GoKawiilYouTuber's tests show Apple Watch Series 12 heart sensor rivals chest straps
The Quantified Scientist's Rob ter Horst compared the Apple Watch Series 12's redesigned heart rate sensor against a Polar H10 chest strap across cycling, running, and weightlifting. He found near-perfect correlation during cycling, strong results while running, and solid but slightly weaker accuracy during weightlifting, an exercise notoriously difficult for wrist sensors to track.