Anaerobic threshold

The anaerobic threshold (AT) is the exercise intensity above which your aerobic system cannot keep up with the energy demand, so lactate starts building faster than your body clears it. It roughly matches the 'second lactate threshold' (LT2), and sits near (but not exactly at) the maximal lactate steady state (MLSS), usually around 75 to 85% of VO2max in fit people. The name is a bit misleading, though. Lactate buildup reflects an imbalance between making and clearing it, not a sudden switch to 'anaerobic' metabolism. So some experts prefer 'lactate threshold 2' or 'respiratory compensation point'. Training sustained at AT drives strong mitochondrial and cardiovascular adaptations. And your performance at or near AT is a strong predictor of endurance capacity, and tracks with lower cardiovascular risk.

Last reviewed: June 22, 2026

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