Cold wheather and again WRONG WRONG WRONG HR values from Garmin Forerunner 955. I had same run today and variation between Downhills and Uphills in just 3-4bpm compared to over 10bpm of warmer climate or previous FW release....same path, same pace, same distance.....of course all datas gets affected like training status, Vo2Max etc....
In cold weather I recommend using a HRM strap (and even that has to be wetted properly to work reliably). And by cold weather I mean < 10°C. Surface circulation on your wrist tends to be much worse in…
as you see I was at minimum 138Bpm on downhill and just up to 141Bpm on Uphill. Compared to previous runs on the same street I had a difference of more than 10Bpm before updates to FW 21.xx and before…
as you see I was at minimum 138Bpm on downhill and just up to 141Bpm on Uphill. Compared to previous runs on the same street I had a difference of more than 10Bpm before updates to FW 21.xx and before cold wheater arrived if that is the reason. For sure it doesn't work now....all datas are calculated wrong like V02Max etc
In cold weather I recommend using a HRM strap (and even that has to be wetted properly to work reliably). And by cold weather I mean < 10°C. Surface circulation on your wrist tends to be much worse in cold weather, especially if you keep your wrist exposed to see the watch.
And when the temperature drops even lower, you'll need a HRM strap anyway, because it's too cold to keep the wrist exposed and you'll wear the watch over your sleeve anyway. 
