Lactic acid is commonly thought to build up during anaerobic exercise and induce muscle soreness, but this is not correct. Lactate, not lactic acid, is generated during exercise,[1] and lactate is not a waste product of anaerobic metabolism. Rather, lactate is created under both aerobic and anaerobic conditions by the conversion of pyruvate to lactate via the enzyme lactate dehydrogenase. This process involves the consumption of a proton and thus acts as a buffer against acidosis. Once created, lactate is used as a fuel source for the body; it may even act as a cell signaling molecule during exercise. Given these roles, it is unlikely that lactate contributes to muscle soreness.[2] Moreover, although lactate levels do increase during exercise, they decrease to pre-exercise levels within one hour, which is well before the onset of DOMS.[3]
Does lactic acid build-up cause muscle soreness?
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•Last Updated: May 16, 2025
Lactic acid does not cause muscle soreness; instead, lactate, which is produced during both aerobic and anaerobic exercise, serves as a fuel source and may even have signaling roles. Additionally, lactate levels return to normal within an hour after exercise, well before delayed onset muscle soreness occurs.