Low hr activity

Stock face (without HR) decreased number of trainings with random HR, however Garmin's OHR still sucks. I fully agree that wrist HR are not designed for accurate training readings, however if OHR mistake is more than 100% (for very long time 60bpm on Garmin while HR is 160bpm) it means that Garmin sells trash. Tomorrow returning my Fenix 5s to Amazon. Goodbye Garmin!

You are absolutely right!

I think I have the same problem - but not only since firmware 10. I bought it in 03/2018 and it doesn´t work since then:
when I start an activity (e.g. "Crosstraining") fenix 5 (internal sensor) shows hr 60-70. But in reality it is 130-140. Everytime only after 20-25 minutes the fenix 5 shows correct hr (or sometimes after stop and new start of activity). It is NOT a problem of the internal sensor. I think it´s a firmware-problem.

Changing fenix 5 - I think - doesn´t help. Do you know if other versions (e.g. new fenix 5 plus) have the same problem?

Fenix 5 Plus has the same problem (or more...). :(
https://forums.garmin.com/forum/on-the-trail/wrist-worn/fenix-5-5s-plus/1371513-fenix-5-plus-hr-very-inconsistent
No chance to get a Garmin-Watch without this problem?

This is actually normal from what I have read. Ever since I bought my F5 almost a year ago, the OHR has been utterly worthless in an activity. I always use a strap when riding/running etc. The only thing the OHR is good for is tracking your resting HR. The first time I used it was for an XC skiing activity, and it said my avg HR during the activity was 98. Normally I run from 140 on up while XC skiing. I don't think its something that Garmin is too concerned with fixing, so just use a strap for more accuracy.

This is actually normal from what I have read. Ever since I bought my F5 almost a year ago, the OHR has been utterly worthless in an activity. I always use a strap when riding/running etc. The only thing the OHR is good for is tracking your resting HR. The first time I used it was for an XC skiing activity, and it said my avg HR during the activity was 98. Normally I run from 140 on up while XC skiing. I don't think its something that Garmin is too concerned with fixing, so just use a strap for more accuracy.

More accuracy yes but this is so wrong that you cant call it accuracy any more and it should not be normal if the watch have a ohr. People who only use watch for light activity should not be forced to buy a hr strap too. Better of buying another watch brand

Do you know one where it works better?

More accuracy yes but this is so wrong that you cant call it accuracy any more and it should not be normal if the watch have a ohr. People who only use watch for light activity should not be forced to buy a hr strap too. Better of buying another watch brand

I do not disagree with you. Only stating that Garmin certainly knows about this flaw and will not fix it. It sucks but that is the reality of it. If I did not do alot of intense activities, I would most certainly not have purchased this watch.

Now that I am alerted to it, I have been able to observe what leads to the issue: Abrupt changes in heart rate.

A slow, easy ramp up in heart rate is tracked well, like with hiking, but an abrupt change like interval training, or a quick sprint (like hockey) where your HR doubles in a short span... The F5 misses it and will stay at 1/2 the actual rate. This really screws me on the reason I bought this thing: to be careful not to overdo it and punish my ticker. It is easy to do at my age.

I would take an educated guess that the OHR sensor has a variable sample rate to help conserve power, and its ability to change that sample rate while heart rate is increasing is not fast enough for many activities. The sensor doesn't have enough data to estimate heart rate if it is sampling too slowly.

I would really like Garmin to track down this issue and make this a great sports watch again. Since I have owned it, it has yet to get OCH correct for intense activities. I am almost certain this could be fixed if there was a will.

Just to be clear, my old VA3 never missed a beat. It got a lot else wrong, like elevation, but HR it did well. Same dang sensor, should behave the same.

i bought a used polar a360 just to have something to compare. WHR on polar is much better and faster.
Fenix 5 on left arm and Polar on right.
this really sucks. this is my replacement fenix5. old one was the same

avg hr garmin 98
avg hr Polar 117ciq.forums.garmin.com/.../1442435.png