Sustained 20-40 min at LT pace. Improves capacity at threshold; raises LT over time.

Z1 easy < LT − 60s. Z2 endurance < LT − 30s. Z3 tempo = LT. Z4 threshold ≈ LT. Z5 VO2 max < LT.

Lab test: incremental treadmill with finger-stick lactate. True LT = 4 mmol/L or breakpoint. Field estimate within 5%.

Tempo + intervals: ~5-8% LT pace improvement in 8-12 weeks for trained athletes.

Lactate Threshold Pace Estimator

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

Result

LT pace

7:25/mi

From 10k race pace + 10s/mi.

Race distance6.21371 mi
Race pace7:15/mi
Adjustment+10s/mi
LT pace7:25/mi
LT HR (~80-85% max)See karvonen-heart-rate-zones

Step-by-step

Race pace = 2700s / 6.21371 mi = 434.5 sec/mi.
LT pace = race pace + 10s/mi = 7:25/mi.

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.