Lactic Acid does NOT cause muscle soreness

We’ve known this for decades, but it continues to be one of the most persistent fitness myths that just won’t go away. Let’s explore further:

When we exercise with a high degree of effort, our body requires a lot of energy. One of the main ways we produce energy is by breaking down sugars, a process known as glycolysis. Glycolysis starts with glucose (a monosaccharide, or the simplest form of sugar) and ends with ATP, or the “energy currency” used to power every process in the body

Glycolysis produces other metabolites as well. Pyruvate is one of those byproducts (it isn’t waste though, it does some important things that we’ll talk about later). Lactic acid (or L-lactate if we’re being particular) is then produced from pyruvate via the enzyme lactate dehydrogenase (LDH). With increasing levels of exertion, there is a greater demand for ATP and the rate of glycolysis increases. More glycolysis means more lactate is produced as well

After we train, our muscles are often sore. This soreness is referred to as Delayed Onset Muscle Soreness, or DOMS, and typically occurs 24-72 hours post-exercise. Because blood lactate levels are high with intense (soreness-inducing) exercise, it was (incorrectly) assumed that lactate was responsible for DOMS

However, that is not the case! In fact, lactate actually plays an important role in providing more energy substrate to produce ATP. Blood lactate rises in part because it is being shuttled to the liver, where it’s converted back to glucose via the Cori Cycle. There’s some indirect evidence that lactate may even mediate hypertrophy, and might be preferentially metabolized by the brain before glucose! Lactate production is a GOOD thing that aids, not hinders, performance and recovery!

We will cover what DOES cause DOMS in an upcoming post, so stay tuned!

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