It is almost a year with Fenix 5 for me and I was very pleased with its performance so far. I upgraded from Fenix 3 mostly to stop using HR strap, as I developed an allergy to its fabric. It worked great, but in recent runs, I noticed that HR is quite unstable. I am not sure what is causing it, as I wear the watch the same way since I bought it. Please look at the graph, I am running on the flat surface, with constant speed, yet there is HR jumps from 155 to 170 and back again. Am I alone with this? ciq.forums.garmin.com/.../1324279.png
