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What is VO2 Max, Why Does It Matter, and How Is It Tested?

Written by Dr. Ruscio on February 11, 2023

Written by Dr. Ruscio on February 11, 2023 — Reviewed by Hannah Hamlin

• What is VO2 max?|
• Why You Need to Know|
• VO2 Max Testing|
• What Your Results Mean|
• Improving Your VO2 Max|
• VO2 Max Limitations|
• The Bottom Line|

A high level of cardiorespiratory fitness (in other words, a strong heart and healthy lungs) is crucial for great quality of life and healthy aging. But how do you know where you stand when it comes to cardiovascular fitness? The most well-validated estimate involves a VO2 max exercise test. This test calculates the oxygen consumption of your body during high-intensity activities.

For the most accurate result, this test should be done in a lab, but there are two at-home versions that can also give you a pretty good estimate of your VO2 max. The Cooper 12-minute run test and the 2,000-meter rowing test both correlate closely with the formal VO2 max lab test [1]. 

I had a great discussion with Dr. Mike T. Nelson on the podcast about VO2 max and both of these at-home tests. He shared that poor cardiovascular conditioning is pretty common. If you’re in this category, then your heart, the rest of your cardiovascular system, and your nervous system have to work harder around the clock. This translates into more fatigue, and intolerance to exercise and stress. So, I think a VO2 max test is great to complete whether you’re a seasoned exerciser or someone struggling with fatigue or a low level of physical fitness. Your results will give you insight into your overall cardiorespiratory health and if needed, can guide you in making improvements. 

In this article, I’ll answer the question, what is VO2 max? I’ll also describe the different VO2 max testing methods and provide you with simple strategies you can use to increase your level.

What is VO2 Max?

Before we get into the specifics, here’s a chart describing the commonly used terms VO2, VO2 peak, and VO2 max: 

VO2 is the shorthand term for oxygen consumption. The “V” stands for volume and the “O2” stands for oxygen, so VO2 = volume of oxygen [4]. VO2 is the rate at which oxygen goes from your bloodstream to the rest of your body, or said another way, it’s the amount of oxygen your body can “absorb” from the bloodstream [4]. Since oxygen is necessary for your cells to make energy, maximal oxygen consumption is going to make it easier for them to perform their important tasks. 

VO2 can be measured directly by breathing into a respirometer. A normal VO2 in a resting person is around 250 milliliters of oxygen per minute [4]. During aerobic exercise, pregnancy, and other conditions with high metabolic demand, VO2 increases because your cells need more oxygen to function under those conditions [4]. VO2 usually declines with age, approximately 10% every 10 years after the age of 30 [5].

When it comes to VO2 peak and VO2 max, some researchers use these interchangeably [6],  but others distinguish between the two like this [3]:  

• VO2 peak is the greatest amount of oxygen your body can take from the bloodstream when you’ve hit your exercise tolerance (made a good effort) but don’t push beyond it.
• VO2 max is the maximum amount of oxygen your body can take from the bloodstream when you’ve pushed beyond your exercise tolerance and reached a VO2 plateau that won’t go any higher with more effort.

So to answer the question, what is VO2 max? It’s the maximum amount of oxygen your tissues can consume during high-intensity exercise [2]. It makes sense that as your exercise intensity increases, so does your oxygen demand and consumption. In fact, during high-intensity exercises, your cardiac output (the liters of blood your heart pumps in 1 minute) can increase to as much as 5 times more than when you’re at rest. Your heart is working harder to push blood throughout your body – the end result being more capillaries (thin blood vessels) are created to move more oxygen [4]. At some point though, your cardiovascular system can’t keep up with the demand and you reach an oxygen uptake plateau [5].

VO2 max levels can range from 20 mL per kilogram of body weight per minute in patients with heart disease to more than 80 mL/kg of body weight per minute for athletes like cyclists and cross-country skiers participating in endurance sports [7]. Obviously, you want to be on the higher end of this range for optimal health and performance. If you’re on the lower end of the range, you’re at higher risk of chronic disease. So, let’s discuss what VO2 max can tell you about your health.

What is VO2 Max: Why You Need to Know

Knowing your own VO2 max is a good way to understand your aerobic fitness and aerobic capacity, but also your chronic disease risk [8, 9]. A 2021 observational study found people with a high VO2 max (despite body size or body composition) had lower risks of cardiovascular disease and all-cause mortality when compared to those with a lower VO2 max [10]. So, knowing this information is something that most people can benefit from.

Your VO2 max or VO2 peak can help you and your doctor better understand what’s going on in your body. For example, a doctor can use your VO2 peak to tell you whether you have good or poor heart and lung health [11]:

• Sign of good heart health: reaching a normal VO2 peak (good exertion without reaching VO2 max) and being limited by only breathing difficulties or fatigue.
• Sign of poor heart/lung health: being unable to reach a normal VO2 peak and having significant trouble breathing.

There may be issues with your heart, lungs, and circulatory health that you wouldn’t otherwise notice if you don’t routinely exercise or when at your resting heart rate [2, 12]. Being aware of your VO2 max or VO2 peak improves your chance of getting a useful diagnosis and treatment plan, if needed [2].

Now that you know what VO2 max is and why it’s important to know your level, let’s discuss the tests you can use to determine your VO2 max.

What is VO2 Max Testing?

If you have access to VO2 max lab testing in a clinic or hospital, this is the gold standard. Essentially, an exercise physiologist will fit you with an exercise mask, and then you’ll exercise (on a treadmill or stationary bike) until you reach your point of tolerance, and then you’ll push beyond that [3, 13]. The gasses you breathe in are collected and measured to give you a very accurate indication of your maximal oxygen uptake, which then gives you some great information about your cardiorespiratory fitness (2). 

However, hospital-based VO2 max testing usually isn’t recommended unless there is a concern from your physician, and many exercise enthusiasts don’t have easy access to other testing facilities. Instead, if you have the ability to run or use a rower [13], there are two at-home options for estimating VO2 max scores. Here’s a chart describing how you would perform both tests:

Both the Cooper’s run test and the rowing test are pretty accessible methods for learning about your VO2 max. Once you’ve completed one of these, you’ll need to know what your results mean, so let’s discuss how to interpret your numbers.

Interpreting Your VO2 Max Results

If you’ve completed either of these tests, you may be wondering what your results mean or what your VO2 max should be. For both of these tests, you can find general population data, which means you’re comparing yourself to the average population (not necessarily people who exercise routinely). Dr. Mike Nelson, a recent podcast guest, recommends a level of “good to average,” but optimally you want to be closer to the “excellent” category. You can take it a step further on the Concept2 rower test because you’ll be able to compare yourself to people who are already relatively physically active. So, this test gives you a better idea of how you rank against other people who are rowing routinely. 

Once you’ve got your VO2 max value, it’s time to put it into action. If you’re in the “excellent” category, then awesome job, you can continue with your current workout plan. If you’re below average (or even in the good-average category), there’s room for improvement.

One of the great things about VO2 max is your ability to optimize it. If you find your VO2 max is suboptimal, there are simple steps you can take to increase it, which will ultimately increase your fitness level (something everyone can benefit from) and decrease your likelihood of dying from a chronic disease (also desirable) [10, 15]. Let’s review some simple recommendations for how to improve your VO2 max.

Improving Your VO2 Max

If you’re new to physical activity, you’ve got to first build a base level of aerobic fitness. I’m a huge proponent of walking as much and as often as you can. I know walking doesn’t sound like much and if you’ve gotten a disappointing VO2 max score, you may be tempted to ramp things up quickly. But I want to caution you about starting out with too much endurance exercise too fast. Starting out like this places you at a higher risk for injury and impaired immune system function [11], but also causes burnout. For new exercisers, start out with walking and gradually increase (over a period of 8-12 weeks) to at least 2.5 hours of walking per week. 

When you’re ready to move on and do more, Dr. Nelson recommends starting with some form of cardiovascular endurance training that you like, whether that be running, rowing, cycling, or swimming. If you like all of these, he tends to recommend cycling as a very effective and underrated way to improve VO2 max. Dr. Nelson encourages people to start out with very low intensity at a higher frequency, so basically working at a lower heart rate (low to moderate intensity) with more training days per week. 

Knowing your heart rate is a very important component of improving your aerobic fitness and it’s an inexpensive way to estimate VO2 max [8]. Dr. Nelson uses the Phil Maffetone equation, which is basically subtracting your age from 180. The number you get here is the number to stay below for a low to moderate-intensity cardiovascular exercise. If your heart rate goes higher, then you’re likely moving from aerobic (exercise that improves cardiorespiratory efficiency) to anaerobic (exercise that doesn’t improve cardiorespiratory efficiency) exercise. Here’s an example:

• For a 40-year-old person: 180 minus 40 = 140 beats per minute. 

This is the heart rate you would want to remain below during your cardiovascular exercise. You can use a heart rate monitor or fitness tracker (like a Garmin, Polar, or Apple watch) during your exercise sessions to help you stay on track with the intensity. 

Once you’ve figured out your heart rate and built your cardiovascular base, you can progress in your training. Here’s an example of how to move to your ultimate goal of 2-3 hours of low to moderate-intensity cardiovascular training per week:

• Start with 10 minutes of cycling (or whatever cardiovascular exercise you choose) 5-6 days per week.
• Once you’ve mastered that, start slowly increasing the amount of time you’re on the bike each day.
• Once you’ve gotten yourself cycling for 20-40 minutes consistently for 5-6 days per week, then retest your VO2 max to see how things have improved.

Once you’ve reached this level of training, then it’s time to filter in some high-intensity interval training (HIIT) or some other type of aerobic capacity training to further optimize your VO2 max.  And you’ll also want to venture into strength training. Here’s a nice resource for balancing strength and cardiovascular exercise. 

While VO2 max has been found to be a very helpful measure of cardiorespiratory fitness overall, it does have some limitations. Let’s look at a few.

Limitations of VO2 Max

A few studies have shown that VO2 max isn’t able to predict long-term changes in body weight and it doesn’t reflect body fat percentage [16, 17]. This just means that specifically training to  improve your VO2 max isn’t likely to help you lose weight or change your overall body composition despite your improved aerobic endurance [16].

In addition, as we age, our muscle mass may have less of an impact on our VO2 max, which suggests VO2 max may be weaker at predicting our aerobic capacity as we get older. One observational study found that muscle mass in older rowers had less of an influence on VO2 max than muscle mass in younger rowers [18].

And, VO2 max alone may not be the best predictor of running performance. One observational study found a runner’s velocity (speed and direction) when they reached VO2 max was a better overall indicator of running performance than VO2 max alone [7].

Increasing Your VO2 Max Can Improve Your Health 

VO2 max refers to the maximum amount of oxygen your body can consume during high-intensity exercise. A higher VO2 max indicates better heart, lung, and circulatory health whereas a lower VO2 max can indicate the opposite.

You can have your VO2 max tested in a lab, but there are 2 at-home tests. Both the Cooper 12-minute run test and the 2,000-meter rowing test can give you a pretty accurate picture of your VO2 max and thus your cardiorespiratory fitness level. 

If your VO2 max is “excellent,” then you’re on the right track and you have less chance of chronic disease. If you fall into the “good-average” or “below average” categories, it’s important to focus specifically on improving your cardiovascular endurance. Start slowly and gradually increase over a period of 8–12 weeks to a goal of 2–3 hours of low to moderate-intensity exercise each week. Once you reach that goal, add in some high-intensity interval training and strength training to take your fitness to the next level. 

If you struggle with sticking to a fitness routine, here’s a resource on how to change your lifestyle for the long-run. If you’d like more personalized health and fitness guidance, please contact us at the Ruscio Institute for Functional Health.

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