Muscle Soreness and Lactic Acid, Fact or Fiction? 1

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Image courtesy of LyndaSanchez under Creative Commons license.

What is the phenomenon when your muscles feel sore a day or two after a good workout?
Why does it happen?
What can massage therapy do to help?

True to its name, delayed-onset muscle soreness (or DOMS) is the condition in which, starting a day or two after a really good workout, your muscles start to feel incredibly sore. It’s completely harmless, just a pain in the butt– sometimes literally!

Most people will tell you this happens because of a buildup of lactic acid in the muscle after an anaerobic workout. This theory started in the early 20th century when a scientist by the name of Otto Meyerhoff cut a frog in half, and conducted an experiment with its legs. He placed the legs (which, because they had no circulation, also had no source of oxygen) in a jar, and gave them an electric shock to make the muscles contract. After a few shocks, the frog legs were no longer responsive. When Meyerhoff examined the muscles, he found they were covered with lactic acid.
So the theory was born: lack of oxygen to muscles leads to lactic acid, and lactic acid leads to muscle fatigue.

To this day, you’ll find everyone from personal trainers to massage therapists saying that lactic acid buildup is the cause of sore muscles, and that massage therapy helps by “flushing” out the lactic acid from your muscles. But, unfortunately, it’s just not true.

These days most physiologists agree that our previous understanding of lactic acid is too simplistic. While it is a byproduct of anaerobic activity, researchers have found that lactic acid actually acts as a fuel for the mitochondria in your muscle cells. Additionally, lactic acid is cleared out of your muscles almost immediately after your workout— within an hour, even. And that just does not correspond to the soreness felt 24-78 hours after your initial exercise.

So if it’s not lactic acid, why are your muscles sore?

These days, it’s understood that exercise beyond what your muscles are accustomed to causes microscopic tears in the muscle. These micro tears cause inflammation, which in turn causes soreness.
Micro tears sound scary, but they’re actually good!
In response to a hard workout, your body repairs these micro tears, and then lays down more muscle fiber so that the next time you lift that much weight, your body is prepared. The process is called hypertrophy, and it’s literally how to build your muscles and grow stronger.

And what about massage? If it’s not flushing out lactic acid, what is it doing?

One of the great benefits of massage is increased circulation, both systemically and to the specific muscles being worked. Proper blood flow helps delivered much needed nutrients and oxygen to cells, and is an important part of the healing process.
Plus, massage just feels really good.

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