What is Lactate Threshold?

definition of terms


Lactate threshold refers to the exercise intensity at which lactic acid begins accumulating rapidly in the blood stream. This causes a burning sensation and fatigue.


  • During intense exercise, cells turn to anaerobic glycolysis for energy which produces lactate as a byproduct.
  • Lactate threshold indicates your body’s ability to clear lactate and buffer acidity. Higher threshold enables higher performance.
  • Many do lactate threshold intervals or tempo training targeting intensity right below threshold speed or watts.
  • Athletes use threshold heart rate and pace as benchmarks for training zones and monitor progress by testing periodically.


  • Sustaining a 10K race pace just under threshold levels
  • Running 5x1000m repeats at lactate threshold heart rate

Related Terms

  • Lactic acid, VO2 max, tempo run, zone training, anaerobic threshold

Common Questions

  • How can I improve my lactate threshold? Interval training focused on threshold levels or slightly above.
  • What happens if I train above threshold? Fatigue quicker as lactate accumulates rapidly forcing you to slow down.

Do Not Confuse With

  • Anaerobic threshold – Same concept, different term.
  • VO2 max – Maximal oxygen uptake indicates aerobic capacity. Different metric.
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