The research I've read [1] says that heart rate monitor in general and Apple Watch in particular should be pretty accurate. If you have darker skin or wider wri

The research I've read [1] says that heart rate monitor in general and Apple Watch in particular should be pretty accurate. If you have darker skin or wider wrists that accuracy may be diminished. [1] https://www.mdpi.com/2075-4426/7/2/3 https://www.mdpi.com/2075-4426/7/2/3