VO2 Max: Everything You Need To Know

Disclaimer: none of the information in this article should be used as medical advice or opinion. It is for general education.

The Significance of VO2 Max in Exercise Science

If I were to ask you how strong you are, you might reply with the amount of weight you can bench press or the number of pushups you can do. But quantifying cardiorespiratory fitness is not as simple.

While some people may know their mile time, that measurement is more about speed than physiology.

Exercise scientists, however, have a powerful tool to gauge cardiorespiratory fitness VO2, which stands for the volume of oxygen consumed by the body per minute.

Not only does VO2 allow us to assign a number to our cardiovascular fitness, but it also serves as one of the most reliable predictors of heart disease and mortality.

What is VO2 Max and How is it Measured

VO2 is measured in milliliters per kilogram per minute, representing the amount of oxygen consumed per minute per kilogram of body mass. This relative VO2 allows for comparisons across different body sizes.

Alternatively, we can calculate absolute VO2 by omitting body weight. Some refer to this measurement as "oxygen consumption."

So, what actually consumes oxygen when we measure VO2?

The primary culprit is the mitochondria in our body's tissues. Mitochondria are known as the powerhouse of the cell because they utilize oxygen to generate energy.

However, people can have varying degrees of mitochondrial efficiency, and mitochondria become less efficient as we age.

Additionally, different organs have different quantities of mitochondria and oxygen consumption rates. For instance, our hearts consume 11% of the oxygen in our bodies, even though they only account for about six-tenths of a percent of our total mass.

Our brains, on the other hand, consume 20% of our oxygen while representing only 2% of our body weight.

Surprisingly, muscles, which constitute about half of our body weight, only consume 27% of our total VO₂ at rest.

However, during exercise, the muscles demand more oxygen, causing overall VO2 to increase.

To calculate VO2 during exercise and at rest, exercise scientists use the Fick Equation: VO2 equals cardiac output times the arteriovenous oxygen difference.

Let's break this down.

Think of systemic circulation as an all-you-can-eat sushi restaurant with a conveyor belt delivering sushi every minute.

The hungry patron represents the oxygen-hungry tissues in the body, and the plates are red blood cells carrying oxygen through the blood vessels (conveyor belt).

To measure the patron's consumption, we count the sushi on one side of the belt and then on the other side, subtracting the difference to determine the amount eaten!

Similarly, in the human body, we can compare the amount of oxygen in our arteries to that in our veins, and the difference is called the arteriovenous oxygen difference (a-VO2 difference).

At rest, this difference is around 4mL of oxygen per 100mL of blood, but during intense exercise, it can increase to about 16mL difference.

This signifies that tissues, especially skeletal muscles, consume more oxygen from the blood during exercise, resulting in a higher a-VO2 difference.

The Importance of VO2 Max For Runners

To meet the oxygen demand during exercise, the body increases stroke volume (the amount of blood pumped out of the left ventricle with each pump) and heart rate.

However, there's a limit to how much oxygen can be delivered to the tissues, known as VO2 max.

This is the maximum capacity of our cardiovascular system to supply oxygen to the working muscles. VO₂ max represents the peak of aerobic performance, and it plays a significant role in gauging overall cardiorespiratory fitness.

Now, let's address why VO2 is so important.

First and foremost, VO2  max is the most representative measure of cardiorespiratory fitness available.

While there are various tests that rank fitness based on different scales and percentiles, they lack direct physiological measurements.

VO2, on the other hand, provides a direct assessment of oxygen transportation from the lungs to the muscles and its utilization for work.

The second reason for the importance of V02 is its correlation with heart disease.

‍Studies have consistently shown that individuals with low VO2 are at a higher risk of heart disease and mortality, independent of other risk factors such as obesity, type 2 diabetes, or high blood pressure.

Improving VO₂ by even a small amount can lead to a significant increase in the chances of survival, making it a valuable modifiable risk factor!

What’s a good VO2 Max

VO2 max numbers vary from person to person. Factors like age, gender and fitness level will affect your VO2 max number.

Check follow tables as a generic guidelines.

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How to improve VO2 Max

You can increase and improve your VO2 max in two ways:

1. By increasing the amount of blood your heart can pump;
2. By increasing how much oxygen your muscles can take up.

The following tips may help you develop these two components!

Opt for High-intensity Intervals

You can train your VO2 max most efficiently by working at a high intensity.

Many running coaches recommend training at around 90 to 95 percent of your maximum heart rate.

Working near your max heart rate helps strengthen the muscles in your heart and increase the volume of bloodTrusted Source it can pump with each beat.

You can approximate your maximum heart rate by subtracting your age from 220.

Hill Training

Find a hill in your neighborhood or nearby with a good grade — something challenging but not overwhelming.

Run as hard as you can up the hill, then run slowly downhill until you get back to where you started. Repeat the process at least ~4 times.

Combine Interval And Continuous Training

Incorporating both continuous training and interval training in your workout program may be more effective than only performing one of the two.

Many of the studies Trusted Source that have found the largest increase in VO2 max have used a 10-week training program consisting of six workouts per week.

In the studies, participants performed intervals and continuous running on alternate days.

On interval days, they performed six 5-minute sessions on a stationary bike at a workload close to their VO2 max separated by 2 minutes of recovery between each interval.

On continuous running days, participants ran as far as possible for 30 minutes per day the first week, 35 minutes the second week, and for at least 40 minutes during the remaining weeks.

It’s worth noting that this program is quite intense and is only suitable for people who are already fit.

In the first study to use this program, participants continued to see increases in VO2 max at the end of the study, but participants started to drop out because of the difficulty of the training.

Conclusion

VO2 Max is a critical metric for understanding cardiovascular fitness and predicting the risk of heart disease. As we continue to explore exercise physiology, there are various topics we can delve into, from VO2 measurement and graded exercise testing to aerobic exercise adaptations and the effects of training on VO2 Max!

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