging occur continuously, unevenly and non-simultaneously. They affect not equally different tissues, organs and systems of the body.

Age-related physiological characteristics lead to a change in homeostasis, the development of stress reactions, a deterioration in the functions of various organs and systems, a decrease in mental and physical performance.

Compared to other tissues of the body, connective tissue is the first to "age". At the same time, it loses its elasticity. Age-related changes in the muscular system and the ligamentous apparatus are expressed in a deterioration in the elastic properties of muscles and ligaments, which, if the dosage of physical activity is incorrect, can lead to rupture of muscle fibers and ligaments; a decrease in the magnitude of the displayed force; slow transition of muscles from a state of relaxation to a stressed state and vice versa; a decrease in muscle volume (muscles become flabby).

As the body ages, the elasticity of the walls of the arteries built of connective tissue decreases. This leads to a decrease in the blood supply to organs, which negatively affects their performance. Especially serious consequences are caused by disturbances in the blood supply to the brain and heart. They are not only accompanied by a deterioration in the overall performance of the body, but can also cause serious illness. Due to a lack of nutrition, the muscle cells of the heart gradually atrophy. This leads to a decrease in the volume of the heart and a change in its functional properties. The excitability, conductivity and contractility of the myocardium are reduced. To provide the required minute volume, the weakened heart of an elderly person must contract more often. If at a young age in people who are not involved in sports, the heart beats about 70 times in 1 minute, then in elderly people the heart rate at rest is accelerated to 80-90 beats.

The elasticity of the blood vessels decreases, their membrane thickens, the lumen decreases, as a result of which the arterial pressure rises (on average, it is 150/90 mm Hg at rest). The pressure increased at rest increases even more during muscular activity, which makes it difficult for the heart to function. It is important to take this circumstance into account when engaging in physical exercises with middle-aged and elderly people. A sharp increase in blood pressure can cause disruption of the integrity of the arterial wall and, as a result, hemorrhage in the tissue.

Age-related changes in the respiratory system are characterized by a deterioration in the elasticity of the lung tissue, a weakening of the respiratory muscles, a limitation of the mobility of the chest, and a decrease in pulmonary ventilation. The vital capacity of the lungs as a result decreases. Pulmonary ventilation at rest also decreases slightly, but the oxygen demand is fully satisfied. When performing even light work, pulmonary ventilation in elderly people cannot increase to the proper extent. As a result, an oxygen debt is formed in the body, while breathing sharply increases.

A decrease in the functions of the cardiovascular and respiratory systems in old age, as well as a decrease in the oxygen capacity of the blood, leads to a sharp decrease in aerobic performance. The maximum oxygen consumption after 25-30 years gradually decreases and by the age of 70 it is 50% of the level of 20 years. Elderly people who regularly exercise can do long-term work. However, its power should not be large. As soon as the power of work, and, consequently, the oxygen demand increase, the body begins to experience insurmountable difficulties and is forced to stop working.

Anaerobic performance also declines with age. In old age, the tissues of the body do not tolerate a lack of oxygen and the accumulation of acidic products. The heart muscle is especially affected. Work that requires high anaerobic performance should be completely eliminated when exercising with the elderly.

Changes in the activity of the endocrine glands play an important role in reducing the efficiency of middle-aged and elderly people. By the age of 40-45, the functions of the sex glands weaken, their hormone release decreases. This leads to a decrease in the intensity of metabolism in the tissues.

Muscle strength decreases with the extinction of the function of the gonads. A reduced amount of sex hormones causes disruption of the activity of other endocrine glands. This is accompanied by a temporary disruption of hormonal balance in the body. The period during which adaptation to new conditions of existence takes place is called climacteric. It is usually more pronounced in women. Exercise is especially necessary at this time. They facilitate the adaptation of the body to the altered ratios of different hormones and maintain regulatory functions at the required level.

The totality of the noted age-related changes of a morphological and functional nature is manifested in a deterioration in working capacity and individual physical qualities. Indicators of speed and accuracy of motional actions fall, coordination of movements becomes less perfect, their amplitude gradually decreases.

In old age, significant changes occur in the activity of the brain, most often this is due to a deterioration in its blood supply. Reactions to stimuli are slowed down, new temporary connections are formed with difficulty. All this should be taken into account when engaging in physical exercise with people of this age. The movements performed should be simple in coordination and, if possible, consist of elements that are already familiar to the student.

In middle-aged and elderly people, vision and hearing deteriorate, touch and proprioceptive sensitivity become dull. In middle-aged and elderly people, the elasticity of the lens is reduced. In this regard, it cannot change its shape, and the eye loses its ability to see closely objects well. Later, the ability to see distant objects is impaired. As a result, in people of this age, visual information about changes in the environment worsens.

A decrease in tissue elasticity in old age also causes hearing loss. With age, the elasticity of the main membrane also decreases, which leads to hearing loss. Elderly people perceive high sounds especially poorly. Deterioration of the functions of the sense organs limits the information necessary for motor activity. This complicates movement control.

Deterioration of coordination of movements in elderly people is caused along with changes in the activity of the brain and sensory organs and age-related changes in skeletal muscles, ligaments and other peripheral links of the motor apparatus. The older a person is, the less strength his bones are. They become brittle, brittle. This is important to consider when engaging in physical exercise. Movements should not be too harsh. Landing points when jumping should not be hard. Students should be protected from possible falls. With age, the volume of skeletal muscles and the number of muscle fibers decrease, muscle tone, extensibility and muscle strength decrease. These changes are combined with a decrease in joint mobility. All this leads to a decrease in the amplitude, speed and strength of movements. Speed \u200b\u200balso deteriorate with age.

The ability for power work remains somewhat longer. However, strength exercises for the elderly should be performed with caution, as this creates tension that adversely affects the activity of the heart.

Longer than other physical qualities, middle-aged and elderly people retain endurance. Endurance to work of moderate power with appropriate training can develop up to 42-45 years old and remain at the achieved level for several more years. There are cases of high sports results shown in long-distance running and cross-country skiing by people over 40 years old.

Physical culture and its effect on the human body

For the normal functioning of the human body and maintaining health, a certain dose of physical activity is required. Physical culture has two types of influence on the human body - general and special. The general effect of physical culture is energy expenditure, which is directly proportional to the duration and intensity of muscle activity, which makes it possible to compensate for the deficit in energy expenditures. It is also important to increase the body's resistance to the action of unfavorable environmental factors. As a result of an increase in nonspecific immunity, resistance to colds also increases.

A special effect of physical culture is associated with an increase in the functional capabilities of the cardiovascular system. It consists in economizing cardiac activity and lowering myocardial oxygen demand. In addition to a pronounced increase in the reserve capacity of the cardiovascular system, physical culture is also a powerful preventive measure against cardiovascular diseases.

Adequate physical activity can largely halt age-related changes in various body functions. At any age, with the help of physical culture, you can increase aerobic capacity and endurance level - indicators of the biological age of the body and its vitality. Thus, the health-improving effect of physical culture is associated primarily with an increase in the aerobic capacity of the body, the level of general endurance and physical performance. An increase in physical performance is accompanied by a preventive effect against risk factors for cardiovascular diseases: a decrease in body weight and fat mass, cholesterol and triglyceride levels in the blood, a decrease in low-density lipoproteins and an increase in high-density lipoproteins, a decrease in blood pressure and heart rate.

In addition, regular physical culture exercises can significantly slow down the development of age-related changes in physiological functions, as well as degenerative changes in various organs and systems. In this respect, the musculoskeletal system is no exception. Physical education has a positive effect on all parts of the motor apparatus, preventing the development of degenerative changes associated with age and physical inactivity. Bone mineralization and calcium content in the body increase, which prevents the development of osteoporosis. The flow of lymph to the articular cartilage and intervertebral discs increases, which is the best way to prevent arthrosis and osteochondrosis.

Physiological characteristics of adaptation of people of mature and old age to physical activity

Age-related changes occurring in the organs and systems of the body are especially clearly manifested during physical exertion. This fully applies to changes in the central nervous system. So, I.P. Pavlov, analyzing the symptoms of age-related decrease in brain reactivity, pointed out that with age there is a decrease in the ability to accurately coordinate the performance of several actions at the same time. On the other hand, regular physical exercises by persons of mature and old age increase the functional capabilities of the body and correct the already developed unfavorable changes in organs and systems. In particular, during physical exercises, the work of the autonomic systems improves, the mechanisms of nervous and humoral regulation of functions are supported, and the established stereotype of life is preserved. For persons who have stopped professional sports activity, the best way to prevent diseases and maintain functional activity is regular physical exercise.

It was found that people of mature and old age, well physically prepared, successfully learn and memorize the exercises both when telling and showing. In the case of insufficiently trained persons, memorization is mainly based on display. Thus, the ability to learn and memorize physical exercises, and, consequently, the development of motor skills depends not so much on the age of the trainees, but on the level of their physical fitness. Observations show that in people aged 40-50 years, the process of forming new motor skills proceeds rather quickly, after 50 years, it slows down. Therefore, in elderly people, the formation of motor skills should be combined: verbal instruction should be supported by a demonstration of the exercise being learned. This position reflects the general physiological laws of the formation of a motor skill on the basis of the interaction of the concrete-figurative (first) and abstract-conceptual (second) signal systems.

The role of the second signaling system manifests itself at all stages of the formation and implementation of motor skills with the constant active influence of both speech reporting and internal speech associated with thinking through exercises. For the successful mastering of new motor skills by persons of mature and old age, the supply of various motor actions acquired earlier, including those not directly related to the exercises being learned, is of great importance. As a rule, people who are versatile physically prepared learn new motor skills faster and better.

In people of mature and old age, great difficulties are caused by the implementation of various game techniques, complexly coordinated movements, which is associated with a weakening of attention and a deterioration in the automaticity of motor acts. It is significantly difficult to perform physical exercises if they are carried out at a fast pace. To successfully complete the subsequent movement, it is necessary to significantly slow down the previous one. Thus, the formation of new motor skills in persons of the age under consideration depends, first of all, on the stock of previously acquired skills, the activity of the second signal system (internal speech) and the nature of the central regulation of movements.

Central regulation of movements is largely individual, but its general physiological regularities in people of mature and elderly age are characterized by the following: weakening of cortical and reticular influences; a decrease in inhibition in the cerebral cortex, the functions of the extrapyramidal systems and the thalamus; deterioration of the lability of spinal cord motor neurons and recovery processes in the central nervous system; slowing down the conduction of excitation along the nerves and in the synapses; a decrease in the synthesis of mediators, etc. According to the feedback mechanism, the functions of the nerve centers are influenced by the weakening of impulses from proprioceptors.

At the same time, certain structural changes are noted in the muscles, which are expressed in a decrease in the number of myofibrils and fast muscle fibers, a decrease in muscle strength, etc.

Many characteristics of central movement regulation are determined by the level of oxygen supply to the nervous system. Due to vascular disorders, oxygen supply deteriorates with age, which is manifested by the development of degenerative changes in the neurons of the brain, spinal cord and in the pathways. Naturally, such structural disorders can cause significant changes in the functions of the nervous system and their regulatory influences on the motor apparatus.

Changes in physical qualities with age are quite individual. You can meet middle-aged and elderly people in whom the state of the neuromuscular system has clear signs of wilting, while other people of the same age have high functional indicators. For example, in some individuals, muscle strength decreases after 20-25 years, when the progressive biological development of the body ends; for others - after 40-45 years. First of all, with age, speed, flexibility and agility deteriorate; are better preserved - strength and endurance, especially aerobic. Significant adjustments in the age-related dynamics of motor qualities are introduced by physical culture and sports, which postpone the onset of involutional processes.

Speed \u200b\u200bdeteriorates with age in all its constituent parameters (latent period of sensorimotor reactions, speed of single movement and pace of movements). From 20 to 60 years, the latency period increases by 1.5-2 times. The greatest drop in the speed of movement is noted at the age from 50 to 60 years, and in the period of 60-70 years, some stabilization occurs. The rate of movement most noticeably decreases at the age from 30 to 60 years, in the period of 60-70 years it changes little, and at an older age it slows down significantly. One gets the impression that at the age of 60-70 some new level of vital activity arises, which provides a certain, albeit somewhat reduced, speed of movements. In persons who regularly perform physical activity, the decrease in all indicators of speed is at a slower pace. For example, in trained persons aged 50-60 years, the decrease in speed is 20-40%, and in untrained persons - 25-60% of the initial values \u200b\u200bobtained at the age of 18-20.

The strength of various muscle groups reaches its maximum values \u200b\u200bby the age of 18-20, remains at a high level until 40-45, and by the age of 60 it decreases by about 25%. The involution of strength as a physical quality can be assessed by its indicators in individual movements and by restructuring the topography of various muscle groups. By the age of 60, the strength of the muscles of the trunk decreases to a large extent, which is primarily due to the violation of the trophism of the neuromuscular apparatus and the development of destructive changes in it.

In persons who are not engaged in physical exercises, the greatest decrease in strength is noted at the age of 40 to 50 years, in those who regularly exercise - from 50 to 60 years. The benefits of trained people are most felt at the age of 50-60 and older. For example, in the streets involved in sports or physical labor, the strength of the hands during dynamometry even at the age of 75 is 40-45 kg, which corresponds to the average level of a 40-year-old person. A decrease in muscle strength is associated with a weakening of the functions of the sympathoadrenal system and gonads (the formation of androgens decreases). These age-related changes lead to a deterioration in the neurohumoral regulation of muscles and a decrease in their metabolic rate.

Speed-strength qualities also decrease with age, but the contribution of one quality or another (strength, speed) to the general motor reaction depends on the nature of the exercises. For example, when jumping long with age, strength decreases more, while throwing - speed. When performing most physical exercises, speed-strength qualities are interrelated and affect each other. Speed-strength training develops these qualities of a person to a greater extent and has little effect on the development of endurance. Conversely, endurance training causes an increase in endurance with little effect on the systems and mechanisms responsible for the manifestation of muscle strength. That is why people of mature and old age, when engaging in physical exercises, should use their various complexes, which allow them to counteract involutionary changes in most organs and systems.

Endurance in comparison with other physical qualities persists for a longer time with age. It is believed that its decline begins after 55 years, and when working with moderate power (with aerobic energy supply), it often remains high enough at 70-75 years. This is confirmed by the well-known facts of the participation of people of this age in long races, swims, hiking trips. When performing exercises of a high-speed, strength and speed-strength nature (with anaerobic energy supply), endurance decreases after 40-45 years. This is due to the fact that the development of endurance depends, first of all, on the functional usefulness of the circulatory system, respiration and the blood system, that is, on the oxygen transport system, which is not trained enough when performing the above exercises. Regular physical activity for endurance (running, skiing, swimming) noticeably postpone its decline, strength exercises (kettlebells, dumbbells, expander) have little effect on the age-related dynamics of endurance.

Flexibility is characterized by the ability to perform movements with maximum amplitude. Without special training, this quality begins to decline from the age of 15-20, which disrupts mobility and coordination in various forms of complex movements. In elderly people, as a rule, the flexibility of the body (especially of the spine) is significantly reduced. Training allows you to maintain this quality for many years. When trying to regain flexibility, the best results are observed in those who have good physical fitness.

The main manifestation of dexterity is the accuracy of motor orientation in space. This quality also decreases quite early (from 18-20 years old); special training slows down the decline in agility, and it remains at a high level for many years.

The influence of physical activity on the functional state, performance and health preservation

Physical exercise is a powerful means of maintaining a high level of all functional parameters of the body.

Movement is the most physiological attribute of life. Muscular activity causes tension in all functional systems, is accompanied by hypoxia, which trains regulatory mechanisms, improves recovery processes, improves adaptation to adverse environmental conditions.

The influence of muscle activity is so great that under its prolonged influence the activity of the genetic apparatus and protein biosynthesis change, aging slows down and many diseases are prevented; the body becomes less susceptible to harmful factors. These provisions are well known, although they are difficult to implement.

What is the physiological role of exercise for people of mature and old age? Under the influence of moderate regular physical activity, the mechanisms of regulation of various organs and systems are improved, and the body's functions are more economical. The latter manifests itself in a decrease in the heart rate and blood pressure level, an increase in myocardial diastole, an increase in the oxygen utilization rate and a decrease in the oxygen cost of work. The use of physical exercises improves blood supply to various tissues, especially skeletal muscles, which reduces hypoxic phenomena. The development of positive emotions and an increase in the stability of the hypothalamic-pituitary system provide an anti-stress effect. For a longer time, the decline in physical qualities slows down and mental and physical performance is preserved. All this contributes to the development of active longevity, prevention of diseases, aging and prolongation of human life.

The adaptation of vegetative systems in people of mature and old age has quite pronounced features. So, the development of myogenic leukocytosis, erythrocytosis, thrombocytosis is less pronounced, and the lymphocytic reaction is especially weak. In persons of this age, the destruction of blood corpuscles is increased, and their restoration is delayed for a longer period.

In people who regularly perform physical activity, more economical activity of the cardiovascular system is noted, and its main functional constants remain at an optimal level for a long time. In particular, they have more stable heart rate indicators, there is no significant increase in blood pressure, the contractile force of the myocardium, its metabolism, excitability and conduction are preserved. In these individuals, there is no significant decrease in stroke and minute volumes of blood flow, its speed and volume of circulating blood. In people who do not exercise regularly, even minor loads cause severe tachycardia, increased blood pressure, decreased stroke volume and total blood flow, and sometimes cardiovascular failure can develop. At the same time, the maximum heart rate achieved during work in people of mature and old age is noticeably reduced.

The indicators of the functions of external respiration with regular exercise remain quite high in the elderly. This is manifested by the preservation of the proper depth of breathing and pulmonary ventilation, the vital capacity of the lungs, the maximum breathing volume and maximum ventilation of the lungs. In persons who do not exercise regularly, physical activity is accompanied by severe shortness of breath, insufficient ventilation of the lungs and a decrease in blood oxygenation.

The functions of the digestive and excretory systems of people leading an active lifestyle remain fairly stable. In particular, they retain the secretory and motor functions of the gastrointestinal tract for a long time, filtration and reabsorption in the kidneys are quite stable, and there are no pronounced edema, which is most often the result of cardiovascular or renal failure. Low physical activity is accompanied by a deterioration in the functions of the digestive system and excretion.

In old age, all types of metabolism (protein, carbohydrate, fat and energy) are reduced. The main manifestation of this is the excessive content of cholesterol, lipoproteins and lactic acid in the blood (even with minor loads). Regular moderate physical activity increases metabolic rate and significantly reduces cholesterol and lipoprotein levels, reducing the possibility of developing atherosclerosis. At the same time, physical activity, even of moderate intensity, but carried out occasionally, is accompanied by excessive accumulation of lactic acid and a decrease in blood glucose levels, a shift in pH towards acidosis, an increase in under-oxidized products in the blood and urine (creatinine, urea, uric acid, etc. ).

Even moderate work in people over 40 is energetically provided, mainly due to anaerobic glycolysis, which is due to a deterioration in the satisfaction of oxygen demand.

The functions of the body's regulatory systems (endocrine glands and central nervous system) also decrease with age. After 40-45 years, the functions of the pituitary gland, adrenal glands and pancreas deteriorate, after 50 years - the functions of the thyroid and gonads. Moderate regular exercise delays the decline in the function of these glands; significant loads, as well as the performance of exercises by persons who are not adapted to them, inhibit the activity of the endocrine glands.

The parameters of the central nervous system and higher nervous activity are the most stable and less susceptible to age-related involutional processes. Improving physical culture activates the functions of the central nervous system and VND, hard physical work oppresses them. Naturally, age-related changes in the functions of the central nervous system and endocrine system worsen the nervous and humoral regulation of all autonomic systems of the body.

Physical exercises are a good way to preserve all parameters of the functional state of the organism of people of mature and old age. In the physiology of labor and sports, the functional state of a person is understood as a set of available characteristics of those functions and qualities that determine the success of his life.

The main functional states associated with motor activity are considered to be fatigue, chronic fatigue, overwork (overtraining), psychoemotional tension, monotony, hypokinesia and hypodynamia. All functional states are divided into three types: normal (fatigue), borderline (chronic fatigue), and pathological (overwork).

It is quite obvious that in old age fatigue develops faster, and it more easily turns into overwork. Elderly people are more susceptible to psycho-emotional experiences, their whole life and activities are more monotonous, they are more often accompanied by physical inactivity and hypokinesia. In older people, the last two factors acquire a special role, which lead to a decrease in the functions of organs and systems and a decrease in energy consumption. These physiological changes are associated with more intimate disorders in the body, associated with a decrease in oxygen consumption and the coefficient of its use, a decrease in tissue respiration, general gas exchange and energy exchange. Ultimately, performance drops significantly, especially in men. Regular use of physical exercise prevents or significantly reduces these disorders.

From a physiological point of view, a change in the functional state and a decrease in working capacity in elderly people are due to many factors. First of all, they have a slowdown in the blood flow rate, a decrease in the volume of circulating blood and its oxygenation, the development of hypoxia of organs and tissues. Small stores of glycogen in muscles and liver lead to a drop in blood glucose levels, a decrease in oxidative processes and energy metabolism. There is also a slowdown in recovery reactions and the development of sclerotic changes in the vessels and tissues of the body. As a result, direct indicators of working capacity (the quantity and quality of work performed) and its indirect criteria (clinical and physiological, biochemical and psychophysiological), which indicate an increase in the physiological cost of the work performed, decrease.

The importance of physical exercise and muscle activity should be considered, first of all, in the light of the theory of motor-visceral reflexes, formulated by R. M. Mogendovich in 1947. According to this theory, motor skills act as a leading system that determines the level of activity of all major body systems. Based on this theory, it seems possible to assess the interaction of the motor and autonomic systems, to prevent adverse functional changes, diseases, and premature aging.

All authors of numerous ways and means of prolonging active longevity and preventing aging put physical training in the first place. Thus, the American physiologist A. Tunney out of 10 considered for these purposes means (nutrition, smoking, productive work, optimism, love and attention to people, training the mind, etc.) again considers the use of optimal physical activity to be the leading one. From a physiological and pedagogical point of view, the optimal load is its smallest volume, which allows you to achieve the highest possible useful result.

The most accessible and reliable criteria for assessing the optimality of health-improving loads are heart rate and% VO2 max (oxygen consumption level). Currently, there are ambiguous opinions on the value of these constants, but it is fundamentally important that all authors recommend taking into account the age, fitness level and state of human health. If we summarize the data of the majority of specialists in this area, we can recommend the average values \u200b\u200bof heart rate for people of different ages when doing health-improving physical culture. So, for persons under the age of 20, loads are recommended at a heart rate of no more than 140 beats per minute, for 30-year-olds up to 130, 40-year-olds up to 125, 50-year-olds up to 120, and 60-year-olds and older - up to 100 -110 beats per minute. When performing special physical exercises, walking and running for health, oxygen consumption in the elderly should be 50-60% of the BMD, in younger people this value can reach 60-75%.

The role and importance of physical culture in maintaining health, preventing premature aging and prolonging active longevity are determined by a number of physiological changes in individuals who regularly perform the recommended physical activity. In such people, oxygenation of blood, organs and tissues improves, regional hypoxia is prevented, the level of metabolism increases and the excretion of end products of metabolism from the body. In these individuals, the biosynthesis of protein, enzymes and hormones remains at a high level, which significantly slows down the aging process of the body. Prevention of coronary heart disease, atherosclerosis and obesity is due to a decrease in cholesterol and lipoprotein levels with sufficient muscle exertion. The latter, by increasing the functional activity of muscles ("muscle pump" or "peripheral hearts", according to NI Arinchin), improve the activity of the cardiovascular system. Regulatory and adaptive mechanisms, the activity of the immune system are preserved and improved, and ultimately the body's resistance to the effects of adverse environmental factors increases, the possibility of a number of diseases decreases, and mental and physical performance is preserved.

Conclusion

1. Mature and old age are naturally coming stages of a person's individual development. The processes of maturation and aging occur continuously, unevenly and non-simultaneously. They affect not equally different tissues, organs and systems of the body.

1. There are a number of theories on aging at the cellular, molecular, and organismal levels. Common to most of these theories is the recognition of the role of age-related mutations in the genetic apparatus of the cell. It can be assumed that this complex biological process has a polymorphic nature and it is not possible to explain its development by any one reason.
2. In old and older age, irreversible changes occur in the systems and organs of the human body, called aging. The intensity of aging depends on the lifestyle, dietary habits, and motor regime. The lower the physical activity of a person, the faster, other things being equal, the changes occur in his body, characteristic of the period of old age. And, conversely, with a sufficiently active lifestyle, the body's performance can be maintained at a high level until old age.
3. Adequate physical activity can largely halt age-related changes in various body functions. The increase in physical performance is accompanied by a preventive effect against risk factors for cardiovascular diseases. In addition, regular physical culture exercises can significantly slow down the development of age-related changes in physiological functions, as well as degenerative changes in various organs and systems.
4. Exercise and the associated changes in functions and emotional reactions have a beneficial effect on the body of people of mature and old age. The most vividly positive influence is manifested when the nature, volume, rhythm, intensity and other qualities of exercises are established taking into account the fitness level, personal characteristics and functional state of the trainees. At the same time, physical activity should ensure the correction of age-related disorders and the prevention of pathological changes in the body.

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