Academician G.V. Folbort determined that performance depends on the balance of two processes - energy expenditure and its recovery, which are ambiguous in different periods of physical activity. In modern conditions, this means that physical work depends on the initial state of the body and its executive systems, the balance between energy needs and their provision.

Optimal physical activity and rest regimes are one of the conditions healthy image life, improving human health, since the load is accompanied by increased adaptation of the visceral systems and metabolic processes of the body when performing work.

During physical activity, 3 periods of performance can be distinguished, recorded on the ergogram when lifting a load to a certain height.

Development period- characterized by a gradual increase in performance at the beginning of physical activity.

Steady state period- accompanied by relatively constant performance when performing work.

Fatigue period- characterized by a decrease in performance during physical activity.

Muscular performance

Direct indicators of performance during muscle activity that can be examined in humans are:

1 Force of muscle contraction.

2 Speed ​​of contraction.

3 Endurance (measured by the time of holding 50% of maximum muscle strength).

Muscular strength is the force that a muscle or group of muscles can produce during work. Maximum strength is considered the force that a muscle develops during contraction, when it slightly moves the maximum load. Power reduction- explosive component of force and speed of movement: power = (force x distance) / hour.

Maximum muscle strength depends on the number and initial length of muscle fibers that contract; frequencies of action potentials generated in their neuromotor units; the physiological cross-section of the muscle, which increases significantly due to training that leads to its hypertrophy, an increase in contraction force.

Under the same conditions, the maximum muscle strength in men is greater than in women. The male hormone testosterone has a significant anabolic effect - it increases protein synthesis in muscles. Even with slight physical activity muscle mass in men is almost 40% greater than in women. Female sex hormones - estrogens stimulate the synthesis of fat, which is mainly deposited in the chest, thighs, subcutaneous tissue: women have about 27% of body weight, and men - about 15%. Sex hormones also influence temperament: testosterone increases aggressiveness and goal achievement in extreme situations in sports, while the influence of estrogen is associated with soft character traits.

The speed of muscle contraction is an innate phenomenon. Based on an analysis of the factors on which the speed of motor reactions depends, the following parameters can be distinguished: the mobility of the main nervous processes in the central nervous system, the ratio of fast and slow muscle fibers, and their motor units. Specialization in some sports can be chosen depending on which types of muscle fibers predominate: “children are born to become sprinters or stayers or jumpers” (Table 8.1).

Energy supply during muscle activity depends on the state of the body's visceral systems - primarily, respiration and blood circulation, transporting oxygen and nutrients to muscle cells and removing waste products from them. Therefore, the determination of their functional indicators, which characterize the adaptation of these systems to physical activity, is an important test for assessing periods of physical activity of the body and its performance.

Today it is known that muscle contraction depends on the amount of energy produced during the hydrolysis of ATP into ADP and Fn. One muscle fiber contains about 4 mmol/l ATP, which is enough to perform

TABLE 8.1. Number of fast and slow muscle fibers (%) in the quadriceps femoris muscle of athletes various types sports

maximum contraction for 2 s. After this time, a new ATP molecule is synthesized with ADP and Fn, which ensures subsequent contraction.

Long-term muscle contraction requires large reserves of ATP. The sources of its formation can be:

1 Creatine phosphate (CP). characterized by the presence of a high-energy phosphate bond, the hydrolysis of which releases a greater amount of energy than the breakdown of ATP. The released energy goes to the binding of ADP to new phosphate, the synthesis of a new ATP molecule, which ensures muscle contraction. However, CF reserves are also small, they are enough for 6-8 seconds.

2 Glycogen is constantly present in muscle fibers. Thanks to glycolysis, which does not require oxygen, glycogen is quickly converted into pyruvic acid and then into lactic acid, which releases energy for the conversion of ADP to ATP. However, glycolysis accumulates a large amount of end products (lactate), which negatively affect muscle contraction.

3 The most reliable supplier of energy for muscle contraction is the oxidative system, which provides 95% of the required energy for long-term and continuous work. The products for oxidation are glucose, fatty acids and amino acids (Fig. 8.22).

Despite the full visceral and metabolic support of physical activity, a person feels tired, which leads to a decrease in performance and requires time to recover. I.M. Sechenov (1903) was the first to show that the restoration of the performance of tired muscles of a person’s arm after prolonged work while lifting a load is sharply accelerated if the work is carried out with the other hand during the rest period.

The same pattern was observed with other types of physical activity. I.M. Sechenov, in contrast to simple rest, called such rest active. This influence of active rest was explained by the relationships that are observed in the centers of regulation of these muscles.

The basic patterns of the processes of fatigue and recovery were described by academician G.V. Folbort, which I.P. Pavlov called “Folbort’s rules.”

Here are some of them:

1 The level of performance depends on the relationship between the processes of fatigue and recovery, between which there is a direct connection - the faster exhaustion develops (during intense work), the faster recovery occurs.

2 Recovery processes do not develop linearly, but in waves. In the recovery process, two phases are distinguished - the phase of achieving initial performance and the phase of stable, constant performance.

3 Knowing the duration of work and rest after it, you can achieve two states - chronic overwork and a gradual increase in constant working capacity. Obviously, this is a well-known training process. If exhausting loads are performed by an organ whose condition has not yet changed, then, on the contrary, the recovery process slows down and weakens - a state of chronic exhaustion develops. These patterns have not lost their significance in our time. on the contrary, we got further development at the molecular level.

The main mechanisms of fatigue development:

■ central mechanisms- fatigue as a consequence of changes in the central nervous system, which are manifested by inhibition processes, impaired coordination of motor functions, decreased

RICE. 8.22.

a decrease in the activity of motor neurons and a decrease in their frequency of AP generation;

■ peripheral mechanisms- fatigue occurs at the cellular level as a consequence of a lack of ATP synthesized in the mitochondria and the accumulation of acidic products that cause acidosis. If central mechanisms can take place in untrained subjects, then significant and maximum physical activity leads to the development of fatigue due to a lack of energy resources at the cellular level, and damage to working muscles.

Intense physical activity is accompanied by pain in the muscles, the nature of which is associated with;

■ increasing the concentration of muscle enzymes in the blood plasma

■ myoglobinemia (presence of myoglobin in the blood)

■ the presence of an inflammatory reaction;

■ violation of muscle structure.

Events developing in muscles have the following sequence:

1 High tension in the contractile-elastic system of the muscle leads to structural damage to the muscle fiber membrane and the muscle itself.

2 Damage to the muscle cell membrane causes a disruption of calcium homeostasis in the damaged fiber, which leads to cell death, the peak of which is observed at 24-40 hours.

3 Products of macrophage activity, as well as intracellular content (prostaglandins, histamine, kinins, K +, H + ions) accumulate outside the cells and irritate the nerve endings of the muscle.

It has also been established that the occurrence of pain in muscles is the result of damage to structures, accompanied by the release of intracellular proteins and an increase in the turnover of myosin and actin. The process of muscle damage and recovery involves lysosomes, Ca2 + ions, free radicals, connective tissue, inflammatory reactions, and intracellular myofibrillar proteins.

Prevention of the identified changes is to reduce the eccentric component of muscle activity at the beginning of work with a gradual increase in load intensity from minimum to maximum.

Aging inherent in any living system, it is an integral property, an attribute of life and therefore is a normal, natural process.
Many researchers believe that the most common result of aging is a decrease in the body's adaptive capabilities
Aging is a destructive process that develops due to increasing damage to the body by external and internal factors. It leads to a lack of physiological functions, cell death, limitation of the body's adaptive capabilities, a decrease in its reliability, the development of age-related pathology, and an increase in the likelihood of death.
Specific manifestations of aging, its pace and direction are determined by genetically predetermined features of the biological organization of the body. A person’s passport and biological age do not always coincide. Biological age is a measure of changes over time in biological capabilities, the viability of an organism, a measure of future life.

With various physical activities and emotional changes, homeostasis is disrupted, the internal environment of the body changes, blood pressure, blood sugar, etc. change. in the course of disturbances in the internal environment of the body, adaptation and regulatory mechanisms are mobilized and improved, contributing to the preservation of homeostasis.

Constant disturbances of the internal environment of the body contribute to the preservation of its “homeostasis” over a long life.

Movement is the most important attribute of life; there is no more physiological method of stimulating various systems of the human body than muscle activity.

In the process of muscle activity, tension occurs in all body systems and oxygen starvation. This constantly trains the level of activity of the body. The influence of muscle activity is so great that the activity of the genetic apparatus and protein biosynthesis changes. Strenuous activity leads to an increase in the mass volume of individual muscle fibers and the entire muscle as a whole.

Under the influence of systematic physical exercise in older people, the general condition improves, motor functions are restored, vascular tone decreases, blood supply to the heart and brain improves, performance increases, the contractility of the heart increases, energy expenditure becomes more economical, etc. physical exercise is a means of maintaining health and prolonging life.

Systematic training helps maintain the normal functioning of the body's main systems - nervous, cardiovascular, respiratory, muscular and others. However, with excessive physical exertion, overload phenomena often occur - coronary insufficiency worsens, blood pressure becomes unstable, and arrhythmias often occur. In this regard, it is very important to choose the right means of physical education, individually dose the load, and control its effect on the body.

It is no coincidence that the main focus of “basic” health clubs today is conditioning training based on bodybuilding.
Is it too late to start bodybuilding? With age, the muscle structure begins to atrophy at an ever-increasing rate. Bodybuilding is the best remedy counteract this process.

However, in bodybuilding, a late start is not as critical as in other sports.
Recent research (Bill Dobbins 2000) has shown that muscles do not necessarily atrophy with age to the extent that was commonly believed. In fact, older people can even significantly increase muscle volume with proper training.
The results can be very impressive. A noticeable surge of strength. Much more toned and muscular body. Energy, mobility, improved quality of life. Independence and self-confidence. What we think of as inevitable aspects of aging are actually just signs of sedentary behavior and neglect of one's body.

From the point of view of physiological processes, in adulthood functional, reversible changes in indicators of physical performance and preparedness occur, while in old age, a decrease in functional and physical capabilities is associated with organic, irreversible changes in the body. These disorders occur in the nervous, endocrine, cardiovascular, respiratory systems, and musculoskeletal system.

Significant disturbances are observed in the musculoskeletal system - articular surfaces narrow, formations along the edges of the epiphyses of bones grow, bone tissue loosens, its density decreases, the calcium content in the bones decreases, the content of synovial fluid in the joints decreases. Bones become weak and brittle, and osteoporosis often occurs in older people.

Spinal deformation appears, postural disorders increase the likelihood of joint-related diseases - arthritis, arthrosis, etc. The shock-absorbing capabilities of joints and their mobility are reduced

Changes occur in muscles and ligaments that lose their elasticity, signs of muscle atrophy appear - the number of motor neurons and fibers responsible for spastic contraction decreases, the concentration of myosin and actin decreases; the network of capillaries is reduced (deterioration of blood supply to the muscles); the volume of connective tissue in the muscles increases. In older people, the speed of movement decreases, potential muscle endurance and flexibility decrease. There is a weakening of the muscles in the pelvic area.

With age, changes are observed in the nervous system - the balance of inhibitory and excitatory processes, as well as their strength, is disturbed, which is expressed in the difficult formation of new motor skills.

The cardiovascular system. The contractile function of the myocardium weakens, efficiency decreases blood vessels, the blood supply to the heart and other organs deteriorates. Gas exchange, lung elasticity and chest. The efficiency of the circulatory system becomes lower, the network of capillaries is reduced and the volume of oxygen delivered to the cells is reduced, and the volume of blood passing through the heart decreases. Signs of increasing hypertension appear, the maximum heart rate decreases, and sensitivity to fatigue and waste products such as lactic acid increases. Increases the likelihood of diseases of the cardiovascular and respiratory systems
In the respiratory system, the elasticity of the lung tissue deteriorates, the respiratory muscles weaken, the mobility of the chest is limited, and pulmonary ventilation decreases.

Nervous system. Short-term memory deteriorates, balance deteriorates, and the coordinating function of the central nervous system decreases. In this regard, older people experience rapid forgetting of the sequence of movements, difficulty maintaining balance, taking a stable position, poor coordination of movements, and a decrease in the speed of performing movements. During the aging process, metabolism changes and becomes less intense. This is due to the slowdown of oxidative processes.

The secretory and motor functions of the intestines weaken, digestion is disrupted. The body's resistance decreases. Adaptation to stress worsens, performance and recovery slow down.
All this leads to a decrease in performance and physical fitness (decrease in speed and accuracy of movements, loss of coordination, decrease in amplitude of movements, etc.).

The main reasons for the deterioration of physical capabilities in old age:

1. Decreased physical performance is associated with:

• limitation of physical activity;
• limiting the possibility of intensifying the functions of individual body systems;
• dysregulation of the functions of the cardiovascular and respiratory systems;
• metabolic disorders;
• decreased aerobic and anaerobic performance;
• slowing down recovery processes;
• reduction in operating efficiency.

2. The decrease in strength is due to a decrease in active mass, a drop in the content of water, calcium and potassium in muscle tissue, leading to loss of muscle elasticity.
3. Decreased endurance is associated with disruption of the oxygen transport systems.
4. The drop in speed is caused by a decrease in muscle strength, impaired coordination in the central nervous system, and a decrease in the function of energy supply systems.
5. Coordination and dexterity are reduced due to deterioration in the mobility of nervous processes.
6. Deterioration in flexibility is associated with changes in the musculoskeletal system.

Thus, in old age, a decrease in functional and physical capabilities is associated with organic, irreversible changes in the body. These disorders occur in the nervous, endocrine, cardiovascular, respiratory systems, and musculoskeletal system.

The level of strength required to perform daily activities does not change throughout life. However, the level of maximum strength, which exceeds the level of strength required to carry out daily activities, gradually decreases with age. Medical research data have shown that physical performance in each decade of life is 10-15% less than in the previous one.

It should be noted that the ability to stand up from a sitting position declines at age 50, and at age 80 some people are unable to do so. Many medical experts have a less optimistic opinion about older people, namely: older people can and must do work that requires little muscular effort.

Sports physiologists believe that performing special strength exercises allows older people to show top scores at age 60 than most physically inactive men half their age.

Strength capabilities decrease with age as a result of a decrease in physical activity and muscle mass. The latter is mainly due to decreased protein synthesis due to the aging process and a reduction in the number of fast-twitch motor units.

At the age of 50 years and older, muscle tone decreases in men and women. The muscles of the back and abdomen weaken first, which leads to deformation of the spine: the shoulders drop, the back becomes rounded, and the abdominal muscles droop. These negative manifestations, together with flat feet, reduce a person’s height. Literature on this issue scientific research proves that weight training has a positive effect on changes in the morphological, biochemical and physiological systems of older people.

According to the study, it was determined that even 60-70 year old people who engage in strength exercises experience muscle hypertrophy and a decrease in the thickness of the fat layer. Over 2 years of strength training, such people experienced an increase in absolute strength (by 50-100%), strength endurance (by 200-300%), vital capacity, and a decrease in heart rate and blood pressure.

As body fat decreases and muscle mass increases, other important changes will occur regarding appearance, well-being, etc.
The aging process can contribute to a decrease in strength ability, but a decrease in strength ability can also contribute to the aging process.

Thus, whether an organism ages or not depends on its ability to function fully and independently. Much of what is evidence of the aging process is a consequence of the limited use of human capabilities.

At age 30, muscle strength typically reaches its peak, and then, if no effort is made, muscle strength levels gradually decline. By age 85, the decline rate reaches about 45%. It is normal for muscle strength to decline with age (even trained athletes experience a slight decline in muscle strength between the ages of 60 and 65), but the degree of decline in most older and physically healthy people is excessive because they tend to limit their motor levels. activity.

Medical supervision of elderly people

Medical examination is an important component when choosing physical activity. This is due to a number of reasons:

• Some people should not exercise at all or only under the supervision of a doctor. A thorough medical examination can identify such people.
• The information obtained from the medical examination is used when planning a physical exercise program.
• A number of obtained indicators, for example, blood pressure, body fat content, blood lipid levels, can be used to motivate bodybuilding.
• A comprehensive medical examination, in particular of physically healthy people, makes it possible to subsequently detect deviations in health.

• men 40 years and older;
• women 50 and older; people of any age at increased risk.
• Contraindications to exercise in the gym: diseases in the acute and sub-acute stages; progressive diseases nervous system; circulatory failure II and III degrees; aneurysm of the heart and large vessels; IHD with severe attacks of angina pectoris; frequent internal bleeding (peptic ulcer and 12- duodenum, hemorrhoids, gynecological and other diseases).

In middle and old age, the following types are used for health purposes: physical exercise: UGG, dosed walking, health path, swimming, cycling, weight training.

The intensity of classes should be reduced compared to younger people. Limitations are usually associated with one or another functional deviation in health.

In the initial period, it is advisable to conduct classes with moderate load 3-4 times a week for 35-45 minutes, and after 1.5-3 months. it can be increased to 45-50 minutes. A further increase in the duration of classes is undesirable - it is better to increase the number of classes to 5-6 per week. The density of the load in the classroom is also important. The functional state during training is monitored by pulse, respiratory rate and a subjective sign of fatigue (pulse should not exceed the value obtained by subtracting the number of years from 220). Classes should be held with pauses for rest, walking, relaxation exercises, etc. Exercises involving holding your breath, straining, with sudden movements, especially of a swing nature, rotation of the head, prolonged tilting of the head down, jumping (or skipping), etc. should be excluded.

According to theory and practice physical culture classes are structured in the form of a lesson consisting of three parts: introductory, main and final. The introductory part includes general developmental exercises, walking, running; This is essentially a warm-up.

The main part, depending on the goal, includes general developmental exercises, elements from various sports, etc. the final part of the lesson aims to gradually restore the function of the cardiorespiratory system, includes walking, breathing exercises, relaxation exercises, stretching exercises, etc.

The greatest muscle strength is achieved either due to the greatest increase in the mass of the load being lifted or moved, or due to an increase in acceleration, i.e., a change in speed to a maximum value. In the first case, muscle tension increases, and in the second, the speed of its contraction increases. Movement in humans usually occurs through a combination of muscle contraction and tension. Therefore, as the contraction speed increases, the voltage also increases proportionally. The greater the mass of the load, the less the acceleration imparted to it by a person.

The maximum strength of a muscle is measured by determining the maximum load it can move. Under such isometric conditions, the muscle almost does not contract, and its tension is extreme. Therefore, the degree of muscle tension is an expression of its strength.

Power movements are characterized by maximum tension with an increase in the mass of the load and a constant speed of its movement.

The strength of a muscle does not depend on its length, but depends mainly on its thickness, on the physiological diameter, i.e. on the number of muscle fibers per largest area its cross section. The physiological cross-sectional area is the cross-sectional area of ​​all muscle fibers. In pennate and semi-pennate muscles, this diameter is larger than the anatomical one. In fusiform and parallel muscles, the physiological diameter coincides with the anatomical one. Therefore, the strongest are the pennate muscles, then the semi-pennate, fusiform and, finally, the weakest muscles with parallel fibers. The strength of a muscle also depends on its functional state, on the conditions of its work, on the maximum frequency and magnitude, spatial and temporal summation of forces flowing to it. nerve impulses, causing its reduction, the number of functioning neuromotor units and from impulses that regulate. Muscle strength increases with training and decreases with fasting and fatigue. At first it increases with age, and then decreases with old age.

The strength of a muscle at its maximum tension, developed at its greatest excitation and the most favorable length before the start of its tension, is called absolute.

Absolute muscle strength is measured in kilograms or newtons (N). Maximum muscle tension in a person is caused by volitional effort.

Relative Muscle strength is calculated as follows. Having determined the absolute force in kilograms or newtons, divide it by the number of square centimeters of the cross-section of the muscle. This allows you to compare the strength of different muscles of the same organism, the strength of the same muscles of different organisms, as well as changes in the strength of the same muscle of a given organism depending on changes in its functional state. The relative strength of the frog skeletal muscle is 2-3 kg, the human cervical extensor muscle is 9 kg, the masseter muscle is 10 kg, the biceps brachii muscle is 11 kg, and the triceps brachii muscle is 17 kg.

Extensibility and elasticity

Extensibility is the ability of a muscle to increase length under the action of a load or force. Muscle stretch depends on the weight of the load. The larger the load, the more the muscle is stretched. As the load increases, more and more load or force is required to produce the same increase in length. The duration of the load is also important. When a load or force is applied for 1-2 s, the muscle lengthens (fast phase), and then its stretching slows down and can last for several hours (slow phase). Extensibility depends on the functional state of the muscle. Red muscles stretch more than white ones. Extensibility also depends on the type of muscle structure: parallel muscles stretch more than pennate muscles.

Skeletal muscles have elasticity, or resilience, the ability to return to their original state after deformation. Elasticity, like stretchability, depends on the functional state, structure of the muscle, and its viscosity. Restoration of the initial length of the muscle also occurs in 2 phases: the fast phase lasts 1-2 s, the slow phase lasts tens of minutes. The length of a muscle after a stretch caused by a large load or force, and after a long stretch, does not return to its original length for a long time. After short-term action of small loads, the length of the muscle quickly returns to its original length. Thus, the degree and duration of its stretching matters for the elasticity of a muscle. The elasticity of the muscle is small, inconsistent and almost perfect.

The length of anisotropic disks does not change during contraction and passive stretching. A decrease in the length of a muscle fiber during contraction and an increase during its stretching occurs due to changes in the length of isotropic discs. When the fiber is shortened to 65%, the isotropic discs disappear. During isometric contraction, anisotropic discs shorten and isotropic discs lengthen.

With contraction, the elasticity of isotropic disks increases, becoming almost 2 times longer than anisotropic ones. This protects the fiber from rupture during a very rapid decrease in the length of the anisotropic discs that occurs during isometric muscle contraction. Consequently, only isotropic disks have extensibility.

Extensibility increases with fatigue in proportion to the increase in fatigue. Stretching a muscle causes an increase in its metabolism and temperature. Smooth muscles stretch much more than skeletal muscles, several times their original length.

The elasticity of the muscle decreases with contractures and rigor. At rest, muscle elasticity is a property of myofibrils, sarcoplasm, sarcolemma and connective tissue layers; during contraction, it is a property of contracted myofibrils.

Stretching of smooth muscles to a critical limit can occur without changing their tension. This is of great physiological importance when stretching the smooth muscles of hollow organs, in which the pressure does not change. For example, the pressure in bladder does not change with significant stretching by urine.

Muscle performance

The work of a muscle is measured by the product of the mass of the load it lifts by the height of its lifting or by the path, therefore, by the height of muscle contraction. The universal unit of work, as well as the amount of heat, is the joule (J). The performance of a muscle varies depending on its physiological state and load. As the load increases, the muscle work initially increases, and then, after reaching the maximum value, it decreases and reaches zero. The initial increase in work with increasing load depends on the increase in the ability of the muscle to be excited and on the increase in the height of contraction. The subsequent decrease in work depends on the decrease in muscle contractility due to increasing stretching by the load. The amount of work depends on the number of muscle fibers and their length. The larger the cross-section of the muscle, the thicker it is, the greater the load it can lift.

The pennate muscle can lift a large load, but since the length of its fibers is less than the length of the entire muscle, it lifts the load to a relatively small height. The parallel muscle can lift a smaller load than the pennate muscle, since its cross-section is smaller, but the height of the lift is greater, since the length of its muscle fibers is greater. Provided that all muscle fibers are excited, the height of muscle contraction, other things being equal, is greater the longer the fibers. The amount of work is affected by the stretching of muscle fibers by a load. Initial stretching with small loads increases the height of contraction, and stretching with large loads decreases the height of contraction of the muscle. The work of a muscle also depends on the number of myoneural apparatuses, their location and their simultaneous excitation. When fatigued, muscle work decreases and may stop; The height of muscle contraction decreases as fatigue develops and then reaches zero.

Laws of optimal load and optimal rhythm

Since as the load increases, the height of muscle contraction decreases, the work, which is the product of the load and height, reaches its greatest value at some average loads. These average loads are called optimal.

All other things being equal, under optimal loads, the muscle retains its performance for the longest time. At optimal load, the performance of a muscle depends on the frequency of the rhythm of its contractions, i.e., on the frequency of uniform alternation of muscle contractions. The rhythm of muscle contractions at an average load, at which the longest muscle performance is maintained, is called optimal,

Different muscles have different optimal loads and optimal rhythms. They also change in a given muscle depending on working conditions and its physiological state.

Optimal load and optimal rhythm are determined primarily by the nervous system (I.M. Sechenov). As for a person, his mental and physical performance is determined by the social conditions of work (tools of labor, attitude to work, emotions, etc.). The optimal load and optimal rhythm for a person vary significantly depending on life experience, age, nutrition and training.

Dynamic work and static force

The work of skeletal muscles, which ensures the movement of the body and its parts, is called dynamic, and the tension of skeletal muscles, which ensures the support of the body in space and overcoming gravity, is called static effort.

Dynamic work varies in power. The meter of power, or intensity, is the work done per unit of time. The unit of power is the watt (W = 1 J/s). There is a natural relationship between the intensity of dynamic work and its duration. The greater the intensity of the work, the shorter its duration. There are low, moderate, high, submaximal and maximum intensity work. When working dynamically, speed, or speed of movement, is taken into account. To measure the speed of movements, the following are used: 1) motor reaction time, reaction speed, or latent period of the motor reflex, 2) the duration of an individual movement with minimal muscle tension, 3) the number of movements per unit of time, i.e. their frequency.

The speed of movements depends on the nature and rhythm of impulses from the central nervous system, on the functional properties of the muscles during movements, as well as on their structure. The ability to perform muscular activity of a certain type and intensity for the greatest amount of time is referred to as endurance. The greater the endurance, the later fatigue begins.

The main types of endurance: 1) static - continuous, for a maximum period of time, maintaining tension in the skeletal muscles with a constant force of pressure or holding a certain load in a constant position. The maximum time of static effort is less, the greater the pressure force or the size of the load, 2) dynamic - continuous performance of muscular work of a certain intensity for a maximum time. The maximum time for dynamic work of skeletal muscles depends on its power. The greater the power, the shorter the limiting time of dynamic endurance.

Dynamic endurance largely depends on increased performance internal organs, especially the cardiovascular and respiratory systems.

Dynamic work is also characterized by dexterity.

Dexterity is the ability to produce coordinated movements with very high spatial accuracy and correctness, quickly and in strictly defined, very short periods of time with a sudden change in external conditions.

Static effort consists of maintaining muscle tension for some time, that is, holding the weight of the body, limb or load motionless. In a physical sense, holding a load or body stationary is not work, since there is no movement of the load or body weight. Examples of static efforts are standing motionless, hanging, standing, motionless holding an arm, leg or load. The duration of the static force depends on the degree of muscle tension. The lower the amount of muscle tension, the longer it lasts. With static forces, as a rule, significantly less energy than during dynamic work. The heavier the static force, the greater the energy consumption. Training increases the duration of static efforts.

Endurance to static forces does not depend on an increase in the performance of internal organs, but mainly on the functional stability of motor centers to the frequency and strength of afferent impulses.

Staff with extensive experience practical work and knowledge, unfortunately, tends to grow old. At the same time, the leaders are not getting any younger. New employees arrive who also have the burden of years behind them. How to organize the work of aging workers so that their activities are as efficient as possible?

First of all, you should know that there is a difference between biological and calendar aging. Biological aging has a decisive influence on human performance. Throughout life, the human body is exposed to influences that cause corresponding changes in biological structures and functions. The time of appearance of structural and functional changes characteristic of individual age groups is individual, therefore, with increasing age, large differences between biological and calendar aging can be observed.

Medicine has proven that the rational work activity of an elderly person allows him to maintain his ability to work longer, delay biological aging, increases the sense of joy of work, and therefore increases usefulness this person for the organization. Therefore, it is necessary to take into account the specific physiological and psychological requirements for the work of older people, and not begin to actively influence the process of biological aging only when a person stops working due to reaching retirement age. It is believed that the problem of aging is a problem of the individual, not of the organization. This is not entirely true. The experience of Japanese managers shows that caring for aging employees results in millions in profits for enterprises.

For implementation individual approach to the employee, it is important for every manager to know certain relationships, namely: the relationship between the professional working capacity of aging people, their experiences and behavior, as well as the physical ability to withstand the load associated with a certain activity.

As biological aging occurs, there is a decrease in the functional usefulness of organs and thus a weakening of the ability to recuperate by the next working day. In this regard, the manager must follow some rules in organizing the work of older people:

1. Avoid sudden high loads on older people. Haste, excessive responsibility, tension as a result of a rigid work rhythm, and lack of relaxation contribute to the occurrence of heart disease. Avoid assigning overly physically demanding or repetitive work to older workers.

2. Conduct regular preventative medical examinations. This will make it possible to prevent the occurrence of work-related occupational diseases.

3. When transferring an employee to another place due to a decrease in labor productivity, attach special importance to ensuring that older workers do not feel disadvantaged due to rash measures or explanations of the manager.

4. Use older people primarily in those workplaces where a calm and even pace of work is possible, where everyone can distribute the work process themselves, where excessively large static and dynamic loads are not required, where good conditions work in accordance with occupational health standards, where quick response is not required. When deciding whether to work shifts for older people, be sure to take into account their general health. Particular attention should be paid to labor protection, taking into account when distributing new tasks that old man is no longer as mobile and, without long-term experience in a given enterprise or workplace, is more exposed to danger than his young colleague in the same situation.

5. It is necessary to take into account that during the aging period, although the functional ability of organs weakens, effective work capacity does not decrease. Some functional deficiencies are compensated for through life and professional experience, conscientiousness and rational work methods. Assessing your own importance becomes important. Satisfaction with one's job, the degree of professional excellence achieved, and active participation in community service strengthen the sense of usefulness. The speed of performing labor operations decreases more intensively than accuracy, therefore, work that requires priority is most suitable for older people! experience and established thinking skills.

6. Take into account the progressive decline in older people's ability to perceive and remember. This should be taken into account when working conditions change and there is a need to acquire new skills, for example to maintain new modern installations.

7. Take into account that after the age of 60 it is difficult to adapt to new working conditions and to a new team, so moving to another job can lead to great complications. If this cannot be avoided, then when assigning a new job, it is imperative to take into account the existing experience and specific skills of the older employee. Work that requires significant mobility and increased tension of several sense organs is not recommended (for example, when managing and monitoring automatic production processes). Perception, and therefore reactions, also change qualitatively and quantitatively. Employees should be promptly prepared for changes in production, and especially older people; require those responsible for professional development to take special care of older employees. We must strive to ensure that their professional skills and abilities do not remain at the same level. This danger is possible mainly where workers are engaged in solving practical problems and they have little time and energy left for further training or there is no incentive for this. It is important for a manager to know that a person’s ability to work lasts longer the higher his qualifications and the more attention he pays to improving them.

To interest an older employee new job, it is necessary to establish a connection between the new and old work, relying on the views, comparisons and rich experience from the industrial and socio-political life of older people and making it clear to the older employee that the manager highly values ​​​​his sense of duty and professional qualities. This will strengthen his self-confidence.

With the weakening of physical and mental capabilities, older people may develop a tendency towards isolation and isolation. The manager must take measures against such isolation. It should be emphasized that the rich life and work experience of an older employee provides positive influence on youth.

8. How should a manager treat the emerging weaknesses of older people? Age-related changes should not be overemphasized. This is a natural process. However, it must be taken into account that age-related depression is possible, which can also be expressed in rapid changes in mood. You need to support the elderly person and praise him more often.

9. Should be carefully monitor the socio-psychological climate in a team where employees of different ages work. It is necessary to recognize both for completing the task assigned to them so that no age group feels discriminated against. It is important to celebrate the older worker’s successes at work and on special occasions in front of the team.

10. Necessary plan in advance to replace older employees and prepare them for this. Avoid tension between predecessor and successor.

11. If an employee has reached retirement age but still wants to work, then at his request, it is advisable to give him the opportunity to be employed at the enterprise part-time, since work promotes good health and reduces the negative effects of the aging process.

12. Necessary help a retiring employee identify a new activity. You can recommend that he take up social work or become a member of the club of production veterans, etc. It is necessary to maintain contact with pensioners (invite them to cultural events, industrial celebrations, inform about events taking place at the enterprise, deliver large circulation copies, etc.).

The manager's policy towards older employees gives all staff confidence in the future. If younger and more aggressive employees strive to occupy a higher position in the organization, which is hampered by the presence of an older colleague, and strive to oust a competitor, then the older generation is already thinking about the prospects of their stay in this organization. And if they have a clear vision that the prospect is more favorable, they will work more fully. The level of conflict will decrease, labor productivity will increase, and the socio-psychological climate in the team will improve.

Physical fatigue

Prolonged and intense muscle loads lead to a temporary decrease in the physical performance of the body - fatigue. The process of fatigue initially affects the central nervous system, then the neuromuscular synapse and last resort muscle. Thus, people who have recently lost an arm or leg feel their presence for a long time. Mentally performing work with the missing limb, they soon declared their fatigue. This proves that the processes of fatigue develop in the central nervous system, since no muscular 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 disruption of the nervous and other physiological systems of the body. Rational rest quickly contributes to the restoration of performance. After physical work, it is useful to change your type of activity, since complete rest restores strength more slowly.

Development of the muscular system

The child's muscular system undergoes significant structural and functional changes during ontogenesis. The formation of muscle cells and the formation of muscles as structural units of the muscular system occur heterochronically. The process of “rough” muscle formation ends by the 7-8th week of prenatal development. At this stage, irritation of skin receptors already causes response motor reactions of the fetus, which indicates the establishment of a functional connection between tactile reception and the muscular system. In subsequent months, the functional maturation of muscle cells occurs intensively, associated with an increase in the number of myofibrils and their thickness. After birth, muscle tissue continues to mature. 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 14-15 years of age, the microstructure of muscle tissue is practically no different from that of an adult. However, thickening of muscle fibers can continue 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. The development of the muscles of the upper extremities usually precedes the development of the muscles of the lower extremities. Larger muscles are always formed before smaller ones. For example, the muscles of the shoulder and forearm are formed 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 increases rapidly during puberty: in boys - at 13-14 years old, and in girls - at 11-12.

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

Table 2.1

Increase in skeletal muscle mass with age

The functional properties of muscles also change significantly during ontogenesis. The excitability, lability, contractility and speed of excitation of muscle fibers increases, muscle tone changes. The newborn has 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 often in a bent state. Intensive development and increase in extensor tone, characteristic of an adult body, occur by the age of 5. In children, the ability of muscles to relax is poorly expressed, which increases with age. This is usually associated with stiffness of movement in children and adolescents. Only after 15 years do movements become more flexible.

In the process of development of musculoskeletal musculoskeletal system motor qualities of 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 periods of individual development, when maximum growth can be obtained. The individual peculiarities of the formation of motor qualities and their manifestation are largely determined by the genetic program. First of all, speed and dexterity of movements develop. The speed (speed) of movements is characterized by the number of movements that a person is able to make per unit of time. Speed ​​is determined by three indicators: the speed of a single movement, motor reaction time and 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 nerve centers are able to reproduce per unit time, which depends on the mutual transition of excitation and inhibition in the motor centers of the cortex and in 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 fastest energy mechanism. The ratio of fast (white) muscle fibers, in which mainly anaerobic breakdown of phosphagens occurs, and slow (red), in which aerobic oxidation of carbohydrates occurs, is to a certain extent genetically programmed, although it can vary depending on the nature of physical activity.

The speed of single movement increases significantly in children from 4-5 years old and reaches adult levels by 13-14 years old. By the age of 13-14 years, the time of a simple motor reaction, which is determined by the speed of physiological processes in the neuromuscular system, 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, while at 13-14 years the frequency of movements in girls exceeds this figure 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 precise, coordinated and fast movements. Consequently, dexterity is associated, firstly, with spatial accuracy of movements, secondly, with temporal accuracy, and thirdly, with the speed of solving complex motor problems. The development of dexterity, starting from 3-4 years, quickly improves in the first and second childhood, which is facilitated by the good elasticity of muscle fibers and ligamentous apparatus in children of this age. The greatest increase in movement accuracy is observed from 4-5 to 7-8 years. Until the age of 6-7 years, children are not able to make subtle, precise movements in an extremely short time. Then spatial accuracy of movements gradually develops, followed by temporal accuracy. Finally, the ability to quickly solve motor problems in various situations improves. Agility continues to improve until age 17. Interestingly, sports training has a significant impact on the development of agility, and 15-16 year old athletes have twice the accuracy of movements than 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 (span) of movements. It depends on the anatomical features of the articular surfaces, the nature of their articulations, the elasticity of the tissues surrounding the joints, as well as on the functional state of the central nervous system and the musculoskeletal system. The ability to reproduce the amplitude of movements increases maximally at 7-10 years and after 12 years remains virtually unchanged, and the accuracy of reproducing small angular displacements (up to 10-15°) increases until 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, so in each age period there are different ratios between the strength of various muscles. In preschoolers, the strength of the trunk muscles is greater than that of the limb muscles. Due to increased muscle tone and the excess strength of the flexor muscles over the extensors, it is difficult for preschoolers and primary schoolchildren to maintain straightened postures, so they can maintain an upright posture without fatigue for no more than 2 minutes. In younger schoolchildren, the flexor muscles 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 years. Poor development of the “muscle corset” causes curvature of the spine and poor posture if hygiene rules are not followed. Weak development of the foot muscles leads to flat feet. The greatest increase in strength is observed in middle and older school age, strength increases especially intensively from 10-12 to 16-17 years. In girls, the increase in strength occurs somewhat earlier, from 10-12 years, and in boys - from 13-14. However, boys are superior to girls in this indicator in all age groups, but a particularly clear difference appears from the age of 13-14.

Later than others 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. Factors in the development of endurance are the degree of formation of the body's oxygen transport system - 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 to the muscles are activated. There are age, gender and individual differences in endurance. Endurance (especially for 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 of age. 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-old adolescents it will be more than 400% (M.V. Antropova, 1968). Endurance to static loads also increases rapidly in schoolchildren from the age of 11-12. In general, by the age of 17-19, students’ endurance is about 85% of an adult’s level. The sensitive period for the development of endurance is adolescence, when the functions of the cardiorespiratory system sufficiently mature. It reaches its maximum level by the age of 22-25.

In general, by the age of 13-15 years, the formation of all parts of the motor analyzer is completed, 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. This occurs due to a decrease in the diameter of 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, and endurance also decrease, which is expressed in a decrease in the amplitude and smoothness of movements, an increase in rigidity, poor coordination (awkward gait), a decrease in muscle tone, and slower movements. This is due to an extension of the action potential in myocytes, a slowdown in the speed of excitation, a decrease in the strength of nervous processes and a deterioration in energy metabolism in cells.