Lactatic Acid Friend or Foe?

The burning question lighting up our telephones and e-mail boxes this week is whether or not lactic acid is good or bad for you. This confusion was sparked by a May 16th article published in The New York Times titled “Lactic Acid Is Not Muscles’ Foe, It’s Fuel” by Times reporter Gina Kolata. In her story, she writes that lactic acid build-up in the muscles, a condition commonly associated with painful muscle contractions at a high level of exertion has been getting a bad rap and is really a source of energy to be maximized. While this assertion is partially correct, it is based on incomplete scientific information. The complete story is still unfolding as scientific research on lactic acid and “the burn” remains inconclusive even today. However, this does not prevent CTS coaches from training athletes with sound experiential and up-to-date scientific fact. Coaches and athletes know the “burn” exists; the physiological and chemical components responsible for the burn are as yet undetermined. Some components associated with the common conception of “the burn,” specifically lactate, do in fact provide a source of energy to working muscles, however this does not mean that members should be training at the highest possible intensity at all times to produce this result. While conflicting scientific theories exist about the burn, training different energy systems is still the best way to maximize performance results.

There’s “Lactate” and Then There’s “Lactic Acid”
The experts in Kolata’s story, George Brooks, a professor of integrative biology at UC, Berkeley and L. Bruce Gladden, a professor of health and human performance at Auburn University, explain how lactic acid is actually the fuel tapped by your muscles to power your performance and not the culprit behind fatigue and muscle soreness.
We have no problem with the Times’ assertion that lactic acid is muscle fuel. Our contention is with the story’s misleading claim that “lactic threshold training” as Ms. Kolata calls it, is “all wrong.” It is not all wrong, nor is her assertion based on sound scientific fact, but rather a partial understanding of the scientific literature. The problem is that the Times doesn’t differentiate between lactate and lactic acid. In reality, lactate is the actual fuel used by muscles while lactic acid is composed of lactate and hydrogen ions.
This confusion isn’t only relegated to Ms. Kolata. Indeed, a recent paper, “Lactate: Not Guilty as Charged” by Len Kraviz, Ph.D., of the University of New Mexico, points out that “most texts simply do not provide and explain the chemically balanced reactions occurring during metabolic acidosis. This incomplete description of acidosis has led to the acceptance of the misconceptions of lactate held by many fitness professionals and exercise scientists.”
Kravis goes on to explain how lactic acid is used as fuel and actually slows down the production of acid in an athlete’s muscles as glucose is turned into lactate and processed by those muscles:

In order to neutralize the soaring accumulation of pyruvate and protons from the splitting of ATP (the high-energy compound from which cells derive energy during vigorous exercise), each pyruvate molecule absorbs two protons into its structure, converting to lactate. Thus, lactate production is ACTUALLY A CONSEQUENCE of cellular acidosis and NOT the cause of the acidosis. More blatantly, lactate production actually RETARDS ACIDOSIS. Lactate is a temporary ‘neutralizer’ or ‘buffer’ to the cells’ elevated accumulation of (acidic) protons during high-intensity exercise.

Does the “Lactic-Acid Burn” Exist?

Between the lactate and hydrogen ions that make up lactic acid, one theory is that it’s the hydrogen ions that increase the acidity in muscle cells. This increased acidity inhibits muscle contractions due to the “stimulation of the free (and available) nerve endings in the muscle (which results) in the perception of pain.” (www.brainman.demon.co.uk/lactic). This pain is the “burn” which any athlete will recognize comes from working his or her muscles hard.
Still further investigation into the root causes of muscle fatigue, or the “burn,” has turned up another theory. A 2002 study published in News in Physiological Sciences cites the work of Drs. Håkan Westerblad, David G. Allen, and Jan Lännergren who theorize that “inorganic phosphate (not acidity), which increases during fatigue due to the breakdown of creatine phosphate, appears to be a major cause of muscle fatigue.”

Will Any of This Affect Training Protocols?
No. This evolving view of lactate and lactic acid by the scientific community only reinforces the training methodology that coaches and athletes have been using for years. In Brooks’ experience, athletic coaches understood this connection intuitively long before the sports scientists grasped it. Through trial and error, coaches and athletes realized that training helps the body better metabolize lactic acid, which then allows the body to perform at a higher intensity for a longer period of time. The goal is to push back the point at which the body is overwhelmed by lactic acid and performance starts to suffer. As Dr. Brooks rightly points out in the Times story, training boosts the production of mitochondria in the muscle cells thereby increasing the ability to absorb more lactate for fuel. The faster and more efficiently a body can process lactate, the stronger it can become. At CTS, we call this connection “lactate threshold training,” and it’s the lynchpin that we build our training programs around.