Short version. VO2 max is the most oxygen your body can use during hard exercise. It falls with age, and it is lower on average in women than in men. In a study of 4,637 people, the average man in his twenties measured about 48, and the average woman about 40. By the fifties those averages were about 39 and 31. Your own number matters less than which direction it is moving. Fitness is one of the strongest predictors of long term mortality in the research, and it is also one of the few you can change.
VO2 max is the maximum amount of oxygen your body can take in and use during exercise. It is written in millilitres of oxygen per kilogram of body weight per minute, which is why you see numbers like 45 rather than a percentage.
Because it is divided by your body weight, the number moves when your weight moves. Losing weight can raise it without your heart or lungs changing at all. That is worth knowing before you read too much into a single reading.
These are averages from the LowLands Fitness Registry, a study of 4,637 Dutch and Flemish people aged 6 to 65. The number after each average is the standard deviation, which tells you how spread out the results were.
| Age | Men | Women |
|---|---|---|
| 20 to 29 | 47.7 (± 6.5) | 39.5 (± 8.8) |
| 30 to 39 | 45.5 (± 7.6) | 35.8 (± 8.0) |
| 40 to 49 | 42.6 (± 8.4) | 34.2 (± 8.7) |
| 50 to 59 | 38.5 (± 9.0) | 31.0 (± 8.8) |
Source: Van de Poppe and colleagues, European Journal of Applied Physiology, reference values from the LowLands Fitness Registry.
Most VO2 max charts online do not say where their numbers came from. This one does, which means you can also see its limits.
The people in it were healthier than average. Known athletes were excluded, and so were smokers and anyone with a BMI over 30. So these are not general population figures. They describe reasonably healthy non athletes.
They were all Dutch or Flemish. Reference values differ between populations, and the same paper shows its numbers running higher than several older reference sets from other countries.
The oldest group was small. Only 32 men and 10 women were 60 or over, so that part of the data is thin. We have left it out of the table above rather than present it as if it were solid.
An average is not a target. The study reported the full spread, from the 3rd percentile to the 97th. Sitting below the average for your age does not mean something is wrong, and sitting above it does not mean you are finished.
Fitness is one of the strongest predictors of long term survival that has been measured.
In a study of 122,007 adults who did treadmill testing at the Cleveland Clinic, the fittest group had roughly a fifth of the death rate of the least fit group over the follow up period. The adjusted hazard ratio comparing the most fit to the least fit was 0.20, with a confidence interval of 0.16 to 0.24.
The same study found the benefit kept going at the top end. The most fit group still did better than the merely high fitness group, with an adjusted hazard ratio of 0.77.
One honest caveat. That study estimated fitness from treadmill performance rather than measuring oxygen uptake directly, so it is a close relative of VO2 max rather than the same test.
Source: Mandsager and colleagues, JAMA Network Open, 2018, cardiorespiratory fitness and long term mortality.
Three ways, and they are not equally accurate.
A laboratory test. You wear a mask on a treadmill or bike while your breathing is measured directly. This is the real measurement and everything else is an estimate of it.
A watch or a ring. Most fitness watches estimate VO2 max from your heart rate and your pace. The estimate is not the same as a lab test, but it is consistent with itself, which makes it useful for watching a trend.
A field test. A timed run or a step test can be converted to an estimate with a formula.
For tracking change over time, the least accurate method is often good enough, as long as you use the same method every time. Switching between a lab test and a watch estimate will show you a change that never happened.
A single VO2 max reading tells you very little. The same person can test several points apart on two days depending on sleep, heat, illness and how hard they pushed.
What is worth your attention is the direction over months. That is also the part almost nobody records, because the number lives inside whichever app produced it and gets overwritten by the next reading.
This is what we built The Health Project for. VO2 max is one of the things it tracks, and you see its trend over time next to your training, your nutrition and your sleep. It connects with your Apple Health, Google Fit, Garmin, Fitbit, Oura and Whoop. Anything it does not pick up from your devices can be entered by hand or uploaded from a lab report.
We show you the trend. We do not tell you what your result means. If something looks off, that is a conversation for your doctor.
Is a VO2 max of 40 good?
It depends on your age and sex. For a man in his forties it is slightly below the average of 42.6 in the study above. For a woman in her forties it is well above the average of 34.2.
Can you improve your VO2 max?
Yes. It responds to training, and the mortality research above found better outcomes at every step up in fitness. How much it improves varies between people.
Why did my VO2 max drop after I gained weight?
Because the number is divided by your body weight. Gaining weight lowers it even when nothing about your heart or lungs has changed.
How often should you check it?
Every few months is enough. Readings taken days apart mostly show noise rather than change.