VO2 Max by Age: Percentile Chart & Reference Standards (FRIEND)

VO2 max, short for maximal oxygen uptake, is the maximum rate at which your body can take in and use oxygen during intense, whole-body exercise. It is usually written as milliliters of oxygen per kilogram of body weight per minute, or mL/kg/min, which simply scales the measurement to your size so a smaller and a larger person can be compared fairly. The higher the number, the more oxygen your body can put to work when you are pushing hard.

What makes VO2 max so useful is that it is not really measuring one thing. It reflects an entire chain working in concert: your lungs pulling in air, your heart pumping oxygen-rich blood, your blood vessels delivering it, and your muscles pulling oxygen out of the bloodstream to produce energy. Because it captures that whole system at once, exercise scientists treat VO2 max as the single best measure of cardiorespiratory fitness — the integrated ability of your heart, lungs, circulation, and muscles to fuel sustained activity. When any link in that chain gets stronger, your VO2 max tends to rise with it.

Think of it as the size of your aerobic engine. Two people can both finish a brisk walk up a hill, but the one with the bigger engine does it with room to spare, recovers faster, and has more capacity left for everything else the day asks of them. That spare capacity is exactly what the number is trying to describe.

Here is where VO2 max stops being a workout stat and starts being a health metric. A growing body of research has linked higher cardiorespiratory fitness to a lower risk of serious disease and a longer life — strongly enough that in 2016, the American Heart Association issued a scientific statement concluding that fitness is a powerful predictor of cardiovascular disease and all-cause mortality, with prognostic strength comparable to long-recognized risk factors like smoking, high blood pressure, high cholesterol, and type 2 diabetes. The same statement urged clinicians to treat cardiorespiratory fitness as a vital sign and assess it routinely, right alongside the numbers you already get checked at a physical.

That is a striking idea, so it is worth being precise about what it does and does not mean. These findings come from large observational studies that follow groups of people over time, and they show a consistent association: people with higher fitness tend to fare better. They do not prove that any single VO2 max test seals your fate, and plenty of factors outside your aerobic engine shape your health. A below-average number is not a diagnosis, and a great one is not a guarantee. What the evidence does suggest is that fitness is one of the more meaningful, and more changeable, signals you can track.

That combination — meaningful and changeable — is what makes the number worth understanding rather than fearing. So let's look at where the trustworthy benchmarks actually come from.

For years, the VO2 max charts people compared themselves against were built largely on estimates — values predicted from how long someone lasted on a treadmill or how much work they completed, rather than from directly measuring the oxygen they used. Those estimates were better than nothing, but they could drift from reality, especially at the higher and lower ends of fitness.

The FRIEND registry changed the picture for US adults. The Fitness Registry and the Importance of Exercise National Database pooled 7,783 maximal treadmill exercise tests from men and women aged 20 to 79 who were free of cardiovascular disease, gathered from eight US laboratories that followed established quality-control procedures. Crucially, every one of those tests measured oxygen uptake directly using cardiopulmonary exercise testing, the gold-standard method, rather than estimating it. The result was the first set of US reference standards for cardiorespiratory fitness built on measured data, which is why it has become the benchmark of choice for clinicians and researchers.

The registry has since been expanded with even larger datasets, but the original treadmill percentiles remain one of the most widely cited US references for healthy adults. When you compare your number against FRIEND, you are comparing yourself against thousands of real people who were measured the careful way — a far more honest mirror than the older estimated charts.

Below are the FRIEND treadmill reference values, broken out by age decade and sex. To use the chart, find your age group and sex, then scan across to see which percentile your VO2 max is closest to. All values are in mL/kg/min, and the data come from the FRIEND treadmill reference standards described above.

Men — VO2 max percentiles (mL/kg/min)

Women — VO2 max percentiles (mL/kg/min)

A quick word on what those columns mean before you read too much into a single box. The 50th percentile is simply the median for your age and sex — half of the people measured scored above it and half below. If your number lands near the 75th percentile, it means roughly three out of four same-age, same-sex adults in the reference group scored lower than you. So "good" is best understood relative to your age and sex, not against one universal target you carry for life.

The most reassuring thing about this chart is also the most freeing: the bar moves with you. A 55-year-old woman at the 50th percentile sits around 23 mL/kg/min, while a 25-year-old woman at the same percentile sits closer to 38. Neither is doing anything wrong. They are simply being measured against their own peers, which is exactly how you should treat your own number too.

You will also notice that the men's values run higher than the women's at every age. That difference is rooted in physiology — on average, men carry more lean muscle mass, larger hearts relative to body size, and higher hemoglobin levels, all of which lift oxygen delivery and use. It is not a scoreboard between the sexes; it is the reason the chart keeps them in separate columns so each comparison stays fair.

A few other things shape where you land, and they are worth keeping in mind so you read your number with the right amount of salt. Genetics set a meaningful part of your starting point. Body composition matters, since the measurement is scaled to body weight. Altitude, recent illness, sleep, and even how hard you were willing to push on test day all leave fingerprints. Treat your percentile as useful context about your aerobic fitness, not a verdict on your health or your worth.

If you have ever compared the number on your smartwatch to one a friend got in a lab, you may have found they tell slightly different stories. That is expected, and understanding why will make your own tracking far more useful.

The gold standard is a cardiopulmonary exercise test, sometimes called a CPET or CPX. You exercise to maximal effort, usually on a treadmill, while wearing a mask or mouthpiece that measures the oxygen you breathe in and the carbon dioxide you breathe out. Because it measures gas exchange directly, it produces the most accurate VO2 max available, and it is the method behind the FRIEND numbers in the chart above.

The test setup also explains a quirk worth knowing. Treadmill testing tends to produce higher VO2 max values than stationary-cycle testing in the same person, because walking and running recruit more total muscle mass than seated pedaling. That is why cycle-based reference values run lower than treadmill-based ones, and why the FRIEND treadmill chart should be compared against treadmill-style results whenever possible. Comparing a cycling number to a treadmill chart is a bit like comparing two recipes that use different cup sizes — the ingredients are similar, but the measurements are not interchangeable.

Then there is your watch. Wearables and submaximal field tests, like a timed one-mile walk, estimate VO2 max rather than measure it, often using your heart rate, pace, age, and other inputs. These estimates are genuinely useful for one thing in particular: tracking your own trend over weeks and months. If your watch number climbs as you train, that is meaningful progress. Just do not treat that estimate as identical to a lab result, and when you place yourself on the chart, give yourself a comfortable margin rather than fixating on a single decimal.

It is true that VO2 max tends to decline as we age. In the original FRIEND analysis, the typical drop worked out to roughly 10% per decade across the adult lifespan — about 9% per decade for men and 10% for women between the ages of 20 and 79. You can see that slope in the chart, where the median values step down steadily from one age group to the next.

But that average hides the part you can influence. Reviews of the research suggest the decline is not a fixed sentence; it is a tendency, and how active you are bends the curve. People who keep training, and especially those who include higher-intensity work, tend to lose ground more slowly than those who become sedentary. The number is not just counting birthdays. It is also reflecting the choices stacked between them.

That is the genuinely hopeful message buried in the age curve. Of all the markers of aging you might track, VO2 max is one of the most responsive to what you do. You cannot stop the calendar, but you have real say over how steep your personal slope turns out to be.

The encouraging headline is that VO2 max responds to training at every age. You do not need to become an athlete to move it; you need to give your aerobic system a reason to adapt. What follows are evidence-based options to consider, not a prescription — the right mix depends on your starting point, your health, and what you actually enjoy enough to keep doing.

A sensible foundation is the national activity target. The Physical Activity Guidelines for Americans recommend that adults get at least 150 to 300 minutes of moderate-intensity aerobic activity each week, or 75 to 150 minutes of vigorous activity, or a combination of the two, plus muscle-strengthening work on two or more days. Hitting that range reliably is the single best thing most people can do for their cardiorespiratory fitness.

From there, intensity is the lever that tends to move VO2 max the most. Vigorous and interval-style efforts — periods of harder work broken up by easier recovery — are an efficient way to reach your weekly activity goals and to push your aerobic ceiling higher, with the sensible caveat that you should scale the intensity to your current fitness and health. And if you are starting from a low base, take heart: the guidelines are clear that some activity is far better than none, and benefits begin the moment you move more than you did before. Even modest gains in fitness, on the order of a single MET, have been associated in observational studies with meaningful reductions in mortality risk — a reminder that the early progress counts, not just the finish line.