Every few weeks when I do a workout and look at it in Garmin Connect, the HR zones have changed for no apparent reason.
This has just happened again now, I did a workout yesterday, and it correctly used my auto-calculated LTHR-based zones as it has for the last few weeks, I've done another workout today and it's used different zones. Even though settings on my watch still shows that the zones are set based on LTHR, from the values shown in GC it looks like it's reset them based on HRmax, but not using its default percentage ranges. I do also have an Instinct 2, but this is also synced to use LTHR to define the zones, and I haven't even used it between workouts. Plus, I can go for weeks on end swapping between both devices, normally without issue.
As I've done previously, I've reset the zones on both watches and resynced them with GC, but there's no way of showing whether they'll be respected until I actually start another workout. Previously it's taken several days of constantly resetting them before they've 'stuck' - as I say, even though the watch will show prior to a workout that the zones are set based on LTHR, using a HR zones data field during a workout shows that it's not using those.
Here's what numbers it should be using, and the random ones it changes to which just seem to be 10% chunks of HRmax
(RHR 53, LTHR 178, HRmax 200)
| Zone | Range | LTHR-based | Random |
| 1 | 56-66% | 116-141 | 100-119 |
| 2 | 67-78% | 142-157 | 120-139 |
| 3 | 79-89% | 158-168 | 140-159 |
| 4 | 90-100% | 169-177 | 160-179 |
| 5 | 101-112% | 178+ | 180+ |
This really messes my stats up, for example you can see that at 140 bpm I am in Z1 but it'll be recorded as Z3 so my easy aerobic recovery sessions are getting logged as threshold when this happens.
Anyone else seeing similar?
