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HRM-Pro-Plus has serious bug with activity HR download, time doesn't add up, zones are short

I don't recall this problem with my (multiple) HRM-TRI, you'd think the firmware would be similar but maybe not, maybe they tried to add a feature and broke something.

I am curious if anyone can reproduce this on other Garmin watches than the Fenix6, I bet you can.

1. go for a run, I suspect ride would work too as long as you use a few zones

2. screenshot your load and zones like below

3. download the HR from the activity menu

4. screenshot that newly calculated load and zones

The zones from BEFORE the download add up to the activity time

The zones from AFTER the download are SHORT by around a minute (sometimes more)

You would think pushing the start button on an activity somehow sends a cue to the HRM-Pro-Plus to sync the timestamp.

Now I am not so sure that's how it works or the functionality is broken on this HRM firmware.

Another guess is that during the activity the HRM estimates the pulse rate by itself.

and maybe after the download the watch tries to more correctly estimate the pulse by R-R intervals in the HRV data

Inside the TempFIT/hrdata.fit  is  "filtered_bpm" where those numbers are entirely too low to be during activity

images backup copy:  https://imgur.com/a/htx7SbB

  • It was already mentioned couple times.
    Garmin is not recommending to download HR data from the HRM after activity when watch was constantly connected to the watch during activity.
    This function is recommended to use for activities during witch you was not wearing your watch (football boxing), or watch was not able to be connected during (like swim).

  • Not sure if you realize that if it cannot match the data from a known activity with realtime broadcast

    then the accuracy of downloading activities without realtime broadcast would be even less trustworthy

    There's a minute of data missing, or more.

    But here's the thing that completely contradicts all other arguments:

    I never had this problem with download from the HRM-TRI for YEARS

    Downloading from the HRM-TRI would only pick up an extra beat or two missed during the broadcast because ANT+ has known data loss.

    Realtime vs download would match almost exactly on the HRM-TRI

    But the HRM-Pro/Plus is very different and loses time because it has a bug they have not found or fixed.

  • I got your point.
    I think you should report it to Garmin support as bug, here we only could talk about it, Garmin will not look at it.

  • another egregious example where supposed VO2MAX level effort is converted to BASE effort after HRM-Pro-Plus download 

    the effort actually was BASE as demonstrated in the HR graph, which really makes me wonder if it's the BEFORE that is done wrong on the Fenix6 (26.97b)

    I am starting to leave the BEFORE and AFTER download FIT files on Garmin Connect for hopefully some Garmin dev to look at someday, now they have the full HRM data

    This one is from Monday May 13th 2024 and Garmin has my full permission to look at them both on Garmin Connect

    (the daily exercise load is also not updated on this one but I don't bother to screenshot anymore, plenty of other examples)