I’m going to take a stab in the dark and bet that when the average gym junkie hears anything about lactic acid in muscles there’s a sudden shiver that shoots down their spine. This is probably because even though current research correctly shows it’s not responsible for muscle fatigue and soreness, word-of-mouth advice from friends or the casual passer-by continues to propel the antiquated wisdom.

I have to admit I was quite surprised when I first heard my knowledge about muscle failure was flawed. This whole time what I believed in training just below the threshold was actually wrong. It did make sense after I pieced together the research. And I did come to the ultimate question: Why would anyone looking to increase their speed be afraid of something our bodies naturally make available for pushing our bodies to perform?

(Photo: joe reicherts)

The theory of lactate being responsible for fatigue and soreness in the muscles stems from 1920s, when Nobel laureate, Otto Meyerhof, shot electric current into a half-cut frog that had been sitting in a jar of lactic acid. When the frog only twitched slightly he drew to the conclusion that without oxygen the muscles gather in lactic acid, and then will hit failure as the result.

How Lactic Acid in Muscles Really Works, and Why

During a hard workout, the body requires oxygen. For the most part, it’s just our natural reflex to breathe harder to bring in more O2. And this works fine because the body would prefer to create energy in an aerobic environment.

However, when we push towards a higher rate of activity, such as in a lifting routine or high intensity cardio session, oxygen consumption will outpace the amount that gets delivered. When this happens, the body sources energy from within. It goes anaerobically.

Glycolysis is the process where glucose is extracted at energy. It gets metabolized, and in a few steps it is transformed into pyruvate.

In case anyone is a little rusty from biochem class, here’s my favorite video on the subject of Adenosine-5′-triphosphate (ATP), and how it converts cell energy for the metabolism process. I’m not exactly sure if these guys are just goofing off, or just goofy after studying about ATP and biological energy. I’m guessing it’s probably the latter.

When oxygen is short supply, the body uses pyruvate and changes it into lactate. It is used as a fuel. This means lactic acid in muscles is not responsible for delayed on-set muscle soreness (DOMS). It’s actually a form of fuel that allows for continuing with strenuous activity.

What some might find interesting is how only after 1-3 minutes of hard working, super huge levels of lactate will accumulate. This acid environment in the muscles prevents other metabolites from doing their jobs. So, lactate build up creates a roadblock, and starts to slow the entire system down.

The Question: Why, when efficiency is the name of the game and, does lactate stall other functions when it’s supposed to push our performance forward?

The Answer: To prevent permanent damage, of course. It’s the safety mechanism that is meant to keep the body from accidentally pushing too far beyond its abilities.

Performance stamina is a big deal for athletes. There are different ways to better staying power, like building the body’s ability to increase vo2 max, but being able to handle lactate threshold levels is also very important.

Here’s what testing for lactate threshold looks like.

Here are a few good articles on how lactic acid in muscles isn’t such a bad thing after all.

ATP, Lactic Anaerobic, and Aerobic Systems of Muscle Energy …

Lactic Acid In Muscles – Friend Or Foe? | Extreme Bodyweight …

So, what’s more likely to be behind DOMS? Current research points to micro-tears in muscle tissue as the main suspect for tender muscles after a strenuous workout. This makes sense, since to build up the muscles you have to break down the muscle first before they can rebound for size or strength.

It’s interesting how the body has such an extensive catalog of check-and-balance systems in place to keep us moving. The build up of lactic acid in muscles is just one that has developed over our evolution, probably of the fight or flee response. But, even though we might not need to run from a herd of wooley mammoths anymore, it’s interesting to see how much it can still play a role in today’s world.