Lactate and Lactic Acid Are Not Toxins: They’re a (Poor) Muscle Fuel

Lactate and Lactic Acid Are Not Toxins: They’re a (Poor) Muscle Fuel

Many massage therapists believe that they can “release toxins” from your body during a massage —  or least accelerate the process. But basic human physiology does not support this popular massage myth that often gets passed on you.

Alice Sanvito, a massage therapist in St. Louis, Mo., quoted someone who wrote, “Lactic acid and cellular waists (yes, that was what was written) wring from the muscles and become accessible to the lymphatic system for easy detoxing after a massage with proper hydration. Without hydration after deep tissue massage results in toxins and acids staying in the muscles resulting it soreness and even headaches.”

Another person asked, “How do we address the overwhelming ignorance of our field?” and used the lactic acid release debate as an example. This shouldn’t even be a debate, no more than debating whether our planet is spherical or flat.

We don’t know where the idea that lactic acid is a toxin and can be squeegeed out of your muscles come from. What we do know is that many massage therapists need to review and understand basic human physiology so that we give our clients, patients, and other healthcare professionals updated information that is supported by good evidence and basic sciences.

Do toxins get released during a massage?

In an interview for The Observer, Professor Edzard Ernst at Exeter University explains the contexts of toxins.

“Let’s be clear. There are two types of detox: one is respectable and the other isn’t,” he said. He went on to indicate that those with life-threatening drug addictions receive medically valid detoxes.

But as far as detoxification strategies in the wellness industry? He explains that these are not so much valid treatments as they are use of a “word being hijacked by entrepreneurs, quacks and charlatans to sell a bogus treatment that allegedly detoxifies your body of toxins you’re supposed to have accumulated.”

Lactic acid is another “toxin” given notoriety in the massage and fitness world for being the cause of many deep burn recovery days. The term “lactic acid” is often incorrectly interchanged with “lactate,” and though they are used in the same context, they are two different substances due to a one proton difference between the two.

It has commonly been taught that lactate is the basis for delayed-onset muscle soreness (DOMS), but there is nothing scientific that supports this teaching.

Dr. Stephen M. Roth, kinesiology professor at the University of Maryland, explained in Scientific American that examinations of lactate levels after exercise had little correlation to later muscle soreness. It is actually lactate, the base component of lactic acid, that is used in the body’s anaerobic process of breaking down glucose to create energy and the fuel for muscle contractions.

What this means is that under heavy exertion and oxygen is not readily available to muscles, the body will convert another substance called pyruvate into lactate in order to produce energy. Once the body slows down enough to get more available oxygen, the lactate is then converted back into pyruvate, and the body goes into recovery.

Although it’s commonly assumed that lactate remains in the body for a period of time, the majority of this is removed by the body’s natural processes within an hour of exercising.

Dr. Roth explained that it is “the production of lactate and other metabolites during extreme exertion results in the burning sensation often felt in active muscles, though which exact metabolites are involved remains unclear.”

Massage therapists have a large number of clients who also ask if they get sore after a massage because the massage “detoxes” their muscles from built up lactic acids released into the body.

This is not the case. There are not yet any firm answers as to why clients may experience soreness when a massage is not excessive.

Post-massage soreness and malaise (PMSM) is often listed as a common, benign side-effect of massage and can include experiencing flu-like symptoms after receiving bodywork.

There could be a number of reasons for mildly unpleasant side-effects from massage. Some people may be naturally more prone to bodywork soreness due to underlying conditions or general nervous system sensitivity. You could be getting a massage on a day when they are more dehydrated, you post-workout DOMS kick in, or you have a mild cold or infection they are not aware of yet.

In an extreme case of an overly-aggressive massage, it’s possible a client can experience an exertion-induced rhabdomyolysis, which is the breakdown of muscle tissue that releases myoglobin into the bloodstream after extreme physical activity.

Even more mysterious still, on occasion, the psychological effects of massage could create an unpleasant contrast between a client’s blissful massage session and the re-entry into a stressful day, as science writer Paul Ingraham alludes to, much like the feeling of a Sunday evening before the start of a Monday work day.

While it’s unclear what creates soreness or side-effects of massage, it’s clear that it’s not because massage detoxifies the body. For most people, the only thing needed to flush toxins from the body are the skin, lungs, intestines, kidneys and the liver. The human body is intrinsically equipped with the ability to process waste-products on its own.

What Is Lactic Acid? 

Lactic acid, or lactateas it is often used interchangeably in lay conversations— is a compound that is produced during glycolysis, a process that is constantly working in your muscles and liver to replenish and supply your body — especially your brain and nervous system — with glucose.

Whether you’re sleeping, watching Netflix, or lifting heavy weights at the gym, glycolysis can happen whether there is oxygen or not, which are categorized into anaerobic and aerobic glycolysis.

When there’s enough oxygen available during exercise, your body uses aerobic glycolysis to produce a constant supply of energy in the form of ATP (adenosine triphosphate) to your muscles. That’s why marathon runners and Tour de France cyclists can sustain their activities for a long time.

But if the demand of oxygen exceeds its availability, then your body undergoes anaerobic glycolysis, which produces less ATP.

Pyruvate (or sometimes called pyruvic acid), a byproduct of glucose breakdown, is converted to lactate, which accumulates in your muscles, especially during high-intensity exercise.

The rate of lactate clearance also decreases, leading to fatigue and less force produced by your muscles. This is where your muscles and nervous system tell you to slow down or stop and catch your breath before you continue.

At this point, your blood becomes more acidic — not too much to the point that could kill you but enough for your body to trigger a response to buffer the mild acidosis.

When an ATP molecule is used for energy, it’s broken down into an ADP (adenosine diphosphate) and a phosphate molecule with the release of a hydrogen ion, which is a proton with a positive (+) charge.

This increase of protons causes acidosis, which decreases the blood pH below its normal range of 7.35 to 7.45.

lactic acid to lactate

Image: Nick Ng

And so, the increased level of protons in the cell is primarily the cause of the “muscle burn” sensation, not lactate itself.

In fact, lactate acts as a buffer to increase the pH level. Because it increases along with a rise in proton accumulation, lactate is used as an indirect marker to measure cell metabolism.

But this can cause some people, including scientists, to form a misconception that lactate is associated with the rise of acidity in the blood.

“Lactate production is therefore good and not bad for contracting muscle. Lactate is not a bad molecule, and it has been given a bad rap from being falsely blamed for the cause of acidosis.” ~ Dr. Len Kravitz, exercise physiologist, University of New Mexico

Lactate Is “Back Up” Fuel

Research in the past few decades found that lactate is actually used in your cells’ mitochondria — the “energy powerhouse” that makes ATP  — including your heart. Trained athletes during intense exercise can use lactate in their muscle cells for fuel better than those who are not physically conditioned for intense exercise.

The more conditioned and well-trained you are, the better your mitochondria can process lactate and shuttle it out of the cell to be recycled.

​When you stop exercising, any lactate that is still in your blood and is not used by your muscle cells gets returned to your liver, is converted into pyruvate, and eventually glucose through a process called the Cori Cycle or Krebs Cycle.

This glucose can be used to rebuild supplies of glycogen in your muscles or further energy use for your muscles and nervous system.

Lactate is part of a complex metabolic system and a vital part of helping you endure and adapt to your workouts and other physical activities. It surely is not a “toxin.”

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A native of San Diego for nearly 40 years, Nick Ng is an editor of Massage & Fitness Magazine, an online publication for manual therapists and the public who want to explore the science behind touch, pain, and exercise, and how to apply that in their hands-on practice or daily lives.

An alumni from San Diego State University with a B.A. in Graphic Communications, Nick also completed his massage therapy training at International Professional School of Bodywork in San Diego in 2014.

When he is not writing or reading, you would likely find him weightlifting at the gym, salsa dancing, or exploring new areas to walk and eat around Southern California.

heather thuesen
Heather Thuesen, LMT
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Heather Thuesen has been a Licensed Massage Therapist in Colorado since 2014. Her areas of interest and specialization are in athletic and movement work, chronic pain conditions, anxiety-related disorders, and working with adolescents and teens ranging in age from 10-17.

She is continuing her studies in psychology and PTSD/trauma-related conditions. In addition to creative writing, she has an avid interest in travel, social culture and photography. Her favorite travels involve chasing storms, good coffee, homemade pie and Kerouac-inspired road trips.