HR went very (unrealistic) high during race day

Hello

Maybe someone has more insight of such strange effects:

  • Race day
  • Wearing HRM-Pro Plus (Good battery, Firmware 8.9)
  • HR only from HRM-Pro (otherwise I get complete wrong readings in training when using hybrid)
  • There were some "showers" along the way, T-shirt got wet
  • After seeing the HR (I paced by PacePro, didn't care for HR) I repositioned the strap 2-3 times with no change in the readings
  • My max HR is around 200
  • It was an all out race and I screwed it up with a to fast pacing at the start

I did a warmup run, HR reading were absolutely in range and reading ware consistent.
We are looking at this segment:

(Green -> Elevation, Blue -> Pace)

If we zoom in, we can see a little jump:

(185 -> 195 -> 215 -> 223)

Those high values continued through the race until the end:

Did any one had such strange readings of HR? How can i prevent such behaviour?
I use this race once in a year to establish an training base for the coming months, but with this readings its not usable as base.

Thanks

Fit file if someone cares: 19083700609.zip

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