The Apple Watch claims to estimate VO2 max based on casual activities such as walking, which is a great feature for people who aren't already athletes.
However, in my experience it is very inaccurate. When I first got my Apple Watch, I went on a run with it to see if it offered anything that my Garmin didn't. After this run, the Apple Watch estimated a VO2 max roughly the same as my Garmin, which I've had for years.
I didn't use the Apple Watch for running ever again, only for things like walking to the store. It then estimated a VO2 max that was over 10 points lower than the estimate from the running activity.
The Apple Watch seems to have a traditional way to estimate VO2 max, which seems roughly comparable with competitors and a treadmill test; and a separate bad way estimated from non-exertional activities.
However, in my experience it is very inaccurate. When I first got my Apple Watch, I went on a run with it to see if it offered anything that my Garmin didn't. After this run, the Apple Watch estimated a VO2 max roughly the same as my Garmin, which I've had for years.
I didn't use the Apple Watch for running ever again, only for things like walking to the store. It then estimated a VO2 max that was over 10 points lower than the estimate from the running activity.
The Apple Watch seems to have a traditional way to estimate VO2 max, which seems roughly comparable with competitors and a treadmill test; and a separate bad way estimated from non-exertional activities.