Heart Rate measurements wrong during activity

I've only tested it once so far (only had it a couple weeks so far) where I was running on a treadmill and had a Polar H7 HR sensor on. I consider the H7 sensor more accurate, so I used it as the baseline. What I found was that there was a lag in it showing my HR increasing, but once my heart rate was steady (per the H7) the vivomove HR matched closely the H7 (within 5 bps). Same thing going down, it took a bit to notice it, but was close. So, no, I found it to be pretty close then, except during the increase/decrease times. I'll try it again tonight though. Otherwise, I don't really pay attention.

My girlfriend also has got the same problem with vivomove hr. She did cardio workout and had a heart rate of ~160 (measured by crosstrainer) but the watch shows 103-104. The watch was sitting correctly on her hand and during the workout she removed the watch and wiped over the sensor and her hand. It didn't work. After ~25 minutes, suddenly the watch detected the correct ~160 bpm. As a result the calories calculation was not correct. This occurs sometimes, sometimes not...

Does anybody know where is the problem? Or will it be fixed by an update?

Optical heart rate measuring is good for daily heart rate tracking and resting heart rate tracking. However, in sport activities including moving or shaking arms, where watch can slide up and down on the wrist or shake and let outer light come to the sensor, optical HR sensors have difficulty keeping the track of light reflected from the blood. That's why for accuracy people still use HR chest straps. What you can do is find an ideal tightness for the strap where it won't shake up and down and it isn't too tight to block the blood flow. For calories etc. you can edit the activity on Garmin Connect app after saving it. Even if it reads the heart rate correctly, burned calories will be different than your ergometer or other devices.

Yes, tightness of the watch is important. I found out that with the rubber band, which has more holes than the leather one and so I can better make the watch fitting well without cutting into the skin, it's more accurate but never as accurate as the HR chest strap of the Edge 520.

Hi
i hope someone can help. My heart rate recording has showed a zero for a bit both today and yesterday. Is this concerning, is the watch having trouble finding my heart rate or is it something else? Any info would be greatly appreciated. ciq.forums.garmin.com/.../1373202.png

I've been looking over (and contributing to) this Reddit thread: https://www.reddit.com/r/Garmin/comments/8lbev1/vivomove_hr_heart_rate_inaccuracy

Here's a summary:
When I first posted I'd only used it at the gym 3 times. The first time my HR didn't go above 100 when the elliptical said it was at ~160, the second time I tried letting my arm hang and it went to about 130, which was better but still not high enough, and the third time I couldn't get it above 100 no matter what I did - I tried letting my arm hang, putting it on the underside of my wrist and using the other wrist.

The next time I went I cleaned and dried the watch and my wrist just before working out.
My HR consistently tracked within ~5 bpm of the cross trainer reading (apart from a short blip half way through, where it tracked ~30 bpm below for a minute or two)

But sadly when I tried the same thing next time it wasn't reproducible - my HR stuck around 90 when it was actually around 160.

I've just ordered this strap to see if it'll help with different tightness options: https://www.amazon.co.uk/gp/product/B073GRW511/ref=ox_sc_act_title_1

Has anyone found anything that works for them (other than adjusting the band tightness) yet?

I have the same problem with the HR accuracy and looking for a solution in this forum for the same issue on similar products (vivactive 3, fenix, etc...),
the only things that seems to work is to wear the watch in a different position during an activity

I've seen that especially when my heart rate rises very quickly at the beginning of a very intensive exercise (climbing stairs, crosstrainer), this is not picked up correctly. Sometimes this corrects during the exercise, sometimes not. As my fitness is getting better, the problem seems to get worse. I've also seen this with chest straps and HR monitors built into fitness equipment, so it's not typical to optical HR monitors.

My ionic does a far better hr count, why can fitbit get it right, but not Garmin

I have the Garmin Fenix 5 plus. The heart rate has seemed reasonably accurate if I strap it tightly well above my wrist bone on a standard training run. However ,it seems to have problems when I do intervals on the track and it is completely hopeless when I hike very slowly in the cold with my wife. My heart rate was 60 as counted at both wrist and neck pulse but my watch measured around 150. I would really just like to know how to correct these activities.