Apple updates VO2max (Cardio Fitness) estimates in iOS 26 / watchOS 26
With the release of iOS 26 and watchOS 26, Apple’s Health app on iPhone can refresh and update past Cardio Fitness (VO2max) estimates. VO2max — the estimated maximum oxygen uptake during exercise — is used as an indicator of cardiovascular fitness and long-term health trends.
What changed
The Health app can now recalculate historical VO2max estimates using available workout and sensor data. This may change previously reported values for some users after the update.
How to trigger an update
- Open the Health app on your iPhone.
- Tap Browse > Heart > Cardio Fitness (or search for “Cardio Fitness”).
- Scroll to the Cardio Fitness section and tap Update if the option appears — the app will use your available workout data to refresh estimates.
Ensure your Apple Watch and iPhone are synced and that recent outdoor workouts are present, as these improve the accuracy of VO2max estimates.
Sources & further reading
- Apple Support — About Cardio Fitness (VO2max) and the Health app
- DCRainmaker: watchOS 26 explained (coverage of VO2max/fitness updates)
Have you noticed a difference in your VO2max after updating? Share your experience in the comments below.