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Abnormal heart rate on FR 45

I recently bought the FR 45 a couple weeks ago. The heart rate appears to be pretty accurate when at rest so far, I'm not sure about how accurate it is during activity as my HR seems a little high at times in the 190's. I went on a few runs and everything seemed to work just fine in regards to the HR monitor. The last 2 runs I went on, almost immediately at the start of my run and occasionally throughout the run I randomly get "Heart Rate 255" . I assume the 255 is what it thinks my HR is at the time, but when I close out of the alert and look at my HR on the data screen, it's usually around 150-180 or whatever it is at the time. After my run, I look at the HR screen on my phone and it doesn't appear my HR ever went above 200 at any time during the run. I do have the Abnormal HR alert set with a 100 threshold. I know it is supposed to alert you when your HR is above 100 BPM after inactivity, but it should have never spiked, as my HR is usually in the 130's after a warmup before I start my run and never goes above 180-190 during my runs, so there's no way it should have went off. Has anyone else experienced this?

So after reading that the sensors draw more power during an activity, I decided to set it on a run while I'm sitting still. The sensor went off 3 times in 2 minutes and then stopped. I discarded the run and turned it back on again. Again it went off another 3 times with "Heart Rate 255". The whole time I was checking my pulse and it never went above 80. Starting to think my watch is defective.

  • So I solved my problem, it turns out, for some reason when you get into the Run > Alerts > HR settings, all of my zones were set at 255-255. I was able to go into the Garmin Connect app in Device > User Settings and ended up having to change the HR Zones to be based off of Resting HR, then Sync to phone and then set it back to % of Max HR and re synced it again. My HR zones displayed correctly on my watch and the alerts went away.

  • Thanks so much for the info Thumbsup

    Had the same issue but this solved the problem.

  • This has happened to me and all my heart rate zones under RUN >ALERTS> HEARTRATES were all set to 255 on my forerunner 45s. My heartrate does not get that high during activities. I followed your directions. on the app, the zones are not all 255. They seem like the right number of bpm for each zon . I hit the sync button and on my watch the zones have not changed to what is on my phone. There is an option to reset but I'm worried what that will do. 

  • I've noticed on my 45s that during sedatw activity (walking about the house) my hr is spiking to 170bpm. It's not. It's only just started doing it in the last day or so. Haven't changed the way I wear my watch so I'm a bit confused.

  • Actually, mine just started doing this also.  I was at the gym yesterday, walking on the treadmill and my HR climbed quickly up to around 150.  I can easily get to 150 when I'm running or cycling, but it takes some effort, much more than strolling on the treadmill.  I tried tightening the band and moving the watch around on my wrist but that didn't fix it.  So I powered the watch off and immediately back on and my HR was around 80 (which is more believable).  But then it quickly climbed again.

    I then moved on to lifting weights and was getting the same behavior -- HR would quickly climb into the 130s.  Typically my HR stays below 110 when lifting.  A quick power-down-power-up showed it in the low 70s, but then it climbed back up again.

    Not sure what's causing this issue.  I might be stuck wearing a chest strap to eliminate this problem.

  • Thank you for posting this - I had the exact same issue - I have made the relevant adjustments and will test not on the next time out - thanks so much 

  • mine has started doing this now too...  did your actions above sort it?  It doesn't seem to be working on mine.  I can do the custom alert but then that has to be done each time.  Previously the heart rate zones were correct....