VO2 Max by Age: What's a Good Score and How to Improve Yours

VO2 max might be the single most important number your wearable measures — and the one most people ignore. It's a direct window into your cardiovascular fitness, your biological age, and your long-term health outlook. If you only pay attention to one metric beyond your daily steps and sleep, make it this one.

The good news: your Apple Watch, Garmin, or other fitness tracker already estimates your VO2 max automatically. The better news: unlike some health metrics that are mostly determined by genetics, VO2 max is highly responsive to training. You can improve it at any age.

Here's what VO2 max actually measures, what the age-based norms look like, and exactly what you can do to raise your number — whether you're 25 or 65.

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What VO2 max actually measures

VO2 max stands for "maximal oxygen uptake." It's the maximum amount of oxygen your body can use during intense exercise, measured in milliliters of oxygen per kilogram of body weight per minute (ml/kg/min). In plain English: it's a measure of how well your heart, lungs, blood, and muscles work together to deliver and use oxygen.

Think of it as your body's engine capacity. A higher VO2 max means your cardiovascular system can deliver more oxygen to working muscles, which means you can sustain higher intensities for longer. It's the physiological foundation that endurance, stamina, and recovery speed are all built on.

The gold-standard measurement happens in a lab — you run on a treadmill or cycle while wearing a mask that measures your oxygen consumption and carbon dioxide production. But your wearable estimates VO2 max using a combination of your heart rate during exercise, your pace or power output, and your personal data like age and weight. While not as precise as a lab test, these estimates are consistent enough to track trends over time, which is what actually matters for most people.

Why VO2 max matters beyond fitness

VO2 max isn't just about athletic performance. It's one of the strongest predictors of all-cause mortality — meaning people with higher VO2 max scores tend to live longer, regardless of other risk factors.

A landmark 2018 study published in JAMA Network Open followed over 120,000 people for an average of 8.4 years. The finding was striking: every 1 ml/kg/min increase in VO2 max was associated with a roughly 2.8% reduction in all-cause mortality risk. For cardiovascular mortality specifically, the reduction was even larger. Low cardiorespiratory fitness was a stronger predictor of early death than smoking, diabetes, or high blood pressure.

Another way to think about it: VO2 max is essentially a measure of biological age. A 50-year-old with the VO2 max of the average 30-year-old has a cardiovascular system that's functionally 20 years younger. And unlike chronological age, you can actually change this one.

VO2 max norms by age and sex

Your VO2 max declines naturally with age — roughly 5–10% per decade after age 30 if you're sedentary. But the rate of decline is heavily influenced by activity level. Consistent aerobic training can cut that decline in half or more.

Here are the reference ranges based on data from the American College of Sports Medicine and the Cooper Institute. Values are in ml/kg/min.

Men

Women

A couple of things to note about these numbers. First, they're population norms — "Good" means you're above average for your age and sex, which is a solid target for most people. "Superior" typically represents the top 5–10% of the population.

Second, your wearable's estimate may read slightly lower or higher than a lab test. That's fine — the absolute number matters less than the trend. A score that's moving upward over time tells you your cardiovascular fitness is improving, regardless of where the starting point sits on the chart.

Why your wearable VO2 max might seem "stuck"

A common frustration: you've been exercising consistently for months, but your VO2 max estimate isn't budging. Before you conclude the training isn't working, understand how your wearable calculates this number.

Most wearables — including the Apple Watch — primarily estimate VO2 max from outdoor walks, runs, and hikes. That's because GPS data combined with heart rate provides the speed and effort data the algorithm needs to estimate oxygen consumption. Indoor workouts, cycling, swimming, and strength training typically don't generate VO2 max estimates.

If most of your workouts happen indoors or in activities your watch can't use for VO2 max estimation, your score may appear stagnant even though your fitness is improving. Try adding one or two outdoor walks or runs per week at a steady pace — at least 20 minutes — to give your wearable the data it needs to update your estimate.

Also worth noting: VO2 max improvements take time. You're not going to see dramatic changes week to week. Look at the 3-month and 6-month trends instead. A 1–2 ml/kg/min increase over 3–6 months is excellent progress for most people.

How to actually improve your VO2 max

This is where the practical stuff lives. Improving VO2 max requires stressing your cardiovascular system at the right intensities, with enough frequency, over enough time. Here's what the evidence supports.

Zone 2 training: the foundation

The biggest lever for improving VO2 max is volume of moderate-intensity aerobic work — often called Zone 2 training. This is exercise at a pace where you can still hold a conversation but you're definitely working. Heart rate typically sits at 60–70% of your maximum.

Zone 2 builds the physiological infrastructure that supports a higher VO2 max: mitochondrial density, capillary networks, and the heart's stroke volume. It's not glamorous, but it's where the majority of your aerobic gains come from. Aim for 2–4 sessions per week of 30–60 minutes each.

High-intensity intervals: the stimulus

If Zone 2 builds the engine, intervals tune it. High-intensity interval training (HIIT) at 85–95% of your max heart rate provides the specific stimulus that pushes your VO2 max upward. Classic protocols like 4×4 minutes at high intensity with 3–4 minutes of active recovery between intervals are well-supported by research.

The key is not overdoing it. One or two interval sessions per week are plenty. More than that and you risk accumulating too much fatigue for the VO2 max benefit you're getting. These sessions should feel hard — you should be breathing heavily and unable to talk comfortably during the work intervals.

Consistency beats intensity

The biggest mistake people make is going too hard too often. High intensity feels productive in the moment, but it accumulates fatigue that limits how much total training volume you can handle. The people with the highest VO2 max scores aren't necessarily the ones doing the hardest workouts — they're the ones who've been consistently training for years.

A 2023 meta-analysis in Sports Medicine examining VO2 max improvements across different training approaches found that total training volume was a stronger predictor of VO2 max gains than training intensity. In other words, doing more total work at moderate intensities produced better results than doing less work at higher intensities.

Don't forget body weight

VO2 max is expressed relative to body weight (ml/kg/min). That means your score improves when your oxygen utilization goes up — or when your body weight goes down, all else being equal. This is why endurance athletes tend to be lean: every kilogram of excess body fat reduces your VO2 max by diluting it across more mass.

You don't need to be a competitive athlete's weight to see improvements. But if you're carrying extra body fat, even modest weight loss can produce noticeable bumps in your VO2 max score that have nothing to do with cardiovascular changes. This is one of the fastest ways to see the number move — though the real health benefits come from the fitness improvements, not just the weight change.

How fast can you expect to improve?

Research on previously sedentary adults starting a structured training program shows typical VO2 max improvements of 10–20% over 3–6 months. That's a 3–7 ml/kg/min increase for most people — significant enough to jump at least one category on the norms chart.

For people who are already fit, improvements come more slowly. Going from "Good" to "Excellent" might take a year or more of consistent, progressive training. Going from "Excellent" to "Superior" is even harder — that's where the genetic ceiling starts to matter.

What's encouraging is that these improvements are possible at any age. A 2020 study in the Journal of Applied Physiology put sedentary adults aged 50–75 through a structured aerobic training program. After 6 months, their average VO2 max increased by 16% — comparable to what you'd see in 20-year-olds following the same protocol. The body adapts to training stimulus regardless of age. It just might take a little longer.

What your VO2 max says about your longevity

The relationship between VO2 max and longevity is one of the most robust findings in exercise science. A 2022 study published in the Mayo Clinic Proceedings analyzed data from over 36,000 people and found that individuals with VO2 max scores in the bottom 25% for their age and sex had a nearly 5-fold higher risk of all-cause mortality compared to those in the top 2%.

To put that in perspective: being in the lowest fitness quartile was a stronger mortality risk factor than being a current smoker. And critically, the biggest jump in risk reduction occurred when moving from the lowest fitness category to just the next one up — from "Low" to "Fair" on the chart above. You don't need to be elite. You just need to not be in the bottom group.

The implication is clear: whatever your current VO2 max is, moving it up by even a modest amount is one of the most impactful things you can do for your long-term health. Your wearable tracks it automatically. Now you know what to do with the number.

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