I have a HRM-Dual which I bought in March 2020 that is paired with a Fenix 6. I am aware of the dreaded heart rate spikes early on in the activity when there isn't a good connection yet, but not aware of this phenomenon later on in the activity once sweaty. This has never happened before and now has happened in two of the last three activities I have done. The first was a bike ride where I was doing hill repeats near my house. On a climb 45 minutes into my workout my heart rate jumped from 170 to 250. It initially freaked me out and I went back down the hill to my house and my heart rate returned to normal. It was about one minute between normal readings which I'm guessing going downhill fast during made it last that long. Today I was backcountry skiing and on my second climb my heart rate jumped from 155 to 219 and then back and was about 20 seconds between normal readings. Also today while skiing while not traveling uphill my heart rate spiked down from 112 to 72 and was around 10 seconds between normal readings. I wear the chest strap snug but not super tight and I was wearing tight non-cotton shirts both times, but this never happened so I never thought to tighten it or wear different shirts. I haven't changed the battery in the year I have had it and I also haven't ever washed the strap. Just curious if this has happened to anyone else? I took screen shots of the plots if that helps. Thanks.
