Fitbit Blaze heart rate inaccurate for long activity sessions

[phatbitzr]

I use the Blaze for spinning class, loosening the strap, using those elastic hair band to hold the tracker closer to the wrist flushed against my wrist.  Heartrate tracks pretty accurately, maybe it would wander off if I stand on the pedal, resulting in my wrist bending too much, but that is resolved if I straighten out my wrist.

Usually, around the 45 minute mark, the heartrate tracking becomes inaccurate.  If it is a 1 hr class, it might be slightly annoying, but I just lose the ending part of the session.  But if I am going for 1.5-2hr straight, it becomes real annoying.  It doesn't matter if I rotate the tracker, move it to the other arm, wipe everything dry, let the fan blow the whole area dry (all while still engaging in the activity, with minimal recovery), it usually is no use, and the heartrate for the 2nd half of the session is all over the place.  A few times, I did notice, when I take a recovery where my heartrate drops to the 110-120 range, the tracker would start tracking my heartrate again.

Now, I am wondering if the algorithm for measuring heartrate somehow wants to think my heartrate is lower than the vigorous activity I am performing, thus never able to produce any meaningful data.

Here is one session, where after around 1hr, heartrate data goes completely bonkers.  At around 1:34, when my heartrate goes down to around 110, does the tracker start tracking again:

Here is another session, where after around 45min, tracker is starting to lose track of heartrate, and after 59min, heartrate is completely erratic:

Moderator edit: Updated subject for Clarity

[FerdinandFitbit]

Hey there @phatbitzr. Great to see you in the Fitbit Community Forums! 🙂

I'm sorry to hear you're having problems with your heart rate monitor not reading your heart rate correctly for long sessions.

This to me is very strange and I've not really heard of similar scenarios where users experience this issue. Because of this, I'd like to know if you've tried by any chance to give your Blaze a restart and see if that makes any difference. If not, You can easily do this by pressing the left and lower right buttons for 10-12 seconds. This will make your tracker to reboot.

Hope that helps and please, let me know if there's any improvement.

[phatbitzr]

@FerdinandFitbit, even though I haven't reboot the tracker, it has booted a couple of time, and I did not notice any difference.