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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?



  • If this isn't the software based smoothening, then I don't know how else this can be explained.

    My feeling is that Garmin maybe using R-R intervals too.

    If you open the run in Runalyze what does the artefact % look like?, assuming you have Log HRV enabled?

  • Thanks for the data!
    Bear in mind that this type of run is actually where Garmin still performs best. My bet is a HIIT type run would show a lot more deviations.

  • For all of you who have problems could you please just comment or upvote the beta thread so the engineers actually see this issue, otherwise this is just pointless complaining....

  • Problem still persists! This is a tennis activity, which naturally includes sudden increases and decreases in BPM. Look at all these huge drops in BPM, which are totally unnatural! For example, at 29:33 I have 148 BPM, and at 29:40 (only 7 seconds later!!!!) I have 116 BPM!! I emphasize: this was NOT happening before 9.33. Now, every HIIT-like activity I do, is like this! In reality I have like 170 bpm, and the watch says 110 bpm (in all these abrupt decreases of BPM that the watch shows, in reality I had an INCREASE of BPM). This is absurd!

  • I guess you should use a chest strap for now. I'm not saying that to invalidate your comment, but because your problem will probably persist for quite a while. 

  • same problem here and the concern is that I have a marathon now on the 20th. it seems that Garmin doesn't want to recognize this error, now for U$ 600 in an equipment that became unusable is complicated. Likely I'll use the old Apple Watch 7 so I don't risk taking the test.

  • the problem is exactly that, it's not working right with heart strap, I have polar h10.

  • Here is some data from my Indoor ride today from a 3 hour Zwift session - 4 recording devices in total.

    The HRM Pro was connected via ANT+ to my laptop, and Fenix 7 (shown in Green). A Coros Vertix 2 was connected to the HRM Pro via Bluetooth (it has no ANT+)

    A Garmin Epix used it's own wrist sensor, and was not connected to the HRM Pro (in purple below)

    The EPIX2 and F7 are on 10.37 firmware

    Note: For some reason DCR's tool doesn't quite align everything but the trends match up. There was a 5 minute break in the Zwift ride so everything stops for a few minutes in the middle.

    There are a few occasions where the Epix 2 reports too low, but generally everything matches up well, for me at least. I cannot see any evidence the F7 is somehow alternating the raw data from the HRM Pro where 3 independent devices are all recording the same HR data stream.

    Anyway, just some more data to add some grist to the mill!

  • the problem now is the h10 polar strap considered one of the most reliable on the market? because there was no problem before? wouldn't it be easier for the engineering team to recognize that something is wrong with the Garmin system? 

  • good? they are reluctant to acknowledge that there is something wrong with the system!