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Heart rate readings suddenly drop during exercise

koral00920
over 8 years ago
Hello everyone :)

I'm having a problem with my Forerunner 735xt. Today I run a 10km race and I'm worried about my heart rate readings, since after few kilometers that showed HR about 175bpm, it suddenly started showing something about 90bpm which I'm sure is pretty impossible, especially that I run with almost exactly the same effort during the whole race. The dropouts weren't just for a moment - I didn't check my HR during the run, but after I uploaded my workouts to the computer, it tells me, that I had that HR 80-90bpm for 1.5km, and then as suddenly as before it came back to showing 176bpm... I've been using my chest strap, so the optical HR isn't the issue here. But I'm confused since it never happened with my old Forerunner 220 (and I was using the same chest strap back then).

I've had 735xt for 2 months now and there was no problem with HR until today. Or maybe - 5 weeks ago I run a marathon and I also had a HR dropout but it wasn't such big a difference and I thought that maybe my heart was going weird (it showed about 130-140bpm, while I should probably have something like 150bpm), now I'm starting to think that maybe it's not my heart but the watch or the chest strap. Does anybody know, what is going on? Low battery maybe? Please help :)

PS Here are the readings from today:
  • 0 over 8 years ago
    Do you wash your strap regularly per the care instructions? That's important to its longevity. Depending on your model of heart rate monitor, you may want to try replacing the strap part.
  • 0 over 8 years ago
    I've had this strap for 2 years now and I'm rather thinking about buying a new one (like HRM-Run), at least I would be getting more data from my 735xt.

    It's a soft strap that I have, I think. I usually clean it right after use, but honestly I do not wash it as often as recommended, maybe that is the issue. I should've taken care of it more, I'll remember in the future.

    I'm gonna change the battery and check if the problem still exists. I only need to get a really small screwdriver :D

    Thank you for your answer :)
  • 0 over 8 years ago
    Sounds like a strap problem to me. Try a new strap, that should fix it.
  • 0 over 4 years ago

    Hi, are you still having this problem? How did you fix it? 

    I've got exactly the same problem. I dont understand how it can be the strap as the HR sensor is on the actual watch unit and the strap is just attached like any normal watch.

    Many thanks 

  • 0 over 4 years ago in reply to 1898022
    1898022 said:
    I dont understand how it can be the strap

    Please read carefully the whole thread. OP's issue is with an external heart rate strap, and that's what is discussed here (or rather was, 4 years ago).