Should you be concerned about the effects of lactic acid build-up in your muscles? If lactic acid really does what some people says it does, then you probably don’t want that substance anywhere near your muscular system.

It’s an acid. It burns, which you can feel directly, and it causes damage, which you experience as muscle fatigue or soreness. If you keep going long enough and produce enough lactic acid, then you “hit the wall.” Your body runs out of steam, and you can’t go any further.

If lactic acid does that, then it’s a bad thing, even if the effects are only temporary. But that’s a really big “if”—is it true what they say about lactic acid?

Many people have invested in the myth that massage can squeeze lactic acid out of muscles that they are reluctant to take on the job of aligning the narrative with current scientific evidence. If massage therapy is to remain relevant in the post-Covid-19 era, practitioners must realize their potential as an actual healthcare professional.

When the evidence shows that scientists were wrong, they adapt by changing their minds to be more right. If massage therapists change and adapt to what new evidence shows, then not only are they performing as science-based professionals and role models, but they are also delivering a powerful message to clients and professional colleagues about their readiness to become members of a healthcare team. The lactic acid massage myth is a good start.

What is lactic acid?

Lactic acid is an organic (carbon-based) acid found in many different natural processes. Like the words galaxies, the lactate ion, and lactation, its name shows its close connection to milk.

Sour milk is where the Swedish chemist Carl Wilhelm Scheele identified it as a specific chemical compound in 1780. Its association with food continues to this day, where that sour taste is valued in foods ranging from yogurt to sourdough bread.

The closely-related chemical lactate is in the fluids given to trauma patients being treated for blood loss until they can rebuild that capacity on their own. It also appears to be a critical component in brain development and metabolism in multiple species, including humans.

Lactate is very important in muscle physiology because exercise causes your muscles to produce it from glucose and to use it for energy. But it’s lactate, not lactic acid as many people still believe, it carries out that metabolic function.

Does massage really get rid of latic acid?

Not only is there no evidence that massage can release toxins—often attributed to lactic acid—from muscles, which would leave that possibility open to be shown in the future, but that idea contradicts what we know about muscle physiology and metabolism.

If it were true, then what many scientists across time and cultures had demonstrated repeatedly about how our body works would be wrong.

To demonstrate the validity of the lactic acid and massage claim would take a lot of work, which is very likely to be impossible. The choice of what message that we want to send to the public is up to therapists.

Where did the lactic acid and massage myth start?

It turns out that reports of lactic acid’s effects are like a game of Telephone. It has been repeated from person to person, often getting tweaked in the telling. But the original message came from an experiment where the scientist was wrong about what he actually saw.

The German biochemist Otto Meyerhof was awarded the Nobel Prize in Physiology and Medicine in 1922 for his work on cell physiology. He examined what was going on at a deeper level in cells and their use of energy.

Although he pushed the boundaries in what had been impossible up until then and pioneered new and complex techniques to observe cellular actions, he got several things wrong about what those observations mean.

He published the idea that fatigue in muscles was caused by lactic acid, which in turn was caused by a lack of oxygen. People took that message and shared it with each other, changing and subtracting pieces of information and combining it with old ideas about toxic substances in the body. Thus, an industry was born.

As to what the evidence shows, Meyerhof’s idea about lactic acid began to fail very soon in scientific time—about seven years after winning the Nobel Prize. Starting with Einar Lundsgaard’s work in 1929, and continuing through many others’ research to the present, the evidence doesn’t match the predictions that the lactic acid hypothesis would imply. It turned out to be lactate instead of lactic acid, and the old ideas about massage squeezing lactic acid out of muscles as a toxin was just a story, not the reality.

As for Meyerhof, even though he was wrong about the role of lactic acid in muscle fatigue, his other work has been borne out. It laid the groundwork for needed quantitative observations and theory in cell physiology and led to understanding the roles of how cells produce energy.

It united chemistry, physics, and biology to show the integrated nature of physiology across scientific disciplines. By showing that these chemical processes work the same way in many different species, including humans, it highlights the unity and diversity of how life works.


When we make an observation of a relationship between two events or data sets, we sometimes make a mistake by indicating one of these events causes the other to happen. In other words, we see trend A associates with trend B; and so, A causes B. This is the classic correlation versus causation problem where many journalists and even scientists make when they report.

correlation causation

Image: Tyler Vigen, Spurious Correlations

Compared to other disciplines in biology, such as genetics and evolution, research in cellular metabolism hasn’t advanced much since the Roaring Twenties. The myth stems from more than 90 years of misinterpretation of observations of an increase of lactate associating with a drop of pH level in muscle and other tissues.

Roberg, Ghiasvand, and Parker said that the term “lactic acid” is a misnomer, since it was first discovered in sour milk (hence “lactic” referring to milk) by Swedish chemist Carl Wilhelm Scheele (1742-1786)  in 1780.

They considered the name “trivial,” yet the term—along with “lactate”—got stuck in the chemistry and medical professions for the next three centuries. Because Scheele isolated the acid under “impure conditions,” many chemists in the early 19th century tried to find alternative explanations to his findings, such as lactic acid is actually impure acetic acid.

Despite the misnomer, Robergs et al. described an early understanding of how lactic acid works in relation to exercise in the 1920s, based on the research by Meyerhof and Archibald Hill.

They highlighted that the knowledge base of acid-base chemistry and cellular respiration were “insufficient” at the time. The two chemists’ research did not directly experiment whether there was a cause-and-effect relationship between lactate and acidosis.

“…it is easy to comprehend how the Nobel prize quality of the work of Hill and [Meyerhof] was proof enough to the scientific world at that time for the interpretation that lactate production and acidosis were cause-and-effect,” Robergs et al. wrote. Hill’s studies suggest that lactic acid is the “immediate energy donor for muscle contraction,” while Meyerhof showed that lactate is a byproduct of glycogen break down.

Robergs et al. argued that much of the current medical education and research on lactate are still based on findings of Hill and Meyerhof’s time, which have not evolved. Tthe idea that lactic acid and lactate are the prime contributors to lactic acidosis still permeates in modern healthcare education.

They suggested that the terms “lactate” and “lactic acid” should be “removed from any association with the cause of acidosis” in sports science, which can make coaches, trainers, athletes—and massage therapists—continue to spread the muscle soreness myth.

Like many health care myths, such as massaging a pregnant woman’s ankles can cause an abortion in her first trimester and “poor” posture is primary cause of back pain, the lactic acid narrative may have been passed down from generations without question. The information spread so wide that even when a solid body of evidence indicates the opposite, the myth is already embedded into the culture. And it’s very difficult to change people’s minds.

Massage therapists and other manual therapists can learn from the past mistakes by keeping themselves updated and question what they learn in courses.

“Lactate can no longer be considered the usual suspect for metabolic ‘crimes’, but is instead a central player in cellular, regional and whole body metabolism.” ~ Bruce Gladden, Ph.D., Muscle Physiology Lab, Auburn University

Getting the role of lactic acid wrong was a mistake that needed correction, but it was not a fatal blow to Meyerhof’s body of scientific work. History is—and will continue to be—kind to him.

ravensara travillian
Ravensara Travillian, PhD, CMT
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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.