| 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 |