Nature has provided us with the opportunity to work in conditions insufficient oxygen supply to tissues... With a lack of oxygen, two reactions of ATP reduction are distinguished:

• alactate ) , i.e. no lactic acid formation (lactate - lactic acid);
• lactate , i.e. with her education.

The first reaction ( anaerobic alactic) - the decay of a special chemical compound - creatine phosphate acid (CrF), providing fast recovery of ATP. However, the reserves of KRF are also limited and are quickly depleted during the most intensive work (within 10 seconds).

The second reaction ( anaerobic lactate) - recovery of ATP due to the energy formed during the decay glycogen.

Anaerobic performance (anaerobic capacity of the body) Is the ability of a person to work in conditions of lack of oxygen due to anaerobic energy sources. It depends on a number of factors (see Fig. 1).

Increase in the amount of glycogen in muscles		Increase in the amount of creatine phosphate in the muscles
	Anaerobic performance
Increased activity of enzyme systems that catalyze anaerobic reactions		Increasing the body's resistance to high concentrations of lactic acid in muscles and blood

Rice. 1. Factors providing anaerobic performance of the body (according to VM Volkov, EG Milner, 1987).

In the process of breakdown, glucose is formed (with a lack of oxygen) lactic acid. The accumulation of lactic acid in the body leads to a change acid-base balance (pH). When the body accumulates too much acidic metabolic products, the person is forced to stop working.

To eliminate these products, oxygen is also needed, because they are destroyed by oxidation. But this oxidation can occur after the end of work, in recovery period.

The amount of oxygen required for the oxidation of metabolic products formed during physical work is called oxygen debt .

Oxygen debt –the most important indicator of anaerobic performance ... The maximum oxygen debt for people who do not go in for sports does not exceed 4–5 liters. For high-class athletes, it can reach 10–20 liters.

There are two parts to oxygen debt: alactate and lactate.

Alactate part can be 2–4 liters for athletes. It goes to the restoration of KrF, which has given its energy to ATP resynthesis, as well as to restore the ATP reserves in the muscles expended during the work.

Lactate , big part oxygen debt is used to eliminate the lactic acid accumulated during work in the muscles and blood, which is partially oxidized during the recovery period, partially used in the formation of carbohydrate reserves in the liver and muscles.

The content of lactic acid in high-class athletes can reach 300 mg per 100 ml of blood (at rest - 10-15 mg). In order to continue to work at the same time, the body must have powerful buffer systems... In athletes, the capacity of the buffer systems of blood and other tissues is increased. But still, the buffer systems can not always completely neutralize the acidic metabolic products that enter the blood. Then there is a shift in the pH of the blood in sour side. In order for a person to perform work of considerable power in the face of abrupt changes in the internal environment of the body, his tissues must be adapted to work with a lack of oxygen and low pH. This adaptation of tissues is one of the main factors ensuring high anaerobic performance. In addition, a person's ability to work with a large amount of accumulated lactic acid largely depends on the blood supply to the brain and heart. These organs must receive sufficient oxygen even under conditions when skeletal muscles are deficient.

Anaerobic metabolic threshold. With a high intensity of running, a further increase in speed occurs due to anaerobic energy sources. However, anaerobic processes during running are included in the recovery of ATP not at the moment when the maximum level of oxygen consumption (VO2 max) is reached, but somewhat earlier. The appearance in the body of the first signs of anaerobic resynthesis of ATP is called the threshold of anaerobic metabolism (TANM). TANM is measured as a percentage of the IPC. For athletes of different qualifications, TANM is equal to 50–70% of the level of maximum oxygen consumption. This means that anaerobic resynthesis of ATP begins when oxygen consumption reaches 50–70% of a given person's BMD. The higher the TANM, the more hard work the athlete performs, restoring ATP at the expense of more economical aerobic energy sources.

Acid-base balance and buffer zones. Blood plasma contains hydrogen ions. They are part of all acids, and therefore its concentration in the blood depends on acidity. To characterize the acidity of the blood, they use the hydrogen index, denoted NS (pH is the logarithm of the concentration of hydrogen ions, taken with the opposite sign). For distilled water, the pH is 7.07; acidic medium has a pH less, alkaline - more. The hydrogen index of arterial blood is on average 7.4, and that of venous blood is slightly less. This means that blood has slightly acidic reaction... During physical work, a large amount of acidic metabolic products gets into the blood plasma. However, during the most difficult work, the blood pH does not drop below 7.0. With a large shift in blood pH to the acidic side, a person is forced to stop working.

Acid-base balance in blood and tissues is ensured by the presence of special substances in them that form buffer systems. There are several buffer systems:

• carbonate system , the activity of which is due to carbonic acid and its salts;
• phosphate system , which contains salts of phosphoric acid;
• plasma protein buffer system ;
• hemoglobin buffer system (it plays the largest role, since it provides about 75% of the buffering capacity of the blood).

For example, if any acid, stronger than coal (for example, milk), it reacts with bicarbonate. As a result, a salt of this acid and carbonic acid are formed, which is split into CO 2 and H 2 O. Carbon dioxide is released from the body through the lungs, which ensures the maintenance of blood pH at a constant level. If they enter the blood alkaline foods, then they bind to the acids of the buffer systems. This prevents the body from shifting the pH of the blood and tissues to the alkaline side.

Alkalis of the buffer systems of the blood, capable of binding acids formed during the metabolic process, are called alkaline reserve ... It is determined by the amount of carbon dioxide (in ml), which is in a chemically bound state (i.e., in the form of H 2 CO 3 and NaHCO 3) in 100 ml of blood plasma. In a healthy person, this figure is 50–65 ml.

The constancy of the pH of tissues and blood is ensured by the lungs (the release of the body from carbon dioxide), the kidneys and the sweat glands.

With intense physical work, a significant amount of under-oxidized metabolic products enters the bloodstream, with an increase in the power of work, their number increases. For example, the content of lactic acid can reach 200–250 mg per 100 ml of blood; increase by 20-25 times in comparison with the state of rest.

Recreational jogging increases the capacity of the buffer systems of blood and tissues.

As physical activity increases, oxygen consumption increases up to the individual maximum (IPC).

In untrained people, the BMD is usually equal to 3-4 l / min or 40-50 ml / min / kg; in well-trained athletes, the IPC reaches 6-7 l / min or 80-90 ml / min / kg. Due to fatigue, the maximum oxygen consumption cannot be maintained for a long time (up to 15 minutes).

During operation, the oxygen demand increases. Figure 14 reflects oxygen supply:

A - light work;

B - hard work;

B - exhausting work.

Oxygen demand (O 2 -request) - the amount of oxygen required by the body to fully meet the energy needs arising in the work due to oxidative processes.

Oxygen input (О 2-input) - the amount of oxygen used for aerobic resynthesis of ATP during work performance. Oxygen intake is limited by the MPC (Fig. 14 B) and the rate of development of aerobic energy supply processes.

Thus, when operating at high power, the oxygen demand may exceed the oxygen intake (Fig. 14B). In this case, to oxygen deficiency (О 2 -deficiency) - the difference between oxygen demand and oxygen intake persists throughout the entire operation and leads to a significant oxygen debt.

Under conditions of oxygen deficiency, anaerobic reactions of ATP resynthesis are activated, which leads to the accumulation of products of anaerobic decomposition in the body, primarily lactate. During work, in which it is possible to establish a stable state, part of the lactate can be utilized during work due to the intensification of aerobic reactions, in which lactate is utilized, turning into pyruvate and oxidizing. The other part is eliminated after work [Holloshi DO, 1982].

If a steady state does not come, then the concentration of lactate in the course of work increases all the time, which leads to refusal to work. In this case, the lactate is eliminated at the end of the work. For these processes, an additional amount of oxygen is required, therefore, for some time after the end of work, its consumption continues to remain increased compared to the level of rest [Volkov NI, Nessen EN, Osipenko AA, Korsun, 2000].

Oxygen debt (О 2 -long) is the volume of oxygen required for the oxidation of metabolic products accumulated in the body during strenuous muscular work with insufficient aerobic energy supply, as well as for replenishing reserve oxygen consumed during physical activity.

Anaerobic energy supply is carried out in two ways:

Creatine phosphate (lactate free);

Glycolytic (with the formation of lactate).

1- "alactate" fraction of oxygen debt;

2- "lactate" fraction of oxygen debt

Fig. 14. Formation and elimination of oxygen debt

when working with different power [according to N.I. Volkov 2000]

Therefore, the oxygen debt has two fractions:

- alactate О 2 -long - the amount of О 2 required for the resynthesis of ATP and creatine phosphate and replenishment of oxygen reserves directly in the muscle tissue;

- lactate О 2 - long - the amount of О 2 required to eliminate the accumulated lactic acid during operation.

And, if the alactate O 2 -long is eliminated quickly enough, in the first minutes after the end of the work, then the elimination of the lactate O 2 -long can last up to two hours.

Methodological conclusions:

1. Alactate oxygen debt is formed during any work and is eliminated quickly, within 2-3 minutes.

2. Lactate oxygen debt significantly increases when the oxygen demand exceeds the MOC.

3. Insufficient rest time between repetitions of increased power loads translates the process of energy supply into a glycolytic "channel".

Features of muscle adaptation

To work on endurance

Cross-sectional skeletal muscle is a mosaic of fast, intermediate and slow fibers. White would Strong fibers are coarser, but not very uniform in thickness. They are not so well supplied with blood capillaries, there are few mitochondria in them. As a result, they do not adapt to long-term work, and their role in increasing endurance is very small. In contrast, red slow fibers are usually surrounded by an abundant capillary network and the number of mitochondria is very large. In addition, red fibers are much thinner (3-4 times). Intermediate fibers are fast red fibers with a pronounced capacity for both anaerobic and aerobic energy production mechanisms.

Under the influence of endurance training, intermediate muscle fibers acquire the properties of slow fibers with a corresponding decrease in the properties of fast muscle fibers. With the help of immunohistochemical methods, which allow the determination of "fast" and "slow" myosin, it was found that fibers of the intermediate type contain both types of myosin and that their ratio can change during training. However, such changes are not detected in the red slow and white fast fibers. The approximate content of slow red fibers in the broad external muscle of the thigh in all-round skaters is about 56%, stayers - about 75% [Meerson FZ, 1986]. The efficiency of aerobic supply at the peripheral level is largely determined by the oxidative potential of the muscles, which, in turn, is determined by the development of the mitochondrial system.

The power of the mitochondrial system of skeletal muscle, which determines both the ability to resynthesize ATP and utilize pyruvate, is a link that limits the intensity and duration of muscle work. The ability of mitochondria to use pyruvate as an energy substrate, preventing its transition to lactate and the subsequent accumulation of lactate, is the most important condition for increasing the level of strength endurance. In this case, the rate of formation of pyruvate in fast glycolytic fibers is approximately the same as the rate of its use in "aerobic" fibers, and in this case the total effect may be due to the simultaneous operation of fibers of one and the other type. It is beneficial both from a mechanical and metabolic point of view [Meerson FZ, Pshennikova MG, 1988].

The absence of hypertrophy of slow muscle fibers does not mean the absence of adaptive biosynthesis processes in them. When training for endurance, preference is given to the synthesis of mitochondrial proteins, and not only in slow, but also in intermediate fibers. With oxidative energy supply, metabolism occurs through the mitochondrial membranes. Consequently, the larger the total surface of mitochondrial membranes, the more efficient the oxidative processes. With different intensity and volume of physical activity, mitochondrial biosynthesis proceeds in different ways.

1. Hypertrophy- an increase in the volume of mitochondria - occurs during "emergency" adaptation to sharply increased loads. This is a quick but ineffective way. Although the total surface of mitochondrial membranes increases, their structure changes, impairing their functioning.

2. Hyperplasia- an increase in the number of mitochondria. The mitochondrial volume does not change, but the total membrane surface area increases. This effective long-term adaptation to aerobic activity is achieved through long-term training.

In this case, the total surface area of ​​mitochondrial membranes can increase even more due to the formation krist- folds on the inner mitochondrial membrane.

Rice. 15. Increasing diffuse distances

in hypertrophied muscle

If strength training causes hypertrophy of intermediate and fast muscle fibers, then slow muscle fibers under the action of endurance loads not only do not hypertrophy, but can also decrease their thickness, which leads to an increase in the density of mitochondria and capillaries and a decrease in diffuse distances.

Thus, during prolonged work, when the delivery of oxygen, energy substrates, and the removal of metabolic products are decisive factors, muscle hypertrophy will negatively affect endurance.

This circumstance directs the search for ways to increase the aerobic performance of the body of highly trained athletes from the center to the periphery, that is, from the cardio-respiratory system to the neuromuscular system.

Methodological conclusions:

1. Decrease in muscle volume helps to increase endurance.

2. The growth of endurance is directly related to the development of the mitochondrial system in muscle fibers.

Aerobic system is the oxidation of nutrients in the mitochondria for energy. This means that glucose, fatty acids and amino acids of nutrients, as shown on the left in the figure, after some intermediate processing combine with oxygen, releasing an enormous amount of energy that is used to convert AMP and ADP to ATP.

Comparison of the aerobic mechanism energy production with the glycogen-lactic acid system and the phosphagenic system according to the relative maximum rate of power generation, expressed in moles of ATP generated per minute, gives the following result.

Thus, it can be easily understood that phosphagenic system use muscles for bursts of power lasting a few seconds, but an aerobic system is essential for prolonged athletic activity. Between them is the glycogen-lactic acid system, which is especially important for providing additional power during intermediate loads (for example, races of 200 and 800 m).

What energy systems used in different sports? Knowing the strength of physical activity and its duration for different sports, it is easy to understand which of the energy systems is used for each of them.

Recovery of muscle metabolic systems after physical activity. Just as the energy of phosphocreatine can be used to restore ATP, the energy of the glycogen-lactic acid system can be used to restore both phosphocreatine and ATP. The energy of oxidative metabolism can restore all other systems, ATP, phosphocreatine and the glycogen-lactic acid system.

Recovery of lactic acid simply means removing its excess accumulated in all body fluids. This is especially important as lactic acid is extremely fatiguing. When there is sufficient energy generated by oxidative metabolism, the removal of lactic acid is carried out in two ways: (1) a small part of the lactic acid is converted back to pyruvic acid and then undergoes oxidative metabolism in the tissues of the body; (2) the rest of the lactic acid is converted back to glucose, mainly in the liver. Glucose, in turn, is used to replenish muscle glycogen stores.

Restoring the aerobic system after physical activity. Even in the early stages of hard physical work, a person's ability to synthesize energy aerobically is partially reduced. This is due to two effects: (1) the so-called oxygen debt; (2) depletion of muscle glycogen stores.

Oxygen debt... The body normally contains about 2 liters of stored oxygen, which can be used for aerobic metabolism even without inhaling new portions of oxygen. This oxygen supply includes: (1) 0.5 liters in the air of the lungs; (2) 0.25 L dissolved in body fluids; (3) 1 L associated with blood hemoglobin; (4) 0.3 L, which is stored in the muscle fibers themselves, mainly in conjunction with myoglobin, a substance that resembles hemoglobin and binds oxygen like it.

With hard physical work almost all of the oxygen supply is used for aerobic metabolism in about 1 minute. Then, after the end of physical activity, this reserve must be replenished by inhaling additional oxygen in comparison with the needs at rest. In addition, about 9 liters of oxygen must be consumed to restore the phosphagenic system and lactic acid. The extra oxygen that needs to be replaced is called oxygen debt (about 11.5 liters).

Figure illustrates oxygen debt principle... During the first 4 minutes, a person performs hard physical work, and the rate of oxygen consumption increases more than 15 times. Then, after the end of physical work, oxygen consumption still remains above normal, and at first it is much higher, while the phosphagenic system is restored and the oxygen supply is replenished as part of the oxygen debt, and over the next 40 minutes, lactic acid is removed more slowly. The early part of the oxygen debt, the amount of which is 3.5 liters, is called alactacid oxygen debt (not associated with lactic acid). The late portion of the debt, which is approximately 8 liters of oxygen, is called the lactacid oxygen debt (associated with the removal of lactic acid).

The maximum level of oxygen consumption characterizes the power of aerobic energy supply processes. The maximum oxygen debt reflects the capacity of anaerobic processes. Below in Fig. 4 shows the dynamics of the increase in the level of oxygen consumption Ro /t, l / min during operation for 4 minutes and during the subsequent recovery within 30 - 40 minutes. The highest consumption level at the end of the exercise will correspond to the maximum working oxygen consumption level. The total oxygen consumption during recovery is equal to the oxygen debt.

Rice. eightOxygen consumption during exercise (4 min) and recovery (up to 30 - 40 min)

The sum of oxygen consumption during work and recovery determines the athlete's energy expenditure and constitutes the oxygen demand.

RO 2 = VO 2 + S DO 2, l.

In turn, the oxygen debt is equal to the sum of the alactate and lactate fractions

S DO 2 = DO 2 al+ DO 2 lact, l.

The oxygen demand level will be

RO 2 / t = VO 2 / t + Σ DO 2 /t, l / min.

The dynamics of oxygen consumption during work can be represented by a two-component exponential equation with a cut-off value equal to the maximum working level for this exercise. The decrease in the level of consumption during recovery can also be expressed by an exponential function with a faster alactate and slow dactate fraction.

Various methods are used to determine the maximum level of oxygen consumption:

1) the method of a single maximum load for 5 - 6 minutes,

2) the method of repeated exercises with increasing load until the maximum aerobic performance is reached,

3) the method of stepwise increase in the load during a single exercise,

4) the method of continuous linear increase in the load during a single exercise. Other methods are also used.

It should be noted that only in the first method is it possible to accurately determine the external work. The latter is important for determining the relationship with the athlete's achievements.

The maximum level of oxygen consumption depends on the performance of the heart and the arteriovenous difference in blood oxygen saturation

VO 2 /t max = Q (A - B) = SV HR(A- B), (8)

where VO2 / tmax is the maximum level of oxygen consumption, l / min,
Q - heart productivity, l / min,
(A - B) - arterio-venous difference in blood oxygen saturation, ml O2 / 100 ml of blood,
SV - stroke volume of the heart, ml / beats.,
HR - heart rate, beats / min.

It is known that the performance of the heart in sports activity ranges from 20 - 30 l / min to 40 l / min, the stroke volume is from 130 to 200 ml / bpm, the heart rate reaches 200 bpm and more. Under intense load, the arteriovenous difference reaches 15 - 20 O2 ml / 100 ml of blood.

Thus, the level of aerobic energy performance is characterized by two main factors: circulatory mechanisms and respiration.

Breathing is divided into external and tissue. In turn, these indicators depend on a number of factors of the oxygen capacity of the blood, the rate of O2 diffusion from the tissue, the vital capacity of the blood, the depth and frequency of respiration, maximum ventilation of the lungs, the diffusion capacity of the lungs, the percentage of oxygen used, the structure and number of metachondria, reserves of energy substrates, the power of oxidative enzymes, muscle capillarization, volumetric blood flow rate in tissues, acid-base balance of blood, etc.

In the literature, there are currently numerous data on the maximum oxygen consumption and its values ​​per unit of body weight in athletes of various specializations. The highest values ​​of the maximum oxygen consumption up to 6.7 l / min are observed among skiers-racers and rowers in rowing. The high values ​​for skiers are largely due to the fact that they compete and train on rough terrain with more ups and downs. Rowers with a high own body weight, due to the design of the boat, develop high power at a distance of 2000 m.

For running, swimming, speed skating and cycling, the maximum consumption is between 5.2 and 5.6 l / min. In terms of oxygen consumption per unit of body weight, the highest values ​​are observed in skiers and distance runners up to 84 ml / kg / min. For rowers, this value is 67 ml / kg / min due to the fact that their body weight is usually in the range of 90 - 100 kg and more. Relatively low values ​​are also seen in sprinter runners and speed skaters. It should be borne in mind that in swimming and rowing, the level of oxygen consumption per unit of weight is less important than in other sports, since the exercise is performed in water, where it is not body weight that matters, but streamlining and buoyancy.

Record values ​​of the level of oxygen consumption are observed among cross-country skiers up to 7.41 l / min and up to 94 ml / kg / min.

Maximum oxygen debt determined after repeated high-intensity exercises (usually above 95 - 97% of the maximum speed for the segment). In sports swimming, such exercises can be distances of 4 x 50 m with a rest of 15 - 30 s, in running 4 x 400 m, on a bicycle ergometer, repeated exercises lasting up to 60 s. In all cases, the exercises are performed to failure, the duration of repeated exercises does not exceed 60 s, with an increase in rest, the intensity of the exercises increases.

Oxygen debt is determined by analyzing gas volumes collected during exercise recovery. The size of gas inflows is determined by subtracting from the oxygen consumption the value of O2 - the consumption of rest. The latter is determined after 30 minutes of rest before exercise at rest while sitting (SMR-sitting metabolic rate), all measurements of gas volumes are reduced to STPD. The calculation of the total oxygen debt, its alactate and lactate fractions is carried out by analyzing the dependence "level of O2 arrival - recovery time" and solving the biexponential equation. It should be borne in mind that since the main lactate fraction of oxygen debt has a high correlation with the concentration of lactic acid in the blood after exercise (up to 0.95 and above), then in sports practice, the determination of blood lactate is used to assess the anaerobic capabilities of an athlete. The latter procedure is much simpler, more convenient and requires less time and equipment.

Anaerobic energy performance depends on a number of factors: the level of development of compensatory mechanisms and buffer systems that allow performing strenuous work in conditions of a shift in the internal environment (towards acidosis) and preventing this shift; efficiency (power) of anaerobic enzymatic systems; supply of energy systems in the muscles; adaptation of an athlete to exercise in conditions of oxygen debt.

The highest values ​​of oxygen debt were obtained after running 400 m four times with decreasing rest - up to 26.26 l, after swimming 50 m four times with 15 s rest - up to 14.43 l, on a bicycle ergometer after repeated high-intensity exercises - up to 8.28 l / 406.505 /. Table 10 shows the values ​​of the maximum oxygen consumption, oxygen debt and its fractions according to the examination of 80 swimmers (age - 16.7  1.75 years, body length 174.6  6.92 cm, body weight 66.97  9.4 kg) and 78 rowers (age 22.9  3.66 years, body length 187.41  4.21 cm, weight 86.49  5.6 kg). Energy indicators for skaters and runners are given according to the data of N. I. Volkov and V. S. Ivanov.

Table 5
Average values ​​of the maximum level of oxygen consumption, oxygen debt and its fractions in cyclic sports among athletes with achievements of different levels

Kind of sport	Energy indicators	MSMK			discharge	discharge
Athletics	V¢ O 2max, l / min S DO 2, l D O 2 al, l D O 2 lact, l
Skating	V ¢ O 2max, l / min S D O 2, l D O 2 al, l D O 2 lac t, l
Swimming	V¢ O 2, max l / min S D O 2, l D O 2 al, l D O 2 lac t, l
Academic	V¢ O 2, max l / min S D O 2, l D O 2 al, l
	D O 2 lact, l

It should be noted that athletes of different qualifications have high values ​​of the lactate fraction of oxygen debt. At the same time, the alactate fraction in all types of exercises does not have such a clear difference.

A high statistical connection of the two main energy indicators considered with achievements at distances of different lengths with significant in volume and extended in qualification groups was noted. For swimmers, the greatest connection between the maximum level of oxygen consumption is observed with achievements at 200m - 0.822, total oxygen debt per 100m - 0.766, lactate and alactate fraction with results at 50m (Table 11).

Table 6
Correlation coefficients between energy indicators and swimming speed at distances of different lengths (n = 80, at p  0.05 r = 0.22)

Energy Indicators	Distance, m