The "Lactic Acid" Myth

After a tough workout, I will hear people brag, "Oh man, that lactic acid is killing me! I'm so sore!" I want to use this post to dispel the myth that lactic acid is what causes DOMS (delayed onset muscle soreness). Yes, you read that correctly. The age old belief that lactic acid was the cursed substance that leaves you hobbling up the stairs after your crazy leg day is actually false.

How did this inaccuracy come to be? Gina Kolata, journalist from the New York times writes:

"Its origins lie in a study by a Nobel laureate, Otto Meyerhof, who in the early years of the 20th century cut a frog in half and put its bottom half in a jar. The frog's muscles had no circulation — no source of oxygen or energy. Dr. Myerhoff gave the frog's leg electric shocks to make the muscles contract, but after a few twitches, the muscles stopped moving. Then, when Dr. Myerhoff examined the muscles, he discovered that they were bathed in lactic acid. A theory was born. Lack of oxygen to muscles leads to lactic acid, leads to fatigue."

Scientists actually believe that lactic acid is not even present in humans. While the blood does become more acidic during exercise, the acidity is not enough to create lactic acid, but rather, lactate is created.

While some industry professionals use the words 'lactate' and 'lactic acid' interchangeably, there is a slight difference between the two substances. "The formation of lactate from pyruvate is catalyzed by the enzyme lactate dehydrogenase. Sometimes, mistakenly, the end result of this reaction is said to be the formation of lactic acid. However, at physiological pH (i.e. near 7), the lactic acid molecule cannot exist. Instead, it’s anion lactate- + H+ (a hydrogen proton) are the results of the lactate dehydrogenase reaction," according to the National Strength and Conditioning Association's Essentials of Strength and Conditioning. For true lactic acid to exist, the blood pH would need to drop below a 4.

Lactate is, however, a fuel for the muscles. An athlete's lactate threshold is the point at which his or her body produces lactate faster than it is cleared. Lactate is not a waste product, nor is it something to avoid, despite the fact that "lactic acid" (lactate) gets a bad rap.

It's not lactic acid's fault!

Although the cause of muscular soreness is still not entirely understood by science today, the residing theory is that soreness is really the result of micro-tears of the muscles after exercise. When you do a new exercise, or you increase the intensity (weight) and/or volume (repetitions) of a movement, your tissues suffer from micro-traumas. Lactate is rushed to the muscles to clear away the damage, but it is the muscular damage that causes the pain, not the lactate itself!

So the next time you hear someone curse lactic acid for their temporary post-workout induced paralysis of the legs, you can spit a little bit of science at them, and explain to them what's actually causing their soreness.


Works Cited:

1. Baechle, Thomas R., and Roger W. Earle. Essentials of Strength Training and Conditioning. Champaign, IL: Human Kinetics, 2008. Print.
2. Brooks, George, and Rhonda Patrick. "Lactate As Brain Fuel with Dr. George Brooks." YouTube. N.p., 02 Dec. 2014. Web. 27 Apr. 2016.
3. Hutchinson, Alex. Which Comes First, Cardio or Weights?: Fitness Myths, Training Truths, and Other Surprising Discoveries from the Science of Exercise. New York: HarperCollins, 2011. Print.