Improved Lactate Threshold Measurement Feature in 21.19

Improved in that it’s automatic.  Not improved in accuracy.  In the past, my watch would only update my LT when I did a threshold level run.  Now, it does it often, and often when the HR is way off.  It kept giving me a max HR that’s 15beats higher than my actual, and then it messed up all my metrics.  Had to turn it off and do manual HR and LTHR settings under User Profile on the watch, and then separately in the app.

Prior to the update my LT (as measured by the watch) was fairly stable at around 5:27 min/km and 168 bpm.  After upgrading to 21.19 and doing a relatively easy run today, my LT shot up to 5:08 min/km and 174 bpm.  I will wait to see if it settles down but I think the original value was more accurate in terms of both pace and HR.  All of this was with an HRM-Pro Plus HR strap.

And don't forget that with each workout, you now have to go into your user profile and click on reset zones so that the zones are adjusted for the next workout... What a piece of crap Garmin just did with this. TOTAL MESS.

Even after automatic detection ? Or if you want to go back to a previous value manually ?

It is hard to say whether the new values are more accurate than the ones provided by the previous version of lactate detection. Like other users’ case, my LTHR is now about 4bpm higher, and my pace (maybe accordingly) is about 11s/mile faster.

LTHR and pace @ LTHR are used among other key values in rules among many rules to determine the overall training benefit of a workout (tempo, threshold, etc) but not to calculate the individual components of training effect (aerobic and anaerobic).

Since training heart rate zones are not used for any of the training metrics, a change in LTHR can impact the target a user will follow for a given workout, but the resulting training metrics will not be less accurate.

In my case, I didn’t see a clear impact on race pace predictions BUT my predicted 10k pace is now 5s/mile *slower* than my new pace @ threshold and it should the opposite.

i have an upcoming 5k race, so I will see whether the change in pace @ threshold is “good” for target pace purposes and/or a closer threshold effort gets me a new detection.

Just another reason disable "Trail Running" activity Physiological results or whatever it calls it to give vo2max/lactate results...  use that when you have wrist only or have easy run planned, hungover, super over dressed, snow, wind, etc.  Where it won't give you an accurate result.  lol

My go-to ... but now even more important with Lactate updates 

Personally, i like the feature.  But if you don’t want to use it, just disable the auto detection.. Doesn’t have to be that hard!

The problem is that once an automatic lactate threshold HR and pace was detected, it seems to be stored in some hidden place in the software and heavily influences the Daily Suggested Workouts, even if the automatic detection was turned off and the realistic values for both HR and pace had been entered manuallly after the automatic detection. My suggestions for DSW are quite randomly jumping from the "normal" realistic values to values about 6 to 7 bpm too high, which is specifically funny for a threshold run, whcih was initially supposed to be at 165 bpm and is now suggested to be at 172 bpm, which is far too high. I tried a lot in resetting all the HR related values (HRmax, LTHR, zones) manually, and sometimes the DSW are okay again for the next run, sometimes I am not able to get it back to normal values - the behavior is quite random for me at the moment.

And I do agree with the opinion of other users that I was also really surprised that this software version was released as a public version after all the critical feedback in the beta forum (I am also beta user and also reported the issue).

I really loved the DSW and had the feeling that training according to those suggestions really improved my performance without risk of injury - and now this most used feature is heavily compromised.

Does anybody know, if the correct setting of the max HR is important for the calculation of the lactate threshold value?
Many sports beginners are never reaching their max HR during training and so all of them would not have a base for calculations depending on this value.

Garmin doesn't publish the details, but patent filing about Firstbeat Technology indicate that Max HR used to help the lactate threshold (LT) algorithm look for certain changes in correlation between ventilation and output (pace or power) at a certain % of Max HR.

In addition, several users have been able to "make" the older version of LT detection work by changing their Max HR (too high, the user would never reach the expected %, or too low, the change of correlation would simply not happen yet).

I have to believe that the new algorithm also depends on Max HR, but uses a different algorithm to predict the LT data pair (LTHR and pace) based on sub-threshold ventilation vs pace trends and Max HR.