Watches and tests

Why is my VO2 max so low?

By GyroscopeUpdated November 14, 20267 sources

Often the estimate is low and you aren’t. Apple Watch came in about 6 points under a lab test on average, indoor workouts don’t count toward it, and Garmin only learns from outdoor runs. Check the number once with a field test before you believe it.

A low VO2 max feels like a verdict, especially when the watch adds a word like “Poor” or a notification that you’re low for your age. But three things that have nothing to do with your heart can drag the number down. The watch may be underestimating you, it may be judging you on the wrong chart, or it may only be seeing your easiest workouts.

We’d test it once with a 12-minute run or a 1-mile walk before deciding anything. If the test agrees, you’re at the starting point where training pays off the most.

1. The watch runs low

In a 2026 lab check, Apple Watch Series 10 came in 6.25 points under a mask test on average and put only 5 of 35 people in their right fitness band. A watch that says 30 most likely means a lab number around 36. For a woman in her 40s, that’s the difference between the 70th and the 87th percentile. Details in is Apple Watch VO2 max accurate?

2. The label uses a tougher chart

Garmin’s labels come from The Cooper Institute’s data, which sit well above the US FRIEND chart. A woman in her 40s at 30 is “Poor” on Garmin and at about the 70th percentile on FRIEND. Bike tests also run lower than treadmill tests, so a bike result needs the bike chart.

3. It only sees some of your workouts

A watch only sees the workouts you show it, like a coach who only watches your warm-ups.

• Apple Watch estimates from Outdoor Walk, Outdoor Run and Hiking workouts only. If you mostly cycle, swim or use gym machines, it’s judging you on your walks.
• Garmin needs at least 10 minutes of running outdoors at 70 percent of your max heart rate or more. Cycling gets a separate estimate, and only with a power meter.
• Your profile feeds the math. Apple uses age, sex, weight and height. Garmin asks for your max heart rate, and the age formulas often miss it.

If it really is low

Then you’re in good company, since a quarter of people are in the bottom quarter of any chart, and in the best place to gain. Across 28 controlled trials of adults aged 18 to 45, steady training raised VO2 max about 4.9 points and intervals about 5.5. People who started less fit gained the most, about 3 points more from intervals than fitter people did.

Start with brisk walks most days, then add one hard session a week (see how do I increase my VO2 max?). For a free check today, see how can I test my VO2 max at home?, or put your watch number in the calculator below to see the range it likely stands for.

Where does your number come from?

Apple Watch± 6.1Garmin± 5Fitbit± 8Oura or WHOOP± 812-minute run± 71.5-mile run± 71-mile walk± 4.4Beep test± 4.4Resting heart rate± 4.7Lab testmeasured

About you, and your number

Ageyrs

Sex

WomanMan

What your Apple Watch saysml/kg/min

Apple Watch shows from 14 to 65, from outdoor walks, runs and hikes only.

38to50where a lab would likely put you, most likely 44. Your watch said 38.

38 on the watch

10th22.125th28.250th35.375th43.090th50.8

LowLowBelow averageBelowAbove averageAboveHighHighTop 10%

You have the engine of a 39-year-old

38 is about the 60th percentile for men in their 40s. Group: above average

If a lab would say 44, that's about the 78th percentile.

How far to trust it. In a 2026 lab check, Apple Watch Series 10 came in 6.25 points low on average and put 5 of 35 people in their right fitness band. Good for your trend, rough for your rank. Lambe and others, Mayo Clinic Proceedings: Digital Health, 2026

When is a change real? Compare a source only with itself. A change smaller than about 2 to 4 points can be noise: a review of 14 studies put a meaningful change at 1.75 to 3.5 ml/kg/min.

Where you standRaise it with the 4x4Get your true VO2 max