How to Find Your VO₂ Max on Apple Watch (And Why It's Your Most Important Health Metric)

Your Apple Watch is quietly measuring one of the most powerful predictors of how long you'll live. It's called VO₂ max, and researchers have found it's a better indicator of mortality risk than smoking, diabetes, or high blood pressure.

So why does Apple bury it five taps deep in the Health app?

I stumbled onto this by accident. After years of wearing an Apple Watch, I discovered it had been tracking my cardiovascular fitness the entire time—I just never knew where to look. That sent me down a rabbit hole of trying to understand what this metric actually means and why Apple makes it so hard to find.

What VO₂ Max Actually Measures

VO₂ max represents the maximum amount of oxygen your body can use during intense exercise. Think of it as your engine's horsepower. The higher your VO₂ max, the more efficiently your heart, lungs, and muscles work together.

The "VO₂" stands for volume of oxygen. The "max" means we're measuring at your limit—the point where your body physically cannot process any more oxygen no matter how hard you push.

Professional athletes obsess over this number. Elite endurance athletes typically score between 60-85 mL/kg/min. Average adults fall somewhere between 30-45, depending on age and gender. You can see exactly what's normal for your age and gender in our benchmark charts—for example, here's what a 45-year-old male should expect.

Why This Metric Matters More Than Step Counts

A 2018 study published in JAMA Network Open followed over 122,000 patients and found that cardiorespiratory fitness was inversely associated with all-cause mortality. Put simply: higher VO₂ max, longer life.

The relationship was striking. People with the lowest fitness levels had nearly five times the mortality risk compared to elite performers. Even moving from "below average" to "above average" fitness cut mortality risk by about 40%.

The study also found that low cardiorespiratory fitness carried comparable or greater mortality risk than traditional clinical risk factors: coronary artery disease increased mortality risk by 29%, smoking by 41%, and diabetes by 40%. Being in the lowest fitness category dwarfed all of these.

Compare that to step counts. Walking 10,000 steps is great for general activity, but it tells you almost nothing about your cardiovascular system's actual capacity. VO₂ max does.

This is why I was so surprised to learn my watch had been measuring it all along.

How Apple Watch Estimates Your VO₂ Max

Your Apple Watch doesn't measure VO₂ max directly—that would require a laboratory, a treadmill, and a mask capturing your exhaled air. Instead, it estimates your cardio fitness using data from outdoor walks, runs, and hikes.

The watch correlates your heart rate response with your pace and terrain. If your heart rate stays relatively low while you're moving at a decent pace, that suggests good cardiovascular fitness. If your heart rate spikes just from a leisurely stroll, that's a different picture.

Apple calls this metric "Cardio Fitness" in the Health app, though it's measured in the same units as VO₂ max (mL/kg/min).

Here's the catch: the Apple Watch only records readings during outdoor activities where GPS is active. Specifically, you need to use one of three workout types in the Workout app: Outdoor Walk, Outdoor Run, or Hiking. Indoor treadmill runs won't trigger updates. Neither will cycling, swimming, or strength training—even outdoors. The algorithm requires the specific combination of GPS movement data and heart rate that only those three workout types provide.

How Often Does It Actually Update?

According to Apple's validation study, approximately 78% of qualifying outdoor workouts generate a new VO₂ max reading. So if you regularly do outdoor walks, runs, or hikes, you'll likely see updates after most of those sessions.

Several conditions need to be met for the watch to record a measurement:

The workout must be outdoor. Apple Watch requires GPS data combined with heart rate information. Indoor workouts don't count—not treadmill runs, not gym sessions, not indoor cycling. Only Outdoor Walk, Outdoor Run, and Hiking workouts in the Workout app will trigger readings.

Your heart rate needs to elevate adequately. The algorithm looks for your heart rate to increase at least 30% of the range between your resting and max heart rate. A very casual stroll might not trigger a reading.

Terrain should be relatively flat. Apple's documentation specifies less than 5% incline or decline for optimal readings. Extremely hilly routes may not generate estimates.

GPS and heart rate signal quality matter. Poor GPS reception or an inconsistent heart rate reading (loose band, sweaty wrist) can prevent the watch from recording.

When these conditions are met, you should see a new data point appear in the Health app within a couple hours of finishing your workout. If you're doing regular outdoor cardio and not seeing updates, check that you're using one of the three supported workout types in Apple's native Workout app.

How to Find Your VO₂ Max in Apple Health (Step by Step)

Here's the path through Apple's interface. It's not intuitive:

Open the Health app on your iPhone
Tap the Browse tab at the bottom
Scroll down and tap Heart
Scroll down again to find Cardio Fitness
Tap to see your current reading and historical data

That's five taps minimum, assuming you know where to look. Most people never make it past step two.

Once you're there, you'll see your most recent reading displayed in mL/kg/min. Tap "Show All Data" to see your complete history. Apple also shows a chart of your readings over time, which is useful for spotting trends.

The interface categorizes your result as "Low," "Below Average," "Above Average," or "High" based on your age and sex. But these labels are vague. What exactly is "above average"? How far above?

That's where comparing to population-level benchmarks becomes useful. If you're a 35-year-old female, you can see precisely where your number falls compared to others your age.

Why Apple Buries This Data

I've thought about this a lot, and I think there are a few reasons Apple doesn't put VO₂ max front and center.

It only works with specific workouts. Unlike step counts or calories—which accumulate from any activity—VO₂ max only updates from outdoor walks, runs, and hikes tracked in the Workout app. That's a narrow slice of what most people do, making it less universally applicable.

It can be discouraging. For people who are just starting their fitness journey, seeing a low VO₂ max number might feel demoralizing. Steps feel achievable. VO₂ max feels clinical.

It's an estimate, not a measurement. Apple is careful about health claims. The company probably doesn't want people treating their watch's VO₂ max estimate as medical data, so they de-emphasize it.

It's complicated to explain. "You walked 8,000 steps today" is instantly understandable. "Your VO₂ max is 38.2 mL/kg/min" requires explanation. Apple tends to hide anything that isn't immediately intuitive.

But here's the thing: the metrics that are hardest to understand are often the most meaningful. Your resting heart rate and heart rate variability are also buried in similar submenus, and they're incredibly valuable health indicators too.

A Better Way to Track It

After discovering how useful this data is—and how annoying it is to find—I started looking for alternatives.

The ideal solution would surface VO₂ max readings automatically, without the five-tap journey through Apple Health. Even better, it would translate that abstract number into something meaningful, like how your cardiovascular fitness compares to your biological age.

That's actually why VO₂ Max Pro exists. The app reads your data directly from Apple Health and sends you a notification whenever your watch records a new reading. You can also see your historical trends and get your result translated into a biological age, which is a more intuitive way to understand what your number actually means.

If your VO₂ max suggests you have the cardiovascular fitness of someone younger than your actual age, your biological age will be lower. If your fitness lags behind, you'll see that too.

What Your Number Actually Tells You

Here's a rough framework for interpreting your results:

For most adults, a VO₂ max between 30-40 mL/kg/min is fairly typical. Above 40 suggests good cardiovascular fitness. Above 50 is excellent. Elite endurance athletes often exceed 60.

But these ranges shift dramatically with age and sex. A 25-year-old with a VO₂ max of 40 is below average. A 65-year-old with the same number is doing remarkably well. This is why looking at age-specific benchmarks matters more than raw numbers.

The good news is that VO₂ max responds well to training. Research shows that untrained individuals can see improvements of 15-30% with consistent interval training over several months. Even a single MET increase (about 3.5 mL/kg/min) is associated with a 10-25% improvement in survival. That's meaningful when you consider the mortality implications.

The Takeaway

Your Apple Watch contains one of the best predictors of longevity available outside a medical lab. It's tracking your cardiovascular fitness automatically, updating it after most outdoor walks, runs, and hikes you record.

The data exists. It's just hidden.

Now that you know where to find it—or how to surface it automatically—you can start paying attention to one of the most important health metrics your watch measures.

Check your VO₂ max today. Note where it falls in the benchmarks for your age and sex. Then check again in a few months after consistent cardio training. The number can change, and watching it improve might be the most motivating fitness feedback you've ever received.