Question 1

What is anaerobic threshold?

Accepted Answer

Anaerobic threshold (also called lactate threshold) is the exercise intensity at which blood lactate begins accumulating faster than your body can clear it. Below this point, you are in steady-state aerobic exercise. Above it, fatigue accelerates rapidly. It is the single most important physiological marker for endurance training.

Question 2

How is threshold heart rate estimated?

Accepted Answer

A common approximation is 88% of maximum heart rate, or 85% of heart rate reserve (Karvonen). For more accuracy, lab tests measure blood lactate during a graded exercise test. Field tests like a 30-minute time trial can also estimate threshold HR — average HR over the final 20 minutes is a good proxy.

Question 3

How do I train at threshold?

Accepted Answer

Tempo runs of 20-40 minutes at threshold pace, or longer interval sessions like 4 × 8 minutes with short recoveries, are classic threshold workouts. Done 1-2 times per week, they raise your sustainable pace and improve lactate clearance.

Question 4

Is threshold the same as VO2 max?

Accepted Answer

No. VO2 max is your maximum aerobic capacity — the ceiling. Threshold is the percentage of that ceiling you can sustain. Two runners with the same VO2 max can have very different threshold paces. Threshold is more trainable than VO2 max in adults, which is why it is a better focus for endurance improvement.

Question 5

Can I estimate threshold pace from a recent race?

Accepted Answer

Yes. 10K race pace + ~5 sec/km is a reasonable threshold pace estimate for most runners. Half-marathon pace − ~5 sec/km also works. This calculator uses 10K time when provided to estimate both threshold HR and pace.

Anaerobic Threshold
Lactate Threshold HR & Pace

Anaerobic / Lactate Threshold

Why Threshold Matters

How to Use the Estimate

Formula

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