935 Ridiculously Low LTHR Estimate

Should also add a caveat that I might just not understand what it's trying to tell me... But from what I can recall from my sports science degree many moons ago, there's not much chance I'm hitting lthr at 102! ????

A couple of questions on this before I or anyone else might be able to help:

-It takes the watch about a month'(ish) to "learn you"
-Have you set your HR zones for running?
-What kind of zone setting are you using for running (LTHR, HRR, BPM etc..)
-Are they (HR Zones) accurate and based on either prior knowledge or after doing a test in a lab?
-Are you using the OHRM or a Chest strap?
-How many runs have you completed?
-Are you using the "Run" activity or the "trail running" activity?

Hi, looks like I'm pretty much on 3 weeks dead on, maybe I'm expecting too much off the back of the "test" and not being a month or more into it, just feels like have had a few different lthr/pace updates that have all been really low.

-Have you set your HR zones for running
yes

-What kind of zone setting are you using for running (LTHR, HRR, BPM etc..)
%HRR currently, think it was %LTHR which I changed due to the low LTHR values and being a bit surprised that my runs were all 99% zone5... Changing it to hrr hasn't really impacted that though!

-Are they (HR Zones) accurate and based on either prior knowledge or after doing a test in a lab?
Zones are the default % splits based off a max HR of 187 (possibly a little low as I've hit that at the end of a non-race 11k recently)

-Are you using the OHRM or a Chest strap?
HRM-TRI strap (plus a footpod if that's relevant!)

-How many runs have you completed?
13 with this watch, worn pretty much 24/7 since getting it

-Are you using the "Run" activity or the "trail running" activity?
using the run activity

Thanks!

Try basing your next few runs on LTHR if you have a prior marker for it (i.e you've migrated from another watch that tracks Lactate Threshold). Set your zones around that LTHR, with it being the top end of the z4 mark and the start of z5. I'll use mine for example (similar vo2 max as you, lower max HR than you) if it might help you have a start point with the watch so it can begin to "learn"


RHR-42/LTHR-164
Z1-107 %65
Z2-131 %80
Z3-146 %89
Z4-156 %95
Z5-164 %100
Max HR 182 %111

HR values are not as important but the percentiles are, try working with those next time you go out and see if it gives a better result.

Fenix 5 owners have been hit by a firmware bug recently, giving them ridiculously low LTHR values. See this thread:
https://forums.garmin.com/forum/on-the-trail/wrist-worn/fenix-5-5s/1325651-lactate-threshold

So I wonder if the same bug has propagated into the 935.

Thanks both.

I've updated my lthr & zones to run off lthr @165 on the GC app and synced with the watch... Planning a shorter 5kish today and a longer 12k odd tomorrow so will try and target zone 4 and see what happens (both to me and the watch!)

Interesting on that bug, sounds very similar. I guess I just didn't have previously sensible values that were suggested because of when I started using the watch, the first value I got was In the 80s!

Interesting on that bug, sounds very similar. I guess I just didn't have previously sensible values that were suggested because of when I started using the watch, the first value I got was In the 80s!

It can be accurate from the beginning. It was on my watch (a Fenix 3).

I think the first estimate from the watch - where I had not done any previous manual configuration of HR zone, max. HR, etc. - was a HR of 162. Since then it has pendled between 161 and 164 for almost a year.

If it is a bug then it is not common across all 935s. I had a new LHT today that was perfectly reasonable 4:48 @ 153.