This. On my F8 I have the 'Source Switching' enabled so the watch records the most reliable measurement from the optical wrist HR sensor or the strap. But the issue I found this morning was that in general, the strap was worse than the wrist sensor HR. It was very, very cold this morning but I did lick all 4 contact pads on the HRM before putting it on about 5 minutes before the run. Then perhaps 1/3rd of the way into the run, I began to sweat. In any event, can anyone think of why the strap would be worse? Or maybe the optical wrist HR sensor is over estimating true heart rhythm?
