4 Lies You Were Told About Lactic Acid

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Lactic acid is often regarded as the bad guy at training. The one that nobody likes or appreciates it. Why? Well because it causes your muscles to fatigue and creates post exercise soreness… right?

Wrong. Read on and you ‘ll find out why lactic acid should be your friend. Okay, it does have a dark side but we ‘ll get onto that later.

Lactic acid 101

Before we get started, we’ll quickly outline how lactic acid enters your bloodstream.

In order to power an athlete’s muscle the body requires energy through the use of ATP (adenosine triphosphate) which is created through the breakdown of the body’s carbohydrates through a process known as glycolysis.

Under aerobic conditions one of the pyruvate is combined with oxygen to create carbon dioxide, water and ATP (click here for further information).

In anaerobic conditions (i.e. the absence of readily available oxygen) the pyruvate is converted into lactic acid through enzymes. This nicely leads us into our first dispelled lie…

Lies #1 & 2: Lactate causes muscles to fatigue and doesn’t contribute to performance

Photo by Rennett Stowe via Flickr

Lactic acid is broken down by enzymes in the body to create lactate and hydrogen ions (H+). Lactate then either remains in the cell to provide energy or travels to other areas of the body such as the heart to provide a valuable energy source.

Unused lactate is then sent to the liver to be converted back into glucose, which during exercise the body works to maintain so there is an adequate amount for proper brain function.

Furthermore, the presence of lactate has been shown to have a relatively minor inhibitory effect on proper muscular contraction with other factors such as the swelling of muscle fibres thought to have a stronger effect.

Lie #3: Better athletes produce less of it

Photo by Guillaume Baviere via Flickr

The ability to use lactate as a fuel source improves through consistent training, in particular through forms of endurance training.

As you put in the hours on the track and the road not only does the ability of your mitochondria to convert lactate into a source of energy improves but it also improves the body’s oxygen delivery system to your muscles and tissues, creating less demand for anaerobic respiration.

So it’s not so much a matter of the top athletes being able to produce less of it – in fact as we’ve already discussed, that would have a negative effect on performance – but it is their improved ability to use the build-up of lactate as an energy source and a heighted ability to break lactic acid down into lactate in the first place.

Lie #4: Lactic acid causes muscle soreness

Photo by Sam Webster via Flickr

Lactic acid or lactate is often branded as guilty for muscle soreness and whilst it is often present at the scene of the crime, it is not the criminal.

If we didn ‘t understand heart rate as well as we do we might assume that a faster beat should be immediately associated with fatigue, however whilst we know that both increase as exercise intensity increases but we also know that an athlete’s heart rate does not cause fatigue in an athlete. The same could be said for lactic acid.

Delayed onset of muscle soreness (DOMS) – that achy sensation you get in the 24-72 hours after a tough session – is created by the muscle damage caused through intense exercise and the post-exercise tissue inflammation that is associated with it. 

Lactic acid: the dark side

We mentioned hydrogen ions earlier when discussing the breakdown of lactic acid. Whilst the primarily component, lactate, has a positive effect on performance H+ may not. A build-up of H+ increases the acidity of the blood and whilst this is initially buffered by your bicarbonate buffer system (H+ + HCO3 = H2CO3) and converted into water (H2O) and carbon dioxide (CO2) and expelled by the lungs some will remain in your system.

There is some evidence to suggest that this may interfere with muscular contractions however other evidence suggests that the inability of the muscle to keep up with the rate and force of muscular contraction may also be due to the progressive loss of potassium from inside muscle cells.

Conclusion

The research shows us that lactic acid shouldn ‘t carry the bad reputation that many athletes will associate it with.

No longer should it be the fall guy for fatigue, sore muscles and cramps.

It should be your metabolic pariah, your body’s effective use of it probably had a large role to play in your personal best performances!

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Reading material

Ahlborg G., Felig P. Lactate and glucose exchange across the forearm, legs and splanchnic bed during and after prolonged leg exercise. J. Clin. Invest. 69: 45-54. 1982.

Ahlborg G., Wahren J., Felig R. Splanchnic and peripheral glucose and lactate metabolism during and after prolonged arm exercise. J. Clin. Invest. 77: 690-699, 1986.

Brooks, G. A. Intra- and extra-cellular lactate shuttles. Med Sci Sports Exerc. 32:790-799, 2000.

Brooks, G. A. The lactate shuttle during exercise and recovery. Med Sci Sports Exerc. 18:360-368, 1986.

Brooks G.A., Fahey T.D., White T. Exercise Physiology: Human Bioenergetics and Its Applications. Mt. View, CA: Mayfield Publishing Co., 1985.

Brooks, G.A. Lactate production under fully aerobic conditions. The lactate shuttle during rest and exercise. Fed. Proc. 45: 2924-2929, 1986.

Brooks, G.A. Mammalian fuel utilization during sustained exercise. Comp. Biochem. Physiol. 120: 89-107, 1998.

Brooks, G.A., Mercier J. The balance of carbohydrate and lipid utilization during exercise: the crossover concept (brief review). J. Appl. Physiol. 80: 2253-2261, 1994.

Brooks, G.A. and Trimmer J.K. Glucose kinetics during high-intensity exercise and the crossover concept. J. Appl. Physiol. 80: 1073-1074, 1996.

Consoli, A., N. Nurjhan, J. J. Reilly, Jr., D. M. Bier, and J. E. Gerich. Contribution of liver and skeletal muscle to alanine and lactate metabolism in humans. Am J Physiol. 259:E677-684, 1990.

Donovan, C. M. and G. A. Brooks. Endurance training affects lactate clearance, not lactate production. Am J Physiol. 244:E83-92, 1983.

Dubouchaud, H., G. E. Butterfield, E. E. Wolfel, B. C. Bergman, and G. A. Brooks. Endurance training, expression, and physiology of LDH, MCT1, and MCT4 in human skeletal muscle. Am J Physiol Endocrinol Metab. 278:E571-579, 2000.

Dutka, T.L and G.D. Lamb. Effect of lactate on depolarization-induced Ca2+ release in mechanically skinned skeletal muscle fibers. American Journal of Physiology – Cell Physiology 278: C517-525, 2000.

Hultman E.A. Fuel selection muscle fiber. Proc. Nutr. Soc. 54: 107-121, 1995.

Miller, B. F., J. A. Fattor, K. A. Jacobs, M. A. Horning, F. Navazio, M. I. Lindinger, and G. A. Brooks. Lactate and glucose interactions during rest and exercise in men: effect of exogenous lactate infusion. J Physiol. 544:963-975, 2002.

Miller, B. F., J. A. Fattor, K. A. Jacobs, M. A. Horning, S. H. Suh, F. Navazio, and G. A. Brooks. Metabolic and cardiorespiratory responses to “the lactate clamp “. Am J Physiol Endocrinol Metab. 283:E889-898, 2002.

Nielsen, J. J., M. Mohr, C. Klarskov, M. Kristensen, P. Krustrup, C. Juel, and J. Bangsbo. Effects of high- intensity intermittent training on potassium kinetics and performance in human skeletal muscle. J Physiol. 554:857-870, 2004.

Westerblad, H., D. G. Allen, and J. Lannergren. Muscle fatigue: lactic acid or inorganic phosphate the major cause? News Physiol Sci. 17:17-21, 2002.

Westerblad, H., J. D. Bruton, and J. Lannergren. The effect of intracellular pH on contractile function of intact, single fibres of mouse muscle declines with increasing temperature. J Physiol. 500 ( Pt 1):193-

Zinker B.A., Wilson R.D., Wasserman D.H. Interaction of decreased arterial PO2 and exercise on carbohydrate metabolism in the dog. Am. J. Physiol. 269: E409-E417, 1995.

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First published on: 27 November, 2013 12:00 am

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