What's a Heart Rate, Anyway?

I've been having issues with my HRM-Tri recently where it just doesn't seem to give me results consistent with my relative perceived effort.  For example, starting out fresh on a treadmill at about 10 min/mile pace and the HRM-Tri shows my heart rate around 140 bpm.  I've been so annoyed recently with this perceived inaccuracy that I actually stopped my warmup to manually take my heart rate.  I completely stopped and took my pulse for 15 seconds and came up with a heart rate closer to 100 bpm.  All the while, my watch was showing right around 140 bpm from the HRM-Tri.  It didn't even slow down despite the fact that I was completely stopped, which is completely different from the issue that I have occasionally with the Scosche Rhythm+, which will lock on to my cadence if I'm not adequately warmed up and it's cold outside.

I want the HRM-Tri to work because there are some metrics that are only unlocked if you have a heart rate strap, as opposed to an optical HRM.  The strap can detect heart rate variability which is used to estimate Lactate Threshold.  Optical HRMs aren't able to discern that with any reliability.

To that end, I've started wearing two heart rate monitors, the HRM-Tri recording on the Wahoo Fitness app on my phone, and the Scosche Rhythm+ recording on my Garmin 945.  I've taken to comparing the files to see how bad the HRM-Tri is.

Below is a "workout" from the treadmill this morning.  At some point during the run, I decided I would throw in some 2-minute intervals, changing my speed from 8 mph to 10 mph and then give myself six minutes of recovery. 

I was running steady-state at 8mph (as reported by the treadmill - actual pace per Stryd was slightly slower).  I hit the quick-speed button for 10 mph, and at the end of the two minutes, hit the 8mph button to bring it back down (my treadmill takes about 45 seconds to get from 8 to 10 mph and another 45 seconds to go from 10 to 8 mph, so the black lines are when I hit the buttons).




The purple is the HRM-Tri, and the blue is the Rhythm+.  I had been running at 8mph for six minutes prior to this interval.  The Rhythm+ shows a relatively steady heart rate, but the HRM-Tri starts increasing before I even start the interval.  There is no reason that my heart rate should be increasing in the first third of that chart - it should be decreasing or steady-state.  Apparently, my HRM-Tri heart rate strap is psychic.  Or possessed by ghosts.  Or possibly a complicated random-number-generator.  It maxes out during that interval at 164 bpm, but then quickly declines once my treadmill reaches 10 mph in the middle of the interval.  It's like it didn't even notice I was doing an interval, it was just randomly increasing, and by chance, it captured part of my increased effort during the interval.

The Rhythm+ accurately shows my heart rate going up consistently during the interval, and then staying up for a while after (keep in mind, it takes 45 seconds before I am back down to 8 mph), but the HRM-Tri seems to ignore my actual effort.

And before you ask the question, the data are not misaligned.  I started the activity at the same time on my watch and phone.  But further, the DC Analyzer tool automatically aligns the data, and it's clear from the rest of the graph that the data are aligned, but that the HRM-Tri is just giving bunk data.

This is just one example.  I've got a bunch more:
Full workout from above
HRM-Tri Vs Rhythm+
Outdoors

And those are just the ones where I've purposefully worn two monitors - there are too many to count where I've just made a mental note about the HR being way off.

I've tried so many troubleshooting steps to try to resolve the issue:
I had electrode gel sitting around from the time before the Rhythm+, which used that for every strap-related activity.  I thought maybe the gel had expired, so I bought new gel.  I thought maybe I was using too much gel, so I cut it back.  I thought maybe I wasn't using enough, so I slathered in on.  I thought maybe the gel was the problem, so I licked the strap.  I thought maybe my saliva wasn't voluminous enough, so I ran the strap under water.  I thought maybe my chest hair was getting in the way, so I trimmed it.  I thought it might be the fan I had going for the treadmill, so I turned it off (that was not a fun workout).  Per Garmin support, I stopped wearing technical t-shirts and either went shirtless or wore cotton.  I moved the strap to my side.  I reset the unit by flipping the battery around for a few seconds and then re-installing it in the correct orientation.

All of this I tried on the new unit they sent me, thinking the initial one I had was bad after going through all of the steps Garmin Support had for me.

I literally don't know what else I can do.  Just as a point of reference, I tried an old Polar H7 HRM strap I had sitting around.  I put a new battery in it and took it for a spin and it was literally unusable.



Full workout

The HRM-Tri looks pretty good there, but it wasn't.  I did actually have my Rhythm+ on this run, which I recorded with my 920XT, but apparently my 920XT is now dead.  It randomly deletes files on it, and I get I/O errors when connecting it to my PC.

I'm going to continue wearing multiple heart rate monitors because this is ridiculous.  One of these days, I'm going to have my wife, who is a cardiac nurse, assess me while doing a workout to see if there's something wrong with my heart.  I mean, I can't understand why heart rate straps, which are supposed to be super reliable literally can't get a read on me.

If anybody out there has any suggestions, I'm open to them.

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