Aerobic performance- this is the body’s ability to perform work, providing energy expenditure due to oxygen absorbed directly during work.
Oxygen consumption during physical work increases with the severity and duration of work. But for each person there is a limit above which oxygen consumption cannot increase. The largest amount of oxygen that the body can consume in 1 minute during extremely hard work is commonly called maximum oxygen consumption(IPC). This work should last at least 3 minutes, because... a person can reach their maximum oxygen consumption (VO2) only by the third minute.
MPK is an indicator of aerobic performance. MOC can be determined by setting a standard load on a bicycle ergometer. Knowing the magnitude of the load and calculating the heart rate, you can use a special nomogram to determine the level of MOC. For those who do not engage in sports, the MOC value is 35-45 ml per 1 kg of weight, and for athletes, based on specialization, it is 50-90 ml/kᴦ. The highest level of VO2 max is achieved in athletes involved in sports that require great aerobic endurance, such as long-distance running, cross-country skiing, speed skating (long distance) and swimming (long distance). In these sports, the result depends 60-80% on the level of aerobic performance, ᴛ.ᴇ. The higher the MPC level, the higher the sports result.
The level of BMD, in turn, depends on the capabilities of two functional systems: 1) the oxygen supply system, including the respiratory and cardiovascular systems; 2) a system that utilizes oxygen (ensuring the absorption of oxygen by tissues).
Oxygen request.
To perform any work, as well as to neutralize metabolic products and restore energy reserves, oxygen is needed. The amount of oxygen required to perform a certain work is commonly called oxygen demand.
A distinction is made between total and minute oxygen demand.
Total oxygen demand- this is the amount of oxygen, which is extremely important for doing all the work (for example, in order to run the entire distance).
Minute oxygen request- this is the amount of oxygen required to perform a given job at any given minute.
The minute oxygen demand depends on the power of the work performed. The higher the power, the higher the minute request. It reaches its greatest value at short distances. For example, when running 800 m it is 12-15 l/min, and when running a marathon it is 3-4 l/min.
The longer the operating time, the greater the total request. When running 800 m it is 25-30 liters, and when running a marathon it is 450-500 liters.
At the same time, the MOC of even international-class athletes does not exceed 6-6.5 l/min and should be achieved only by the third minute. How does the body, under such conditions, ensure the performance of work, for example, with a minute oxygen demand of 40 l/min (100 m run)? In such cases, work takes place in oxygen-free conditions and is provided by anaerobic sources.
Anaerobic performance.
Anaerobic Performance- this is the body’s ability to perform work in conditions of lack of oxygen, providing energy expenditure from anaerobic sources.
Work is provided directly by ATP reserves in the muscles, as well as through anaerobic resynthesis of ATP using CrF and anaerobic breakdown of glucose (glycolysis).
Oxygen is needed to restore ATP and CrP reserves, as well as to neutralize lactic acid formed as a result of glycolysis. But these oxidative processes can occur after the end of work. To perform any work, oxygen is required, only at short distances the body works on debt, postponing oxidative processes for the recovery period.
The amount of oxygen required for the oxidation of metabolic products formed during physical work is usually called - oxygen debt.
Oxygen debt can also be defined as the difference between oxygen demand and the amount of oxygen the body consumes during work.
The higher the minute oxygen demand and the shorter the operating time, the greater the oxygen debt as a percentage of the total demand. The greatest oxygen debt will be at distances of 60 and 100 m, where the minute demand is about 40 l/min, and the operating time is calculated in seconds. The oxygen debt at these distances will be about 98% of the request.
At medium distances (800 - 3000m), the operating time increases, its power decreases, and therefore. oxygen consumption increases during work. As a result, the oxygen debt as a percentage of the demand is reduced to 70 - 85%, but due to a significant increase in the total oxygen demand at these distances, its absolute value, measured in liters, increases.
The indicator of anaerobic performance is - maximum
oxygen debt.
Maximum oxygen debt- this is the maximum possible accumulation of anaerobic metabolic products that require oxidation, at which the body is still able to perform work. The higher the training level, the greater the maximum oxygen content. So, for example, for people who do not engage in sports, the maximum oxygen debt is 4-5 liters, and for high-class sprinters it can reach 10-20 liters.
There are two fractions (parts) of the oxygen debt: alactic and lactate.
Alactate the debt fraction goes to restore the reserves of CrP and ATP in the muscles.
Lactate fraction (lactates - lactic acid salts) - most of the oxygen debt. It goes to eliminate lactic acid accumulated in the muscles. The oxidation of lactic acid produces water and carbon dioxide, which are harmless to the body.
The alactic fraction predominates in physical exercises lasting no more than 10 seconds, when the work is carried out mainly due to the reserves of ATP and CrP in the muscles. Lactate predominates during anaerobic work of longer duration, when the processes of anaerobic breakdown of glucose (glycolysis) proceed intensively with the formation of a large amount of lactic acid.
When an athlete works under conditions of oxygen debt, a large amount of metabolic products (primarily lactic acid) accumulates in the body and the pH shifts to the acidic side. In order for an athlete to perform work of significant power under such conditions, his tissues must be adapted to work with a lack of oxygen and a shift in pH. This is achieved by training for anaerobic endurance (short high-speed exercises with high power).
Anaerobic performance level is important for athletes, work
which lasts no more than 7-8 minutes. The longer the work time, the less impact anaerobic capacity has on athletic performance.
Anaerobic metabolism threshold.
With intense work lasting at least 5 minutes, a moment comes when the body is unable to meet its increasing oxygen needs. Maintaining the achieved work power and its further increase is ensured by anaerobic energy sources.
The appearance in the body of the first signs of anaerobic resynthesis of ATP is usually called the threshold of anaerobic metabolism (TAT). In this case, anaerobic energy sources are included in the resynthesis of ATP much earlier than the body exhausts its ability to provide oxygen (ᴛ.ᴇ. before it reaches its MIC). This is a kind of “safety mechanism”. Moreover, the less trained the body is, the sooner it begins to “insure itself.”
PAHO is calculated as a percentage of MIC. In untrained people, the first signs of anaerobic ATP resynthesis (ANR) can be observed when only 40% of the level of maximum oxygen consumption is reached. For athletes, based on their qualifications, PANO is equal to 50-80% of the MOC. The higher the PANO, the more opportunities the body has to perform hard work using aerobic sources, which are more energetically beneficial. For this reason, an athlete who has a high PANO (65% of MPC and above), other things being equal, will have a higher result at medium and long distances.
Physiological characteristics of physical exercise.
Physiological classification of movements
(according to Farfel B.C.).
I. Stereotypical (standard) movements.
1. Movements of quantitative value.
Cyclic.
Powers of work: Types of locomotion:
‣‣‣ maximum - movements performed by the legs;
‣‣‣ submaximal - movements performed with
‣‣‣ a lot of help from your hands.
‣‣‣ moderate.
2. Movements of qualitative significance.
Types of sports: Assessed qualities:
Sports and artistic - strength;
gymnastics; - speed;
Acrobatics; -coordination;
Figure skating; - balance;
Diving; - flexibility;
Freestyle, etc. - unsupported;
Expressiveness.
A large group of physical exercises is performed under strictly constant conditions and is characterized by strict continuity of movements. This is a group of standard (stereotypical) movements. Such physical exercises are formed according to the principle of a motor dynamic stereotype.
By doing non-standard movements there is no rigid stereotype. In sports with non-standard movements, there are certain stereotypes - techniques of defense and attack, but the basis of the movements is the response to constantly changing conditions. The athlete’s actions are related to solving the problems of a particular moment.
3. Factors determining aerobic performance
The most important of all the considered parameters of bioenergetic mechanisms is the indicator of the power of aerobic mechanisms - the MIC indicator, which largely determines the overall physical performance. The contribution of this indicator to special physical performance in cyclic sports, in distances, starting from middle distances, ranges from 50 to 95%, in team sports and martial arts - from 50 to 60% or more. At least in all sports, according to A.A. Guminsky (1976), the MPC value determines the so-called "general training performance".
MOC in physically unprepared men aged 20-30 years averages 2.5-3.5 l/min or 40-50 ml/kg.min (about 10% less in women). In outstanding athletes (runners, skiers, etc.), MOC reaches 5-6 l/min (up to 80 ml/kg/min and higher). The movement of atmospheric oxygen in the body from the lungs to the tissues determines the participation of the following body systems in oxygen transport: the external respiration system (ventilation), the blood system, the cardiovascular system (circulation), the body’s oxygen utilization system.
Increasing and improving (increasing efficiency) aerobic performance (AP) during training is primarily associated with increasing the performance of ventilation systems, then circulation and utilization; their inclusion does not occur in parallel and gradually all at once, but heterochronically: at the initial stage of adaptation, the ventilation system dominates, then circulation, and at the stage of higher sportsmanship - the utilization system (S.N. Kuchkin, 1983, 1986).
General the size of the increase in AP is determined by different authors from 20 to 100%, however, studies in the laboratory of physiology of the All-Russian State Academy of Physical Culture (S.N. Kuchkin, 1980, 1986) showed that the total increase in the relative MIC indicator is on average 1/3 of the initial (genetically determined level ) - i.e. about 35%. Moreover, at the stage of initial training, the increase in VO2 max is most noticeable and amounts to up to 20% (half of the total increase), at the stage of sports improvement (stage II adaptation) the increase in VO2 max/weight slows down and amounts to about 10%, and at the stage of higher sports mastery (stage III adaptation) the increase is minimal - up to 5-7%.
Thus, the initial period of adaptation is the most favorable for training aerobic capabilities, and the end of this stage is important for determining the prospects of a given athlete in relation to aerobic performance.
Let us briefly consider the main changes in the body systems responsible for oxygen transport during the development of endurance.
IN external respiration system First of all, power reserves increase - these are indicators of vital capacity, MVL, strength and endurance of the respiratory muscles. Thus, for highly qualified swimmers and academic rowers, vital capacity indicators can reach 8-9 liters, and MVL – up to 250-280 l/min and higher. Power reserves are the reserves of the first echelon, and they are included in the increase in AC already at the initial stages of adaptation. Therefore, all novice athletes and at the beginning of the general preparatory period can safely recommend a variety of breathing exercises, which will contribute to better aerobic adaptation.
At later stages of adaptation, the ability to mobilize power reserves improves, and later, the efficiency (efficiency) of external respiration increases (S.N. Kuchkin, 1983, 1986, 1991). Thus, master athletes can use vital capacity by 60-70% during hard work (versus 30-35% for beginners). Oxygen is absorbed more efficiently from the inhaled air (in terms of oxygen utilization factor, ventilation equivalent, etc.), which ensures high MIC values with ventilation of “only” 100-120 l/min and a low respiratory rate. Mechanisms for more efficient work also contribute to this. tissue disposal systems oxygen in working muscles, which can use almost 100% of the oxygen delivered to them.
IN blood system As a rule, there is no increased content of red blood cells and hemoglobin. But an increase in the exchange of circulating blood (mainly due to plasma), the emergence of the so-called hemoconcentration(increasing hemoglobin content due to the release of part of the plasma into the tissue), as a result of which, during operation, circulating blood has 10-18% more hemoglobin, which leads to an increase in the so-called blood oxygen capacity.
Significant changes during the development of endurance occur in circulatory system - cardiovascular system. First of all, this affects the increase in power reserves - cardiac performance (systolic volume can reach 180-210 ml, which, with an effective heart rate of 180-190 beats/min, can give an IOC of 32-38 liters/min). This is due to a mandatory increase in the total volume of the heart from 750 ml to 1200 ml or more, caused by working hypertrophy and tonogenic dilatation (expansion) of the cavities of the heart.
Reserves of regulatory mechanisms consist in the formation of resting bradycardia and relative working bradycardia when performing aerobic work. Compare: the heart rate reserve for trained people is: , and for untrained people it is:
. That is, in terms of heart rate alone, the reserve with training will be 164%.
Another important regulatory mechanism: much more blood passes through the vessels of working muscles in trained people, and into non-working muscles. V.V. Vasilyeva (1986) showed that this is due to changes in the lumen of blood vessels in the corresponding muscles. Improvement recycling systems associated largely with changes in working muscles: an increase in the number of slow muscle fibers with aerobic mechanisms of energy production; working hypertrophy of the sarcoplasmic type and an increase in the number of mitochondria; significantly higher capillarization, and, consequently, higher oxygen supply; significant aerobic biochemical changes in the muscles (increasing the capacity and power of the aerobic mechanism due to an increase in the content and activity of oxidative metabolism enzymes by 2-3 times, an increase in the myoglobin content by 1.5-2 times, as well as glycogen and lipids by 30-50%, etc. .).
Thus, endurance training causes the following main functional effects:
Increasing and improving all qualitative and quantitative indicators of the aerobic energy supply mechanism, which manifests itself during maximum aerobic work.
Increasing the efficiency of the body's activity, which is manifested in a reduction in costs per unit of work and in smaller functional changes under standard loads (heart rate, ventilation, lactate, etc.).
Increasing resistance - the body's ability to resist changes in the internal environment of the body, maintaining homeostasis, compensating for these changes.
Improving thermoregulation and increasing reserves of energy resources.
Increasing the efficiency of coordination of motor and autonomic functions with direct regulation through nervous and humoral mechanisms.
Limitation of aerobic performance is associated with a low rate of oxygen delivery to muscles, insufficient diffusion capacity and oxidative potential of muscles, and excessive accumulation of metabolites of anaerobic glycolysis.
The oxygen delivery and utilization system is quite complex and includes several stages. No wonder that it is not possible to identify a single, “main” reason, limiting aerobic performance of people of different levels of functional fitness. The problem of identifying factors limiting aerobic performance becomes especially relevant when it comes to highly trained athletes working with extreme tension in the systems of autonomic support of muscle activity.
Currently, the most commonly used parameter characterizing aerobic performance is MOC. In the same time it has been shown many times that sports results over long distances (work lasting more than 3-4 minutes) depend on the power developed at the PANO level.
With increasing training, the rate of lactate utilization by working muscles increases, which is accompanied by a decrease in lactate concentration in the blood. Thus, the higher the aerobic capacity of the athlete, the lower the contribution of anaerobic glycolysis when refusing to work during a test with increasing load. It follows that a situation is possible when oxygen consumption at the ANSP level comes very close to the maximum value (MIC).
Assuming that specific oxygen consumption (oxygen consumption divided by muscle weight) approaches a maximum value, then further increases in oxygen consumption (working power) can only be achieved by increasing active muscle mass. It is logical to assume that the most effective way in this case is to increase oxygen consumption by increasing the volume of muscle fibers with high oxidative capabilities, that is, primarily type I fibers (slow muscle fibers).
These considerations suggested that PANO should depend mainly on the total volume of type I fibers in the muscle, that is, slow muscle fibers.
Conclusions:
- When working with a small muscle mass (for example: extending a leg at the knee joint), an increase in load always leads to a proportional increase in blood supply to the working muscle and oxygen consumption by the body. In the case of working a large muscle mass (for example: working on a bicycle ergometer), for some people, when maximum power is reached, the body's oxygen consumption and blood supply to the working muscle reach a plateau, and peripheral mechanisms do not affect this effect.
- When working with a large muscle mass, the power at which the blood supply to the working muscle decreases coincides with the threshold of anaerobic metabolism, however, in half of trained people, the intensification of anaerobic glycolysis occurs without a decrease in blood supply.
- In highly qualified endurance athletes, a negative correlation was found (r=-0.83; p<0,05) между ПАНО, определяющим уровень тренированности, и концентрацией лактата в крови при максимальной аэробной нагрузке. У 20% высококвалифицированных спортсменов порог анаэробного обмена практически совпадает с максимальной мощностью, достигнутой в тесте. Соответственно, потребление кислорода достигает максимума при низкой концентрации лактата в крови (5,6±0,4 ммоль/л).
- In athletes training endurance, when working with large muscle mass (for example: working on a bicycle ergometer), oxygen consumption at the level of PANO correlates (r=0.7; p<0,05) с объемом волокон I типа (медленных) в основной рабочей мышце и не зависит от объема волокон II типа (быстрых).
- Low-intensity strength training (50% of maximum voluntary strength) without relaxation leads to an increase in the size of predominantly type I (slow) muscle fibers. Thus, this training technique makes it possible to further increase aerobic performance (oxygen consumption at the level of ANNO) in athletes with low lactate concentrations at maximum aerobic load.
Source of information: based on materials from Popov D.V. (2007)
FUNDAMENTALS OF ANAEROBIC PERFORMANCE ANALYSIS When assessing the operating performance of various energy generation systems, it is important to understand the difference between system capacity and power. Energy capacity is the total amount of energy that is used to perform work and is produced in a given energy system. The energy power of a system is the maximum amount of ATP energy that is generated under load per unit time by a given energy system.
METABOLIC PROCESSES OF ENERGY FORMATION AND THEIR INTEGRATION □ Creatine phosphokinase (alactate) - an instantaneous mechanism for replenishing ATP (ATP-Cr. F system); regeneration of ATP from the ATP-Cr system. F through the creatine kinase and adenylate kinase pathways does not lead to the formation of lactate and is called alactic. □Glycolytic, lactate (glycogen to lactate conversion system) represents the phosphorylation of adenosine diphosphate (ADP) through the glycogenolysis and glycolysis pathways, leads to the production of lactate and is called lactate. The generation of ATP energy in these processes occurs without the use of oxygen and is therefore defined as anaerobic energy production.
High-intensity anaerobic work can cause a 1000-fold increase in the rate of glycolysis compared to the resting state. ATP replenishment during maximal sustained exercise is never achieved solely by one energy production system, but rather is the result of a coordinated metabolic reaction in which all energy systems contribute differently to power output.
PRACTICAL APPROACHES It is more feasible to measure peak operating performance over periods ranging from a few seconds to almost 90 seconds. With such a duration of work, ATP resynthesis depends mainly on the alactic and lactate anaerobic pathways. Simple estimates of anaerobic energy expenditure can be obtained from test results, supplemented if possible by biochemical or physiological
1. Muscle ATP reserves are assumed to support only a few contractions and are better assessed by muscle strength and maximum instantaneous power measurements. 2. It is assumed that maximal exercise lasting several minutes or longer is primarily aerobic and requires information about aerobic metabolism. If it is necessary to collect data on the anaerobic components of the special performance of athletes performing in sports in which the duration of maximum effort is about 2 minutes or a little more, it is necessary to take into account the interaction
SHORT-TERM ANAEROBIC WORK CAPACITY This component is defined as the total work output during a maximum power exercise duration of up to 10 s. It can be considered as a measure of alactic anaerobic performance, which is provided mainly by muscle ATP concentration, the ATP-Cr system. F and slightly anaerobic glycolysis. Highest working productivity per second in process
INTERMEDIATE ANAEROBIC WORK PERFORMANCE This component is defined as the total work output during a maximum exercise period of up to 30 s. Under such conditions, working performance is anaerobic with a major lactate (about 70%), significant alactic (about 15%) and aerobic (about 15%) components. The work power during the last 5 s of the test can be considered an indirect assessment of lactate anaerobic power.
CONTINUOUS ANAEROBIC WORK PERFORMANCE Defined as the total work output during a maximum workload of up to 90 s. Characterizes the limit of the duration of work, which can be used to assess the anaerobic capacity of the energy supply system of athletes. The advantages of these tests are that they allow the overall operating performance of anaerobic systems to be assessed at maximum demands on them and to quantify the decrease in operating performance from one part of the test to the next (for example, the first 30 s versus the last 30
AGE, GENDER AND MUSCLE MASS Anaerobic performance increases with age during growth in boys and girls. The maximum values of this type of performance are achieved at the age of 20 to 29 years, and then its gradual decrease begins. The decline with age is the same in men and women. This decline appears to be almost linear with age, amounting to 6% per decade. Men perform better than women on 10-, 30-, and 90-second maximal tests, and the work output per kilogram of body weight in women is approximately 65% of the work output per kilogram of body weight in men. Similar
Maximum performance is associated with: anaerobic body size especially lean mass muscle mass. Some age- and sex-specific differences in maximal anaerobic performance are more related to changes in muscle mass than to other factors.
STRUCTURAL AND FUNCTIONAL FACTORS AFFECTING ANAEROBIC PERFORMANCE. Muscle Structure and Fiber Composition Muscle structure plays a significant role in the level of power and amount of work it can generate. The degree of polymerization of actin and myosin filaments, their arrangement, sarcomere length, muscle fiber length, muscle cross-sectional area, and total muscle mass are structural elements that appear to contribute to muscle performance under anaerobic conditions, especially for absolute work performance. The relationship between muscle fiber composition and anaerobic performance is not simple. Athletes who specialize in sports that are anaerobic in nature or sports that require high anaerobic power and capacity exhibit a higher proportion of fast-twitch fibers (FTFs). The more BS fibers or the larger the area they occupy, the higher the ability to develop 1
2. SUBSTRATE AVAILABILITY The energy output for maximal exercise of very short duration is explained mainly by the breakdown of endogenous energy-rich phosphagens, but it appears (at least in humans) that the generation of maximal exercise even for very short periods of time is provided by the simultaneous breakdown of CP and glycogen. Depletion of reserves of Kr. F limit anaerobic performance under maximum power and very short-term load. But the main role of Kr. Ph in muscle is the role of a buffer between the concentrations of ATP and ADP.
3. ACCUMULATION OF REACTION PRODUCTS Anaerobic glycolysis unfolds with a very short delay after the onset of muscle contraction and is accompanied by the accumulation of lactate and, accordingly, an increase in the concentration of hydrogen ions (H+) in body fluids. Muscle lactate concentrations increase significantly after short-term exercise and can reach values of about 30 mmol kg-1 wet weight during exhaustion. Muscle buffer systems create a partial buffer for hydrogen ions. For example, muscle bicarbonate concentration decreases from 100 mmol L-1 liquid media
However, the muscle cannot buffer the hydrogen ions produced for long, and p. The muscle H decreases from 7.0 before the load to 6.3 after the maximum load, causing exhaustion. Decrease in river Sarcoplasmic H disrupts the interaction of Ca 2+ with troponin, which is necessary for the development of contraction and is explained by the competition of hydrogen ions (H+) for calcium-binding sites. Thus, the frequency of formation of actomyosin cross-bridges decreases with decreasing p. H and also the rate of synthesis and breakdown of energy is reduced (according to the feedback principle and due to disruption of the activity of catalysts and enzymes) The ability to resist acidosis increases
EFFICIENCY OF METABOLIC PATHWAYS Determined by the speed of deployment of the energy process. The rate of the creatine kinase reaction is determined by the activity of creatine kinase. The activity of which increases with a decrease in ATP in the muscle and accumulation of ADP. The intensity of glycolysis can be stimulated or delayed by various signals (hormones, ions and metabolites). The regulation of glycolysis is largely determined by the catalytic and regulatory properties of two enzymes: phosphofructokinase (PFK) and phosphorylase. As mentioned above, high-intensity exercise leads to an excessive increase in H+ and a rapid decrease in p. N muscles. The concentration of ammonia, which is a derivative of the deamination of adenosine 5"-monophosphate (AMP), in skeletal muscle increases during maximal exercise. This increase is even more pronounced in subjects with a high percentage of BS fibers. However, ammonia is recognized as an activator of PPA and can create buffer for some changes in intracellular pH. In vitro studies have shown that phosphorylase and PPK are almost completely inhibited when the pH level approaches 6.3. Under such conditions, the rate of ATP resynthesis should be greatly reduced, thereby impairing the ability to continue performing mechanical work due to the anaerobic pathway
Depends on the quality and quantity of muscle fibers: BS fibers are rich in ATP, CK and glycolytic enzymes compared to slow-twitch fibers. From this summary, it is clear that training maximizes anaerobic performance because most of the limiting factors adapt in their interaction in response to high-intensity training.
CHARACTERISTICS OF MUSCLES NECESSARY TO ACHIEVE A HIGH LEVEL OF ANAEROBIC PERFORMANCE AND THE RESULTS OF THE IMPACT OF HIGH-INTENSITY TRAINING ON THE INDICATORS THAT DETERMINE IT Characteristics of muscles Factors of anaerobic performance Value of ATP CP Glycogen Buffer ny ability Maximum lactate p. N in case of exhaustion Proportion of BS fibers Recruitment of BS fibers CK activity Phosphorylase activity FFK activity Yes Probably no Probably yes Probably no Yes Yes Yes Probably yes Yes Effect of training = or = or ↓ = = or
OXYGEN DELIVERY SYSTEM All other factors being equal, oxygen delivery and utilization systems probably make a very significant contribution to peak operating performance during load durations of 90 seconds or longer. Obviously, the longer the load, the higher the importance of the oxidative system. Under conditions of shorter duration maximum loads, the oxygen delivery system will not function at its maximum level, and oxidative processes in the final part of the work
During work with a load of maximum intensity lasting from 60 to 90 s, the oxygen deficiency associated with the beginning of work will be overcome and the oxidation of substrates in mitochondria at the end of work will lead to an increase in the share of aerobic processes in the energy supply of work. In this case, individuals who are able to quickly mobilize oxygen delivery and utilization systems and have a correspondingly high aerobic power will have an advantage in conditions of intermediate duration and
INHERITANCE It is now established that an individual's genotype largely determines the prerequisites for high aerobic power and endurance capacity, as well as a high or low level of response to training. We know much less about the heredity of anaerobic performance. Short-term anaerobic work performance (based on 10-second maximal work performance on a bicycle ergometer) had a significant genetic influence of approximately 70% when data were expressed per kilogram of lean mass. Recently, several sprinting studies involving twins and their families, conducted in Japan and Eastern Europe, were analyzed. Heritability estimates for sprint performance ranged from 0.5 to 0.8. These data suggest that an individual's genotype has a significant effect on short-term anaerobic work performance. There is no reliable evidence yet regarding the role of heredity in long-term anaerobic work performance. On the other hand, we have recently obtained evidence of genetic influences on the distribution of fiber types and
TRAINING Training increases power and capacity during short-term, intermediate and long-term anaerobic work. Variations in training response (trainability) to a specific anaerobic training regimen have been studied extensively. The response to short-term anaerobic performance training was not significantly dependent on the genotype of individuals, whereas the response to long-term anaerobic performance training was largely determined by genetic factors. Trainability for overall 90-second work performance was characterized by genetic influence accounting for approximately 70% of the variation in response to training. This data is of great importance for coaches. Based on test results, it is easier to find talented people for short-term anaerobic work than for long-term anaerobic work. WITH
Aerobic endurance- this is the ability to perform (low work) for a long time and resist fatigue. More specifically, aerobic endurance is determined by lactate threshold. The higher the , the greater the aerobic endurance.
The aerobic threshold is the point of peak aerobic capacity of the body, upon reaching which anaerobic “energy channels” begin to work with the formation. It occurs when you reach about 65% of your maximum heart rate, which is about 40 beats below the anaerobic threshold.
Aerobic endurance is divided into types:
- Short - from 2 to 8 minutes;
- Average - from 8 to 30 minutes;
- Long - from 30 or more.
Aerobic endurance is trained using continuous and.
- Continuous training helps in improvement;
- Interval training is necessary to improve the muscular activity of the heart.
Basic article on aerobic endurance training:
Methods for measuring aerobic capacity
Unfortunately, it is impossible to directly estimate the total amount resynthesized due to aerobic reactions in working muscles and even in an individual muscle. However, it is possible to measure an index proportional to the amount of ATP resynthesized in aerobic reactions.
To indirectly assess the rate of ATP resynthesis during muscle work, the following main methods are used:
- direct measurement of oxygen consumption;
- indirect calorimetry;
- 1H and 31P magnetic resonance spectroscopy;
- positron emission tomography;
- infrared spectrometry.
It should be noted that only the most popular methods used to study energy during muscle work are noted here.
Direct measurement of oxygen consumption. Oxygen consumption (OC) is equal to the product of blood flow and the arteriovenous difference in oxygen in a given area. Local blood flow in the area under study is determined by thermodilution, label dilution, or ultrasound techniques. As a rule, the Fick method is used to determine PC in a separate working muscle (for example, in an isolated preparation) or in a separate area (for example, in leg tissue). This is an advantage of this method. The disadvantages of the method are invasiveness and significant methodological complexity in carrying out measurements, associated both with the procedure for catheterization of arteries and veins, and with methodological difficulties in determining local blood flow and gas tension in blood samples. In addition, if measurements are not carried out on an isolated preparation, then it should be taken into account that the analyzed venous blood comes not only from the working muscle, but also from inactive tissues, which can distort the real results. Nevertheless, the determination of PC according to Fick is actively used in maximum tests during local work (for example, when extending the leg at the knee joint) and when working with large muscle mass (bicycle ergometry).
Indirect calorimetry (gas analysis of inhaled and exhaled air). Total PC is proportional to the total amount of ATP resynthesized due to oxidation reactions in the body. PC is calculated as the product of the pulmonary ventilation indicator, normalized to standard conditions, by the difference between the proportion of oxygen in inhaled and exhaled air. By calculating the respiratory quotient (the ratio of carbon dioxide released to oxygen consumed), it is possible to determine which substrate is used in oxidation. Then, using the caloric equivalent of oxygen, the amount of energy obtained by the body from the oxidation of a given substrate can be calculated.
The advantage of this method is its non-invasiveness, ease of use and the ability to take measurements in almost any type of muscle activity. The possibilities of using the method have expanded significantly with the advent of portable gas analyzers. The disadvantages of gas analysis include the following. Using indirect calorimetry, it is possible to estimate PC and energy expenditure only for the whole organism.
This means that it is impossible to determine how much of the oxygen is used to power active muscles, the heart, the respiratory muscles and other tissues. This task becomes especially relevant when working in which small muscle mass is involved. In this case, oxygen consumption by the heart and respiratory muscles can make a significant contribution to the total oxygen consumption.
1H and 31P magnetic resonance spectroscopy. The method is based on measuring the electromagnetic response of the nuclei of hydrogen atoms to their excitation by a certain combination of electromagnetic waves in a constant high-intensity magnetic field. The method allows non-invasive assessment of changes in the concentration of hydrogen ions, inorganic phosphorus, creatine phosphate, ATP and deoxymyoglobin in a specific area of the tissue being studied. This method is the standard for assessing changes in macroerg energy both under conditions of rest and during physical activity. Under some conditions, the change in creatine phosphate concentration is directly proportional to aerobic ATP resynthesis. Therefore, this method is actively used to assess aerobic metabolism.
Currently, using this method, a signal proportional to the concentration of deoxygenated myoglobin is also isolated and the partial pressure of oxygen in the myoplasm is calculated. The change in the partial pressure of oxygen and the absolute value of this indicator are a characteristic of the change in the ratio of oxygen delivery to the mitochondrion/oxygen utilization by the mitochondrion and a criterion for the adequacy of the operation of the oxygen delivery system to the mitochondrion. Despite the undoubted advantages of the method, its use is significantly limited by the very high cost of the equipment and the bulkiness of the device, as well as the strong magnetic field created during the measurement.
Positron emission tomography. The method is based on recording a pair of gamma rays produced during the annihilation of positrons. Positrons arise from the positron beta decay of a radioisotope that is part of a radiopharmaceutical that is introduced into the body before the study. Using a special scanner, the distribution of biologically active compounds labeled with short-lived radioisotopes in the body is monitored. To assess tissue oxygen consumption, breathing a gas mixture with a labeled oxygen molecule - O 2 - is used. Oxygen consumption by working muscle is calculated as the product of oxygen concentration in arterial blood, the regional extraction coefficient and the regional perfusion coefficient. The limitations of the method are associated with the high cost of a scanner and a cyclotron, a device necessary for the production of radioisotopes.
Infrared spectrometry. The method is based on the fact that biological tissue is permeable to light in the region close to infrared. The light source and receiver are located on the body surface at a distance of 3-5 cm. The average depth of light penetration will be equal to half the distance between them. Changes in the concentration of oxygenated and deoxygenated hemoglobin in the measured tissue (muscle) can be calculated using different wavelengths in the infrared region (600-900 nm), at which light is predominantly absorbed by oxygenated or deoxygenated hemoglobin and myoglobin. Since the concentration of hemoglobin is several (4-5) times higher than that of myoglobin, the main changes recorded using this method will be associated primarily with changes in the oxygenation of hemoglobin. The recorded signal will contain information about the total change in oxygenation of all tissues located in the measurement area.
Assuming a constant linear velocity of blood flow or in the absence of blood flow (occlusion), changes in the concentration of deoxygenated hemoglobin will be directly proportional to changes in PC in the measured area. By summing changes in oxygenated and deoxygenated hemoglobin concentrations, changes in hemoglobin concentration can be calculated. This indicator reflects the blood supply to the measured area. The method also allows you to calculate the total tissue oxygenation index - the ratio of oxygenated hemoglobin to total - expressed as a percentage.
The advantages of infrared spectrometry include non-invasiveness, ease of use and the ability to carry out measurements in almost any type of physical activity, both in laboratory and field conditions, using portable devices. The disadvantage of the method is the integral assessment of oxygenation of tissues located in the measurement area. For example, a significant layer of skin and fat can greatly distort the signal from active muscle tissue.
Exercise tests to study aerobic capacity
To determine the aerobic capabilities of the body in laboratory conditions, simulation of real muscle activity is used - load tests. The main requirements for these tests should be reliability, information content and specificity. The last requirement is especially important, since when choosing a test, it is necessary that the exercise used involves the same muscle groups as in the competitive movement, and also uses a movement pattern that is as close as possible to real conditions (competitive movement). For example, a runner should be tested while running on a treadmill, and a rower should be tested while working on a special rowing ergometer. It makes no sense to determine the general physical fitness of a swimmer in a test on a bicycle ergometer (leg work), while the main working muscles in this event are the muscles of the arms and torso.
All tests used in the physiology of muscle activity come down to measuring physiological reactions in response to a given or selected load. In the growth of any physiological indicator in response to an increase in load, there is a stage of rapid growth (0.5-2 min), a stage of slow increase (quasi-steady state) and a stage of the indicator reaching a true steady state. At maximum loads, the third stage is not always achievable. In order to clearly describe the body’s response to a particular load, it is necessary to achieve physiological indicators reaching a true steady state or maximum level. As a rule, reaching a true steady state can take 5-15 minutes for different indicators, even with a relatively small (10-15% of the maximum value) increase in load.
Ideally, when testing, it is necessary to determine how certain physiological indicators change in response to loads of different intensities, up to the maximum. In this case, the smaller the increase in load, the more accurate the dynamics of changes in the studied indicator will be obtained. However, if you wait until the indicator reaches a true steady state, the test will take too long.
Based on these considerations, a testing method with a stepwise increasing load is proposed. This test model allows you to evaluate the body's response over the entire range of loads from minimal to maximum aerobic load. Hereinafter, maximum aerobic load (power) will be understood as the maximum power achieved in the test under increasing load, i.e. power comparable to the power at which (MPC) is achieved.
Subsequently, an analogue of this test appeared - a test with a continuously increasing load. Both methods of setting the load have become widespread and are almost universally accepted models for testing aerobic performance.
The disadvantages of these models are the presence of a lag period between the increase in load and the increase in the physiological indicator, since the physiological indicator in this case does not have time to reach a true steady state. Therefore, the test results (indicator related to power) will be somewhat inflated relative to a long test with a constant load. The lag period is especially pronounced at low loads and is somewhat stronger in the test with a continuously increasing load than in the test with a stepwise increasing load.
On the other hand, a continuously increasing load test has a number of advantages. Different physiological indicators have different rates of reaching a quasi-stable state, therefore, with an abrupt increase in load, heterogeneity is inevitable: for example, the rate of increase in oxygen consumption in this case will be higher than the rate of increase in carbon dioxide emissions. This may distort some calculations, such as the aerobic-anaerobic transition determined using the V-slope method. In addition, if in a test with a stepwise increasing load the magnitude of the power increase is quite large (50 W), then the athlete can refuse to work at the last stage without ever reaching his individual maximum. Therefore, tests with continuously increasing load are becoming increasingly popular for assessing the aerobic capacity of the body.
Indicators characterizing the aerobic capabilities of the body
In the literature, many indicators are discussed as a criterion for aerobic performance, to one degree or another associated with sports results at distances lasting more than 5 minutes, i.e. where ATP resynthesis during work is provided primarily by aerobic reactions. To check the information content of the selected criterion, as a rule, its relationship with the sports result is determined and its contribution to the variance is assessed. In addition to sufficient information content, an important characteristic for a method for assessing aerobic capacity should be its non-invasiveness and ease of use. Therefore, this section will primarily consider routine methods for assessing aerobic capacity. In modern literature, the following most popular approaches to testing aerobic performance can be identified:
- assessment of maximum indicators characterizing the performance of the oxygen transport system;
- direct assessment of the maximum power at which a quasi-steady state is observed between the production and utilization of glycolytic products;
- indirect assessment of aerobic-anaerobic transition.
Indicators characterizing the maximum performance of the oxygen transport system. The maximum capabilities of the oxygen transport system are usually determined in a maximum test with increasing load during global operation. The most widely used maximum measures are maximum cardiac output (CO) and VO2 max.
Cardiac output (CO) is a highly informative indicator characterizing aerobic performance, since it determines the delivery of oxygen to all active tissues (not just working muscles). According to a number of authors, maximum CO is a key factor determining the aerobic capabilities of the body.
The maximum SV can be determined either by the direct Fick method or indirectly. The direct method is invasive and therefore cannot become routine. Of the non-invasive methods, the most reliable (comparison with the direct method r = 0.9-0.98) has proven to be the method of inhaling a gas mixture containing soluble and poorly soluble (biologically inert) gases. The testing procedure is breathing with a gas mixture (6-25 breathing cycles), which can be organized either by the type of return breathing or by the type of breathing in an open circuit (exhalation into the atmosphere). The method is based on the principle of mass balance: the rate of consumption of soluble gas (acetylene, carbon monoxide), taking into account the solubility coefficient, is proportional to the blood flow in the pulmonary circle. In the first respiratory cycles, the amount of total consumption of soluble gas depends not only on its solubility in the blood, but also on its mixing with alveolar air. Therefore, to correct the total consumption of soluble gas, a biologically inert gas (helium, sulfur hexofluoride) is used as a marker characterizing the complete filling of the alveolar volume with the respiratory gas mixture. The method is not widely used due to the high cost of gas mass spectrometers, the most suitable measuring instruments for this technique.
This is an integral indicator that characterizes the PC of the entire body (not only working muscles), i.e. the total amount of ATP resynthesized through oxidation. MIC can be determined non-invasively by indirect calorimetry (gas analysis). Thanks to the widespread use of gas analyzers, MIC has become one of the most popular criteria characterizing the aerobic capabilities of the body.
The disadvantages of these two indicators (maximum SV and MIC) are integrativeness. It is known that during global aerobic exercise, the main share of blood flow and oxygen consumption occurs in the working and respiratory muscles. Moreover, the distribution of oxygen between these two muscle groups depends on the load and at maximum load is 75-80% and 10-15%, respectively. During submaximal work, pulmonary ventilation can increase exponentially. Energy is required to ensure the functioning of the respiratory muscles. The diaphragm - the main respiratory muscle - has high oxidative capabilities/needs, so the energy supply to the diaphragm occurs primarily through the aerobic pathway. This means that the proportion of oxygen consumed by the respiratory muscles can increase precisely at the end of the work. This assumption was confirmed in studies assessing the power developed by the respiratory muscles during aerobic exercise of varying intensity up to maximum, and in experiments where the PC of the respiratory muscles was determined when simulating the working respiratory pattern at rest. The redistribution of blood flow from working to respiratory muscles can be facilitated by the metaboreflex, which occurs when the respiratory muscles become tired.
It is also impossible to exclude the possibility of additional redistribution of blood flow from the main working muscles to muscles that are additionally activated at maximum load. As a result of the action of these factors, the proportion of blood flow/oxygen consumption attributable to working muscles can sharply decrease precisely at near-maximal and maximum aerobic loads. However, changes in maximum CO and VO2 max will not necessarily reflect changes in oxygen consumption by the main working muscles. Another drawback of the maximum CO and MOC indicators should be considered the testing procedure itself. In order to achieve truly maximum performance, the subject must be highly motivated and determined to perform at maximum level, which is not always possible. This condition imposes additional restrictions on the quality of maximum tests and the frequency of their conduct.
Indicator of the maximum steady state of blood lactate. During low-intensity work, ATP resynthesis in active muscles occurs almost entirely due to aerobic reactions. The end products of oxidation are carbon dioxide and water. Carbon dioxide diffuses into the blood, binds to hemoglobin and is removed from the body through the lungs. Starting from a certain power, ATP resynthesis is ensured not only by oxidation, but also by glycolysis. The product is pyruvate and hydrogen. Pyruvate, under the action of the enzyme pyruvate dehydrogenase, can be converted into acetyl-CoA and enter the tricarboxylic acid cycle. If muscle fiber has high activity of muscle-type lactate dehydrogenase, then pyruvate is converted to lactate. If there is high activity of the cardiac-type lactate dehydrogenase enzyme in a muscle cell, then lactate is converted into pyruvate and is further used as a substrate for the tricarboxylic acid cycle.
Lactate accumulating in the cytoplasm can be released into the interstitium by diffusion or with the help of special carriers. From the intercellular space it enters neighboring fibers, where it can enter the tricarboxylic acid cycle, at least when the lactate concentration in the interstitium is low, i.e. during low-intensity work, or into the blood. In the blood, lactate is transported to active skeletal muscles and other tissues (for example, heart, liver, skeletal muscle), where it can be utilized. If the production of lactate and hydrogen ions (lactic acid) in the cell is greater than their utilization and removal, then the lactate concentration in the muscle fiber begins to increase and fall. An increase in lactate concentration contributes to an increase in osmotic pressure inside the cell (one of the mechanisms of working hemoconcentration). According to some authors, lactate does not have a direct negative effect on the contractility of muscle fiber. However, lactate can indirectly contribute to a decrease in pH by affecting Na+/H+ and Na+/Ca2+ metabolism in the cell. It has been shown in animal muscles that lactate ions are able to inhibit the functioning of calcium channels and activate ATP-dependent potassium channels in the sarcoplasmic reticulum and cell membrane, which can also indirectly affect the contractility of the muscle fiber.
On the other hand, an increase in the intracellular concentration of hydrogen ions negatively affects the contractility of the muscle fiber. As is known, with severe muscle fatigue, the pH inside the fiber can drop to 6.17-6.5. It is assumed that in this case, hydrogen ions can influence the process of attachment of myosin cross bridges to actin by reducing the sensitivity of troponin to calcium. This leads to a decrease in the force of contraction of the muscle fiber, and in extreme cases, with a pronounced decrease in pH, to a significant loss of contractility. In addition, a decrease in pH has an inhibitory effect on the activity of some enzymes of anaerobic metabolism, in particular the key link in glycolysis, phosphofructokinase.
The fatigue that occurs during muscular work should not be associated only with the accumulation of hydrogen ions and lactate. Most likely, the development of fatigue has a complex nature, caused by changes in the concentration of various metabolites and ions, changes in the magnitude of membrane potentials and excitability. Nevertheless, these changes are directly or indirectly associated with a pronounced intensification of glycolysis.
Indirectly, the degree of activity of muscle glycolysis during the work of large muscle mass can be assessed by determining the concentration of lactate or blood pH, since the transport of protons and lactate from the muscle fiber is proportional to their formation. Moreover, a significant relationship was found between the concentration of lactate in muscle tissue and in the blood after dynamic exercise. Assessing the activity of glycolysis by changes in pH and lactate concentration in the blood gives valid results only when working with a large muscle mass. Otherwise, changes in blood lactate concentration are small. Of course, one cannot equate the concentration of lactate in the blood or blood pH with the activity of glycolysis, since part of the lactate can be utilized by other tissues (liver, heart, etc.). Therefore, the most objective method for assessing the activity of glycolysis is to calculate the total lactate output from cells as the product of blood flow and the veno-arterial difference in lactate, but this is an invasive method that is not suitable for routine testing.
Changes in the concentration of lactate and/or hydrogen ions during exercise are also assessed directly in the interstitium or in the muscle fiber itself, using microdialysis or needle biopsy methods and the non-invasive method of 1 H and 31 P magnetic resonance spectroscopy. Modern microdialysis technology makes it possible to evaluate the dynamics of interstitial chemistry directly during static and dynamic work. A study with parallel measurements of lactate in the interstitium and venous blood during an increasing load test showed similar dynamics of these indicators. Moreover, the concentration of lactate in venous blood in the second half of the test did not differ from the concentration of lactate in the interstitium 1H and 31P magnetic resonance spectroscopy also makes it possible to evaluate the change directly during work, but due to methodological limitations, measurements are only possible during local work.
If during long-term work (10-30 minutes) at constant power the activity of glycolysis is low, then after some time a balance will be established in the muscle cell between the production and utilization of glycolytic metabolites. With greater power, glycolytic activity will increase and equilibrium will be established at a new elevated level. At some point, an increase in power will lead to a pronounced increase in the activity of anaerobic reactions: the production of metabolites will be greater than their utilization. The concentration of hydrogen and lactate ions in the cell, interstitium and blood will begin to continuously increase at constant operating power. Ultimately, the pH of the cell will drop to extremely low values, the contractile capabilities of the muscle will decrease, and the person will be forced to refuse to continue working (maintaining a given power level).
These arguments were confirmed in experiments with human participants, when lactate and/or blood pH were measured during work with a constant load. Lactate concentrations in response to the onset of exercise change rapidly during the first 1-4 minutes. Then the indicator slowly reaches a plateau. Most authors use an empirical criterion to assess whether this indicator reaches a plateau: an increase in lactate concentration of less than 0.025-0.05 mmol/l/min in the period from the 15th to the 20th minute of a test with a constant load. The power at which the maximum stable state is observed between the release into the blood and the utilization of glycolysis products (the dependence of lactate concentration on the operating time at a given power reaches a plateau) is called the maximum stable state for lactate. As a rule, it is not possible to perfectly accurately select the load corresponding to the power of the maximum steady state for lactate. Therefore, two or three loads are performed with an empirically selected power and, by extrapolation, the power at which the critical rate of lactate growth is observed is determined.
It turned out that the population average lactate concentration at the maximum steady state is 4 mmol/l. In this case, quite wide variations can be observed (2-7 mmol/l). It was not possible to identify a relationship between lactate concentration at maximum steady state and training level. However, a clear relationship has been identified between the power at which the maximum steady state for lactate is manifested and the level of aerobic performance: the higher a person’s fitness, the greater the power at which the maximum steady state for lactate is achieved. From the point of view of training athletes, the maximum steady state of lactate characterizes the maximum power (speed of movement along a distance) that an athlete is able to maintain for several tens of minutes. In this case, ultra-long (marathon) distances are not considered, where one of the factors limiting performance may be depletion of carbohydrate reserves.
Indicators that indirectly assess the aerobic-anaerobic transition. Despite the obvious prognostic significance of the maximum steady state indicator for lactate, this method of assessing aerobic capacity has a significant drawback - it is more labor-intensive and stressful. This places serious limitations on the use of this test as a routine diagnostic tool. Considering the fact that most physiological indicators change quickly in response to an increase in load - within the first one or two minutes, it is possible to evaluate the transition from “purely” aerobic to aerobic-anaerobic metabolism in a test with a stepwise increasing load with a step duration of 2-3 minutes . Subsequently, for the same purposes, a test with a continuously increasing load with a similar load increase gradient was used. Many authors have tried to propose their own criteria for identifying the power (oxygen consumption) at which the aerobic-anaerobic transition occurs. The most popular criteria for assessing the aerobic-anaerobic transition are discussed below.
As already noted, the increasing load test is a model that allows you to evaluate the entire range of physiological responses to loads from minimal to maximum. For a reasonable interpretation of the results obtained, it is necessary to imagine what happens in the body when the power changes from minimum to maximum. It is assumed that during an increasing load test, muscle fibers are recruited in accordance with Henneman's rule. At the beginning of the test, at minimum power, predominantly type I muscle fibers are activated. With an increase in power, higher-threshold motor units are involved in work, i.e. type IIA and II B fibers are included. Although direct measurements during dynamic work in human experiments cannot be made, there is a lot of indirect evidence confirming the correctness of this assumption. Thus, during work on a bicycle ergometer with a constant load of moderate intensity, glycogen depletion was demonstrated in muscle