Why You Should Embrace 'The Burn' When Working Out

Understand the role lactic acid plays in your training regimen.

For a long time lactic acid was bad news because of its association with the horrible burn in the  muscles during intense exercises. Many people still see it this way, and rightfully so.

But since its discovery in the early 19th century, what we know about lactic acid has changed. Research endeavors have uncovered more information. The purpose of this article is to help make sense of this compound as it relates to exercise and hopefully to shift the paradigm.

Lactic Acid is Short-Lived

During short bouts of intense activity, when our demand for energy exceeds our supply of oxygen, we tap into anaerobic glycolysis, which is the metabolic process that breaks down glucose to create energy in the absence of oxygen. Lactic acid forms but rapidly separates into hydrogen ions and lactate. Lactate is in fact a different substance and should not be used interchangeably with lactic acid. It seems that lactate is what society has meant to talk about all along, and, to be honest, lactate is what this article is really meant to help us understand.

The Incomplete Truth

The body moves lactate and hydrogen ions from the cells of working muscles to the blood for buffering. Buffering is a way of regulating pH to maintain homeostasis, or balance, in the body. When the amount of lactate and hydrogen ions in the cells increase faster than the body's ability to remove them, pH lowers and the environment becomes acidic. This is called metabolic acidosis. Enzymes that would otherwise source chemical reactions are deactivated, and the result is fatigue and inhibited muscle mechanics. For centuries, this was the end of the story.

Some individuals take bicarbonate as a supplement to help regulate pH. However, more research is needed to determine an effective dose that minimizes side effects.

An Unlikely Hero

Since high levels of lactate correlate with muscular fatigue, it's rational to point fingers. But correlation is not causation. Rather, excess hydrogen ions are thought to be the primary contributor to metabolic acidosis. This makes sense considering pH stands for "potential of hydrogen." Its rate of removal is independent from that of lactate, and several mechanisms such as the exchange of other ions contribute to the amount of hydrogen in a cell.

Recent evidence suggests that lactate itself may actually help regulate pH. Lactate has properties that allow it to combine with oxygen and serve as a precursor for energy production. When lactate leaves the cells of anaerobic tissues and enters the blood, it can be utilized by aerobic tissues. During what is known as the Cori cycle, the liver takes lactate released into the blood and, through a series of chemical reactions, converts it to glucose for energy. The Lactate Shuttle theory supports the concept of lactate transportation to supply energy across neighboring cells, such as those within the myocardium of the heart—a fascinating example of how lactate integrates the energy systems.

Well-conditioned athletes have shown an increased tolerance to metabolic acidosis, suggesting an enhanced buffering capacity for sustained performance.

Moving Forward

Similar to how an older brother is blamed for the younger brother's wrongdoing, lactic acid took the blame for quite some time. We've come a long way in our understanding of lactate over the years. It's safe to say that it's not just a metabolic waste product. Neither is it the culprit for that burning sensation after a drop set of Bicep Curls. Instead, maybe we have lactate to thank for sustained energy and performance.

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REFERENCES

McArdle W.D., Katch F.I., & Katch V.L.. (2014). Exercise physiology: Energy, nutrition, and human performance.  Lippincott Williams & Wilkins.

Baechle, T.R., Earle, R.W., & National Strength & Conditioning Association (U.S.). (2008). "Essentials of strength training and conditioning." Human Kinetics.

Dunford, M. & Doyle, J.A. (2015). "Nutrition for sport and exercise." Stamford, CT: Cengage Learning.

Kowalchuk, J. M., Heigenhauser, G. J., Lindinger, M. I., Sutton, J. R., & Jones, N. L. (1988). "Factors influencing hydrogen ion concentration in muscle after intense exercise." Journal of Applied Physiology, 65(5), 2080-2089.

Brooks, G. A. (1998). "Mammalian fuel utilization during sustained exercise." Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology, 120(1), 89-107.

Brooks, G. A. (1986). "The lactate shuttle during exercise and recovery." Medicine and Science in Sports and Exercise, 18(3), 360-368.

Hebisz, R., Hebisz, P., Borkowski, J., & Zatoń, M. (2016). "Differences in physiological responses to interval training in cyclists with and without interval training experience." Journal of Human Kinetics, 50(1), 93-101.

Photo Credit: vladans/iStock/Thinkstock


Topics: ENDURANCE TRAINING | RUNNING | LACTIC ACID