Prolonged Heart Rate Spike During Cooldown

[wilson_a]

Wondering if anyone has experienced anything like this or can offer an explanation. 12 minute warmup, did 4x3' at transport/race pace, then as soon as I started my 12 minute cooldown my heart rate spiked well above max and stayed there for the entire cooldown. Resting ~40BPM, max is roughly 180BPM. Below is the HR data and info. Can rule out hr strap failure or anything similar because I manually checked heart rate post cooldown to verify.

Time Distance Avg Pace /500m Avg HR Max HR
Warmup 12:00.0 2847 02:07.3 117 129
Rest 00:57.2 0 -- 116 129
3' 03:00.0 819 01:49.8 136 153
Rest 01:33.0 0 -- 126 153
3' 03:00.0 827 01:48.8 141 158
Rest 01:48.0 0 -- 130 158
3' 03:00.0 835 01:47.7 146 164
Rest 02:23.0 0 -- 125 163
3' 03:00.0 845 01:46.5 150 166
Rest 02:59.0 0 -- 124 167
Cooldown 12:00.0 2744 02:12.1 185 200

[johnlvs2run]

Wondering if anyone has experienced anything like this or can offer an explanation.

Yes, in my case I ran 19 miles on roads over rather steep (15 to 20%) hills, and ran in at a rather comfortable good pace to the finish.
I took a few steps at the finish to cool down, and my heart rate started racing out of control.

What I should have done was to lay down on my back in the shade, but instead of that I kept trying to walk around (not realizing the cause),
and drove 7 miles home while trying to keep focus, which kept waning. Although driving conservatively, I mistakenly went through a stop sign
and then drove a block past my house. At home I lay down in the bottom of the shower, while consuming lots of liquid, and after 30 minutes or
so dried off and got into bed. Meanwhile my heart rate was still racing, and I was making moaning sounds, probably due to fear of what the heck
was happening. Finally after about two hours, my heart rate got back to normal, and all was okay.

The next day I continued training as usual, and this never happened again. The cause turned out to be simply dehydration, due to the effort
and the very hot day. I had been well hydrated before starting, and I'd been dehydrated before on hot days, once at the end of a 50km race that
had no water stations enroute, but on that occasion I was simply wobbly and my heart rate was fine. Maybe the hills had something to do with it.

Be sure to hydrate well and, if this happens again, lay down on the floor on your back, so the blood can circulate more easily.

[Nick]

I'm not a doc - but I have a little heart issue known as AFib (Atrial Fibrilation) - while the issue you're experiencing may very likely be a matter of dehydration - my suggestion is that if it concerns you - consider consulting with your doctor -

[wilson_a]

Although driving conservatively, I mistakenly went through a stop sign
and then drove a block past my house.

This is so weird because the exact same thing happened to me the night before this workout. I drove right past the exit for my house and kept thinking I felt out of the ordinary. I had attributed it all to being tired but it sounds like I was dehydrated!

Thanks for the response.