Fenix 6 Pro: Increased Heart Rate Inaccuracy (too high for running activities) Since Beta 11.75 and Now 12.20 Release


It seems my Fenix 6 Pro optical heart rate sensor is reading with even greater inaccuracy than prior to the beta 11.75 and now official, 12.20 release. One could argue my perceived exertion is simply less but when I take the time to manually check my heart rate during a run or immediately after, I find the Fenix 6 to be around 20-25 BPM higher.

It also seems to be reading higher while cycling but not by as much. I have always found the Fenix line and the optical HR to be a bit more stable and reliable while cycling. 

My resting heart rate, with a little distance between the measurement and an activity tends to be quite accurate still though.

Is anyone else experiencing a significant increase in the recorded optical heart rate during runs (both trail and road) (if not other activities)? 

Thank you!

  • Former Member
    0 Former Member over 3 years ago

    The biggest problem is that a large portion of owners don't really know what is right or wrong.  This whole heart rate thing is a big black eye on either the sensor or Garmins programmers.  I think Garmin, since when they first released the watch over a year ago, it was near perfect.  On firmware 3.1.   Then they did an update and it has never been very good since.

  • I have the same problem. I'm trying to follow a workout suggestion of running 1 h at 140 bpm but the HR as measured by the watch is at 180... it is close to impossible that I have that kind of heart rate while running at 7' per km...

  • It is really bad since the last update yes. I always used a hr strap  for intervall sessions, but for easy jogs i don´t really bother too much. But the readings from the fenix are just really really bad. It is optical, so no problem for it beeing not so accurate as the strap BUT i end up running completly above 180 beats per minute no matter how easy i run. I am quite a good runner and i normally run every single day, i know my paces you could say and i also have quite a good "feeling" of my HR, but after round about 30 minutes  running the data is totally wrong as mentioned. 180 would be around 03:30 pace and i also get that while running close to 05:00 and while beeing able top speak TOTALLY NORMAL. After 30 Minutes the Data (at the latest!) totally go wild and are nowhere near usable

  • I agree, it's bad since 11.75.

    HR is too high when running using the HR on the watch, and the training status doesn't work either. I compared using the Apple Watch, and the difference where 30 to 50 bpm, which is huge !

    I did a lots a run during the beta phase and I had to use my HR strap to get correct results

    finally I downgrade to 11.10 (and sensor hub to 7.12) to have the WHR correct again

  • I 've experienced the same: About +35 bpm ...

    Tested on version 12.20 Fenix 6 Pro.

    Resting HR seems ok

  • same problem here. Contacted Garmin, had to re-install everything and update everything again. No change only a lot of time lost!

  • Same issue repeated on a treadmill run. Effort was very steady and suddenly i got a jump of about 35 bpm. After a few minutes it returned to normal,  see pic

  • Aside from the terribly inaccurate and unusable training data, I've also found that after mile 7 on a run I will get lap notifications that are not on the mile. For example, I will get an audio notification through my buds saying "lap 8, x:xx mile pace" but I'll only be a third into mile a given mile (e.g. tonight it was 7.37miles) . 

  • I know I'm going to catch sh*t about this post and I honestly wish everyone's watch would work well for them.  But after reading months worth of threads that the HR measurement is way too low and doesn't work properly, especially with actives such as hiking and why can't Garmin adjust how HR is sampled, I can't help but have a chuckle and think of the old adage "be careful of what you wish for" when I read this thread.  Another old adage. "You can please some of the people all of the time, you can please all of the people some of the time, but you can't please all of the people all of the time."