Lactate and muscle soreness after exercise

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The “lactic acid” often discussed during intense exercise exists largely as lactate under normal body conditions. It is misleading to regard lactate simply as harmful waste accumulating in muscles.

What does lactate do?

Lactate can be produced even when oxygen is available. Different tissues, including muscles and the heart, can use it as fuel. Some also contributes to glucose production in the liver. No special detox or product is needed to “flush it out.”

Why do muscles hurt the next day?

Delayed muscle soreness after unfamiliar or strenuous exercise is particularly associated with movements in which a muscle lengthens under load. Soreness often becomes noticeable the following day and can last several days. Lactate remaining in the muscle for days is not an appropriate explanation.

Introduce new activities gradually, allow recovery and adjust subsequent training to symptoms. Soreness is not a necessary sign of a productive workout.

Do not assume that exceptionally severe pain, marked weakness, major swelling or dark urine is ordinary exercise soreness. These symptoms need prompt medical assessment.

Sources

• Brooks et al.: Lactate metabolism (2022)
• Cheung et al.: Delayed muscle soreness (2003)

This article provides general information. Individual diagnosis and treatment require a clinical assessment.