You might be under the impression that the day-after muscle soreness we feel from a workout is the result of lactic acid buildup. Many people turn to foam rolling or massage in an attempt to remove the lactic acid, and therefore, the soreness.

The truth is that lactic acid has little or nothing to do with what’s also known as delayed-onset muscle soreness (DOMS). Lactic acid is part of a chain events, but not the culprit. Here’s what you need to know.

Muscles and energy production

Your body consumes two types of energy production during exercise.

  1. At the start, the body uses aerobic metabolism to convert oxygen into energy.
  2. Then, as oxygen stores are depleted, your body switches over to anaerobic metabolism. A substance in your body called pyruvate gets converted to lactate – otherwise known as lactic acid) to promote glucose breakdown.

Here’s the thing about this second form of energy production. It can only be used for about three minutes before the body signals that it’s time to stop. The buildup of lactic acid has created an environment of acidity in your muscles. You’re “feeling the burn.” It’s your body’s way of prompting you to stop, rest, and breathe. And, as you breathe, your body returns to aerobic metabolism.

Feeling the burn

The muscle burn we feel is a natural protective mechanism. Our body prefers the energy production method of aerobic metabolism. By the way, any excess lactate gets converted back to pyruvate. The soreness you feel the next day isn’t because of lactic acid. It’s gone.

Why the soreness, then?

DOMS occurs anywhere from 24 to 72 hours after working out. Nobody argues about that. Researchers, however, aren’t sure of the actual cause – other than that it is definitely not lactic acid. Medical experts believe the soreness is caused by elevated substances known as metabolites – which can be find in muscle tissues after a workout.

Other medical experts believe that the soreness is the result of what’s known as rhabdomyolysis. The workout has caused microtrauma to your muscles, which then release proteins. As a result, the muscles trigger an inflammatory response. This causes your muscles to swell and become sore.

There’s still more research to be done to determine the true cause of muscle soreness caused by exercise. Meanwhile, lactic acid is sending a shout out and asking not to be blamed.

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