Anaerobic threshold is the exercise intensity above which oxygen demand exceeds supply, forcing increasing reliance on anaerobic glycolysis.
Mechanism — Roughly equivalent to LT2 — where lactate accumulation accelerates. Above this point, sustainable duration drops from hours to minutes. Trainable upward by 10-20% in untrained populations; smaller gains in trained athletes.
Use case — The threshold to push during interval training. Threshold sessions (4-6 min repeats) lift the ceiling over 6-12 weeks.
Caveats — Different testing methods produce different numbers — use one method consistently. Heart rate is less precise than power or pace at threshold.