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9.33/9.36 has ruined heart rate monitoring!

Hi!

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?

Thanks,

Michael

  • It would be interesting to know how many people are seeing this issue. Given that it's been in Beta for quite some time, I'd assume it's not everyone. I hope there will be someone to point out what's going on very soon, because currently this is killing my running-buzz.

  • Yeah, exactly. I wonder how many people are taking part in the new beta programme compared to how many used to. I never really look into these forums because I'm not taking part, but the discussions look more limited.

  • Why does it alter external HR data at all?

    It is bad enough that the optical HR data is smoothed on about 30-60 sec interval, which makes it useless for interval training. But now Garmin is ruining the external sensor HR data as well. 

  • Thank you for informing us on the forum. 

    I will leave software update disabled as long as Garmin continues releasing untested software updates.

  • Hello everyone, I don't know what to think anymore about the accuracy of the heart rate sensor. Didn't Garmin underestimate this part of the watch (Hardware / Software) of the heart rate sensor?

  • Ok, more data on this. I did a 3x3x15 Session today as suggested by my watch. I tracked the heart rate with the watch and also with my old M400 + chest strap.

    To be able to compare the data properly, I made sure the time on both watches was in sync. (<1s difference).

    I started the session on the M400 first and also stopped it after the Fenix 7. That way I was able to cut off the start and end of the session recorded with the M400 manually later on. -> Now the <Time> Tag matched exactly in the first and last <Trackpoint> of both recordings. -> They had exactly the same length now. So we're good on the X-Axis.

    To match the Y-Axis (HR) I manually punched in a 0 for the HR in the very first <Trackpoint> of the M400. That did the trick to give me a scale from 0 to 175 on both.

    Then I overlayed them. Blue is F7, Red is M400.

    While the data matches in general, the M400 seems to react much quicker to changes in HR. Since this is an (almost) 1h session, the temporal differences are a bit squished together.

    Side note: After this session, the F7 wanted to adjust my Max Heart rate to 187 which makes no sense at all when you look at the graph.

    Maybe someone from Garmin can shed some light on what's going on here? I've seen the "WHR improvements" item in the 9.33 release notes. Is this a result of these changes?

  • While the data matches in general, the M400 seems to react much quicker to changes in HR.

    This is something to be expected given M400 is connected to a strap while F7 is OHR I presume? All OHR sensors have a lag, which could also lead to less accurate measurements during intervals if OHR doesn't catch up fast enough.

    After this session, the F7 wanted to adjust my Max Heart rate to 187 which makes no sense at all when you look at the graph.

    I believe this is a new Firstbeat piece that was introduced in the first alpha whereas the watch is trying to estimate your maximum HR from a decidedly submax effort. How they do that I don't know... Perhaps same was Polar is trying to determine your VO2 Max from HRV during their fitness test at rest.

    For me the watch estimated 181 on sub-150 runs. I'd say my max is probably between 179 and 180 given what I see during heavy sessions and my LT HR. So, the guesstimate isn't far off. Who knows? Maybe I'm not pushing hard enough? Cold sweat

  • If these two graphs compare WHR and strap, as nickk@ suggested, it looks good - maybe not all watches are impacted, or maybe the problem happens only in some circumstances?

  • This is something to be expected given M400 is connected to a strap while F7 is OHR I presume? All OHR sensors have a lag, which could also lead to less accurate measurements during intervals if OHR doesn't catch up fast enough.
    If these two graphs compare WHR and strap, as nikk@ suggested, it looks good - maybe not all watches are impacted, or maybe the problem happens only in some circumstances?

    Well, the point of this thread is that it used to be better before the upgrade to 9.33. Even when sitting down, being at rest, it sometimes takes the F7 20s to realize that I have stood up and started walking around. It's just not reacting properly anymore. Here I'm just trying to add more data to figure out what's going on.

    And since 9.33 my chest strap simply doesn't work anymore with the F7.

    Also look at what J posted earlier:

    The Frontier X's graphs showed the linear increase in HR, but the watch logged the weird plateau and rapid vertical jump after catching up.

    That's just not right.

    I believe this is a new Firstbeat piece that was introduced in the first alpha whereas the watch is trying to estimate your maximum HR from a decidedly submax effort.

    I mean, kudos to them if they can pull that off, but my current Max HR was already set to 187 before today. So why the message? (I know I can go above 190 though. I just haven't done that yet on my F7.) But this is really not the point of this thread.

    maybe not all watches are impacted, or maybe the problem happens only in some circumstances?

    And if it's only on some watches, it's also useful to know, because then mine is obviously broken.

  • Well, the point of this thread is that it used to be better before the upgrade to 9.33. Even when sitting down, being at rest, it sometimes takes the F7 20s to realize that I have stood up and started walking around

    Which is normal. Heart rate always lags behind effort, at least 15-20 sec. if not more. It will be even more so for low efforts like walking. How much response you get would be dependent on a bunch of other factors: ambient temperature and humidity, hydration level, sleep, chronic strain, medication -- you name it. Now, if you got up and walked briskly for a minute or two and your heart rate still showed rest/sitting type of numbers, that would certainly be a problem. 

    Also look at what J posted earlier

    Not clear if he's showing OHR from his watch or his watch was connected to Frontier X? I'd imagine the latter, given it's intervals and he' wearing a strap.

    Here's an alternative explanation: his strap was recording raw data, available to Frontier X itself hence smooth charts there, but not properly broadcasting it.

    Or perhaps strap was disconnecting for some reason during running uphill -- notice the issues are only going up, not down.

    Or perhaps the problem was on the watch side with pockets dropped because I don't know... He listened to music over BLE headphones. 

    Or perhaps Frontier X was actually losing data, but its own charts are made to connect remaining data points smoothly. Many apps do that, but Garmin is notorious for showing breaks and flat lines. 

    I know it's no consolation at all, but I've been working out, OHR and heart rate strap, using Epix 2 and F7X SS since initial alphas all the way to 9.33 and I haven't noticed anything different. Today I did a progression run with T7 that still has 8.37, and T7 recorded run looks no different HR-wise than a similar progression run from last week, recorded with 9.33 F7X.