What Is VO2max?
The more you exercise, the better your fitness becomes. VO2 max, sometimes described on wearables as a “cardio fitness” metric, is typically higher in people with a more developed cardiovascular system. But it’s not the only fitness metric, and you should know what it really means.
What does VO2max actually mean (as measured in a lab)?
Smartwatches and fitness trackers don’t actually measure VO2max; they only estimate it. To accurately determine your VO2max, you’ll need to go to a fitness lab and take a test on a treadmill or exercise bike, connected to equipment that measures your heart rate and exhaled air volume. I conducted just such a test to compare my actual VO2max with those of nine different devices. You can read about my experience and why this is important here .
VO2max, properly translated as VO2max , is the maximum volume (V) of oxygen ( O2 ) your body can use per minute during exercise, scaled by your body size, as larger people naturally consume more oxygen. It’s considered a good indicator of aerobic fitness because—recall your high school biology class—your body uses oxygen and food to create an available form of chemical energy called ATP. You then use this ATP to power your muscles. The amount of oxygen directly correlates with the amount of energy produced. Or, more simply, the more work you do, the more oxygen you need.
So, someone with excellent aerobic fitness—say, an elite marathon runner—can perform a greater volume of work (run faster) than someone who’s out of shape. As a result, they’ll inhale much more oxygen per minute while running than, say, me.
What is a “good” VO2max?
The average person in relatively good physical condition has a VO2 max of 30 to 40. This can be higher with intense training. Elite cyclists, skiers, and ultramarathon runners can reach 70-80 , and some even exceed 90. I would consider myself a recreational athlete (I run a little), and my laboratory-measured VO2 max was 43. Most of my fitness trackers showed values in the 30-40 range—a good reminder that such estimates can be useful, but not necessarily accurate.
Why is a high VO2max beneficial?
To efficiently utilize large amounts of oxygen, you need more than just healthy lungs. You also need a strong heart and a healthy circulatory system to deliver oxygen to your muscles. And you need large muscles capable of producing a high volume of work per minute—which means you’re strong and capable of performing a lot of athletic work. VO2 max is a way to summarize many important aspects of cardio fitness in one simple number.
Daily newsletter
But it’s important to understand that this metric doesn’t reflect the full scope of physical fitness, or even aerobic endurance. Firstly, comparing your VO2 max to that of others isn’t particularly meaningful, as it’s influenced by factors like blood volume and muscle mass. For example, men’s VO2 max is typically about ten points higher than women of similar fitness. Furthermore, there are many aspects of physical fitness that aren’t captured by VO2 max. Compare two athletes with the same VO2 max, and you might find that one can run an endurance race longer than the other. Or one might be better at sprinting, while the other is better at moderate-intensity exercise. One person might be stronger than the other, have better technique, or be more injury-resistant.
There are studies linking VO2max to longevity, but this doesn’t mean that increasing your VO2max by a few points will extend your life. Overall fitness is generally correlated with longevity and overall health. Scientists studying this relationship typically select one or two simple metrics to measure, such as VO2max or grip strength. But in real life, we don’t need to choose one metric to maximize; we can work on multiple aspects of fitness. It’s better to be well-rounded than to focus too much on just one metric.
How to measure your own VO2max?
The gold standard is laboratory testing. Elite athletes sometimes undergo this test if they or their coaches want to know their actual, accurate VO2max. But aerobic fitness can be measured in other ways, and there are workouts that can help you get a good estimate of VO2max. If you’re a runner, you can look at your recent race results on this chart to determine your VDOT, which roughly correlates with your VO2max. (For example, my best mile time gives me a VDOT of 38.)
To estimate your VO2 max based on your training, you need something that allows you to reach your absolute maximum aerobic capacity. Running is a great way to do this; a test like running as many laps on a treadmill as possible in 12 minutes works well, too. I remember one time in gym class we had to take a test where we had to walk up and down a high platform as many times as possible. These tests aren’t exactly fun, but their results can serve as a benchmark to show whether your fitness is improving over time.
How does a watch measure VO2max?
Smartwatches and fitness trackers typically estimate VO2max by comparing your heart rate during exercise to the amount of work you’re doing. This most often happens when running or walking outdoors. Your running or walking speed is measured using GPS, and the device compares it to your heart rate. If you can run fast with a low heart rate, you’re reasonably fit, and your VO2max will be rated as fairly high. If your heart rate is high even when running or walking at a slow pace, your VO2max will be lower.
These estimates aren’t always accurate. If your maximum heart rate isn’t set correctly in your device settings, if it’s hot outside, if your running route includes hills, or if you rarely go for runs or walks outdoors, your VO2 max estimate will likely be inaccurate. However, a VO2 max estimate doesn’t have to be completely accurate to be useful. If your VO2 max increases over time, you’re likely becoming more fit. If it decreases, you’re likely losing fitness.