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9.33/9.36 has ruined heart rate monitoring!


After upgrading my my fenix 7 to 9.33 I have noticed a few odd things about the heart rate that's displayed/recorded on my watch. Here's what I noticed:

First run with the new Firmware: My old H7 chest strap sensor, which worked fine before, showed sudden drops in HR of about 30 bpm while running at a constant pace. (H7 has a fresh battery.)

I thought was just the chest strap, but then I noticed sudden mayor changes in HR with the integrated HR sensor as well, when I was just at home. Within 2 seconds it jumped or dropped by about 20 bpm.

Also, when I stand up after sitting for a while, my heart rate does not change at all on the watch. It keeps showing mid to high 40s. However I can clearly feel that it's way off for about 15 to 20s and then it starts "catching up". > Again I big jump in HR on the watch. I tested this multiple times by comparing it to the data from my H7 + old watch where it behaved as expected – a gradual increase in HR.

I also restarted the watch which didn't help and I made sure I was wearing it correctly. (I wore it the same way before upgrading the firmware.)

Before the upgrade it felt very reliable and now I don't know what to think. Has anybody else noticed something similar? Any suggestions on what to do now?



  • I noticed that in the latest beta version (10.41) there’s a sensor hub version update included. I decided to try this beta version and after 2 runs I’m pretty confident that the WHR issue I was experiencing is now solved. There’s nothing in the release notes about a potential fix, but it looks good to me so far Fingers crossed tone1

  • On line 955 the same problem, please fix it. It's getting annoying already.

  • Can anyone of those on Beta 10.41 confirm whether the issue is solved/WHR back to performing like it used to? Thank you!

  • I'm on Beta 10.41 ... for me the issue still exist...

  • Today I did a very simple test. I connected the same Polar H10 chest HR monitor to both Garmin Fenix 7X and an old Suunto Ambit 3 Peak at the same time. I believe it is connected to Fenix via Ant+ and to Suunto via Bluetooth.

    Then I went for a walk checking HR on both watches at the same time.

    Would you say the HR should be identical because it comes from the same external sensor? That's what I would expect, but in reality HR readings on the two watches diverge quite a bit. It is pretty clear that Fenix 7X does some sort of smoothening because the HR readings on it change with a delay vs. Suunto and show less variance. Suunto showed higher peaks and lower deeps than Garmin. Also Suunto reacted faster to changes in the effort. At steady speed the HR didn't differ by more than 1-2 beats, although even that seems wrong to me. But at times I saw the two HR values differ by up to 6-10 beats per minute.

    That isn't encouraging. It isn't right for Fenix to alter the external sensor data in any way. 

     I'll try repeating the same test while running and see if I can overlay the two HR graphs together. 


  • Former Member
    0 Former Member over 1 year ago in reply to silentvoyager

    If this is true my watch is going back today and I am all done with Garmin. 

    My only trust has been that my chest strap is raw and untouched data.

    The only way Garmin is going to give a *** and change is it people start going to the BBB. 

  • My only trust has been that my chest strap is raw and untouched data.

    FYI - What you receive from a 3rd party HRM is what you will see attached to your activity metrics. Your comment is not accurate which is why I have commented to correct any confusion.

  • Former Member
    0 Former Member over 1 year ago in reply to Garmin - Chris

    Then how are users getting different readings across devices using the same strap at the same time?

  • You would need to ask the manufacturer's of those 3rd party HRM straps. Everything has software on it these days and metrics can be manipulated. Overall, there is often a misunderstanding of how OHR is read and how a HRM works. I highly recommend everyone read up on it across the internet. It is not as straight forward as most assume it is.

  • Former Member
    0 Former Member over 1 year ago in reply to Garmin - Chris

    So the issue is the industry standard Polar H10. Got it.