12 Days of CrossFit 2016 – Day 9

By Coach Rachael

While on the floor with blue racquet balls lodged between shoulder blade and spine, grimacing from the pain, a fellow athlete turns to me and asks…”So does this get the lactic acid out of our muscles or something? Why does this hurt so bad and what the heck is lactic acid anyway?”

What is lactic acid? Good question…

Lactic acid is a substance produced by the body as a way to quickly produce energy for muscle performance. It is “a compound produced when glucose is broken down and oxidized” (, Lactic Acid).

Let’s start with how the body converts energy for performance. Sweating, breathing heavy and, some may argue, dirty stares in the coach’s direction are all involuntary responses to strenuous exercise. Panting, in particular, is caused by the body frantically trying to move energy from oxygen to the muscles so they can perform the tasks being requested. Using oxygen to generate energy is known as aerobic activity. Performing tasks such as our beloved mile run is an example of aerobic activity, basically activities lasting over 90 seconds and requiring low power.

However, where does that then leave all the other CrossFit movements that are short bursts of high intensity? These exercises are known as anaerobic activity. Since these activities require an immediate response from the muscle, the body does not have time to wait for the delivery of energy through oxygen. Therefore, the body has to come up with plan B.

Plan B is where lactic acid comes into play. Without oxygen muscles have to generate energy through glycolysis (the breakdown of glucose by enzymes, releasing energy and pyruvic acid, thank you wikipedia). No oxygen is required, therefore the working muscle cells can continue to produce high levels of energy for minutes at a time. That causes lactate and hydrogen ion accumulation to build in the muscle and make the surrounding environment acidic ( Fuel, Not Foe? The Truth About Lactic Acid). In recent research, it has been determined that lactic build up is NOT responsible for muscle soreness the days after Grace, Ralph, Murph or Fran, instead, lactic acid buildup is what causes the muscles to burn DURING those wall sits, v-ups or sled pulls. “Hydrogen ions are what create acid and lactate actually is produced to neutralize the growing number of hydrogen ions. It is when the buffering process can’t keep up that our

muscles burn.” ( Fuel, Not Foe? The Truth About Lactic Acid). Muscle burn acts as a defense mechanism to slow the body down. On-going soreness, or DOMS as it is known (delayed onset muscle soreness), which peaks 48-72 hours after extreme activity is caused by inflammation and micro-tears in the muscles. What was known as “lactic acid” is actually “gone from your muscles within an hour of exercise” according to Dr. George A Brooks, a professor in the department of integrative biology at the University of Califorinia, Berkely. Brooks also says that the initial beliefs of lactic acid were so popular and “stuck because it seemed to make so much sense.” “It’s one of the classic mistakes in the history of science.” (, Lactic Acid Is Not Muscles’ Foe, It’s Fuel)

Brooks explains that the long time misconception of lactic acid being a bad thing that builds up in our body stemmed from research over a century ago by Dr. Myerhoff. How you ask?

Myerhoff performed an experiment where he electrically shocked frog legs until the muscles stopped responding. He then examined the frogs’ muscles and they were full of “lactic acid”. So this brings up the question, if Myerhoff would have examined the frog muscles days later when the dead frog was complaining of soreness would if have changed history? According to today’s research the answer would seem to be: YES!





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