Heart rate "dropouts" (for lack of a better term)

The only time I've seen drops like that was when using a Mio Fuse paired to an FR220 and wearing them on different arms. Never had a problem like that with either the 225 or 235. It's like it lost the signal completely.

Thanks for the feedback. It actually still had a heart rate reading, but it was about 80 (and below the x-axis on the graph). My Garmin 620 with HR strap registered about 130 during this period.

What's also troubling is that the heart rate just immediately set back up to 130 after this drop.

I've had this problem constantly with both the 3.10 and 3.20 versions. However, in my case the start of my activites look like yours, with a starting HR in the 80-90 range and then a sudden leap to my actual HR. 3.13b seemed to work well for the week or so I used it.

I don't see that on Garmin Connect App... but see it in the raw unmodified data via the PC Software "Golden Cheetah".

I'm not doing straight runs - but an outdoor mixed circuit type class.

What I don't get is that the drop-outs seem to only be in the middle of straight-line runs and not during the situps/pushups or other activities.

I would not expect drop-outs to occur in normal running where the arm/wrist is not being flexed or under stress.

Have tried the watch on either arm and in a few different locations - but similar result - and as yet no solution.

Here's my HR chart from my 16-mile run today: https://connect.garmin.com/modern/activity/980972427.

I am on v3.20. I seem to have had about the same luck with HR data under all the firmware versions so far. I stopped for water and Gu at about mile 6.85. However, it looks like my HR dropped at about mile 6.6 and I just didn't notice because I was focused on getting to the stopping point. When I started back running, I got to about mile 7.05 before I noticed that my HR was <100. At that point, I stopped, paused my watch timer, jiggled the watch face, and just sat there for a second. I saw the HR jump to around 120 so I thought I was fine and started running again. Again, it sank back down, so I stopped a second time. You can see two little pace blips at about 7.09 and 7.11. This time, after pausing and jiggling and waiting, it seemed to catch back up when I ran again. It stayed reasonably consistent for the rest of the run, even though I paused again at a traffic light and a final time for a sip of water.

It's almost like you have to somehow shock the watch into realizing it needs to take a new reading. However, that first drop seemed to have happened for no reason. There was no elevation change (the whole course is flat), and my pace was fairly stable.

I didn't mind pausing and fiddling with it a little this time, but sometimes I don't notice it right away (if I'm gabbing with a friend), or sometimes I'm in the middle of a faster interval and don't want to break my stride to fool with the watch.

Anyway, that's just some feedback. Hopefully the watch's HRM will keep improving. It's decent now, but it's not quite as accurate as I'd like.

Thanks for all the follow-up. I tried working with Garmin on this, but they kept going round in circles. I ended up swapping the watch for a new one which I should have this week.

In the interim, I've gone back to my 620 with it's HR strap and I realized two competing things – (1) the HR strap gives me more consistent readings and (2) I hate wearing HR straps :-(

I was an early adopter of the 620 and went through months and months of bugs and crashes before the watch became stable. One would think I would have learned my lesson two years ago, but the allure of a built-in HR monitor was just too much to resist.