When you run easy, your body clears lactate — a byproduct of energy production — as fast as it produces it. When you sprint, lactate accumulates rapidly and you’re forced to slow down within minutes. Somewhere between those two extremes is a pace where production and clearance are roughly balanced.

That’s your threshold pace. It represents the boundary between sustainable and unsustainable effort.

Why It Matters

Lactate threshold is one of the strongest predictors of distance running performance. VO2max tells you how much oxygen your engine can process. Threshold tells you what percentage of that engine you can actually use for extended periods.

Two runners with identical VO2max values can have dramatically different race performances if one has a higher threshold. The runner whose threshold is at 85% of VO2max will outperform the runner whose threshold is at 75% at every distance from 10K to marathon, because they can sustain a faster pace before lactate forces them to slow down.

For distances from 10K through the marathon, threshold pace is arguably more important than VO2max.

What It Feels Like

RPE 6-7. “Comfortably hard.” You can say a few words but not hold a conversation. You feel the effort — it’s real work — but you could sustain it for 45-60 minutes if you had to. It doesn’t feel like you’re racing, but it doesn’t feel easy either.

Jack Daniels describes it as the pace you could hold for about an hour in a race.[1] For most recreational runners, this is somewhere near their current 10K race pace or slightly slower.

How to Train It

Tempo runs are sustained efforts at threshold pace. A classic tempo run: warm up 10-15 minutes easy, run 20-40 minutes at threshold effort, cool down 10 minutes easy.

Cruise intervals are Jack Daniels’ variation — break the tempo effort into segments with brief recovery. Example: 4 × 1 mile at threshold pace with 1-minute jog between. This achieves the same physiological stimulus as a continuous tempo run but is psychologically easier to manage, especially for longer sessions.

Both work because the key variable is time spent at or near threshold intensity. Whether that time is continuous or broken into segments matters less than the total accumulated minutes at the right effort level.

Common Mistakes

Running tempo runs too fast. Threshold pace feels moderate. If your tempo run feels like a race effort, you’ve crossed from threshold into VO2max training — a different workout targeting different adaptations. The “comfortably hard” descriptor is doing important work.

Running tempo runs too short. A 10-minute tempo provides some stimulus, but meaningful threshold adaptation requires 20+ minutes of accumulated time at intensity. If the tempo portion of your run is under 15 minutes, you’re getting a warm-up with a brief push rather than a threshold workout.

Skipping tempo runs because they’re not exciting. Easy runs are comfortable. Intervals are thrilling. Tempo runs are… hard work at a non-spectacular pace. They don’t feel like progress the way a fast interval session does. But for race distances from 10K and up, they may be the single most productive quality workout you can do.

How Pacewright Handles It

Pacewright prescribes threshold work as part of the 20% of training that’s at moderate or hard effort. The frequency and duration depend on your goal distance:

  • 5K focused: Less threshold work, more VO2max intervals
  • 10K-half marathon: Threshold is a primary training stimulus
  • Marathon: Threshold plus marathon-pace work form the quality backbone

You don’t need to calculate your threshold pace from race times or lab tests. Pacewright uses RPE-based effort targets — “RPE 6-7” — which naturally calibrate to your current fitness. If your threshold improves, the pace at RPE 6-7 gets faster automatically. The effort stays the same. The speed follows.