Lactic Acid: Friend or Foe

Ten miles into a long run you accelerate your pace to fire up those muscles and push your heart rate into the next zone.  After a minute or two at this higher intensity level, you experience a burning in your limbs – which most likely subsides when your pace slows down again.  Does this sound familiar? This feeling you’ve experienced is a build-up of lactic acid in response to higher intensity exercise. 

The terms “lactic acid” and “lactate” are often used interchangeably – however they occur in the body in different forms.  Lactic acid is a by-product of carbohydrate breakdown during anaerobic conditions (those that lack oxygen); lactate appears in the blood in the form of a salt during high intensity activity.

The build up of lactic acid in the muscles is often the scapegoat for post-workout cramping, soreness, and muscle fatigue athletes may experience.  But is it really worthy of all this blame?  Recent research says no.   There is no conclusive evidence associating increased lactic acid production with cramping, soreness or higher fatigue levels.  Muscular fatigue can occur with very low muscular acid levels, or no acid at all.   Cramping and soreness follow suit – these symptoms can exist with or without increased lactic acid. 

So, what is the cause of these common high intensity post-exercise complaints?  A variety of factors can contribute, but two familiar (and easily remedied!) culprits are dehydration and inadequate energy intake.  Athletes can avoid these issues by developing effective fuel and hydration plans for training and racing events. 

All previous opinions aside - lactic acid/lactate is not something to avoid, but rather to embrace. The more of it you produce, the more effective you become - especially in sprint and olympic distance races.  Athletes who produce a high amount of lactate are supplying their muscles with anaerobic energy.   A common way to increase lactate levels is through the use of dietary carnosine (meat products), or supplemental beta-alanine. The essential amino acid carnosine assists in utilizing lactic acid as fuel (through the help of beta-alanine).  Carnosine has been shown to improve anaerobic and aerobic performance – what every endurance athlete wants!

Ryan, M (2007). Sports Nutrition for Endurance Athletes. Boulder, CO: VeloPress.

Seebohar, B.  (2011).  Nutrition Periodization for Athletes (2nd ed.).  Boulder, CO:  Bull Publishing Company.

Taylor, L.  (2012).  Nutritional Guidelines for Athletic Performance: The Training Table, CRC Press. 

Thibault, G., Péronnet, F. (2006). It is not lactic acid’s fault. New Studies in Athletics, 1, 9-15.