Originally Posted by Stig:
“Interesting. I've never heard of 'target HR training', so maybe I'm not in the demographic for that type of fitness device. I feel I get pretty good HR data when running, and I'm not concerned if it is 'accurate' as long as it's consistent between sessions.”
It'll depend on what you're training for; opticals tend to be okay when running (at any sort of speed), reasonably accurate. But when weight training you may as well be using a random number generator, it won't be in the slightest bit consistent ... But I must give credit to Apple for supporting an external HRM on the watch, they're the only manufacturer to do it.
(incidentally, my training is fairly specific of late - was on a team that set a endurance world record on indoor rowers, and now training for another distance based team record, it mildly uncomfortable)