VO2 max as an indicator of fitness and athletic prospects. What is VO2 max and what is it for? Factors Affecting VO2 Max

Some time ago we smart watch Withings, who learned how to measure the level of VO2 max. If you're serious about fitness, you've probably come across these terms at some point in your training. But what does it mean?

VO2 max is the maximum amount of oxygen a person can use. In other words, it is a measurement of your ability to consume oxygen. In addition, this is a great way to determine the strength of the heart vascular system. People with a high VO2 max have better blood circulation, which means it is more efficiently distributed to all the muscles involved in physical activity.

How VO2 max is measured

This indicator is the sum of the number of milliliters of oxygen consumed per minute per body weight. Professional athletes undergo this test in special laboratories on a treadmill. During the test, the amount of oxygen required by the athlete is determined, including in those moments when the intensity of the load increases. The process usually takes about 10-15 minutes.

For the Withings Steel HR Sport, VO2 max is determined using data from your workout speed and heart rate.

Highest VO2 max

The highest figure was recorded by cyclist Oskar Svendzen, he was 97.5 ml / kg / min. Generally, top scores show representatives of those sports that require special endurance. Statistically, rowers and runners have the highest V02 max among other athletes.

What affects V02 max

Genetics and physical fitness play a huge role. However, there are several other factors that determine a person's VO2 max to some extent.

• Gender: Generally, women have about 20% lower VO2 max than men.
• Height: The shorter a person is, the higher his performance.
• Age: The maximum level is fixed at the age of 18 to 25, after which it decreases.

You can also improve your V02 max by increasing the duration and intensity of your workout, or by simply starting to exercise if you haven't already. And as you become more experienced, you need to gradually increase the intensity of your workouts.

is an indicator of the body's ability to absorb oxygen from the environment. In some cases, this indicator is interpreted as the degree of efficiency of the work done in training or an indicator of aerobic physical performance.

VO2 was first measured by scientists Archibald Vivien Hill and George Lupton back in 1923.

During the experiment, a runner was used as a test subject, who overcame a distance at a variable speed on a grassy surface. As a result, using special equipment of the time, it was found that the athlete reaches a maximum VO2 of 4,080 liters per minute at a speed of 243 meters per minute.

The figure of 4,080 l / min was taken as the maximum for the reason that further increase in speed by the athlete did not lead to an increase in VO2.

As a result of the experiment, the scientists came to the following conclusion:

“During running, the oxygen demand steadily rises and reaches extreme values, while the true oxygen consumption can no longer be exceeded”

In fact, this was the first mention of the concept of oxygen debt or anaerobic running, which is often used in modern sports physiology.

How to determine VO2 max?

The maximum oxygen uptake is measured for every athlete who crosses the line of an amateur and becomes a professional. To measure VO2 max, you need special equipment, which is installed in many centers. sports medicine and physiology.

There are 2 ways to measure this indicator: laboratory (accurate) and using fitness trackers.

Laboratory method of measurementVO2max.

Before the start of the study, the athlete is put on an oxygen mask, with which he will breathe throughout the measurements. After that, the athlete gets on the treadmill and starts running. During the study, the running speed gradually increases, as well as the angle of the track.

The moment the athlete makes cyclic work, the researchers measure the remaining oxygen in the air that the athlete exhales. The measurement lasts until the athlete reaches the maximum level of physical activity. indicators of achievement maximum load serve:

• Speed;
• Breathing rate;
• Maximum heart rate.

When the subject can no longer continue the test, he shows the command to the doctor and treadmill stops. Thus, VO2 max is determined with high accuracy.

Measurement with fitness trackers fromGarmin andPolar.

The essence of this method comes down to simply following the instructions that are written specifically for measuring VO2 and only for a specific tracker model. This means that this method of measurement has nothing to do with the technique that is used in the laboratory.

When using a fitness tracker, all that is needed from the test subject is to buy a tracker and follow simple instructions.

To get results that will be as close as possible to the laboratory, you must follow 5 rules:

1. The environment should be calm. Any distractions must be eliminated. You can't talk to anyone. The rest of the test can be done at home, at work, or at a fitness club;
2. It is necessary to refrain from eating or smoking for 2-3 hours before testing;
3. Before turning on the test, you must lie down and relax for 2-3 minutes;
4. If re-testing is necessary, it is important that the environment and time of day are the same.

Based on numerous studies, the norm for men was determined - 45 ml / kg / min, and for women - 38 ml / kg / min. Interestingly, this figure for Ole Einar Bjoerndalen is 96 ml / kg / min. For example, in a horse, as in the most enduring animal - 180 ml / kg / min.

After using one of the methods you get the test result, you need to use table below to determine your aerobic fitness level.

Table of indicators for men.

Age	Extremely low	Short	Normal	Average	Good	Very good	Excellent
20-24	< 32	32-37	38-43	44-50	51-56	57-62
	< 31	31-35	36-42	43-48	49-53	54-59	> 59
30-34	< 29	29-34	35-40	41-45	46-51	52-56
	< 28	28-32	33-38	39-43	44-48	49-54	> 54
40-44	< 26	26-31	32-35	36-41	42-46	47-51
	< 25	25-29	30-34	35-39	40-43	44-48	> 48
50-54	< 24	24-27	28-32	33-36	37-41	42-46
	< 22	22-26	27-30	31-34	35-39	40-43	> 43
60-65	< 21	21-24	25-28	29-32	33-36	37-40

Table of indicators for women.

Age	Extremely low	Short	Normal	Average	Good	Very good	Excellent
20-24	< 27	27-31	32-36	37-41	42-46	47-51
	< 26	26-30	31-35	36-40	41-44	45-49
	< 25	25-29	30-33	34-37	38-42	43-46	> 46
35-39	< 24	24-27	28-31	32-35	36-40	41-44
	< 22	22-25	26-29	30-33	34-37	38-41	> 41
45-49	< 21	21-23	24-27	28-31	32-35	36-38
	< 19	19-22	23-25	26-29	30-32	33-36	> 36
55-59	< 18	18-20	21-23	24-27	28-30	31-33
	< 16	16-18	19-21	22-24	25-27	28-30

VO2 is heritable, meaning it is passed down from parents to children. This has positive and negative sides. On the one hand, having a high VO2 from birth is good, but on the other hand, people with a low VO2 at birth, even with long grueling workouts may not reach the same level.

What physical qualities are affected by VO2 max?

The rate of oxygen uptake from the air plays an important, if not decisive, role in achieving success in all sports with a cyclical focus and not only. The higher the VO2, the easier the athlete tolerates the load and recovers faster. In other words, this indicator has become almost the most important during the sports selection.

Main physical qualities that depend on this indicator are speed and speed-strength endurance. The higher the VO2 max, the longer the athlete can maintain maximum speed. In addition to these two qualities, this indicator plays a key role in determining the overall endurance of an athlete. This is largely why famous biathlete Bjoerndalen has such an impressive 96ml/kg/min, which is 51 points more than an untrained young man.

How to improve VO2max?

Any system of the body and its components can be improved by the right influence. In the case of an indicator of oxygen digestibility, you can use different kinds exercises that include:

• Running lessons;
• Fast walk;
• A ride on the bicycle;
• Skiing;
• Swimming.

We use running as an example, as the simplest and most accessible sport.

The best type of running, which will effectively increase the indicator we need, is. Therefore, to properly affect VO2, use the following workout option: 4-6 800-meter bursts at a fast pace, then transition to slow run. Or jogging at a high pace for 20 minutes.

Studies were also conducted that proved that this indicator develops more effectively in mountainous areas at an altitude of 1500 meters above sea level.

On our site - about the concept of VO2max, breathing while running and how this information can be usefully applied by an ordinary runner like you and me.

Runners of all levels, from enthusiastic amateurs to pros, are looking for ways to improve their training to improve their performance and break new records.

Running on long distances requires the athlete a large amount of endurance training to overcome constant physiological stress. Various ways manipulation of physiological parameters to improve endurance and performance in runners has been underway for more than 30 years, although a fair number of questions remain (1). Most of the techniques known today have emerged as a result of numerous trials and errors, and only a few of them have received a clear scientific justification (2, 3, 4).

For a long time, the maximum oxygen consumption (VO2max) indicator has been used as a kind of “magic bullet”, allowing you to build training based on its value and analyze the performance and progress of an athlete. But is it really that good, is it suitable for everyone, and can you rely on it?

It is believed that for every person who is passionate about running, VO2max (or VDOT for Daniels) actually determines his talent or potential. VO2max measures your maximum oxygen consumption (VO2max) and is one of the most commonly used metrics to track your progress in training. Of course, we all heard about the incredible VO2max numbers in many professional athletes: Lance Armstrong (84 ml/kg/min), Steve Prefontaine (84.4 ml/kg/min), Bjørn Dæhlie (96 ml/kg/min) and many others.

But is it necessary to pay such close attention to these figures? In short, no.

Contrary to popular belief, VO2max is just a measurement and does not represent an athlete's fitness or potential. In fact, among a few trained runners, it's impossible to determine the fastest runner based on VO2max alone.

The measurement of VO2max does not very accurately reflect the most important processes of transport and utilization of oxygen in the muscles. Let's try to start by taking a closer look at this indicator, its components, as well as the impact that various stages of oxygen transport have on VO2max.

VO2max concept

The term "maximum oxygen uptake" was first described and used by Hill (5) and Herbst (6) in the 1920s (7). The main points of the VO2max theory were:

• There is an upper limit for oxygen consumption,
• There is a natural difference in VO2max values,
• High VO2max is essential for successful participation in races for medium and long distances,
• VO2max is limited by the ability of the cardiovascular system to carry oxygen to the muscles.

VO2max measures the maximum amount of oxygen used and is calculated by subtracting the amount of oxygen exhaled from the amount of oxygen taken in (8). Because VO2max is used to quantify aerobic capacity, it is influenced by a large number of factors along the long oxygen journey from the environment to the mitochondria in the muscles.

Formula for calculating VO2max:
VO2max \u003d Q x (CaO2-CvO2),

where Q is cardiac output, CaO2 is the oxygen content in arterial blood, CvO2 is the oxygen content in venous blood.

This equation takes into account the volume of blood pumped by our heart (cardiac output = stroke volume x heart rate), as well as the difference between the oxygen level in the blood flowing to the muscles (CaO2 - arterial oxygen content) and the oxygen level in the blood, flowing from the muscles to the heart and lungs (CvO2 - oxygen content in venous blood).

Essentially, the difference (CaO2-CvO2) is the amount of oxygen taken up by the muscles. While measuring VO2max is of little value for practical purposes, developing the ability to consume and utilize oxygen more efficiently has an impact on runner performance. The absorption and utilization of oxygen, in turn, depend on a number of factors that occur along the long path of oxygen.

The movement of oxygen from atmospheric air to the mitochondria is called the oxygen cascade. Here are its main steps:

• Oxygen consumption

The entry of air into the lungs
- Movement along the tracheobronchial tree to the alveoli and capillaries, where oxygen enters the blood

• Oxygen transport

Cardiac output - blood flows to organs and tissues
- Hemoglobin concentration
- Blood volume
- Capillaries from which oxygen enters the muscles

• Oxygen utilization

Transport to mitochondria
- Use in aerobic oxidation and electron transport chains

Oxygen consumption

The first step in the oxygen journey is to get it into the lungs and into the bloodstream. This part is mainly the responsibility of our respiratory system(Fig. 1).

Air enters the lungs from the oral and nasal cavities due to the pressure difference between the lungs and the external environment (in the external environment, the oxygen pressure is greater than in the lungs, and oxygen is “sucked” into our lungs). In the lungs, air moves through the bronchi to smaller structures called bronchioles.

At the end of the bronchioles special education- respiratory sacs, or alveoli. Alveoli is a place of transfer (diffusion) of oxygen from the lungs to the blood, or rather to the capillaries braiding the alveoli (Imagine a ball entangled in a web - these will be alveoli with capillaries). Capillaries are the smallest blood vessels in the body, their diameter is only 3-4 micrometers, which is less than the diameter of an erythrocyte. Receiving oxygen from the alveoli, the capillaries then carry it to larger vessels that eventually empty into the heart. From the heart through the arteries, oxygen is carried to all tissues and organs of our body, including muscles.

The amount of oxygen entering the capillaries depends both on the presence of a pressure difference between the alveoli and capillaries (the oxygen content in the alveoli is greater than in the capillaries), and on total capillaries. The number of capillaries plays a role, especially in highly trained athletes, as it allows more blood to flow through the alveoli, allowing more oxygen to enter the blood.

Rice. 1. The structure of the lungs and gas exchange in the alveolus.

Oxygen use or demand depends on running speed. As the speed increases, more cells in the leg muscles become active, the muscles need more energy to maintain the pushing movement, which means that the muscles consume oxygen at a higher rate.

In fact, oxygen consumption is linearly related to running speed (higher speed - more oxygen consumed, Fig. 2).

rice. 2. Dependence of VO2max and running speed. On the horizontal axis - speed (km / h), on the vertical axis - oxygen consumption (ml / kg / min). HR - heart rate.

The average 15 km/h runner is likely to consume 50 ml of oxygen per kilogram of body weight per minute (mL/kg/min). At 17.5 km/h, the consumption rate will rise to almost 60 ml/kg/min. If the runner is able to run at 20 km/h, the oxygen consumption will be even higher, around 70 ml/kg/min.

However, VO2max cannot increase indefinitely. In his study, Hill describes a range of changes in VO2 in an athlete running on a grass track with different speed(9). After 2.5 minutes of running at 282 m/min, his VO2 reached 4.080 L/min (or 3.730 L/min above the measured value at rest). Since VO2 at speeds of 259, 267, 271 and 282 m/min did not increase above the value obtained at a running speed of 243 m/min, this confirmed the assumption that at high speeds VO2 reaches a maximum (plateau), which cannot be exceeded, no matter how running speed (Fig. 3).

fig.3. Achievement of "equilibrium state" (plateau) for oxygen consumption at different paces of running at a constant speed. The horizontal axis is the time since the start of each run, the vertical axis is the oxygen consumption (L/min) above the resting value. Running speeds (from bottom to top) 181, 203, 203 and 267 m/min. The three lower curves represent the true equilibrium state, while in the upper curve the oxygen demand exceeds the measured consumption.

Today, the fact of the existence of a physiological upper limit of the body's ability to consume oxygen is generally accepted. This the best way was illustrated in the classic plot by Åstrand and Saltin (10) shown in Figure 4.

fig.4 Increase in oxygen consumption during heavy work on a bicycle ergometer over time. The arrows show the time at which the athlete stopped due to fatigue. The output power (W) for each job is also shown. The athlete can continue to perform work at 275 W output power for more than 8 minutes.

Speaking about the intensity of work, it is necessary to clarify one fact. Even at high intensity, blood oxygen saturation does not fall below 95% (this is 1-3% lower than that of a healthy person at rest).

This fact is used as an indicator that oxygen consumption and transport from the lungs to the blood are not limiting factors in performance, as blood saturation remains high. However, a phenomenon known as “exercise-induced arterial hypoxemia” has been described in some trained athletes (11). This condition is characterized by a drop in oxygen saturation of 15% during exercise, relative to the level of rest. A 1% drop in oxygen at an oxygen saturation below 95% results in a 1-2% decrease in VO2max (12).

The reason for the development of this phenomenon is as follows. The high cardiac output of a trained athlete leads to an acceleration of blood flow through the lungs, and oxygen simply does not have time to saturate the blood flowing through the lungs. For an analogy, imagine a train passing through a small town in India where people often jump on trains as they go. At a train speed of 20 km/h, say, 30 people can jump on the train, while at a train speed of 60 km/h, 2-3 people will jump on it at best. The train is the cardiac output, the speed of the train is the blood flow through the lungs, the passengers are the oxygen trying to get from the lungs into the blood. Thus, in some trained athletes, the consumption and diffusion of oxygen from the alveoli into the blood can still affect the value of VO2max.

In addition to diffusion, cardiac output, the number of capillaries, VO2max and blood oxygen saturation can be influenced by the breathing process itself, more precisely by the muscles involved in the breathing process.

The so-called "oxygen cost" of breathing has a significant effect on VO2max. In "ordinary" people with moderately intense physical activity approximately 3-5% of the absorbed oxygen is spent on respiration, and at high intensity these costs rise to 10% of the VO2max value (13). In other words, some part of the absorbed oxygen is spent on the process of breathing (the work of the respiratory muscles). In trained athletes, 15-16% of VO2max is expended on breathing during intense exercise (14). The higher cost of breathing in well-trained athletes supports the assumption that oxygen demand and performance-limiting factors are different between trained and untrained individuals.

Other possible reason The fact that the breathing process can limit the athlete's performance is the existing "competition" for blood flow between the respiratory muscles (mainly the diaphragm) and skeletal muscles(e.g. leg muscles). Roughly speaking, the diaphragm can “pull” on itself part of the blood that does not get into the muscles of the legs because of this. Because of this competition, diaphragmatic fatigue can occur at intensity levels above 80% of VO2max (15). In other words, with a conditionally average running intensity, the diaphragm may “get tired” and work less efficiently, which leads to depletion of the body with oxygen (since the diaphragm is responsible for inhalation, when the diaphragm is tired, its efficiency decreases, and the lungs begin to work worse).

In their review, Sheel et al showed that after including special breathing exercises, athletes showed improved performance (16). This hypothesis was supported by a study conducted on cyclists, when during 20 and 40 km segments, athletes developed global inspiratory muscle fatigue (17). After training the inspiratory muscles, athletes were found to improve performance on 20 and 40 km segments by 3.8% and 4.6%, respectively, as well as a decrease in respiratory muscle fatigue after the segments.

Thus, the respiratory muscles affect VO2max, and the degree of this influence depends on the level of training. For athletes over high level respiratory muscle fatigue and hypoxemia (lack of oxygen) caused by physical activity will be important limiting factors.

Because of this, well-trained athletes should use breathing training, while runners entry level, most likely, will not get the same effect from it.

by the most in a simple way training of the respiratory muscles, which is also used in clinics, is to exhale through loosely compressed lips. It is necessary to feel that you are exhaling with the entire diaphragm, start with slow and deep inhalation and exhalation, gradually increasing the exhalation speed.

Oxygen transport

Since the first experiments of A.V. Hill's VO2max measurement, oxygen transport has always been considered the main limiting factor for VO2max (18).

It has been estimated that oxygen transport (all the way from oxygen entering the bloodstream to being taken up by the muscles) affects VO2max by about 70-75% (19). One of the important components of oxygen transport is its delivery to organs and tissues, which is also influenced by a large number of factors.

Adaptation of the cardiovascular system

Cardiac output (CO) is the amount of blood ejected by the heart per minute and is also considered an important factor limiting VO2max.

Cardiac output is dependent on two factors - heart rate (HR) and stroke volume (SV). Therefore, to increase the maximum CO, one of these factors must be changed. The maximum heart rate does not change under the influence of endurance training, while the VR in athletes increases both at rest and during work of any intensity. The increase in SV occurs due to an increase in the size and contractility of the heart (20).

These changes in the heart cause an improvement in the ability to quickly fill the chambers of the heart. According to the Frank-Starling law, as the expansion of the chamber of the heart increases before contraction, the contraction itself will be stronger. For an analogy, imagine a strip of rubber being stretched. The stronger the stretch, the faster the contraction. This means that filling the heart chambers in athletes will cause the heart to contract more rapidly, and thus lead to an increase in stroke volume. In addition, long-distance runners have the ability to quickly fill the chambers of the heart at a high intensity of exercise. This is a fairly important physiological change, since normally, with an increase in heart rate, there is less time to fill the chambers of the heart.

Hemoglobin

Another important factor in oxygen transport is the ability of the blood to carry oxygen. This ability depends on the mass of red blood cells, erythrocytes, as well as the concentration of hemoglobin, which serves as the main carrier of oxygen in the body.

Increasing hemoglobin should improve performance by increasing oxygen transport to the muscles. Research clearly shows this relationship by examining how lower hemoglobin levels will affect performance ( 21Trusted Source ). For example, a decrease in hemoglobin levels in anemia leads to a decrease in VO2max (22).

So, in one of the studies, after a decrease in hemoglobin levels, a decrease in VO2max, hematocrit and endurance was observed. However, after two weeks, a recovery of baseline VO2max was noted, and hemoglobin and endurance remained reduced (23).

The fact that VO2max can be maintained at normal levels when hemoglobin levels are low raises a number of questions and demonstrates the vast adaptive capacity of the body, a reminder that there are a huge number of ways to optimize oxygen delivery to increase VO2max. In addition, the return of VO2max, but not endurance, to normal values ​​may indicate that VO2max and endurance are not synonymous.

At the other end of the spectrum are studies where hemoglobin levels were artificially raised. These studies have shown increases in both VO2max and performance (24). Eleven elite runners included in one study showed a significant increase in time to exhaustion and VO2max after blood transfusion and an increase in hemoglobin from 157 g/L to 167 g/L (25). In a study with blood doping that artificially increased hemoglobin, VO2max improved by 4%-9% (Gledhill 1982).

Taken together, all of the above facts suggest that hemoglobin levels have a significant impact on VO2max.

Blood volume

With an increase in hemoglobin, the blood becomes more viscous, since most of it contains red blood cells, and not plasma. With an increase in the number of red blood cells, viscosity increases and such an indicator as hematocrit increases. For analogues, imagine how water flows through pipes of the same diameter (this is an analogue of blood with normal hemoglobin and hematocrit) and jelly (hemoglobin and hematocrit are increased).

Hematocrit determines the ratio between red blood cells and plasma. With high blood viscosity, blood flow slows down, making it difficult and sometimes completely stopping the delivery of oxygen and nutrients to organs and tissues. The reason is that blood with high viscosity flows very “lazy”, and it may not get into the smallest vessels, capillaries, simply clogging them. Therefore, an excessively high hematocrit can potentially reduce performance by interfering with the delivery of oxygen and nutrients to the tissues.

In endurance training, the normal situation is an increase in both blood volume and hematocrit with hemoglobin, with an increase in blood volume of up to 10% (26). In medicine, the concept of the so-called optimal hematocrit has changed quite a lot of times, and disputes still do not subside, what level of this indicator is considered optimal.

Obviously, there is no unequivocal answer to this question, and for each athlete, the hematocrit level at which there is maximum endurance and performance can be considered optimal. However, it must be remembered that a high hematocrit is not always good.

Athletes who use illegal drugs (such as erythropoietin (EPO) to artificially increase red blood cells) will have very good endurance and performance. The downside of this can be a dangerously high hematocrit level, as well as an increase in blood viscosity (27).

On the other hand, there are endurance athletes who run with low hematocrit and hemoglobin levels, which in normal life can be a sign of anemia. It is possible that such changes are a response to the high-altitude adaptation of athletes.

Adaptation to highlands can be three different types (28):

• Ethiopia - maintaining a balance between blood saturation and hemoglobin
• Andes - an increase in red blood cells with a decrease in blood oxygen saturation
• Tibet - normal hemoglobin concentration with decreased blood oxygen saturation

Several adaptation options suggest that there are several ways to optimize blood counts. There is still no answer to the question of which of the options (low or high hematocrit) in sports has better oxygen delivery. Most likely, no matter how trite it may sound, the situation with each athlete is individual.

Another important parameter that plays a role during running is the so-called blood bypass.

This mechanism is useful when the muscles need more blood and oxygen with nutrients. If at rest the skeletal muscles receive only 15-20% of the total blood volume, then during intense physical activity, approximately 80-85% of the total blood volume goes to the muscles. The process is regulated by relaxation and contraction of the arteries. In addition, during endurance training, the density of capillaries increases, through which all the necessary substances enter the bloodstream. Capillary density has also been shown to be directly related to VO2max (29).

Oxygen utilization

Once oxygen has reached the muscles, it must be utilized. Mitochondria, the “energy stations” of our cells, are responsible for the utilization of oxygen, in which oxygen is used to produce energy. How much oxygen the muscles have absorbed can be judged by the “arteriovenous difference”, that is, the difference between the oxygen content in the blood flowing (arterial) to the muscle and the oxygen content in the blood flowing (venous) from the muscle.

In other words, if 100 units of oxygen flow in and 40 units flow out, then the arteriovenous difference will be 60 units - that is how much the muscles have absorbed.

The arteriovenous difference is not a limiting factor for VO2max for a number of reasons. First, this difference is quite similar between elite and non-professional runners (30). Secondly, if you look at the arteriovenous difference, you can see that very little oxygen remains in the vein. The oxygen content in the blood flowing to the muscles is approximately 200 ml of oxygen per liter of blood, while the outflowing venous blood contains only about 20-30 ml of oxygen per liter of blood (29).

Interestingly, the arteriovenous difference score can improve with exercise, which means more oxygen uptake by the muscles. Several studies have shown an increase in arteriovenous difference of approximately 11% with systematic endurance training (31).

Given all these facts, it can be said that although the arteriovenous difference is not a limiting factor in VO2max, important and useful changes in this indicator occur during endurance training, indicating a greater absorption of oxygen by the muscles.

Oxygen ends its long journey in the mitochondria of the cell. Skeletal muscle mitochondria are the site of aerobic energy production. In the mitochondria themselves, oxygen is involved in the electron transport chain, or respiratory chain. Thus, the number of mitochondria plays an important role in energy generation. In theory, the more mitochondria, the more oxygen can be utilized in the muscles. Studies have shown that the number of mitochondrial enzymes increases with exercise, but the increase in VO2max is small. The role of mitochondrial enzymes is to enhance the response in the mitochondria to greatly increase energy production.

In one study examining changes during and after exercise, mitochondrial power increased by 30% during exercise, while VO2max increased by only 19%. However, VO2max persisted longer than mitochondrial power after exercise was stopped (32).

Conclusions:

1. The VO2max indicator characterizes the maximum amount of oxygen used.
2. VO2max is used to quantify the capacity of the aerobic system.
3. For practical purposes, measuring VO2max is of little value, but developing the ability to consume and utilize oxygen more efficiently affects runner performance.
4. As the running speed increases, the muscles consume oxygen at a higher rate.
5. VO2max has an end point of growth, after which it reaches a plateau, or equilibrium state
6. The breathing process itself significantly affects VO2max.
7. Respiratory muscles influence VO2max, and the degree of this influence depends on the level of training.
8. The maximum heart rate does not change under the influence of endurance training, while the stroke volume in athletes increases both at rest and during work of any intensity.
9. The hemoglobin level has a significant effect on VO2max.
10. An excessively high hematocrit can potentially reduce performance by interfering with the delivery of oxygen and nutrients to the tissues.

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Scientists have been manipulating various physiological parameters for more than three decades to increase the effectiveness of training. However, there are still far more questions than answers. Many modern methods were created thanks to numerous mistakes, but at the same time, only a small part of them have a scientific basis.

For quite a long time, the indicator VO2 max (maximum oxygen consumption) has been used to build the training process and it is with its help that the performance and progress of an athlete is determined. However, the question often arises as to the need to use this parameter. Today we will tell you why VO2 max is important for runners.

VO2 max: what is it and how to decipher

People who are interested in running have probably heard about the incredible values ​​\u200b\u200bof this parameter in pro athletes. Let's say Lance Armstrong has a VO2 max of 84 ml/kg/min. However, the question arises - to what extent these figures can be trusted and whether it is worth doing it at all. If you do not go into scientific terminology, then the answer will be - no.

Contrary to popular belief, VO2 max is a simple measurement and cannot fully represent an athlete's fitness level or potential. If we use only this indicator to determine the fastest among several runners, then we will not be able to do this.

The fact is that this indicator is not able to accurately reflect the most important processes - the transport and utilization of oxygen in muscle tissues. To understand what this is about, you should learn more about VO2 max. That is what we are going to do now. For the first time the concept of "maximum oxygen consumption" was described and began to be used in the twenties. The main postulates of this theory were:

• There is an upper limit for oxygen consumption.
• There is a significant difference in VO2 max.
• To successfully overcome medium and long distances, an athlete must have a high VO2 max.
• The limiter of VO2 max is the ability of the cardiovascular system to deliver oxygen to muscle tissue.

To calculate this indicator, a simple subtraction of the amount of oxygen exhaled from the amount absorbed is used. Since VO2 max is used to quantify the volume of the aerobic system of athletes, it is influenced by various factors.

Today, scientists use the following formula to calculate this indicator - VO2 max \u003d Q x (CaO2 - CvO2), in which Q is cardiac output, CaO2 is the amount of oxygen in the arterial bloodstream, CvO2 is the amount of oxygen in the venous bloodstream.

The equation we are considering takes into account the volume of blood that is pumped by the heart muscle, as well as the difference in the amount of oxygen incoming and outflowing from muscle tissues. While VO2 max is not important for practical purposes, increasing this capacity has a definite impact on an athlete's performance.

In turn, the ability to absorb and utilize oxygen depends on various factors that can be seen along the entire path of oxygen movement through the body. To determine why VO2 max is important for runners, you need to understand the movement of oxygen from the lungs to the mitochondria. Scientists call this pathway the oxygen cascade, which consists of several stages.

1. oxygen consumption. After inhalation, oxygen enters the lungs and travels through the tracheobronchial tree, eventually entering the capillaries and alveoli. With their help, oxygen is in the bloodstream.
2. Transportation of oxygen. The heart muscle ejects blood, which enters the organs and tissues of our body. Through a network of capillaries, oxygen enters the muscles.
3. Utilization of oxygen. Oxygen is delivered to the mitochondria and used for aerobic oxidation. In addition, he takes an active part in the electrolyte transport chain.

Influence of the respiratory system on VO2 max?

The human respiratory system is responsible for the supply of oxygen to the blood. From the oral and nasal cavities, air enters the lungs and begins its movement through the bronchi and bronchioles. Each bronchiole at the end has special structures - alveoli (breathing sacs). It is in them that the diffusion process takes place, and oxygen finds itself in a network of capillaries that tightly braid the alveoli. The oxygen then moves into the larger blood vessels and ends up in the mainstream.

The amount of oxygen coming from the respiratory sacs into the capillaries directly depends on the pressure difference between the vessels and the alveoli. Also of great importance here is the number of capillaries, which increases as the athlete's fitness increases.

It is quite obvious that the amount of oxygen used directly depends on the speed of running. The higher it is, the more actively the cellular structures of muscle tissues work and they need more oxygen. An average-trained athlete develops a speed of about 15 km / h and consumes about 50 milliliters of oxygen per minute for every sour body weight.

But VO2 max cannot increase indefinitely. In the course of research, it was found that at a certain speed a plateau occurs, and the indicator of maximum oxygen consumption no longer increases. The presence of this peculiar physiological boundary has been proved in the course of numerous experiments and is beyond doubt.

If you want to know why VO2 max is important for runners, then one important factor to consider is training intensity. Even if an athlete works hard, oxygen saturation cannot drop below 95 percent. This tells us that oxygen uptake and transport from the lungs to the bloodstream cannot limit an athlete's performance because the blood is well saturated.

At the same time, scientists discovered a phenomenon called “arterial hypoxia” in experienced runners. In this condition, blood oxygen saturation can drop to 15 percent. There is a direct relationship between VO2 max and blood oxygen saturation - a decrease in the second parameter by 1 percent leads to a drop in the second by 1–2%.

The cause of the phenomenon of "arterial hypoxia" has been established. With a powerful cardiac output, the blood quickly passes through the lungs, and does not have time to be saturated with oxygen. We have already said that the number of capillaries in the alveoli, the rate of the diffusion process and the force of cardiac output affect the VO2 max. However, here it is necessary to take into account the work of the muscles involved in the breathing process.

This is due to the fact that the respiratory muscles also use oxygen to do their work. During training for an experienced athlete, this figure is about 15-16 percent of the maximum oxygen consumption. There is another reason for the ability of the breathing process to limit the performance of a runner - competition for oxygen between the skeletal and respiratory muscles.

Simply put, the diaphragm is able to take some of the oxygen, which as a result will not reach the muscles of the legs. This is possible when the intensity of running is 80 percent of VO2 max. Thus, a conditionally average running intensity can cause diaphragm fatigue, which will lead to a drop in the oxygen concentration in the blood. Studies have proven the effectiveness breathing exercises to improve the performance of runners.

How does oxygen transport affect VO2 max?

Almost since the introduction of VO2 max, scientists have been confident that oxygen delivery can limit VO2 max. And today this influence is estimated at 70-75 percent. It should be recognized that the transport of oxygen into tissues is affected by many factors.

First of all, we are talking about the adaptation of the heart muscle and the vascular system. One of the strongest limiters of VO2 max is considered to be cardiac output. It depends on the stroke volume of the heart muscle and the frequency of its contractions. The maximum heart rate cannot be changed during training. But the stroke volume at rest and under the influence physical activity is different. It can be increased by increasing the size and contractility of the heart.

The second most important factor in the transport of oxygen is hemoglobin. The more red cells in the blood, the more oxygen will be delivered to the tissues. Scientists have done a lot of research on this topic. As a result, we can safely say that the concentration of red cells in the blood has a significant impact on the VO2 max.

In fact, this is why many athletes use drugs to speed up the process of producing red cells. They are often referred to as "blood doping". Too many scandals big sport was associated with the use of these funds.

How to increase VO2 max?

by the most fast way increase in this indicator is running for six minutes with maximum speed. Your training process in this case it might look like this:

• Warm up for ten minutes.
• Run for 6 minutes at maximum speed.
• 10 minute rest.

However this method is not the best, because the athlete can be very tired after such a workout. It is better to apply a little less effort in a certain time period, which will be separated by recovery periods. We suggest starting training with a 30/30 scheme. After a ten-minute warm-up (jogging), work at maximum intensity for 30 seconds, and then move at a slow pace for a similar period. To increase VO2 max, the 30/30 and 60/60 regimens are optimal.

If you have sufficient training experience, then you can use the so-called lactate intervals. After warming up at a high pace, cover a distance of 800 to 1200 meters and go to a slow run (400 meters). However, we recall that lactate intervals can only be used by well-trained runners.

Surely you have heard of such an indicator - VO 2 max, especially if you are fond of running or triathlon. We understand what it is with the help of a chapter from the book “Cardio or Strength”.

VO 2 max - this term invariably pops up as soon as it comes to any sports competition, requiring enormous endurance, for example, about the Tour de France cycling race. VO 2 max means maximum oxygen consumption. That is, VO 2 max means the maximum amount of oxygen that you are able to transfer to the muscles when you are doing extremely intensive. The logic here is simple: the more oxygen your body can process, the faster you will run. Therefore, many athletes are looking for an opportunity to get a VO 2 max test at universities and laboratories, where it costs $100-150.

How to measure VO2 max

Usually this test goes like this: a person begins to train on a treadmill or on an exercise bike at moderate pace, and then gradually accelerates and after 10-12 minutes reaches the maximum level of intensity. The amount of oxygen that the subject consumes (measured using tubes in the mouth) increases as he accelerates, and usually levels off shortly before stopping: this is the signal that the individual VO 2 max level has been reached. .

Some scientists believe that this happens when the heart pumps oxygen-rich blood to the muscles as quickly as possible; others believe that everything comes from the individual characteristics of the muscles. A more modern theory says that these limits cannot be explained from the point of view of physiology at all, since in this case everything is dictated by the instinct of self-preservation and is regulated by the brain.

Sure, professional endurance athletes usually have a higher VO2 max than so-called weekend fighters, but it's not for the reasons you might think. There is a common misconception that, supposedly, as a person acquires a good physical form, his heart begins to beat faster, which means it pumps more oxygen. In fact, high-level professionals tend to have lower heart rates than non-athletes. It's just that their heart muscles are bigger and more flexible, able to eject more blood with every powerful beat.

The volume of blood pumped by an athlete's heart can vary from 5 liters per minute at rest to 30 liters per minute at the limit of physical activity - and this is twice Furthermore level that an untrained person can achieve. (The highest documented figure was 42.3 liters per minute; it belongs to the master of sports international class orienteering.)

Differences in VO 2 max levels are partly due to simple genetics, and partly due to intense training. The average adult male will have a VO2 max of between 30 and 40 ml/min/kg, and in an adult woman - from 25 to 35 ml / min / kg.

VO 2 max of the famous cyclist Lance Armstrong during his victory in the Tour de France, according to Edward Coyle, a sports physiologist at the University of Texas, was at least 85 ml / min / kg. “We estimate that even if Lance lay motionless on the couch in front of the TV all day, his VO 2 max would not drop below 60 ml/min/kg,” Coyle wrote in the study report. “At the same time, if a typical university student trained intensively for two or more years, his VO 2 max would still not rise above 60 ml/min/kg.”

Despite a very impressive figure, it would be a mistake to conclude that Armstrong's victory was the result of a high VO 2 max, since many of his competitors had the same figure. Coyle believes that Armstrong's success can be explained by the fact that his efficiency increased by 8% between 1992 and 1999, although other scientists dispute these findings. Physiologists agree only that (fortunately for sports fans) based on measurements and calculations made in the laboratory, even the most accurate, complete and comprehensive, it is impossible to predict who exactly will win the competition.

So what does the measurement of VO 2 max give, in addition to the elementary satisfaction of curiosity? Comparing the results of several tests conducted over a long period of time allows you to track whether a person is improving their performance. However, as you understand, it is quite possible to notice this without any laboratories: it is quite enough, say, to participate in competitions. Experts generally recommend that athletes measure their lactate threshold: This test provides much more useful practical information than the VO 2 max test.

What is lactate threshold and should I check mine?

Although scientists are still arguing about what the physiology of the lactate threshold is and how it should be correctly determined, the essence of the phenomenon in this case is extremely clear.

If you're in pretty good shape and run or bike at a slow pace, you'll feel like you can keep doing it for hours. If you run or ride too fast, you will probably feel uncomfortable and want to stop or slow down after a few minutes. Somewhere between these two extremes there is a point after which the body starts burning energy (it happens at a pace that a person cannot sustain for long), and this point is characterized by a sharp jump in the rate of formation of lactate in the blood.

The lactate threshold corresponds to the pace at which you can work for approximately an hour., and is accompanied by other physiological changes: for example, you begin to breathe heavily, and therefore, as a rough method for determining your threshold, you can use the "talking test" (a pace at which you can also talk without panting). The pace at which you move when you reach the threshold is the most reliable of all the parameters that scientists have at their disposal today, by which they can predict how you will perform in competition.

In addition, this is a valuable hint with which you can calculate at what speed you are best to run (ride) during classes. That is why many athletes regularly do a lactate threshold test to track progress and adjust the training process.

Initially, scientists mistakenly believed that lactate is harmful product activity that causes pain and fatigue. However, as it turned out, they confused the cause with the effect. Lactate levels rise when your muscles are oxygen deficient or forced to burn energy less efficiently because they don't get enough oxygen; but in reality lactate is more of a fuel than a metabolic product.

However, you can use an increase in blood lactate as a rough indicator of when your body stops relying primarily on aerobic metabolism (when your muscles get enough oxygen to keep moving) and switches to anaerobic metabolism (when your muscles no longer get enough oxygen). oxygen and you can't keep moving without a time limit).

Like the VO2 max test, the lactate threshold test (usually 20 minutes to an hour) is done on a treadmill or stationary bike. At the same time, the speed is constantly increasing, on average this happens every 5 minutes. At the end of each such period, blood is taken from the test subject for analysis from a finger or earlobe. The absolute values ​​of the amount of lactate are not very significant and depend on many parameters (for example, they may fluctuate depending on what you ate before).

An important indicator in this case is your speed (and heart rate) from the moment when lactate levels begin to rise significantly. This will be your lactate (anaerobic) threshold.

In 2009, Sports Medicine published a review of 32 studies on the relationship between lactate threshold and performance in competitive running, cycling, race walking and rowing.

The results showed that the lactate threshold test was much more accurate than the VO 2 max test at predicting performance—between 55% and 85% of race runs on various distances(from 800 m to marathon).

Moreover, the lactate threshold is just an ideal parameter for tracking the effectiveness of training. Adam Johnson, trainer and director of the Toronto Endurance Research Lab, recommends that athletes get their lactate threshold tested every 4 months. “When a person sees significant changes after 4 months of training, it gives him confidence in his abilities,” he says. “In addition, the test helps to detect if something is not working and correct the situation.”

Of course, there are many other ways to track the effectiveness of training, starting with a modest stopwatch. Changing the lactate threshold is more likely to interest those who crave objectivity, have a weakness for advanced technology and have always dreamed of catching up with Lance Armstrong. Today, such studies are widely available.

“There is a misconception that only serious athletes, elite professionals, can take this test,” says Johnson. “However, in fact, we are approached by many different people who are going to achieve certain results in sports, and we successfully help them all.”