[nradov]

I've watched it and TheQuantifiedScientist is totally missing the point. Current optical sensors on the wrist are plenty accurate enough for general health and fitness tracking. If you don't believe me then you can literally count your pulse with your finger and compare against the watch: very close. Optical sensors aren't great for high-intensity training so for those activities everyone knows you need to use a chest strap if you want accurate data.

For a more practical take on heart rate accuracy see the DC Rainmaker reviews instead.