What is VO2max and how does the respiratory system work when running. VO2 max is an indicator of the level of running training. What affects V02 max

The Polar Fitness Test is simple, fast and safe way Assess your aerobic fitness (cardiovascular function) at rest. The result, Polar OwnIndex, corresponds to your maximum oxygen uptake (VO 2max), which is usually an indication of your aerobic fitness. The OwnIndex value is also affected by your training experience, heart rate, resting heart rate variability, gender, age, height, and body weight. The Polar Fitness Test is intended for healthy adults.

Aerobic fitness is a measure of how well your cardiovascular system transports and uses the oxygen that enters your body. The better your aerobic condition, the stronger your heart and the more efficient it works. A good aerobic state has a beneficial effect on overall health. For example, it reduces the risk of hypertension, cardiovascular disease and stroke. If you want to improve your aerobic fitness, it will take you an average of six weeks of regular training to see significant changes in your OwnIndex. If you are not in very good physical shape initially, you will see progress even faster. The better your aerobic condition, the less your OwnIndex will change.

To improve aerobic condition, training is optimal that involves large groups muscles. These include running, cycling, walking, rowing, swimming, skating and cross-country skiing. To track your progress, measure your OwnIndex two times during the first two weeks, and then repeat the test about once a month.

To ensure the reliability of the test results, the following basic conditions must be met:

• You can perform the test in any conditions: at home, at work, in a fitness center; however, a calm environment must be ensured. Eliminate any disturbing noise (TV, radio, phone sounds); you don't have to talk to anyone.
• A repeat test should be carried out under the same conditions, at the same time of day.
• For 2-3 hours before the test, refrain from heavy food and smoking.
• On the day of the test and the day before, refrain from excessive exercise, alcohol, and stimulant medications.
• Relax and calm down. Lie still for 1-3 minutes.

Before the test

Please note that you can only take the test if you have configured the A300 device Online flow.polar.com/start .

The fitness test only works with compatible Polar heart rate sensors. Fitness Test is Polar's own smart training feature that requires an accurate measurement of your heart rate variability. That is why a Polar heart rate sensor is needed.

Before starting the test, check that the data you have entered in the Flow web service is correct.

Conducting a test

1. Go to menu Fitness Test > Start Testing. Your A300 will start searching for your heart rate sensor. The display will show Heart rate sensor found And Lie down and relax. The test starts.
2. Lie down, stay relaxed, limit body movements and contact with people. As the test progresses, the bar on the A300 will fill up.
3. When the test is completed, Test completed will appear and the test results will be displayed.
4. Press the DOWN button to see the VO 2max value. Press the START button and select Yes to update the VO 2max value displayed in the Polar Flow web service.

You can stop testing at any time by pressing the BACK button. Test canceled appears on the display.

Troubleshooting

• The inscription is displayed Touch the sensor with the A300 if the A300 cannot find the heart rate sensor. Tap the sensor on your A300 to find the sensor and pair it.
• Could not find heart rate sensor. Check if the heart rate sensor electrodes are wet and if the belt is tight enough.
• If the A300 cannot find the heart rate sensor, it will display Polar HR sensor required.

Test results

The result of the last test can be viewed in the menu Fitness Test > Test Results. You can also view your results in the Training Diary in the Flow app.

For a visual analysis of your fitness test results, use the Flow web service, where you can view detailed information about your test from the Diary.

Physical state level classes

Men

Age / Years	Extremely low	Short	Satisfactory	Average	Good	Very good	Excellent
20-24	< 32	32-37	38-43	44-50	51-56	57-62	> 62
25-29	< 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	> 56
35-39	< 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	> 51
45-49	< 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	> 46
55-59	< 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	> 40

Women

Age / Years	Extremely low	Short	Satisfactory	Average	Good	Very good	Excellent
20-24	< 27	27-31	32-36	37-41	42-46	47-51	> 51
25-29	< 26	26-30	31-35	36-40	41-44	45-49	> 49
30-34	< 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	> 44
40-44	< 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	> 38
50-54	< 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	> 33
60-65	< 16	16-18	19-21	22-24	25-27	28-30	> 30

The classification is based on a review of 62 studies that directly measured VO2max in healthy adults in the US, Canada, and 7 European countries. References: Shvartz E, Reibold RC. Aerobic fitness norms for males and females aged 6 to 75 years: a review. (A study of the norms of the aerobic state in males and females aged 6 to 75 years). Aviat Space Environ Med; 61:3-11, 1990.

Vo2max

There is an established relationship between maximum oxygen consumption (VO2 max) and cardiorespiratory endurance, since the amount of oxygen supplied to tissues depends on the work of the lungs and heart. VO2 max (maximum oxygen consumption, maximum aerobic capacity) is the maximum level at which the body is able to use oxygen at maximum exercise; it is directly related to the maximum capacity of the heart to deliver blood to the muscles. VO2 max can be measured or calculated using fitness tests (e.g. maximal exercise tests, submaximal exercise tests, Polar Fitness Test). VO2 max reliably reflects cardiorespiratory endurance and allows you to predict endurance during long runs, bike rides, cross-country skiing or swimming on long distances.

VO2 max can be expressed in millimeters per minute (ml/min = ml ■ min-1) or in millimeters per minute divided by weight in kilograms (ml/kg/min = ml ■ kg-1■ min-1).

Now I have a Garmin Forerunner 630, another perfect one running watch, like , only newer and in blue. They look a little more ... masculine (I had white and orange 620s). The set of functions of this watch will satisfy a runner of any level of advancedness (if you don’t believe it, everything is the same in the new ones, only even better) and there will probably be a few features in reserve that few will get to. Today is just about those.

VO2 Max, aka MPC
It was like this with me: I lived calmly and did not pay attention to the new VO2 Max value periodically popping up on the watch screen, and it appeared approximately every time the training was faster and more difficult than all the previous ones performed with this watch. But to determine this figure, people put on masks and run on the track. How can a watch know how it really is? Now, when I did a real ANMS and MIC test with a gas analyzer and lactate sampling, I know everything about myself. So you can compare the results!

“VO2 Max refers to the maximum amount of oxygen (in milliliters) per kilogram of body weight that you can absorb in a minute at maximum physical activity. In other words, VO2 Max is a measure sports training, which should increase as fitness improves” – definition from Garmin manual.

On August 27, on a test in the clinic, it turned out that my IPC, aka VO2 Max, is equal - in order to find out, I had to run up to a heart rate value of 206 beats per minute. Garmin Forerunner 630, with which I ran for about the whole summer, all my workouts and two nightly tens - and by that time managed to fix the number 52.

In the clinic, of course, I didn’t wear a watch, so the maximum heart rate that they (the watch) had to see with me was 197 beats per minute. Perhaps the fact that the IPC recorded by Garmin turned out to be lower than the real maximum is precisely due to the fact that I did not reach the maximum with it? I decided to ask Dr. Mikhail Nasekin what he thinks about all this. And Doc thinks so:

“You were right to point out the difference in heart rate: if you had kept your heart rate at 206 beats per minute in training for any long time, Garmin would write the VO2 Max value closer to the real one. But I am a supporter of making a conclusion about the correct / incorrect calculation based on statistics. Two, three, and even ten observations are not enough to draw a conclusion. In practice, most of those who accurately record all runs, the readings are the same + -2 ml / kg / min. But, I repeat, it is possible to assert that it actually exists or not after a full-fledged study. Then it will be reliable and relevant, and before that - all our fantasies. On the other hand, you will not (and no one will) do the maximum test every month. It will ruin all workouts. Therefore, Garmins are indispensable for assessing the dynamics of the IPC.”

So-so, dynamics, you say? Let's see what happened with VO2 Max before and after testing in the clinic.

On July 17, I reached the value of 52 ml / kg / min, after which for some time the indicator fluctuated between 51 and 52, and on September 25, at the satellite race of the Moscow Marathon, the clock recorded 53 ml / kg / min.

The record on the top ten could not be updated, but the watch recorded a new VO2 Max

In October, the figure has already changed twice (even without races) - first by 54, and then by 55. That's how the growth went! Isn't it time to get the MIC back on the gauges, Doc?

According to him, 55 for a girl of 20-29 years old is excellent, and even for a man very much. (This is me, like, boasting).

Such results predict me hours. Ten and marathon I have already run faster!

lactate threshold
Yes, Garmin Forerunner 630 are taken to guess lactate threshold. Sounds impressive, especially when the word "lactate" is associated with blood draw. But watches cannot scan blood, so in reality everything is much simpler.

The definition of the lactate threshold from the instructions looks like this:

“The lactate threshold is the intensity of exercise at which lactate (lactic acid) begins to accumulate in the bloodstream. When running, the lactate threshold indicates the level of effort. When an athlete exceeds this threshold, fatigue begins to arrive at an accelerated pace. For advanced runners, the lactate threshold corresponds to approximately 90% of maximum heart rate at a pace between 10K and a half marathon. For intermediate runners, the lactate threshold often corresponds to a heart rate below 90% of maximum. By knowing your lactate threshold, you will be able to determine the intensity of your training, as well as choose the right moment to snatch in competition.”

The watch tells the athlete two numbers - the pulse and the pace at which this threshold is reached. My Garmins thought I had it at 180 heart rate and 4:29 min/km pace. Dr. Nasekin did not agree with this:

“The definition of the lactate threshold from the instructions is not bad: it describes the situation and the physiology of what happens after it is overcome quite fully. There is an inaccuracy: Garmin calculates it from the maximum heart rate, which calculates either according to the formula HR Max = 220 - age, or from the HR Max value that you set with your hands. In fact, your lactate threshold is where PANO is, that is, at 196 beats / min. Oops!

The clock did not guess the lactate threshold. But! Firstly, they calculated it from the maximum heart rate = 202, which I myself once indicated (I’m already running to set the correct Max heart rate and see what happens). Secondly, my TANM was a little closer to the maximum heart rate (95%) than one might think. In any case, accuracy is not as important here as the ability to follow the dynamics : at the same lactate threshold pulse, the watch periodically updates the pace. It's nice when it grows.

The watch itself
In the box, here is a set of the device itself, a chest heart rate monitor HRM-RUN4 and a recharging cord:

There is a complete set without HRM - you can connect any other Garmin heart rate monitor to the watch, even an older model. But this one is the newest and most accurate. It is he who collects information about the pulse, as well as the length and frequency of steps, about the time of contact with the ground (each leg! It turns out that it can differ for the left and right), about the height of vertical oscillations (how high you jump while running. By the way, I jump as much as 8 cm!). Running statistics are mega-detailed, it can be considered and analyzed for a long time if you understand what's what.

In the "Running indoors" mode (for arenas, for the winter), GPS is turned off and the distance is determined using the accelerometer. I tried twice, the numbers were very close to the truth.

In addition to all the data, the watch evaluates the effectiveness of training, gives recommendations for recovery and easily replaces a fitness bracelet: if you wear it during the day, it will count the steps and will periodically remind you that it’s time to get up from your office chair and walk up the stairs, and if you also do not take them off at night, they will show how much you managed to sleep. When you carry your phone somewhere in your pocket with Bluetooth turned on, the watch displays all sorts of notifications - well, there are calls or messages in Telegram. So, looking at your watch, you can decide whether to answer or whether it can wait until the end of the run.

A photo posted by Lena Kalashnikova (@site) on Oct 25, 2016 at 11:03am PDT

Forerunner 630 is not only accurate, but also fast: you just have to go outside and press the button with the runner - and the GPS is immediately caught, and the heart rate monitor is found. No need to stand still and wait for a signal, you can immediately start training, which is especially important in cold autumn and winter. But most of all in Forerunner 630 I appreciate independence, namely, synchronization via wi-fi. What does it look like? And like this: I run home, do a hitch, and at this time the information about the run itself is sent to Garmin Connect, and at the same time to Strava and Nike+. You don't even have to do anything! It seems that I already wrote this ... Exactly, in.

And this is something else that is pleasant for owners of different Garmin devices: through the special Face-it application, you can put any photo on the screensaver of your watch and walk around to rejoice every time you look at the screen. So that.

The cost of watches at the time of publication of the material: from 29,890 rubles. without HRM-Run4 sensor and from 33,670 rubles. included with HRM-Run4 at www.garmin.ru

Photo: Andrey Morozov, Petr Tuchinsky, Marathon Photo

VO2 max, or maximum oxygen uptake (MOC), is one of the most common indicators of an athlete's fitness (especially cyclic sports). What it characterizes, what it depends on and how to increase it, you will learn by reading this article.

VO2 max shows maximum amount oxygen that the body can use within one minute and is measured in ml/min/kg. The higher this value, the more oxygen gets to the muscles, and the longer and faster you can run. Also, VO2 max affects cardio-respiratory endurance (this parameter determines how efficiently the heart and lungs provide the body with oxygen during prolonged physical activity).

There are two main factors that affect VO2 max:

The ability of the cardiovascular system to deliver oxygen-rich blood to working muscles. A high stroke volume (the amount of blood moving through the heart with each beat) as well as large elastic veins and arteries that can handle increased blood flow and a high heart rate increase VO2 max.

The body's ability to extract and use oxygen for energy. Aerobic energy production occurs in structures that are located in muscle cells and are called mitochondria. A muscle that has more mitochondria can use more oxygen and therefore produce more energy. There are also a number of muscle enzymes that help process oxygen. Endurance training can increase both the number and size of mitochondria in the muscles and the activity of enzymes.

Heart rate and VO2 max

During physical activity there is an increase in oxygen consumption and an increase in heart rate. Since these indicators are interrelated, they are often used to assess the level of cardio-respiratory endurance.

According to the American College sports medicine You can increase your VO2 max by exercising at 64-94 percent of your maximum heart rate for at least 20 minutes three times a week. People who have a higher BMD have also been found to have a lower resting heart rate, lower blood pressure, and are less likely to develop chronic disease.

How does body weight affect VO2 max?

Body Mass Index or BMI is a value that is commonly used to estimate body weight. A BMI value between 18.5 and 24.9 is normal, a value of 25 or more indicates overweight. When the BMI is over 30, the condition of the person is diagnosed as obese.

According to multiple studies published in the Journal of Sports Medicine and Physical Fitness, high BMI is often associated with lower VO2 max. This is primarily due to changes in the respiratory capacity of the lungs and the endurance of the cardiovascular system.

A study published in the journal Chest has shown an association between high BMI and impaired lung function. Scientists have found that when a BMI value reaches 30, functional residual capacity - the volume of air that remains in the lungs after a normal exhalation - decreases by 25 percent, and expiratory reserve volume - the extra volume that a person can exhale after a normal exhalation - by more than 50 percent. Although these two lung measurement functions are not present during normal breathing, they limit their ability to achieve maximum efficiency and result in a decrease in VO2 max.

Standard VO2 Max Ratings

These tables list the standard classifications for estimated VO2 Max values ​​by age and sex.

Other factors that affect VO2 max

Floor. Women have a lower VO2 max than men. This is because the latter have larger lungs and hearts, allowing them to pump more blood and consume more oxygen.

Age. Both sexes between the ages of 18 and 25 have a VO2 max that gradually decreases as they get older. From around age 25, VO2 max decreases by about 1 percent per year.

Genetics. Heredity directly affects what type of muscle fibers will prevail in your heart and what size your heart and lungs will be. Researchers at Cerritos College (California) found that genetics determines 20-30 percent of VO2 max.

Height above sea level. Low air pressure at high altitudes makes oxygen less available, and the oxygen tension in the arterial blood also decreases.

Temperature. Hot air contains less oxygen, which increases the risk of hypoxia and can also affect VO2 max.

Workout examples to increase VO2 max

Interval running 30/30 or 60/60

This method was created by the French physiologist Veronica Billat and is perfect for novice runners and those who have a modest physical form.

Do a light jog for 10 minutes, then run for 30 seconds at a race pace or at the fastest pace you can maintain for 6 minutes, then go back to easy running. Continue alternating fast and slow 30-second stretches until you've done 12-20 reps.

A more advanced workout option involves increasing the interval time to 60 seconds.

Interval uphill

Short uphill bursts of 20-90 seconds are great for developing power, strength and speed, longer ones (120-180 seconds) are great for increasing VO2 max.

Before starting a workout, warm up well and run lightly for 10-15 minutes.

Then, depending on your fitness level, run uphill for 2-3 minutes. Return to the starting point with an easy, recovery run. Do 3-4 reps. Try to calculate the forces in such a way that all segments are performed at the same pace.

Interval running at anaerobic threshold

Running at the ANSP level requires good physical condition and is recommended for advanced amateurs.

Best suited for this type of workout. athletics arena or stadium. Warm up well and run lightly for 10-15 minutes, then run 800m at a competitive pace, and switch back to easy running (400m).

Run a total of about 5000m fast run(6-7 x 800m, 5 x 1000m or 4 x 1200m).

Try to overcome all intervals with uniform intensity.

According to the site http://www.livestrong.com

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 sports medicine and physiology centers.

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.

At the moment when the athlete performs 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. The indicators of reaching the maximum load are:

• 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 exhausting workouts, may not achieve 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.

The main physical qualities that depend on this indicator are speed and speed-strength endurance. The higher the VO2 max, the longer the athlete can support top 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 the famous biathlete Bjoerndalen has such an impressive 96 ml / 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 influence VO2, use the following training option: 4-6 bursts of 800 meters at a fast pace, followed by a transition to a 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.

Long-distance running requires the athlete to do a lot 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 uptake (VO2max) and is one of the most commonly used metrics for tracking your workout progress. 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,
• A high VO2max is essential for successful participation in middle and long distance races,
• 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 system capacity, it is influenced by a large number factors on the long path of oxygen 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 take it to 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 the total number of 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, large quantity cells in the muscles of the legs 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 at different speeds (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 was best 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 “normal” people, moderate intensity physical activity consumes about 3-5% of the oxygen absorbed by breathing, and at high intensity, this cost rises to 10% of VO2max (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 during intensive loads 15-16% of VO2max is spent on breathing (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.

Another possible reason that the breathing process can limit an athlete's performance is the existing "competition" for blood flow between the respiratory muscles (mainly the diaphragm) and the skeletal muscles (eg, 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 being included in training cycle 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 higher level athletes, fatigue of the respiratory muscles 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, 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 the filling of the heart chambers in athletes will cause the heart to contract more rapidly, and therefore 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 demonstrated 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 other side of the coin can be dangerous high level hematocrit, 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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