Whoop reliability

Good morning.  I have a St Jude dual chamber pacemaker (installed in 2018) to help me cope with consequences of heart block (likely arising from His-Purkinje Disease).  I'm 68 and an avid cyclist (4000+ miles/yr).  Recently, I've been struggling with upper limits on my heart rate that won't allow me to ride as hard as I'd like.  I've been using a Wahoo optical heart rate monitor that has been recording heart rates much (2-3 times) higher than my carotid pulse.  I've been considering a subscription to a Whoop monitor, but I'm reluctant to follow through if it too is as (apparently) as inaccurate as the Wahoo (given that it uses the same(?) technology to monitor heart rate).  

If anyone has insights into Whoop accuracy (and/or why the Wahoo is giving such apparently inaccurate heart rates) I sure would appreciate reading what you have to say.

Cheers - Paul


I like garmin HRM

by Pinkit94 - 2021-05-30 16:22:13

Hey Paul!

Much like yourself, I am an avid cyclist (80% mtb, 20% road) and I too have an icd+pacemaker. Over the years, I have tested multiple heart rate monitors, my favorite being garmin HRM and the HRM plus, as it seamlessly connects to garmin edge 530. Garmin then connects to Strava, which has helped my mds program my device in a way that I no longer feel exhausted while riding and can actually keep up with my friends. Second favorite is Scosche heart rate monitor +, this one is arm based monitor. In regards to your current HRM, try changing the batteries, or maybe call your device clinic and ask if during the times of mismatched HR you might be in afib. Best of luck and keep riding on! - Paula

Whoop is something else entirely.....HRM but more, maybe not?

by ar_vin - 2021-05-30 22:33:51

But all optical HRMs (arm-band, wrist worn etc - basically not chest strap) can be highly unreliable for PM recipients.


Save your money.....



Reliable/Accurate HRM with dual chamber pacer

by PaulSoth - 2021-05-31 09:50:32

Hello Pinkit94 and ar_vin - Thanks very much for your reply.  Do you use a chest-strap HRM?  If so, do you seem to get odd HRs while getting paced?  That is, do you think the pacing of your ventricle interferes with electrical signals from your heart to your HRM?  If that's the case, and if all optical HRMs are unreliable for PM recipients, then PM recipients are sorta screwed if they're trying to get reliable measurements of HR.  Yes?

Again...thanks for your thoughts.

Cheers - Paul

A chest strap is probably best...

by crustyg - 2021-05-31 13:07:29

A chest strap will give the most reliable HR measurements: however there are a couple of challenges that you may run into.  Lead I (which is what a chest strap measures) isn't particularly very high voltage.  For many folk a chest strap never detects a QRS complex which is what it uses for HR measurement.  A Heath-Robinson workaround is to buy some TENS pads and stick one just below the apex beat (well down on L side about an inch below and to the side of the nipple) - and then stick a matching TENS pad on the inside of the chest strap on the L side - effectively turning your chest strap into a V6 recorder - nice big voltages to work with. Obviously you have to connect the pads together - length of wire and a pair of 2mm male connectors.  Your favourite online bazaar will have something suitable.

Second challenge: there *may* be a pacing artefact which can mess up QRS-detection, but it's usually pretty small with modern, bipolar pacing.  It's big and noticeable with unipolar pacing.

Or you can be lucky and find that a chest strap works ok anyway: I like my Garmin one, it's ANT+ so easy to link to and generally pretty reliable.  On a static bike with realtime PM-console my chest strap was beat-for-beat the same as the PM config console.

Reliable/Accurate HRM with dual chamber pacer

by PaulSoth - 2021-05-31 16:47:54

Hey crustyg - Thanks VERY much for your Heath-Robinson workaround.  (And...thanks for introducing me to Heath Robinson!)  I understand the use of TENS pads, a cool idea.  What I don't understand is whether I should attach the "inside of the chest strap" pad to my skin or to the strap.  I'm guessing that the skin would be sufficient.  What say you?

Cheers - Paul

I didn't explain it very well

by crustyg - 2021-05-31 17:34:57

On the Garmin HR chest strap, the two rubbery sections either side of the central module are the pickups for your heart's electrical signal.  The R side needs to contact your skin as usual, the left side will be mostly covered by a TENS pad (conductive side down, i.e. facing outwards, making contact with the rubbery L side of the chest strap) and this TENS pad is connected by a short length of wire to another TENS pad below and to the left of your heart - at the apex.  Now your chest strap should see a V6 signal - move the TENS pad a little towards the centre of your chest and it will be V5, possibly even better signal.

It often helps to moisten the inside of the chest strap's conductive sections a little to get a good signal - happened to me this PM - had to stop 500m down the road as my chest strap wasn't recording anything.  A little moisture from the mouth and all was good.  Well, until the chain snapped on my MTB....

Many TENS pads will be reusable a number of times.

TENS pads to increase HRM reliability

by PaulSoth - 2021-05-31 18:13:22

Thanks, crustyg.  I now have a clear picture of how to use the TENS pads.  Soon I will qualify as a Borg in a Star Trek episode.  Hah!

And...yeah...spit serves as a sufficient conductor until I start sweating enough. :-)

Cheers - Paul

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At age 20, I will be getting a pacemaker in few weeks along with an SA node ablation. This opportunity may change a five year prognosis into a normal life span! I look forward to being a little old lady with a wicked cane!