[sdfhbdf]

The product that this article is advertising seems to be pretty inaccurate and their marketing seems to be burying that information.

The big copy on the front page says:

> Your Apple Watch *tracks* VO2 Max—one...

While you have to read through FAQ where you see:

> The watch *estimates* your cardio fitness during outdoor activities and stores it in Apple Health, which our app reads automatically.

All emphasis are mine.

I think it's a little disingenuous to sell this as "Your VO2 Max, finally visible" when it's actually just an estimate from a watch, based on biomarkers. When the real VO2 is measured in a lab with a more involved equipment.

A 2025 validation study involving 30 participants found that Apple Watch underestimated VO2 max by a mean of 6.07 mL/kg/min (95% CI 3.77–8.38) when compared to indirect calorimetry, the gold standard method. The mean absolute percentage error (MAPE) was 13.31%, and the limits of agreement showed considerable variability ranging from -6.11 to 18.26 mL/kg/min [1]. Another 2024 study found similar results, with the Apple Watch Series 7 showing a MAPE of 15.79% and poor reliability (ICC = 0.47) [2].

[1]: https://journals.plos.org/plosone/article?id=10.1371%2Fjourn...

[2]: https://biomedeng.jmir.org/2024/1/e59459

[Madmallard]

yeah there's no reliable way to measure VO2 max without breathing into tubes.

[ajb]

There's (vo2master) device that can apparently measure it in one breath; there was a video on some swimmer using it on turnaround without much interference with their exercise. $7k though.