Lactate Threshold

The lactate threshold is the point during increasing exercise intensity where blood lactate concentration begins to climb steeply, signalling that production has outstripped clearance. Below it, effort feels sustainable for long periods; above it, fatigue accumulates comparatively quickly. It is often reported as a pace, power output, or heart rate, and can be measured in a lab from graded exercise tests or approximated in the field.

Because it marks the intensity an athlete can hold for extended efforts, the lactate threshold is a strong predictor of endurance performance, frequently more useful for pacing than VO2 max. Training at or just below it (threshold training) aims to push the threshold to a higher intensity. The term describes a physiological marker, not a workout, though the two are commonly discussed together.