Lactate Threshold

You lactate threshold is the point at which the activity you're doing goes from sustainable to unsustainable, or when your fuel metabolism changes from aerobic to predominantly anaerobic.

Lactate is produced during the metabolism of fuel in your muscles. Lactate is produced from hydrogen ions and pyruvate. Your lactate threshold is the point at which hydrogen ions accumulate faster than they can combine with pyruvate. The accumulation of hydrogen ions makes the muscles more acidic, not the lactate, which results in more difficult muscle contractions.

References

Openfit. “Lactate Threshold: What Is It and How Do You Improve It?,” October 9, 2018. https://www.openfit.com/lactate-threshold.