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Optical HRM still totally wrong with 21.19 - In fact, worse than ever

Grumpy from dawn till dusk
3 months ago

Hi 

unfortunately I have bad news. You closed OHR related topics like this
https://forums.garmin.com/sports-fitness/running-multisport/f/forerunner-955-series/384760/heart-rate-values-from-optical-hrm-still-totally-wrong-with-20-26

and this
https://forums.garmin.com/sports-fitness/running-multisport/f/forerunner-955-series/362273/heart-rate-values-totally-wrong-after-update-18-22

But you were asking to give you feedback, if we encountered that bug again.
This is the case - in fact, in my opinion the optical HRM is worse than ever now.

With 20.26 I was quite ok with the measurements of the OHR while walking/hiking and for higher intensity workouts I usually use a HRM strap (beside bike commuting).
With 21.19, the OHR cannot be trusted AT ALL, even for low intensity stuff like walking/hiking.

See this heart rate values, that I recorded during an hours walk today:

The average is a HR of 70!!!
While walking one hour with a pace below 10 minutes/kilometer.

My resting HR is 48, still, this is just random. It is nowhere near the real pulse I had during that walk.
And regarding blood flow: Yes, it is cold now in Germany (4 degrees Celsius), but I was wearing a thick fleece pullover and Polartech gloves and the watch was below it all.

Yes, you may contact me and have a look at my activities and I live in Germany.

  • 0 2 months ago in reply to 9094594

    What is your question related to excatly?

    I assume that the measurements of the chest strap are correct since the method is much more robust then the optical method.

    So strap: correct, OHR wrong (either the sensor is not able to generate a correlating signal or the algorithm fails in picking the right signal)

  • 0 2 months ago

    Three intervals yesterday:

    It's weird that the HR is correct at the start of the second interval but then immediately drops too again for the entire duration of the interval. 7 minutes in this case.

  • 0 1 month ago

    I downgraded to 15.19 several weeks ago. All modules were also downgraded (sensor module 24.22). This is not recommended by Garmin, but it solved all OHR problems. I have done a lot of running and cycling activities and the heart rate was also accurate at the beginning of an activity without jumps.
    Last week I had the bootloop problem and also did a factory reset (had to do this several times).
    The firmware is still on 15.19 and all modules have the same version numbers as before.
    BUT: Since the factory reset, the OHR problems have returned. I went running two times and cycling two times. At all 4 activities the heart rate was initially too low and I had to turn / remove the watch etc. to solve it. After that the heart rate jumped up.

    This seems to indicate to me that it is not necessarily due to the firmware version. Possibly this is caused by other installed files??? This could also be the reason why it doesn't occur for some people.
    This may help with troubleshooting, although I don't know if Garmin even wants to fix this.

  • 0 1 month ago

    Just to contribute what is my typical experience: from my perspective heart rate is heart rate. There should be no activity required. I understand that some smoothing makes sense but it should be able to follow along with a modest delay. Below is today's heart rate 955 with no activity taken shortly after I got off the bike trainer and an Edge 1040 w/Garmin HR Duo strap for the ride. The results are not on the same planet.

    Forerunner max hr 111

    Edge max hr w/strap 149.

  • 0 1 month ago in reply to Christian888

    This is a very interesting report. Can you imagine any outer circumstances which might be related to the lower performance of the OHR measurement after a reset of the watch.

    I'm still guessing in my case the jumps in the HR reading are related to the ambient temperature and wearing a long sleeve shirt. So the watch does not generate any signal where the HF can be extracted. Watch is mooving a bit and als blood vessels are small at the beginning. As use system is getting to more load all vessels are widening even get swollen so the theres much more useful signal to evaluate.

    But assuming   had similar influences before and after the reset, it could indicate that garmin uses a self learning algorithm to evaluate the HF signal. It might geht "stuck" somewhere since it is not ideal at the end. (Link there seems to be reports for the automatic lactate evaluation.

  • 0 1 month ago in reply to Stefan

    I have a new example of a run two days ago:

    It was about -1°C, I was wearing a long sleeve und got an acceptable result.

    So I have to say: I could not find any "real" pattern so far and I do not know if my guesses were right so far. Sweat smile

  • 0 1 month ago

    Running the latest firmware 22.22, pleasant 13 degrees Celsius weather, long sleeves:

  • 0 1 month ago in reply to Matthias

    Firmware 22.22 did not change anything in my case. Probably the hardware can not do better.

    But I'm wondering how the automatic source switching algorithm works. Maybe anybody has an idea.

    2 activities and always the same setup. I wore the watch on my left wrist and the HRM Pro chest belt.

    First activity alpine skiing - chest belt fails to measure the correct HF. Probably my skin got too dry due to the wind.

    But the watch takes the HF from the chest belt which is slightly too high with 190bpm Joy.

    Second activity running:

    Same procedure as every day - the wrist HR is too low in the first minutes but the algorithm takes it anyway.

    So I'm wondering what the "automatic source switching" does besides logging both sources in the fit file and taking the wrong source.

  • 0 1 month ago in reply to Stefan

    What really bugs me though, is I've bought this watch back in the day based on several reviews which explicitly stated that the wrist HR is one of the best out there: https://www.dcrainmaker.com/2022/05/garmin-forerunner-solar-review.html

    Arguably among the best wrist-based sensors out there, to the point where for my body/wrists/whatever, I can use it pretty reliably on most workout types, including intervals. Like most optical HR sensors, it can have a bad day, but these are few and far between here, and the one time it clearly failed while running was actually an easy part. It nailed every hard interval I threw at it over multiple workouts.

    And this used to be the case. It was spot-on every single time. But somewhere in the last few months one update completely borked it to the point I now have to run with a chest strap to get any meaningful HR readings at all...

  • 0 1 month ago in reply to Matthias

    So there were some guys which downgraded the firmware to a seemingly "good" version but nobody came up with any kind of evidence that the problemes were fixed.

    In the end you would need a big data analysis over a huge amount of users how some features of the heart rate change with modifications in the software. E.g. deviation to external sensor or average heart rate in the first 5 minutes...

    But nevertheless the automatic source switching failed in my case because a HF above my max HF during alpine skiing should be recognized as wrong measurement.