| What it is | Where lactate builds faster than it's cleared |
| Marks | Upper limit of sustainable pace |
| Roughly | ~1-hour race effort |
| Improved by | Tempo / threshold training |
Lactate threshold is the exercise intensity at which lactate begins to accumulate in the blood faster than the body can clear it, marking the upper limit of a pace you can sustain for a prolonged period. It’s a key determinant of endurance performance — roughly the effort you could hold for about an hour — and is improved through threshold (tempo) training, raising your sustainable race pace.
Your sustainable ceiling
Raised by the tempo run; one of the big three endurance markers with VO2 max and aerobic base built in zone 2.
Frequently asked questions
What is lactate threshold?
Lactate threshold is the intensity at which lactate (a byproduct of hard effort) starts building up in your blood faster than your body can remove it. Below it, you can sustain effort for a long time; above it, fatigue accumulates quickly. It essentially marks the fastest pace or highest effort you can hold for a sustained period.
Why does lactate threshold matter for runners?
Because it largely determines the pace you can sustain in longer races — a higher threshold means you can run faster before fatigue spikes. Along with VO2 max and running economy, it's a key predictor of endurance performance, and it's very trainable, so raising it directly improves race times.
How do you improve lactate threshold?
Mainly through threshold work — tempo runs and threshold intervals at 'comfortably hard' effort — which trains your body to produce less lactate at a given pace and clear it more efficiently. A strong aerobic base from easy running and long runs supports these gains, gradually pushing your sustainable pace faster.
Sources
- Lactate threshold — American Council on Exercise
- Endurance physiology — American Trail Running Association