Lactate Threshold Heart Rate (LTHR) is the heart rate at which lactate accumulates faster than your body clears it — roughly the effort you could hold for 45–60 minutes. It anchors running intensity zones when pace or power is unavailable.
How to estimate LTHR
30-minute time trial: average heart rate from the final 20 minutes approximates LTHR.
Alternatively, use a lab lactate test or a coached field test for precision.
Zone anchors from LTHR
- Zone 2 (aerobic): 65–80% of LTHR
- Zone 3 (tempo): 80–90% of LTHR
- Zone 4 (threshold): 90–100% of LTHR
- Zone 5 (VO2): above LTHR
Common mistakes
- Using max heart rate formulas instead of a threshold test.
- Ignoring cardiac drift on hot days.
- Setting zones once and never retesting.
Using Vo2Max
Vo2Max uses your threshold pace or heart rate to calibrate running workouts and weekly load targets.
Related guides
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Frequently asked questions
Is LTHR the same as max heart rate?
No. Max HR is genetic; LTHR is trainable and more useful for setting workout intensity.
How often should I update LTHR?
Retest every 8–12 weeks or after a block of consistent training.