Heart Rate Wildly Inaccurate

I recently upgraded to the 6x Sapphire and immediately noticed my heart rate data was way off. Prior to getting the 6x I used a 5x for a couple years and a 630 before that. With the 630 I used an HRM Run strap and kept it with the 5x until I was confident in the 5x accuracy (it was always very close to the HRM Run strap). Now with the 6x I'm getting results on easy runs that show my HR higher than my heart is capable of beating. It is impacting everything. All the stats are off since the watch thinks I'm sprinting every run.

Here is an example of a recent easy run. I used a data field that recorded the HRM Run data along with the watch HRM.

Here the watch says I maxed out at 186 BPM (that's higher than I can get if I'm sprinting 800 meter repeats or 5k races). According to this I'm overreaching and in zone 5. Not true - it was an easy run and I was talking the entire time.

Watch HRM

Same run as recorded by the strap. I never got much above 160 and that was only briefly as I ran up a dangerous hill (because getting run over by a large truck doesn't sound like much fun)

HRM Run HR

I'm not sure what to do next. The watch is not lose on my wrist. It feels the same as my 5x did.

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0 Former Member over 4 years ago

Unfortunately you won't find much help on this. It's plagued many of us, and many of us just gave up and went a different route/watch. Hoping the Fenix 7 has a more robust sensor for HR and SPO2.

0 DarrinC over 4 years ago in reply to Former Member

The final stage of grief: "Acceptance" (and the purchase of an HR strap)

0 Former Member over 4 years ago

I added that data field to my 6x sapphire and did a small walking test using a Garmin chest strap. I short pretty fast paced walk and added a short jog at the end. Here are the results...

Today I am going on a 5 mile hike with a meetup group that we do every Saturday. It is a very hilly hike with a pretty fast pace and my HR is usually all over the map on this hike, so it would be a better comparison test than just a short walk. I will post the result here later today.

There are a lot of variables to consider with OHR sensors...

skin type, tattoos, not wearing it tight enough, not wearing it high enough on the wrist, sleeves/gloves obstructing it somehow (in winter), swinging your arms enough to cause the device to jiggle on your wrist (even a little), and probably others that i have not thought of or mentioned.

You mentioned that you had no issues with your 5x, but the 6x has a new sensor design and may be more sensitive to one or more of these variables. There is also a good chance that you got a defective unit.

You could try some more experimentation or just try to get a replacement to eliminate the chance of a defective unit. If you do some more testing post the results here. Maybe some folks with more knowledge can be of some help also.

0 nonparametric over 4 years ago in reply to Former Member

I’m curious how you’re recording both OHR and chest strap? My understanding is that wrist HR turns off when a chest strap is detected.

0 Former Member over 4 years ago in reply to nonparametric

You can download this data field...

https://apps.garmin.com/en-US/apps/a9734c04-fb8a-49b9-89e1-9ac16a9a6f5e?fbclid=IwAR1I5fBs2Cb09iqv8zvkldEvt9y-0VZlX1JfAplIIIDgzHK7YPlaBnRQwtc#0

Add it to an activity and it will connect to a chest strap (if detected). It will display and record both the chest strap and OHR data during an activity. Make sure the chest strap is not paired to your watch. The data field will detect the chest strap.

0 Former Member over 4 years ago

Here are the results from todays hike...

Pretty much spot on for the most part aside from a few minor hiccups. You could maybe call Garmin support and see what they say, or do an exchange in case it's a defective unit.

Maybe someone else with more knowledge will chime in here.

0 silentvoyager over 4 years ago

I use chest strap with my 6X on pretty much 100% of my runs. Wrist HR sensor is OK for measuring HR at rest but it is unreliable even when walking at moderate pace.

0 Former Member over 4 years ago in reply to silentvoyager

Here is todays interval run comparing the OHR to a chest strap. You can see it is pretty much spot on for the most part.

0 Martin868 over 4 years ago in reply to Former Member

This graph suggest the OHR is actually very accurate. Is that your point ?

0 Former Member over 4 years ago in reply to Martin868

Yes.

The OP (and others) could very well have defective devices, or some other factor like some of the variables i mentioned earlier.

If you get one that is not defective and avoid any of the things that could interfere with the sensor, you should get performance very close to a heart rate strap.