Heart rate turned to dashes above 132 BPM

[mpemburn]

Hi,

I was out on a bike ride today, and wanted to know my heart rate while climbing the steepest hill.  I checked my Charge 6 a couple of times as I was going up and it read 126, then 132, but at top of the climb, it showed three dashes.  Once I got on the flat again, it resumed showing numbers.  Was it freaking out?  Some strange setting?  I know it was tight up against my wrist the whole time.

Thanks in advance,

Mark

[RiekoC]

Hello @mpemburn 

Did you have a chance to check your heart rate graph for your ride in the Fitbit app? If so, did it show a section where you were missing heart rate data?

[mpemburn]

The only thing it says for heart rate on my phone is 49 - 138.  The web app shows a graph, and it doesn’t have a gap in the place where I was on the hill (by my best guess).  The highest peak is 143 BPM, which is consistent with what I’ve seen in that section with my Garmin heart rate monitor.

The question, though, is why the dashes? 

[LZeeW · Accepted solution]

@mpemburn   You see dashes when the optical heart rate monitor (OHRM) can't sense a heart rate.  Fitbit recommends wearing the device three finger breaths away from the prominent bone on your wrist during exercise.  There is another possible reason -- get ready for some physics.  An OHRM emits light and it is reflected back.  You can get a type of interference called muscle motion artifact and it interferes with the signal.  The muscle artifact is from your grip on the hand grips.  Is you Garmin a chest strap?  Chest straps are more accurate than wrist worn OHRMs.

[Triletics]

@mpemburn two dashes mean that watch is unable to detect your HR. You mentioned riding bike. Bike is probably the only type of activity I haven't had successfuly captured HR on any Fitbit I owned 🤷 somehow, Fitbits and bikes are not best friends. Even if Fitbit detects HR while on bike it's not correct (not by little but by a lot).

[mpemburn]

Thanks!  Most interesting!

My Garmin HRM is a chest strap, but I don't like it because it's uncomfortable.  The Charge 6—unlike my old Charge 2—shows the HR continuously, so it's handy just to be able to glance down at my wrist to see what's going on.

Btw: it's a shame that FitBit doesn't support the ANT+ protocol.  It'd be cool to have the HR on the Garmin while I'm riding.

Mark

[Triletics]

@mpemburn if you don't like chest strap, get Polar Verity Sense (or older model - Polar OH1, although this one is probably long discontinued) armband. It's optical but nearly as accurate as chest strap and you can wear it on forearm, bicep or calf. This is probably best solution if you need to see HR on Garmin bike comp and you don't want to use chest strap.