What Is a Good VO₂max? Reference Values and Why Every Increment Counts

Your watch says your VO₂max is 38. Is that good? The honest answer is: it depends on your age, your sex, and what you're comparing it to. But the question is worth asking carefully, because VO₂max is one of the strongest predictors of long-term health we can measure — the American Heart Association has formally argued it should be treated as a clinical vital sign, alongside blood pressure and resting heart rate (Ross et al., 2016).

This article sets out what a good VO₂max actually looks like, using published reference data rather than guesswork — and what the evidence says about moving your number upwards.

What is VO₂max?

VO₂max, or maximal oxygen uptake, is the maximum amount of oxygen your body can take in, transport and use during intense exercise. It's expressed in millilitres of oxygen per kilogram of body weight per minute (ml/kg/min), and it reflects how well your heart, lungs, blood and muscles work together as a system.

That's why it matters beyond sport. A higher VO₂max means your cardiovascular system has more capacity in reserve — for exercise, for illness, and for the demands of aging.

What counts as a good VO₂max?

The most widely used reference values come from the FRIEND registry — the Fitness Registry and the Importance of Exercise National Database — which pooled thousands of laboratory cardiopulmonary exercise tests from healthy adults in the United States (Kaminsky et al., 2015).

In that dataset, the 50th percentile — the middle of the distribution — for treadmill-tested adults aged 20–29 was 48.0 ml/kg/min for men and 37.6 ml/kg/min for women. By ages 70–79, the median had fallen to 24.4 and 18.3 ml/kg/min respectively. A 2022 update, drawing on 22,379 tests from adults aged 20 to 89, refined these standards further and confirmed the same pattern (Kaminsky et al., 2022).

A practical way to read your own number:

• Around the 50th percentile for your age and sex — you're typical for a healthy adult. Not a bad place to be, but not protective either.
• Above the 50th percentile — reasonably described as good. You carry more aerobic reserve than most people your age.
• In the top quartile or higher — excellent, and this is where the largest reductions in long-term health risk are observed.

One caveat on wearables: wrist-based estimates are derived from heart rate and pace algorithms, not measured gas exchange, so treat them as a trend indicator rather than a laboratory value. The reference standards above come from direct measurement.

Why your VO₂max deserves your attention

The link between VO₂max and long-term health is unusually consistent across large studies.

A meta-analysis of data from more than 100,000 healthy adults found that each 1-MET increase in cardiorespiratory fitness — roughly 3.5 ml/kg/min of VO₂max — was associated with a 13% lower risk of all-cause mortality and a 15% lower risk of coronary heart disease or cardiovascular events (Kodama et al., 2009).

In a Cleveland Clinic cohort of 122,007 adults followed over more than two decades, fitness was inversely associated with mortality with no observed upper limit: even people classed as having "high" fitness had greater long-term risk than those in the "elite" group two standard deviations above average (Mandsager et al., 2018).

The same relationship holds in healthy, low-risk populations. In the Norwegian HUNT Fitness Study of 4,527 adults with directly measured VO₂peak, each 1-MET higher value was associated with a 15% lower risk of coronary heart disease across the whole fitness continuum (Letnes et al., 2019). There is no threshold above which more fitness stops helping — the gradient runs all the way up.

A good VO₂max is relative — and it moves

Two points of nuance are worth holding onto.

First, VO₂max declines with age. In the FRIEND data, the median value roughly halves between your 20s and your 70s (Kaminsky et al., 2015). That decline is normal — but its rate is not fixed. The percentile you occupy within your age group is the more useful benchmark than any single absolute number.

Second, "good" depends on the goal. For an endurance athlete, 55 ml/kg/min may be unremarkable. For long-term health, the evidence suggests the biggest wins come from not being in the bottom of the distribution: in the Cleveland Clinic data, moving out of the lowest fitness group was associated with risk reductions comparable to reversing major clinical risk factors (Mandsager et al., 2018).

How to improve your VO₂max

VO₂max is trainable at any age, and the most efficient stimulus we know of is brief, maximal-intensity work.

A meta-analysis of sprint interval training studies found that a typical program of repeated all-out cycle sprints improved VO₂max by an average of 7.8% — and, counterintuitively, that reducing the number of sprints per session did not reduce the improvement (Vollaard et al., 2017). Two sprints appear to capture most of the adaptive signal.

That finding underpins REHIT — Reduced Exertion High-Intensity Interval Training — the protocol CAROL Bike was built around: two 20-second all-out sprints inside a roughly five-minute ride. In the original six-week REHIT trial, VO₂max increased by 15% in men and 12% in women, alongside a 28% improvement in insulin sensitivity in men — from three short sessions a week (Metcalfe et al., 2012).

Responses vary between individuals — some people adapt faster than others, which is why we recommend REHIT is individualised. But the direction of the evidence is clear: you do not need long training hours to shift your number meaningfully within weeks.

The bottom line

A good VO₂max is one above the median for your age and sex — roughly 48 ml/kg/min for men and 38 for women in their 20s, declining with each decade (Kaminsky et al., 2015). But the more important message from the evidence is that VO₂max is a dose–response variable: every increment is associated with lower long-term risk, with no ceiling yet observed (Mandsager et al., 2018).

Wherever your number sits today, it deserves your attention — and it responds to remarkably small amounts of the right kind of training. Two 20-second sprints at a time.