Latacte Thresold pace from garmin

I believe physiological true-up moved those values on to this watch after setup.

It’s worth checking, just in case something’s not coming across right. VO2 Max is confirmed after every run in the ‘Achievements’ screen, even if it is not updated. The max and resting HR can be confirmed under Settings>User Profile>Heart Rate (also check if you have set separate values in the ‘Sport Heart Rate’ setting). If that’s all OK and it seems your HR plot from chest strap seems good (other than the brief drop out), then I’m not sure why you are getting the odd HR value. It’s at least worth trying another guided test or just gradually increase pace in 3 minute blocks on your next run until you are just over 90% max HR (which should trigger the auto detect and shows up just after you save the Run).

Thank you for the advice. Yes, I've checked max and resting HR in my user profile. Both normal and under the sport heart rate. They're both correct, or at least as close to correct as possible.

I'll do a progression run tomorrow and hope for the best.

I just bought a Fenix 5x and ran the lactate threshold test this morning.

[...]
Afterward, it alerted to a detected lactate threshold of 88 BPM and 6:54 min/mi.

This is a well-known problem of the Fenix 5. When it occurs, it is always a high 2-digit LTHR, never a low 3 digit. Some have speculated that it simply strips the "1" from a 3 digit LTHR, but I have never seen it confirmed.

It is a long time ago I last read about this problem, so I assume it has been solved in a firmware update. Did you update the firmware in your watch before you did the test?

This is a well-known problem of the Fenix 5. When it occurs, it is always a high 2-digit LTHR, never a low 3 digit. Some have speculated that it simply strips the "1" from a 3 digit LTHR, but I have never seen it confirmed.

It is a long time ago I last read about this problem, so I assume it has been solved in a firmware update. Did you update the firmware in your watch before you did the test?

Yes, I updated the firmware as soon as I unboxed it.

If the leading 1 was stripped, that would mean a LT of 188. This is quite high, as my max HR is around 196.

I looked at the recorded HR data during the test and my HR did not even reach 188. Could the watch be extrapolating?

Do you recall whether users ever received a reasonable reading during the LT test or were the results always erroneous? Thanks.

In my opinion, heart rate zones are good, but zones based on your threshold pace are better and a more accurate indicator of how well you trained that day. Your heart rate can easily be affected by a number of things (sleep, caffeine, weather conditions). Also, every run workout shouldn't reach your maximum heart heart. Every workout shouldn't be a steady pace either. Both these variations make it difficult for a fitness watch to calculate your threshold pace.

I would encourage you to do a lactate functional threshold pace (FTP) test. Run one mile at your hardest consistent effort (a pace you can hold steady for the entire distance). The time you finished is your FTP.

If you have any questions, feel free to reach out to me. I have a YouTube channel where I post lots of informative & entertaining videos that talk about running, swimming, and cycling. https://www.youtube.com/watch?v=u3hwFB8-ZuQ&t=226s

As far as I remember, the problem could be worked around by selecting zones based on LTHR and manually setting a plausible first guess for your assumed LTHR, before you did the run. Then the watch would detect a new LTHR in roughly the same range.

But perhaps my memory is wrong, so you should try to dig out some of the old threads. Or make a new thread in the 5X forum. In this forum you will probably not get much help, because the 5Plus watches aren't suffering from the same problem.

I just wanted to post an update for anyone who may read this with the same problem I had.

After the bad result from the lactate threshold test (88 bpm), I manually set my lactate threshold heart rate to 175 bpm on Garmin Connect.

This was an estimate on my part, but I figured it was close to reality.

This morning I did a cruise interval workout with the following structure. Warmup 2 miles, 5 x 5 minutes at lactate threshold pace, push hard for 1 minute after the final interval, cool down 2 miles.

The watch auto-detected a new lactate threshold: 175 bpm and 7:00 per mile. Thanks, everyone, for the help.

Heh, even if it was my advice you followed, I find that result somewhat fishy.

I would have liked to see a result which was a few beats different from your initial guess of 175. Just to be sure that the watch hasn't simply used your guess.