Apple Watch vs. Lab Test: How Accurate Is VO₂ Max?

VO₂ max is one of the strongest predictors of cardiovascular fitness and long-term health. The gold standard for measuring it involves treadmill or cycling tests with gas analysis — accurate, but costly and impractical for routine use. The Apple Watch and other wearables estimate VO₂ max using heart rate responses during everyday exercise combined with demographic and GPS data. But how close do these estimates come to lab results? In this study, we tested 40 healthy young adults. Each participant generated a VO₂ max estimate on the Apple Watch Series 10, then completed a lab-based cardiopulmonary exercise test with indirect calorimetry. The results show that the Apple Watch systematically underestimated VO₂ max by about 6 ml/kg/min, with an error margin around 13%. This level of error may be acceptable for tracking general trends over time, but it limits the watch’s use for clinical care or precise research applications. 📄 Full study available here: https://doi.org/10.1371/journal.pone.... #vo2max #applewatch #wearables #digitalhealth #fitnesstech #applewatchultra #applewatch11 #applewatchseries11 #applewatchultra3 #appleevent2025 #appleevent