Help debugging HRV data?

[johnpane]

Hello,

I recently switched back to my Garmin strap heart rate monitor because I found the accuracy of the wrist sensor on my Forerunner 935 to be poor. With the strap I am getting much more authentic-looking heart rate statistics. However, the HRV plots all have a 8-12 minute section at the beginning that looks very different than the rest of the plot and different than other examples I have seen.

Has anyone seen anything like this or can offer a possible explanation?

Thank you,
John

[laufhannes]

I typically see that shortly before the battery is empty.

Another possibility is bad connectivity. Do you moisten the belt a little before you start?

[johnpane]

Thank you for the suggestions. I did replace the battery and started moistening the strap. Neither made a difference.