I am finding that heart rate monitoring while doing interval training is highly inaccurate. At first, I thought it was related to fit issues (the earbud moving around while I am working out), but I seem to have no problem doing a steady run - I get great tracking, even with the rhythmic bouncing that you’d think would cause the bud to come loose.
It almost seems like the software in the earbud gets confused with interval training - the rapid changes in heart rate. After a hard set, when my HR is close to 160 or 170, it will read as low as 80 or even 40! Once my heart rate stabilizes again during rest, it comes back and seems to work around the 130 range.
It might still be related to fit issues, I haven’t fully confirmed yet. However, it would be nice if we could add a profile for interval training, so I don’t have to keep marking them down as runs.