Editing Openai/691758fe-9cf4-8009-9395-a2bf64f4b5c9 (section)

=== Assistant: Easiest way: let Garmin do it for you. ===
Easiest way: let Garmin do it for you. But here are all the options, quick and simple:

==== Your Edge 840 can estimate your LTHR automatically if: ====
* You pair a chest strap (much more accurate than wrist HR)
* You do a ride with sustained hard efforts (long climbs, steady tempo, etc.)

Check if Garmin already has a number:
Garmin Connect → More → User Settings → Heart Rate Zones → Cycling → Lactate Threshold

If it shows something like 168 bpm (just an example), that’s your LTHR.

If it’s blank, turn it on:
Device → Settings → User Profile → Heart Rate Zones → Lactate Threshold Detection → Enable

Then just ride normally. After a few rides with consistent efforts, Garmin will pop up a notification:
“New Lactate Threshold Detected.”

==== If you want to set it yourself: ====
# Warm up 10–15 minutes
# Ride 20 minutes as hard as you can sustain, not sprinting
# Take your average HR during the last 15 minutes
# Multiply that by 0.95

Example:
Avg HR (last 15 min) = 174 bpm
174 × 0.95 ≈ 165 bpm LTHR

This is the gold-standard cycling field test.

==== If you don’t want testing, a cheat formula: ====

<syntaxhighlight>LTHR ≈ 85–90% of max HR

</syntaxhighlight>

Not super accurate, but usable.

==== Honestly? ====
Turn on Garmin’s auto-detection and just ride like normal.
It’s usually within a few beats of the real number, especially with a chest strap.

If you want, tell me:
* Your max HR you usually hit
* Your “hard but sustainable” climb HR

I can estimate your LTHR pretty well.