Fenix 5S HR monitoring is grossly inaccurate?

I got my watch about a week ago, installed all the proper updates, and have been using it daily. I have noticed an issue with the HR monitoring across the board. I primarily do CrossFit, which means my activities vary from lifting to running to random cardio movements to strength. I can push myself to the brink and be lying on the floor breathless and the watch is reading my HR as something like 110 or even as low as something like 84. The only time I seem to get any semblance of accurate HR is if I am actually running or jogging, with my arms pumping. When I check, I will then be in the cardio zone with something like 140-150. Other than that, my watch does not seem to pick up changes in HR accurately. I have tried the strength setting, cardio setting, etc and was starting to think maybe I needed to update my software, but it is up-to-date. I have also tried re-positioning the watch on my wrist, as well as both tightening it and loosening it. Nothing I have done has seemed to improve the HR monitoring.

Note: I previously had the Forerunner 225 with HR monitor, so I am familiar with the wrist HR monitoring. I would have issues from time to time with that watch's HR monitoring, but not like this. I recognize that wrist HR monitoring is less accurate than a chest monitor, but I have upgraded my watch (at a hefty $$$) for what appears to be less accuracy.

Can anyone help? Is anyone else experiencing this?

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0 andrej-svk over 7 years ago

I wrote to the support because I have the same problem during tennis session... Previously with a polar M600 OHR All records where perfect..

The same for me... dont want to repeat myself but I agree with almost all in this thread.
See more here:
https://forums.garmin.com/forum/on-the-trail/wrist-worn/fenix-5-5s/155633-fenix-5-very-poor-heart-tracking-with-tennis

0 benrubenstein over 6 years ago

I've had the same issue with my Fenix5. In fact I just returned it. I did a track workout last night, in which I did hard-effort 400 meter repeats with recovery after each one. The HR info from my Fenix 5 was utterly nonsensical.

I previously was running with a Garmin Forerunner 220 paired with a separate "Mio" wrist HRM. It worked superbly. (I lost the Mio and am going to order a replacement for it.)

Attached are charts showing 3 recent track workouts that I've done, comparing the chest strap, the Mio wrist-based HRM, and the Fenix 5 built-in HRM. The chest strap and the Mio report data that makes sense. The Fenix5... I have no idea. It just looks... random. Very frustrating and disappointing. ciq.forums.garmin.com/.../1287183.jpg

0 dewarner over 6 years ago

I have been getting what I think is a reasonable HR on my runs outside and on a treadmill, and when I am wearing the watch over night. Today I did a stress test, and the machine indicated that my heart rate topped out at 170. When I checked my Fenix 5S, it said the maximum heart rate during that time was 120. When I was walking/running on the treadmill during the test, I was told to hold onto the bar which prevented my arms from moving as they would in running outside or even like I would normally do on a treadmill. Is he fact that my arms were not moving the probable reason for the HR on the Fenix 5S not being correct?

0 Ma73ko over 6 years ago

I have been getting what I think is a reasonable HR on my runs outside and on a treadmill, and when I am wearing the watch over night. Today I did a stress test, and the machine indicated that my heart rate topped out at 170. When I checked my Fenix 5S, it said the maximum heart rate during that time was 120. When I was walking/running on the treadmill during the test, I was told to hold onto the bar which prevented my arms from moving as they would in running outside or even like I would normally do on a treadmill. Is he fact that my arms were not moving the probable reason for the HR on the Fenix 5S not being correct?

My feeling is that arm movement has some impact on the algorithm... but we need a Garmin technician to know.

0 TiagoFerrao over 6 years ago

I agree. This is not a technological limitation. My old 200$ A360 worked fine. As well as most all the wrist heart rate watches I had. The fact that the watch register 85 bpm to all of us on the strength mode is at least too much of a coincidence and indicates a programming routine to make it do exactly that for some odd reason. Garmin should clearly state that the WHR is only built for running and do not make us spend 600$ on a device. It is at least misleading.

0 Eddy over 6 years ago

I am also very disappointed with the WHR in my f5s.
I do strength training every day and I get the same results as described earlier.
The garmin website did not inform at all about this limitation when using strength training program, if so, I probably wouldn't buy this expensive model. And all reviews I see didn't explicitly refer this issue.
I also see the f5s manual and I can't find any reference about strength training like the manual of VA3.
My suspicious is that f5s get the upgrade software after the VA3 go to market but the hardware sensor was not tested and prepared to give more accurate hr data from strength training workouts.
My question is if the VA3 have the same strength program and hr sensor as f5s (need confirmation) have the same problem? If soo is only a software problem and it could be solved ...
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0 HappyHammer over 6 years ago

I have a brand new (1month old) Fenix 5s and have the same issue with HR. if I’m jogging, it seems ok. If I’m on the bike, like I just was, it rarely gets beyond 80/85, normally it sits between 65-75. It should be about 120. As a previous poster noted, I think it’s the arm motion of the jogging that improves the accuracy when in an ‘activity’ mode. When it’s just on my wrist and it records HR over the day, it seems about what I’d expect.

Very irritating, as the ability to lose the chest strap etc, was one of the real appeals that made me shell out £530!

0 SupaDucta over 5 years ago

HR is not all that is buggy and imprecise. When I was on an ergometry test on a professional medical device, the watch hasn't even detected almost a minute of pulse going over 160. Floors are a party (how can one go 6 floors up and 11 down?). Custom workouts are a mess - every now and then it gets lost from the watch, when I update it on Garmin Connect it doesn't transfer to the watch although it says it did, even if I delete it first it doesn't get transfered. It did get transferred once though, and not once since. Battery life is much shorter from what's advertised (although it was much better before software upgrade to 11 and then 12) and in just a month it seems to be shortening more and more - a friend of mine already returned 2 and finally went for other brand). Today the thing displayed 1,46 kilometers of walking whereas the real distance is 2,6 (as per previous readouts). When software gets updated, it resets the watch face and half settings. Along with such smaller or larger bugs or quirks, there is no way for it to be connected to multiple devices, WiFI is absurd (if it gets software updates via WiFI, why in the world isn't there an option not to use bluetooth)? And detecting crossfit-like (+ trx + treadmill) training one day ended up as an hour and a half of indoor rowing :p so I gave up on it.

I am going to reset this thing to see if any of those numerous bugs and quirks improve but from what I see, returning this thing is more likely... Garmin developers should really get their act together. This... thing... is a king of bugs. Sorry but it is unreliable, imprecise and buggy.

0 Forestknights1 over 5 years ago

Mine used to perform ok. Not so since the last couple of updates. Now expensive junk. Thinking of buying a Fitbit charge 3

0 Former Member over 5 years ago

i agree its is totally inaccurate and very disappointing for a $1000+ watch. the garmin soft strap makes it usable for track calories.