VO2 max by age: a chart for men and women, and what the decline really looks like

Short answer

VO2 max falls with age in almost everyone. In US lab treadmill tests, the median for men drops from 48.0 ml/kg/min in their 20s to 24.4 in their 70s, and for women from 37.6 to 18.3, roughly 10% per decade (1). Read your number against your own age and sex band, not against a 25-year-old.

A 47-year Swedish study published in 2025 followed the same 427 people from age 16 to 63. Aerobic capacity peaked between the mid-20s and mid-30s, and by 63 it was on average 37–40% below that peak (2). People who became active as adults had about 6–7% higher aerobic capacity, an association rather than proof, and the authors conclude that the rate of decline can be influenced by physical activity.

If your watch says your cardio fitness has slipped, that is common, not your fault and not a verdict on you. Watch numbers are estimates that can be several points off a lab test (3). Before you blame yourself, look at what your own data shows over time: the trend over months, your resting heart rate and how fast your heart rate recovers.

Note: this article explains a fitness measurement and is not medical advice. A low VO2 max estimate is not a diagnosis. Call 911 if you have sudden crushing, squeezing or tight chest pain or pressure, pain that spreads to your jaw, left arm or between your shoulder blades, or chest pain with nausea, dizziness, sweating, a racing heart or shortness of breath (16).

What is VO2 max, in plain words?

VO2 max is the most oxygen your body can take in and use during all-out exercise. It is written in milliliters of oxygen per kilogram of body weight per minute, or ml/kg/min.

Think of it as the size of your engine. Your lungs bring oxygen in, your heart and blood carry it, and your muscles burn it. VO2 max describes the ceiling of that whole chain, which is why doctors and researchers use it as the main measure of cardiorespiratory fitness.

Two details make the number easier to read:

• It is per kilogram. Lose weight and the number rises even if your heart and muscles have not changed. Gain weight and it falls.

• It is a ceiling, not your everyday effort. Nobody lives at VO2 max. But a higher ceiling makes stairs, hills and carrying shopping feel easier, because each task uses a smaller share of what you have.

One more unit you will see: METs. One MET is the energy you use sitting still, conventionally set at 3.5 ml/kg/min of oxygen. So a VO2 max of 35 ml/kg/min is about 10 METs. Many health studies report fitness in METs rather than VO2 max.

VO2 max by age chart: men and women

The most useful US reference for measured VO2 max comes from FRIEND, the Fitness Registry and the Importance of Exercise National Database. Eight experienced US labs pooled 7,783 maximal treadmill tests from adults aged 20 to 79 without heart disease, tested between January 2014 and February 2015. Every value was measured directly with a mask and gas analysis during a cardiopulmonary exercise test, not estimated (1).

VO2 max at a glance: median (50th percentile), ml/kg/min

VO2 max chart for men by age, ml/kg/min (FRIEND, treadmill)

VO2 max chart for women by age, ml/kg/min (FRIEND, treadmill)

How to read the chart

• Find your row first. A percentile tells you what share of people your age and sex scored below you. At the 75th percentile, about three in four people in your band were lower.

• "Average VO2 max" usually means the 50th percentile. For a 45-year-old woman that is 26.7 ml/kg/min; for a 45-year-old man, 37.8.

• A "good" VO2 max is a band, not one number. Many charts call the top quarter or so "good" or "excellent". We explain the categories and what they mean in what is a good VO2 max.

• This is a lab chart. It describes people who did a maximal treadmill test with gas analysis. A watch estimate is a different kind of number, which we come back to below.

VO2 max for women: why the numbers are lower

At every age, women's values in FRIEND sit below men's: 37.6 versus 48.0 at the median in the 20s (1). That gap is about physiology, such as body composition, heart size and the amount of oxygen-carrying hemoglobin, not about effort. A woman at the 75th percentile for women is fit, whatever that number looks like on a men's chart. Always use the chart for your own sex.

Why different VO2 max charts give different answers

If you have compared charts online, you have probably noticed they disagree. There are three main reasons.

1. Measured versus predicted. FRIEND measured oxygen directly. Older and widely used Cooper Clinic tables were built from treadmill time and workload, then converted into a predicted VO2 max. In the same paper, FRIEND printed both side by side, and the differences are large in older adults: the median for women aged 60–69 is 20.0 ml/kg/min in FRIEND but 28.8 in the Cooper Clinic predicted values; for men of the same age, 28.2 versus 33.8 (1).

2. Different populations. In the same paper, FRIEND's average values were lower than reference data from Norway at every age (1). Charts built on fitter populations make everyone else look worse.

3. Different devices use different charts. Apple says its low cardio fitness classification is based on the FRIEND registry (5). Garmin's manual says its VO2 max analysis is provided with permission from The Cooper Institute, and Garmin Connect shows where your estimate ranks for your age and sex (7). The same estimate can therefore land in a different category depending on which app you open.

The practical rule: pick one chart, ideally one based on measured tests like FRIEND, and compare yourself against it consistently.

What a 47-year Swedish study found about VO2 max and age

Most VO2 max charts, including FRIEND, are cross-sectional. They compare different people of different ages at one moment, then infer how fitness changes with age. A 2025 study from Karolinska Institutet did something rarer: it followed the same people for 47 years (2).

In the Swedish Physical Activity and Fitness cohort (SPAF), 427 men and women born in 1958 (48% women) had their physical capacity tested repeatedly from age 16 to 63. The researchers measured aerobic capacity, muscular endurance (bench press repetitions) and leg power (a vertical jump test). Here is what they reported:

• Peak. Estimated aerobic capacity and muscular endurance peaked between ages 26 and 36 in both sexes. Relative aerobic capacity, the ml/kg/min figure, peaked at 26 in men and 31 in women. Jump power peaked earlier: 27 in men and 19 in women.

• Slow start, faster later. After the peak, aerobic capacity per kilogram fell by about 1.1% a year at age 40, speeding up to about 2.2% a year by 63.

• By 63. Relative aerobic capacity was 40% below peak in men and 37% below peak in women. Across all the tests, the drop from peak ranged from 30% to 48%.

• No sex difference in the rate of decline. Men and women lost capacity at a similar pace once decline began.

• People spread out with age. Differences between individuals in relative aerobic capacity were 25 times larger at older ages than in adolescence.

• Activity mattered. Being active at 16 and becoming active in adulthood were both associated with better performance on every test. Switching from inactive to active was linked with 6–7% higher aerobic capacity, 11% more bench press repetitions and 4% higher jumps.

The study's estimated averages show the shape of the curve:

• 16 — Men, ml/kg/min: 40.8; Women, ml/kg/min: 34.5

• 30 — Men, ml/kg/min: 41.9; Women, ml/kg/min: 39.7

• 40 — Men, ml/kg/min: 38.5; Women, ml/kg/min: 37.9

• 50 — Men, ml/kg/min: 33.0; Women, ml/kg/min: 32.8

• 63 — Men, ml/kg/min: 25.2; Women, ml/kg/min: 24.9

What this study does and does not tell you

It is a strong design, but it has real limits, and the authors list several of them:

• One cohort, one country, one generation. Everyone was Swedish and born in 1958. The authors note this may limit how far the findings apply to other generations and cultures.

• Aerobic capacity was estimated, not measured. Adults did the Åstrand test, a submaximal cycle test that predicts VO2 max from heart rate at a set workload. At 16, a 9-minute run was converted into an estimate. So these numbers are not directly comparable with the FRIEND lab chart above.

• Activity was a yes-or-no question. The authors had no detailed data on how much, how hard or how consistently people trained. The 6–7% difference for people who became active is an association, not proof that starting exercise caused it.

• These are group averages. The curve describes the cohort, not you. The 25-fold spread at older ages means some 63-year-olds were far fitter than others.

The authors' conclusion is not "after 35 it's over". They write that peak timing seems largely fixed, but that how much you improve before the peak, how high you get and how fast you decline afterwards are all modifiable and can be positively influenced by physical activity (2).

How fast does VO2 max decline per decade?

It depends on how you measure it and how old you are.

• Cross-sectional estimate: in FRIEND, the decline across five decades was approximately 10% per decade (1).

• Following the same people: in the Baltimore Longitudinal Study of Aging, 810 healthy adults had repeated treadmill tests with measured oxygen uptake. The decline was 3–6% per 10 years in the 20s and 30s, accelerating to more than 20% per 10 years in the 70s and beyond (8).

• The Swedish cohort showed the same speeding-up pattern: about 1.1% a year at 40 and 2.2% a year at 63 (2).

Both longitudinal studies make the same point: comparing different people at different ages tends to underestimate how fast one person's fitness changes over time (2, 8). That is one more reason not to panic over a single reading. A small drop over a year in your 40s is consistent with the gradual decline these studies describe.

Can you slow the decline or raise your VO2 max?

Training raises VO2 max in controlled trials, although nobody stops ageing entirely. The Swedish authors put it plainly: no one escapes the age-related decline, but its rate appears to be modifiable by physical activity (2).

The training evidence is consistent. A meta-analysis of 28 controlled trials in healthy adults aged 18 to 45 found that continuous endurance training raised VO2 max by about 4.9 ml/kg/min compared with no exercise, and high-intensity interval training by about 5.5 ml/kg/min. Intervals came out slightly ahead, by about 1.2 ml/kg/min (9). Gains were larger in people who started less fit and in longer programs.

To put 5 ml/kg/min in context: for a 50-year-old woman at the FRIEND median of 23.4, that would mean moving to about 28, close to the 75th percentile for her age (1). These trials were in younger adults, so treat this as an illustration, not a promise.

We cover the actual training plan, interval formats and timelines in how to improve VO2 max, so we will not repeat it here.

Why VO2 max matters for health

In large studies, cardiorespiratory fitness is strongly associated with long-term health outcomes.

• A meta-analysis of 33 studies in healthy adults found that each 1-MET higher fitness level (about 3.5 ml/kg/min) was linked with 13% lower risk of death from any cause and 15% lower risk of heart disease or cardiovascular events (10).

• A study of 122,007 adults who had treadmill tests at a US academic medical center, followed for a median of 8.4 years, found that risk of death fell steadily with higher fitness. The fittest ("elite") group had an 80% lower adjusted risk than the least fit group, and the authors observed no upper limit of benefit (11).

Two honest caveats. These are associations, so fitness may partly be a marker of other healthy habits or of illness that has not been diagnosed yet. And the biggest difference in risk is between the least fit people and everyone else. Moving out of the bottom band for your age matters more than climbing from good to elite.

How smartwatches estimate VO2 max

No watch measures the oxygen you breathe. Wearables estimate VO2 max from how your heart rate responds to a known effort, usually walking or running pace from GPS, combined with your age, sex, weight and height.

Apple Watch (Cardio Fitness). Apple's estimate uses heart rate and motion sensors during Outdoor Walk, Outdoor Run or Hiking workouts. Indoor workouts do not count. Apple says it can take at least 24 hours of wear, plus several qualifying outdoor workouts, before the first estimate. Apple Watch supports a range of 14–65 ml/kg/min, and the cardio fitness levels are available to users aged 20 and over. Apple also notes that conditions or medications that limit heart rate may cause an overestimate (4). In its 2021 white paper, Apple reported a mean error of 1.4 ± 4.7 ml/kg/min in its own validation group of 221 people, measured against a projected value from a submaximal reference test rather than a maximal lab test, and said the low cardio fitness notification uses the lowest fifth of the FRIEND registry for ages 20–59, with fixed thresholds of 18 ml/kg/min for men and 15 for women from age 60 (5).

Garmin. Garmin's VO2 max estimates come from Firstbeat Analytics. For running, the watch needs an outdoor run with GPS and heart rate, at least 10 minutes at 70% or more of your maximum heart rate. For cycling, it needs a paired power meter and at least 20 minutes of steady, hard riding (7).

How accurate is Apple Watch VO2 max, and other watches?

Independent studies compared watch estimates with VO2 max measured in a lab during a maximal test. They are small, use different lab protocols and are not head-to-head comparisons, so do not use them to rank brands.

• Apple Watch, 30 adults, 28 analysed (2025). The watch underestimated lab VO2 max by 6.07 ml/kg/min on average, with a mean absolute percentage error of 13.3%. The limits of agreement were wide, from about 6 points above to 18 points below the lab value (3).

• Apple Watch Series 10, 40 adults (2026). Again an average underestimate of 6.25 ml/kg/min and a 13.2% mean absolute error. Using the FRIEND percentile bands, the watch put 14% of people in exactly the right band and another 34% one band away (6).

• Garmin fēnix 6, 19 adults (2025). A mean absolute percentage error of about 7% against lab testing (12).

• Garmin Forerunner 245, 35 endurance athletes (2026). The watch underestimated VO2 max by about 4–5 ml/kg/min overall, and by 6.3 in the most highly trained athletes (13).

What this means for you:

• The absolute number is approximate. Being 5 to 7 points off can move you a whole category on a chart.

• The trend is more useful. Comparing readings from the same watch, with the same settings and similar workouts, is fairer than comparing one reading with a lab chart. A steady change over months tells you more than one reading.

• Help the estimate. Keep your age, sex, weight and height correct in settings, wear the watch snugly, and do regular outdoor walks or runs on fairly flat ground. Apple lists medications that might affect your heart rate among the information its estimate takes into account, and notes that conditions or medications that limit heart rate might cause an overestimate, so keep your health details up to date (4).

VO2 max test: the options

If you want a real number rather than an estimate, these are the main routes:

• Cardiopulmonary exercise test (CPET). You walk or run on a treadmill, or cycle, while wearing a mask that analyzes your breath, until you cannot continue. This is how FRIEND and other lab charts were built (1). It is available in hospitals, some sports medicine clinics and university labs.

• Submaximal tests. You exercise at a set, moderate workload and VO2 max is predicted from your heart rate. The Swedish study used one, the Åstrand cycle test (2). Safer and simpler, but less precise.

• Field tests. Timed runs or walks converted to VO2 max with an equation. Cheap, but sensitive to pacing and motivation.

• Wearable estimates. Convenient and continuous, but approximate, as above.

If you have a heart or lung condition, or symptoms during exercise, do maximal testing only under medical supervision.

What is the highest VO2 max, and where do athletes sit?

At the top of the FRIEND chart, the 95th percentile for people in their 20s is 66.3 ml/kg/min for men and 56.0 for women (1). Trained endurance athletes can sit higher: in the Garmin study above, 35 competitive runners averaged 60.1 ml/kg/min in the lab (13). The highest values of all are found in elite endurance athletes, but there is no official register of records, so treat any single "world's highest VO2 max" figure you see online with caution.

But VO2 max does not decide races on its own. A classic review of champion endurance athletes describes three factors working together: VO2 max, the lactate threshold (how much of that ceiling you can hold for a long time) and efficiency, meaning how much oxygen it costs you to run or ride at a given speed (14). That is why two people with the same VO2 max can perform very differently, and why VO2 max alone does not predict who wins.

Other everyday markers of fitness

VO2 max changes slowly and is hard to measure well at home. Three markers your watch already records can tell you about fitness and recovery sooner:

• Resting heart rate. As aerobic fitness improves, resting heart rate often drifts down over weeks. It also rises with illness, poor sleep, alcohol and stress, so read it as a trend. See what is a normal resting heart rate.

• Heart rate recovery. How fast your heart rate falls after you stop exercising. In a classic study of 2,428 adults having exercise tests, a drop of 12 beats per minute or less in the first minute was linked with a fourfold higher risk of death in unadjusted analyses (15). That was a clinical stress test, not a smartwatch reading, so use it as context. Our guide on how fast your heart rate should drop after exercise explains how to check yours.

• HRV trend. Heart rate variability often shifts with recovery: it can dip with stress, illness, poor sleep and hard training blocks, and recover when those ease. The trend against your own baseline matters more than the number itself; see what is a good HRV.

Living with a VO2 max number: the questions people ask next

Why did my VO2 max drop suddenly?

A sudden drop on a watch is more often about the data than your fitness. Common reasons: fewer outdoor walks or runs, a lot of indoor or cycling workouts the estimate ignores, a loose strap, a recent illness, heat, poor sleep, or a change in weight entered in settings. A real drop over weeks without a change in training is worth mentioning to a doctor, especially with new breathlessness.

Does VO2 max matter if I have ME/CFS, long COVID or POTS?

The number may still be interesting, but raising it is not the goal for everyone. In conditions with post-exertional malaise, pushing hard can make symptoms worse a day or two later, so high-intensity intervals are not a safe default. Welltory's Help Center makes the same point about its own effort scores: a drop in maximum effort in energy-limiting conditions often reflects the condition, not lost fitness or motivation (17).

Does losing weight raise VO2 max?

Yes, on paper. Because VO2 max is divided by body weight, losing weight raises the number even if your heart and muscles have not changed. That is not cheating, since carrying less weight genuinely costs less oxygen, but it means a jump after weight loss is not the same as a jump after months of training.

Do beta-blockers affect VO2 max on a watch?

They can. Beta-blockers are one example of medicines that limit how high your heart rate climbs, and Apple notes that conditions or medications that limit heart rate might cause an overestimate of VO2 max (4). If you take one, read your watch number with extra caution and do not change your medicine because of it.

Is my VO2 max good for my age if I'm a woman over 50?

Use the women's chart above. At 50–59, the FRIEND median is 23.4 ml/kg/min, the 75th percentile is 27.6 and the 90th is 32.0 (1). If your watch shows a number near those, remember it may be several points off in either direction. Your trend over months is more telling.

What kind of doctor tests VO2 max?

A cardiologist, a pulmonologist or a sports medicine physician can order a cardiopulmonary exercise test. Many people start with their primary care doctor, who decides whether a test is needed.

Before you blame yourself

People who look up VO2 max by age are often reacting to a watch notification that says their cardio fitness is low, or to a number that has slipped since last year. It is easy to read that as proof of laziness or of getting old too fast. It is not.

Look at what the evidence actually says. Fitness falls with age in everyone, including athletes. Lab charts and watch estimates are different measurements, and the watch can be several points off. And the Swedish study found that people who became active in adulthood were fitter on average than those who stayed inactive.

Before you blame yourself, look at what your own data shows over time. What has your resting heart rate done over the last three months? How has your heart rate recovery changed after your usual walk or run? Were there weeks of illness, poor sleep or no outdoor workouts? Then pick one lever, such as two brisk outdoor walks or one interval session a week, and look at the trend after six to eight weeks, not after six days.

When to see a doctor

See a doctor if your fitness falls noticeably over weeks or months without a change in training, if you get breathless doing things that used to be easy, if you need to stop on stairs or hills where you did not before, or if you have swollen ankles, palpitations or unusual fatigue alongside a falling number. Anaemia, thyroid problems, lung and heart conditions and the after-effects of infections can all lower fitness.

Call 911 if exercise brings on sudden crushing, squeezing or tight chest pain or pressure, pain that spreads to your jaw, left arm or between your shoulder blades, or chest pain with nausea, dizziness, sweating, a racing heart or shortness of breath (16).

How to bring this up with your doctor

What to ask for, by name. "Could my reduced exercise tolerance be checked, and would a cardiopulmonary exercise test be useful?" If relevant: "Could we check for anemia and thyroid problems?"

What to bring. Your watch's VO2 max trend over several months, your resting heart rate trend, a short list of symptoms with dates, and every medicine you take, especially beta-blockers.

What to say, out loud. "My estimated VO2 max has gone from about [X] to [Y] over [N] months. My training hasn't changed. I also notice [breathlessness / needing to stop on stairs / fatigue]."

If you're told it's just age. Ask: "The usual decline is gradual. Mine has been faster than that. What would you want to rule out?"

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How Welltory helps — and what it cannot do

The limits first. Welltory is a general wellness product, not a medical device. It does not measure VO2 max, does not run a lab test and does not diagnose heart or lung conditions. Every consumer VO2 max figure is an estimate.

What it can do is help you see the signals around cardio fitness over time.

Your effort ceiling from real workouts. In the Workout Report for Apple Watch users on iOS, Welltory shows your Max METs, the highest effort level you have reached in past activities, and sets personal heart rate zones each day from your morning heart rate and that Max METs value. If a workout beats your previous maximum, the new value is used for your zones from the next day (Workout Report for Apple Watch). Android users with Samsung Watch or Pixel Watch get a similar Workout Analysis (Workout Report for Android). Max METs reflects the hardest efforts you have recorded, but it is not a VO2 max measurement and should not be read against the chart above. How METs work is explained in Redefining effort: why METs are the future of activity tracking.

Morning state and resting heart rate. On iOS with an Apple Watch or Oura, the Today screen shows a morning Battery level calculated from your resting heart rate on waking and the quality and quantity of your sleep (Today screen). Over weeks, that gives you a resting heart rate trend to look at alongside your watch's VO2 max.

HRV as a trend. With an Apple Watch you can take HRV measurements through the Breathe app, at least 3 minutes long (taking measurements with your Apple Watch). For a fair comparison, measure at the same time, in the same position, before coffee (accurate HRV measurements). The free version allows one Apple Watch measurement a day; Premium has no daily limit.

What happened, in your own words. On iOS with an Apple Watch or Oura, when Welltory marks a stress or rest episode, it asks what was happening. Answer with a tag such as "interval run", "long walk", "bad sleep" or "had a cold". Over weeks, My Patterns shows which tags tend to come with stress and which with recovery; some sections, such as full tag details, require a paid plan. These are associations in your own data, not proof of cause.

A record for your doctor. From the web app you can export a chart or your full dataset as a CSV file (Dashboard → choose a chart → Export) (export guide). Bring it to your appointment as context. Patterns are associations, not a diagnosis.

Learning alongside others. If your falling numbers come with an energy-limiting condition such as ME/CFS, long COVID or POTS, pushing your VO2 max up is usually the wrong goal. Welltory Energy Lab is a paid, moderated online community for women aged 35 to 65 living with energy-limiting conditions; it offers education and peer support, not medical care. You can join Energy Lab here or read what the community is, who it is for and what it costs.

How we made it

We based this article on the FRIEND registry reference standards for VO2 max measured with cardiopulmonary exercise testing (Kaminsky and colleagues, Mayo Clinic Proceedings 2015), the 47-year Swedish SPAF cohort (Westerståhl and colleagues, Journal of Cachexia, Sarcopenia and Muscle 2025), the Baltimore Longitudinal Study of Aging, a meta-analysis of interval and endurance training, two large studies of fitness and mortality, independent validation studies of Apple Watch and Garmin VO2 max estimates, Apple's and Garmin's own documentation, and a classic study of heart rate recovery. Every number in the tables was checked against the original papers. Urgent-help guidance follows MedlinePlus. Search questions came from what people in the United States most often ask about VO2 max by age. For the product section, we checked every function against the Welltory Help Center on October 22, 2026.

Made with AI tools, then edited and fact-checked by the Welltory team. See our Editorial & AI policy.

Jane Smorodnikova, co-founder of Welltory, built the methodology behind how we read physiological data.

Written by Tatsiana Yashyna.

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