To move, think, digest food, and do anything in general, the human body needs oxygen. Therefore, maximum oxygen consumption (MOC) is a potentially useful indicator for determining fitness. It can now be measured and evaluated by fitness trackers and other wearable electronics. They all learned to record the amount of oxygen consumed during training. The higher this indicator, the better the physical fitness, the process of recuperation, and the general state of health. Is it being judged correctly by gadgets? Good question.
What is VO2 max
VO2 max (VO2 max) is the maximum oxygen consumption (maximum aerobic capacity). It is equal to the amount of oxygen that the body can consume in one minute per kilogram of body weight (ml/kg/min). Its growth means delivering more oxygen to the muscles during physical activity. The BMD index is interconnected with several different factors: the amount of oxygen consumed with each breath, the amount of oxygen consumed by tissues from the blood, the number of red blood cells, the maximum cardiac load, and so on.
How long you can do cardio workouts depends on your VO2 max: run long distances, ride a bike, use the appropriate equipment in the gym. This indicator is closely related to the type of energy system that the body is currently using. When the available energy reserves in muscles and blood are depleted in simple terms, the source of strength changes – fat burning begins. It continues as long as the pace is kept constant. Therefore, the higher the VO2 max, the longer it can take.
However, if you try to run faster than your BMD allows, your heart rate will exceed the limit at which the body will be forced to return to an energy system that relies on available energy supplies. As a result, there will be a gradual accumulation of hydrogen in the muscles, which will cause the athlete to slow down, slow down and slow down again. Thus, the VO2 max is directly related to the anaerobic threshold – the point at which the transition to less efficient energy systems occurs. In short, if your BMD is high, you will be able to burn fat longer and more efficiently.
BMD is also related to the density of mitochondria, the energy factories of cells responsible for about 95% of energy requirements. They convert fat, glucose, and amino acids into usable energy, producing adenosine triphosphoric acid (ATP), a universal type of energy for all biochemical processes.
During exercise, the number and efficiency of mitochondria in each muscle change. If you run a lot for long distances, there will be more of them in your legs. Rowers use their arms more, so they gather there – the latter’s VO2 max will be higher during rowing and not while running, despite their excellent general physical shape.
Since muscles are actively used during daily activities, it is not surprising that higher BMD levels improve overall health. For example, the brain works better when more oxygen is consumed, and this, in turn, increases professional productivity, regardless of the chosen mental activity.
How is BMD measured in the laboratory?
From all of the above, it is easy to guess that the MPC is a rather complex indicator to calculate since it depends on a mass of a wide variety of factors. The only way to get a truly accurate VO2 max reading is to visit a sports medicine laboratory and take a series of expensive tests.
During the study, the athlete is asked to work out on a treadmill or use an exercise bike. By constantly increasing the load, the body is gradually brought to complete exhaustion. During this time, the equipment takes a series of measurements. It evaluates the efficiency of ventilation of the lungs, fixes the concentration of oxygen in the inhaled air and carbon dioxide in the exhaled air. In other words, it accurately measures how much air is inhaled and how much oxygen from it enters the body. When the amount of oxygen consumed remains unchanged, the maximum value of the VO2 max is obtained despite the increase in load.
How fitness trackers measure VO2max
Fitness trackers (for example, Fitbit and Garmin) suggest measuring your VO2 max without laboratory tests. To do this, they use, to a greater extent, only software algorithms. Therefore, the accuracy of such measurements should be treated with a grain of healthy skepticism. On the other hand, some methods allow you to determine the IPC using simple equations and tests that can be done at home. Fitness trackers rely on something similar.
Heart rate assessment. One method for determining the VO2 max measures the heart rate at rest and maximum load. In this case, the ratio of these values is used, and also age, gender, possible diseases, and so on are taken into account.
Cooper’s test. It requires the athlete to run as far as possible for 12 minutes. After that, the VO2 max is assessed based on the distance covered. Unfortunately, this method does not consider the strength of the legs and the length of the stride, so it is also difficult to call it too accurate.
Interval test. As the name implies, it determines the VO2 max during an interval run of 20 meters from one point to another back and forth. At the same time, the athlete needs to keep within the time intervals, which are determined by sound signals and are constantly decreasing, forcing to increase the speed.
Walk test. After all, a couple of kilometers of walks are also arranged to assess the VO2 max. After them, the pulse is measured, which enters the algorithm and body weight, age, gender, and other factors.
Of course, all the methods described above, which are used in one form or another by fitness trackers, determine VO2 max. Moreover, at least to some extent, this indicator will be assessed only after several measurements of runs and walks. It should also be understood that fitness trackers, in principle, cannot have all the necessary information to determine the VO2 max – they do not know what physical form the user is in and do not follow the history of his bad habits.
However, fitness trackers do have a ton of data that can be taken into account when assessing VO2 max. For example, they can track heart rate during exercise and rest, measure stride length. They are also able to estimate the oxygen level in the environment using GPS and an altimeter.
It is a pity that most companies do not disclose the algorithms they use to estimate the VO2 max. This may be partly due to fear of competitors who also keep their best practices secret. But it is more likely that all this secrecy is needed to avoid criticism that could question the data’s reliability. This is why companies are cleverly using alternative names for their maximum oxygen consumption (VO2 max) readings – what Fitbit calls a cardiac fitness score, for example.
However, consistency is more important than accuracy, so tracking your BMD progress with the same assessment method is a great motivation for exercising regularly. Of course, this will not work for professional athletes, but specifically, they probably have access to full-fledged laboratory tests.
What is the BMD indicator that can be considered normal for yourself
In professional athletes, the VO2 max can be as high as 80 ml/min/kg, and animals like the Alaskan husky can even reach 200 ml/min/kg. For the rest, values on average from 30 to 60 are considered normal.
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How to raise your maximum oxygen consumption
High-intensity interval training. In this case, the muscles are constantly subjected to maximum stress. However, if you don’t have enough strength for a high rhythm, you can start jogging, improving cardiac activity and VO2 max.
Threshold training. It includes running at the fastest speed available. At the same time, hydrogen does not accumulate in the muscles, but lactate is produced, which allows you to break down glucose and produce energy.
In general, to increase the VO2 max, no matter how electronics manufacturers call it today, it is important to exercise regularly. That’s the whole secret.