Lactate Threshold Pace Estimator

LT pace ≈ pace you can hold for 60 min. Estimate from recent race or HR zone.

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Result

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How to use this calculator

  • Pick base race.
  • Enter time.

About this calculator

Lactate threshold (LT) is the pace at which lactate accumulates faster than the body can clear — the "fastest pace you can hold for ~60 minutes." LT corresponds roughly to 80-85% max HR. Tempo runs at LT pace are the bread-and-butter of endurance training. Estimating: LT ≈ 5K pace + 30s/mi, 10K pace + 10s/mi, half-marathon pace.

Frequently asked

Why "threshold"?+
Below LT: lactate clears as fast as produced. Above: accumulates exponentially → fatigue.
Tempo run?+
Sustained 20-40 min at LT pace. Improves capacity at threshold; raises LT over time.
Training zones?+
Z1 easy < LT − 60s. Z2 endurance < LT − 30s. Z3 tempo = LT. Z4 threshold ≈ LT. Z5 VO2 max < LT.
Lactate test?+
Lab test: incremental treadmill with finger-stick lactate. True LT = 4 mmol/L or breakpoint. Field estimate within 5%.
Improves how fast?+
Tempo + intervals: ~5-8% LT pace improvement in 8-12 weeks for trained athletes.

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