What is lactate threshold pace?

When you run, your muscles break down glycogen for energy and produce a byproduct—lactate.

At low intensity, your body can clear lactate fast enough, so you can keep going comfortably for a long time.

As intensity rises, lactate production outpaces clearance and the concentration in your blood starts to rise rapidly—this is the lactate threshold (LT).

Lactate threshold pace is the running speed you can sustain right around this tipping point.

  • Below LT pace: you can run relatively comfortably for a long duration.
  • Near LT pace: it feels hard but sustainable for about 30–60 minutes.
  • Above LT pace: fatigue builds quickly and you soon need to slow down or stop.

For well-trained runners, this often occurs at about 90% of max heart rate, roughly aligning with 10K or half-marathon pace; for recreational runners it may be at a lower intensity.

Why does LT pace matter?

LT pace is a key marker of endurance fitness and helps you:

  • Set training intensity precisely
    • Different goals require different intensity zones; LT pace helps you anchor those zones.
  • Improve race performance
    • Raising LT pace means you can hold a faster speed for longer.
  • Manage fatigue intelligently
    • Avoid spending too much time above LT to reduce excessive fatigue and injury risk.

How does PeakWatch estimate your LT pace automatically?

Lab lactate testing is accurate but expensive and inconvenient. If you have enough running history, PeakWatch analyzes your past running data, heart-rate profiles, and fitness state, then uses exercise physiology models to estimate your LT pace range—no extra tests needed.

If you lack sufficient running history, PeakWatch will estimate a default LT pace from your VO2max plus your age and sex.

If you already know your LT pace, you can enter it manually at any time.

How to use your LT pace

PeakWatch derives your training pace zones from your LT pace.

In PeakWatch custom run workouts, you can set intensity targets for each step using the pace zones that fit your goals, helping you achieve the intended training stimulus.

PeakWatch also offers multi-session running programs that leverage pace-zone intensities to improve your running performance.