Switching from optical to HRM-Run how do you tell? Any why low HR?

Former Member over 7 years ago

I've been trying to get my Fenix 5 use the HRM-Run instead of the optical sensor, but the data I've getting doesn't seem accurate. And I'm hoping for some advice.

Is there a way to know that the device is using HRM-Run? I've checked that it is connected, but there isn't an icon or something that indicates that it is using the HRM-Run. I'm doing high-intensity functional training and with the HRM-Run strap:
a) my overall heart rate is too low. I'm showing my max at 160, but I'm maxing out and it should be 180+ (I'm also wearing a whoop wrist strap that confirms that I should be at much higher HR)
b) when I finish the workout and am stretching it gives me a notification on the watch that says "External HR Connected" (but I verified at the beginning that it was connected and also never got a notification that it dropped the connection. So I can't tell if it was on the whole time.
c) when I'm in garmin connect (web) it doesn't indicate that I've used the chest strap (should it? I thought it would.) for the workout. It does show in Garmin Connect my "Ground Contact Time Balance" which I think is only available from the HRM-Run strap (of course this data means nothing for this kind of workout)

Any thoughts on what I'm missing? Or how to make sure it's using the HRM-Run instead of OHR?

Thanks in advance!

0 nmyeti over 7 years ago

At the start of the run when you are waiting for GPS to be ready you should get a notification that the external HR is connected. Occasionally i'll miss this notification as i'm doing my pre-run routine so the easiest way is to just lift the watch a bit and peak under it to see if the green HRM lights are on. If they are off, the external is connected. If you look in Garmin Connect after a run you should see all the other HRM-Run metrics. As long as those don't drop out, your heart rate is coming from the HRM-Run.

As for it being too low, I've never had great luck with optical HRMs. I use the HRM run trust it's accuracy much more than anything optical at this point. My optical monitors seem to lock in more on my cadence than my actual HR. One tip, wet the strap before putting it on. That helps it get synced up at the start of a run. I have no experience with the Whoop wrist strap so i can't say it is more/less accurate than the HRM-Run, but my general experience is that the HRM-Run outperforms any optical monitors I've tried.

0 mcalista over 7 years ago

a. A common problem with wrist HRMs is that if they are loose, they can bounce on your wrist and pick up your cadence, leading to a higher than actual HRM reading. Are you really sure that your HR should be 180+, or is that just what you have got used to from your Whoop measurements?
b. The Ext. HR Connected message after a workout is normal (weird, but normal). I think it drops during the Save process, then reconnects. It doesn't mean your HRM-Run wasn't connected during the workout.
c. The LED's should shut down once the watch detects an external HRM. As above, peek under the watch - if you can't see the LED's, the HR data must be coming from the strap.

0 JSRUNNER_ over 7 years ago

As per above don't know the whoop wrist strap but very unlikely that Optical will give more accurate figure than Chest strap. How have you determined your Heart Rate zones in the first place 180+ is quite high. Would also be interesting to know exactly what the content of your workout is and its duration.

0 Former Member over 7 years ago

Thank you for the advice and thoughts.
I've also compared the data to my Polar V800 (chest strap) for these workouts and it matches what the Whoop is giving me of 180+ (also my body is fully spent at the end of the workout). And that's why I'm concerned that the readings from my Fenix+strap is too low.

Other thoughts on it?

As for the workout, it's a high intensity interval workout. Lots of sprinting, ball slams, plyometrics and TRX (strap + rip trainer), burpees etc. 3 rounds of 10 stations with 15 sec break between them and 90 sec break between rounds 2 and 3.

0 JSRUNNER_ over 7 years ago

Ah now that's interesting - which HRM run have you got - if its the one where the unit in-pops from the strap (two press studs) then you should be able to put it on the Polar strap - that will at least tell you if the strap is the problem.

May also be worth changing the battery in the HRM - don't know how old it is or whether you have used it with any other device?

Do you wet the strap before running ?

0 Former Member over 7 years ago

The strap is a HRM-Run from Garmin (brand new). It's the one where you can't remove the cpu (red unit) from the strap. So no way to remove it.
Also haven't used it with any other devices (I would prefer to use my polar strap since its much nicer, but sadly polar vs garmin & ant+)

Other ideas?
Thx!

0 JSRUNNER_ over 7 years ago

Well If you have tried all those things then sounds like you may have a faulty unit and you should return to retailer