Wearables now hand everyone a VO2 max score with no context, so here is the actual peer-reviewed reference data, not the uncredited chart that keeps getting shared.
What VO2 max actually measures
VO2 max is the maximum rate at which your body can take in, transport and use oxygen during intense exercise, measured in millilitres of oxygen per kilogram of body weight per minute. Measured properly, it takes a cardiopulmonary exercise test: running or cycling to exhaustion while breathing into a mask that tracks oxygen in and carbon dioxide out. That lab number, not a wrist estimate, is the one researchers actually use when they study how VO2 max relates to health.
The query "VO2 max by age" gets searched heavily because almost everyone who owns a fitness watch now gets handed a VO2 max estimate with no context for whether it is good, average or something to worry about. The honest answer depends entirely on which reference numbers you compare it to, and most of the charts that circulate online do not say where their numbers came from.
The numbers that actually have a citation behind them
The most complete modern reference comes from the Fitness Registry and the Importance of Exercise National Database, which pooled 7,783 maximal treadmill tests from 4,611 men and 3,172 women across eight US exercise physiology labs. Leonard Kaminsky and colleagues published the percentiles in Mayo Clinic Proceedings in 2015, covering ages 20 to 79.
At the midpoint of that dataset, the median man in his twenties scored about 48 ml/kg/min; by his seventies that median drops to about 24, roughly half. Women follow the same slope from a lower baseline: about 38 in their twenties, falling to about 18 by their seventies. Every decade in between loses a few more points, which is simply what happens to the heart and lungs' capacity to deliver oxygen as people age and, often, move less.
Compare that with the chart format that gets shared everywhere, with crisp bands like "excellent," "good" and "poor" by five-year age brackets. Trace most of those back far enough and the trail runs cold: one widely copied version credits a decades-old personal trainer manual that in turn cites a 1986 textbook, with no study anyone can point to today. That does not make the categories useless, but it does mean a specific cutoff presented as settled science usually is not.
“Max VO2 is very important, that's indisputable. But when do you use max VO2 in your daily life? Never.”
Why researchers care about this number at all
The reason VO2 max gets so much attention beyond gym bragging rights traces largely to a 2002 study in the New England Journal of Medicine. Jonathan Myers and colleagues followed 6,213 men referred for exercise testing for a mean of 6.2 years and recorded 1,256 deaths. Each one-MET increase in measured exercise capacity, equivalent to about 3.5 ml/kg/min, was associated with a 12% improvement in survival, and peak exercise capacity outpredicted other established cardiovascular risk factors in that group.
That is a genuinely strong, often-replicated association between fitness and survival, and we've looked separately at how VO2 max tracks with longevity and what actually raises it. It is not, on its own, proof that deliberately chasing a higher number adds years to your life, and at least one exercise physiologist who studies this for a living thinks the number gets more daily attention than it deserves. "Max VO2 is very important, that's indisputable. But when do you use max VO2 in your daily life? Never," says Dr. Claudio Gil Araújo, director of research and education at CLINIMEX in Rio de Janeiro, who has pushed to develop simpler submaximal measures precisely because almost nobody actually gets a true VO2 max test in a lab.
What your watch is estimating, and why it won't match a lab test
The number that shows up on an Apple Watch, Garmin or Whoop is not measured, it is estimated from resting heart rate, pace, heart-rate response to effort and, on some devices, GPS-derived elevation data. Those algorithms are reasonably good at tracking whether fitness is trending up or down over months, and less reliable at nailing an exact lab-equivalent figure, which is why the same person can get different numbers from different brands of watch in the same week. If your number has been reasonably stable for years and suddenly drops, that is more worth mentioning to a doctor than the absolute figure itself.
Our take
Use the FRIEND registry's percentiles if you want a real, sourced answer to "what's good for my age," treat any neat round-number chart you find online with some suspicion unless it names a study, and read your watch's VO2 max as a trend line rather than a verdict. Raising the number matters less than the plain training that raises it: consistent zone 2 volume plus some genuinely hard intervals, kept up for months, beats any shortcut.
This is general information, not medical advice. Talk to a clinician before changing anything, especially if you are pregnant, nursing, or managing a condition.
Frequently asked questions
What is a good VO2 max by age?
Using peer-reviewed reference data, a median man scores around 48 ml/kg/min in his 20s, 42 in his 30s, 38 in his 40s, 33 in his 50s, 28 in his 60s and 24 in his 70s. Median women score roughly 38, 30, 27, 23, 20 and 18 across the same decades. These are averages, not a pass or fail line.
What is a good VO2 max for a 40 year old man?
Around 38 ml/kg/min sits at the median for men in their 40s in the FRIEND registry data, with the top 25% scoring above roughly 45 and the top 10% above about 52. Training history, body weight and genetics all move this number, so it is a range, not a single target.
Does VO2 max decline with age?
Yes. Reference data shows a steady drop of several points per decade from the 20s onward, roughly halving by the 70s in untrained adults. Regular aerobic training slows that decline but does not stop it, since maximum oxygen delivery is tied to heart and lung capacity that naturally reduces with age.
Can a smartwatch accurately measure VO2 max?
Not precisely. Wearables estimate VO2 max from heart rate, pace and sometimes GPS elevation data rather than measuring oxygen use directly, which is why the same person can get different scores from different devices. The estimate is reasonably useful for spotting a trend over weeks or months, less so as an exact figure.
How can I improve my VO2 max?
The most consistent approach combines a large base of easy, zone 2 aerobic work with one or two sessions a week of harder intervals near your current max effort. Improvements of 10 to 20% over several months are realistic for previously untrained adults who train consistently; gains slow as fitness rises.
Where do VO2 max by age charts online get their numbers?
Many widely shared charts trace back to decades-old, uncredited sources rather than a named study. For a sourced reference, the Fitness Registry and the Importance of Exercise National Database (FRIEND), published in Mayo Clinic Proceedings, pools thousands of real lab tests by age and sex.
Sources
- 1
Reference Standards for Cardiorespiratory Fitness Measured With Cardiopulmonary Exercise Testing: Data From FRIEND, Mayo Clinic Proceedings (Kaminsky, Arena, Myers, 2015)
- 2
Exercise capacity and mortality among men referred for exercise testing, New England Journal of Medicine (Myers et al., 2002)