by Evie Ullman, DPT

Many of you avid exercisers out there complain of muscle soreness post workout and blame it on lactic acid hanging around in the muscles. “I need a massage to clear out the lactic acid,” you may say.  This is actually a myth. I will give you the scoop on lactic acid.

In a nutshell, we derive our energy from a molecule called Adenosine Triphosphate, aka ATP. Our bodies use three basic energy systems to replenish ATP and the use of them varies depending upon the intensity of exercise. The three systems are the Phosphagen system, the Oxidative system and Glycolysis. The Phosphagen system comes into play during short high intensity activity such as weight lifting and sprinting, but it is also active at the start of all exercise, regardless of intensity. The Oxidative system serves as a source of ATP when our bodies are at rest or performing lower intensity, long-term activity such as long distance jogging. Lastly, Glycolysis works during moderate to high intensity and medium to short duration of exercise. This is the only energy system that produces what was once thought of as lactic acid.

In reality, lactic acid cannot even really exist in the body because blood pH is too neutral, (around 7) and acids require very low pH. As soon as lactic acid is produced in the body, it dissociates into lactate and hydrogen.  Really what we are talking about when we say “lactic acid” is lactate. So you should not use the words “lactic acid” and “muscles” in the same sentence!

Now, what exactly is lactate, and does it make our muscles sore? During Glycolysis, carbohydrates are broken down to resynthesize ATP- remember, that is the molecule we need for energy. In short, multiple chemical reactions occur in our muscle cells during Glycolysis and an eventual end product is pyruvate, which either goes through the Krebs Cycle, where oxygen is required to synthesize ATP, or it gets converted to lactate. It is true that lactate levels increase as our muscles fatigue and burn from exercise. But lactate is not the cause of this fatiguing, burning sensation during exercise, nor is there any evidence that it is the cause of Delayed Onset Muscle Soreness (DOMS) after exercise. In fact, lactate is shuttled out of the muscles to the liver, where it is in turn converted back into carbohydrate and reused as an energy source. Lactate is helpful to us! If the lactate is not needed, it is transported away in the blood and oxidized. You may wonder, would massage help the transport of lactate from the muscles?  A study performed at Queen’s University in Kingston Ontario concluded that massage actually impeded blood flow to the muscles and lactate removal was impaired. Massage has benefits, but lactate clearance is not one of them.

So there you have it. Lactic acid disappears as soon as it is formed in the body, and it is not the cause of muscle soreness.

Sources:

1. Wiltshire EV, Poitras V, Pak M, Hong T, Rayner J, Tschakovsky ME. “Massage impairs postexercise muscle blood flow and “lactic acid” removal.” Med Sci Sports Exerc. 2010 Jun;42(6):1062-71.
2. Baechle, Thomas R and Roger W. Earle. Essentials of Strength Training and Conditioning 3^rd Ed. Chicago: Human Kinetics, 2008.

Dr. Ullman is a Physical Therapist at Boston Sports Medicine

“Hello, I am an LMT and I have a comment on your article,  “The Lactic Acid Myth” by Evie Ullman. A generalized claim made in this article may be misleading, and the cited supporting study does not provide evidence to universally support this claim.

The quote from the article that is problematic “A study performed at Queen’s University in Kingston Ontario concluded that massage actually impeded blood flow to the muscles and lactate removal was impaired. Massage has benefits, but lactate clearance is not one of them.”

The supporting study: Wiltshire EV, Poitras V, Pak M, Hong T, Rayner J, Tschakovsky ME. “Massage impairs postexercise muscle blood flow and “lactic acid” removal.” Med Sci Sports Exerc. 2010 Jun;42(6):1062-71.

The part of the claim made that I specifically think is not accurate is this: “massage actually impeded blood flow to the muscles”. The claim can be both true and false at the same time, but it encourages the reader to believe “massage impedes blood flow” as a general truth. Certain types of massage DO impede blood flow, especially to certain areas and under certain body conditions pre-massage, however certain types of massage encourage blood flow more than others, especially with certain body conditions pre-massage. I checked out this study, and the massage techniques that they used in their study could ALL be used in a way that impedes blood flow to muscles. Additionally, in many places the conductors of this study do not provide adequate differentiation of what type of massage they are referring to when they make the claim from other sources that massage in general impedes blood-flow.  The claim that massage in general impedes blood-flow to muscles is uninformed regarding the vastly varying effects that different types of massage produce in the body during and at different intervals of time after the massage and misinforms readers by overgeneralizing massage and the effects it has on the body.

There is certainly evidence within the cited study that the types of massage techniques used and the way they were used impede blood flow to muscles when performed directly after exercise, but this conclusion is only applicable to these circumstances. At the end of the study, it actually acknowledges that conclusions from its results should not be generalized to all types of massage in all circumstances. Many people are not well-informed about massage, and I would like to see that change. It is important to let therapists and lay-people alike know about certain myths regarding massage, such as how it does not remove lactate buildup, but it is also important to be very clear with our language so as not to further mislead people by failing to give them the whole picture. There would not be a problem with the claim made in this article if there was only a little more information to let the reader know in what circumstances and regarding what types of massage this claim is relevant, especially because it would provide a more accurate representation of the study from which this claim is cited.”