A longtime Apple Watch user who switched to WHOOP for better health tracking is now considering returning to Apple Watch Series 12, which offers improved health monitoring features including more frequent heart rate collection and a new Readiness app similar to WHOOP's recovery score, alongside the redesigned Apple Health app in iOS 27.
The Quantified Scientist tested the Apple Watch Series 12's revamped heart rate sensor against a Polar H10 ECG chest strap across indoor cycling, running, and weightlifting. The Series 12 performed very well with correlations of 1.0, 0.98, and 0.97 respectively, placing it above 85% of competing devices during weightlifting.