Lactate Threshold

Quick question on this. I did a 2 mile brick run last night having cycled for an hour beforehand. I'm not the best of runners, wasn't going all that fast, and tried keeping my heart rate below 165 (I think my max is around 185).

Anyway when I finished, I noticed the F5 saying it had detected my LTHR as 165 @8:15m/mile. I've read about doing the correct 20 mins faster pace test to determine this value, so because I wasn't stressing myself as much as I could be, is it likely this number (and the zones) the watch has now set are wrong and probably reading a bit low?

I'd imagine I would be at 175bpm doing approx 7:45m/mile at a sustained 20 minute pace if I retested and sped up.

In the user profile my max is set to 185bpm, LTHR 165 and resting HR is empty. I haven't set any of these on the watch.

0 C966 over 7 years ago

If you maxHR is 185 I doubt you LTHR is 175, more likely around 90% of your maxHR so 165 sounds close, though you may need more runs to get a more precise measurement and may be a bit higher still, but not by much I don't expect unless you are in really really high form.

0 Former Member over 7 years ago

Guys just did a guided lthr test on my fenix 5 using an hrm run and got very strange results. The lhtr shown on the device is 74 bpm! The pace is a more reasonable 5:27 min/km. Am 38, with a max heart rate of 184, and a vo2max of 47. HELP!

0 chatlow over 7 years ago

If you maxHR is 185 I doubt you LTHR is 175, more likely around 90% of your maxHR so 165 sounds close, though you may need more runs to get a more precise measurement and may be a bit higher still, but not by much I don't expect unless you are in really really high form.

Hmm, having looked this up some, 165 is around 90%, so it does seem in the ball park. I guess what threw me was the manual Friel test says to run 30 mins at a tough pace and take an average heart rate of the last 20 mins. So for me, 7:30 - 7:45min/mile is fast (comfortable at 8:30 for a HM) and I know my HR would usually be between 170-180 at that pace (until I become a more proficient runner!)

0 R_Tellis over 7 years ago

How did you come up with your HRMax value? If it's from a cycling based test your running Max is probably a bit higher. If it's based on a formula it might be a lot higher.

0 C966 over 7 years ago

Guys just did a guided lthr test on my fenix 5 using an hrm run and got very strange results. The lhtr shown on the device is 74 bpm! The pace is a more reasonable 5:27 min/km. Am 38, with a max heart rate of 184, and a vo2max of 47. HELP!

It's a bug, only thing you can do is set your real LTHR manually until this gets fixed, cause if you do a LTHR test the result will just get over written with some ridiculous figure like that 74bpm

0 C966 over 7 years ago

Hmm, having looked this up some, 165 is around 90%, so it does seem in the ball park. I guess what threw me was the manual Friel test says to run 30 mins at a tough pace and take an average heart rate of the last 20 mins. So for me, 7:30 - 7:45min/mile is fast (comfortable at 8:30 for a HM) and I know my HR would usually be between 170-180 at that pace (until I become a more proficient runner!)

Could be that your LTHR may be around 175, but then maybe your MaxHR is higher than 185? try some more runs and keep checking the LTHR to see if it changes.

0 Former Member over 7 years ago

It's a bug, only thing you can do is set your real LTHR manually until this gets fixed, cause if you do a LTHR test the result will just get over written with some ridiculous figure like that 74bpm

Is it the watch or the hrm with the bug? Was actually hopeful of getting a reading as I'm not sure what my real lthr is. Anything Garmin can do or is this permanent. Cheers.

0 C966 over 7 years ago

It's the watch, it used to work fine until one of the last firmware updates, so I'm sure it can be fixed, problem is when cause there is a long list of bugs.

0 chatlow over 7 years ago

Also just noticed this bug - my LTHR was set to 165 as expected but I decided to change the zones to be calculated using my max HR and once this saved my LTHR had changed to 74 and resting 30 :-D

I've since set manually on F5 and GC and kept the zones to use max HR and after a few syncs the numbers are still there. Great success. Does anyone know if Garmin are aware of the LTHR/Resting HR bug? If not, I'll fire them over an email.

0 AllanOlesen67 over 7 years ago

so because I wasn't stressing myself as much as I could be, is it likely this number (and the zones) the watch has now set are wrong and probably reading a bit low?

This should not affect the result. The watch looks for changes in heart rate variability. Even when you run at a steady heart rate, there will be small differences in the time between each heart beat. These differences change behaviour when you reach your LTHR.

So running for some time at heart rates around your LTHR ought to be adequate for the watch to detect your LTHR. Running at heart rates higher than that will probably not give any additional info.