Amino Acids 101: Do they positively affect performance?
Posted March 11th, 2007 at 12:52 PM by Megan Hueter
Section: Nutrition, Supplements
Amino acids are the building blocks of proteins. About two-thirds of a person’s body consists of water, and most of the rest is made of proteins. Proteins are one of the three principal nutrient elements, along with carbohydrates and fats. About 100,000 different kinds of proteins are found in the human body. These proteins are made up of only 20 amino acids, some of which are produced by the body (non-essential amino acids), others of which we have to ingest (essential amino acids). (1)
Amino acids act in various ways. During physical exercise, your body needs energy to do work. Initially, the body uses carbohydrates for energy, and then after a period of time, it resorts to fat. When the body breaks down fats, it goes through a process called the Krebs Cycle, where lactic acid is formed. A buildup of lactic acid makes muscles very fatigued. During prolonged physical activity such as a marathon, if sugars and fats are no longer available for energy, lactic acid builds up in the muscles and stamina declines and the athlete tires very quickly. (1)
Proteins are actually the body’s third energy source;a largely unknown fact. Branched-chain amino acids (BCAAs), including leucine, isoleucine, valine, are available as supplements and even in some advanced sports drinks (ie: Amino Vital Endurance and Pacific Health Lab’s Endurox R4). (1) Companies claim BCAAs boost stamina by preventing the buildup of lactic acid in the muscles. BCAAs also prevent muscle fatigue by controlling the consumption of glycogen. (1) Companies also assert that if an athlete takes in amino acids before and during exercise, then amino acids will used as an energy source, reducing fatigue.
It has been theorized that the intake of BCAAs will make the athlete feel less fatigued by altering levels of serotonin and melanonin, hormones in the brain, which, when released, cause sleepiness. Prolonged exercise in humans causes and increase in tryptophan (an essential amino acid) in the blood. Tryptophan and BCAAs compete for receptors in the blood. BCAA concentrations are disadvantaged because of their use as a metabolic fuel by muscle. Thus, with prolonged exercise, tryptophan is transported to the brain, where it causes a release of serotonin and melatonin, making people feel very tired, often altering a performance. Theorists suggest that ingestion of BCAAs during prolonged exercise will prevent tryptophan from being transported to the brain, and a feeling of fatigue will not occur in the athlete. (7)
Let’s take a look at some of the research behind these claims:
- In 2001, Blomstrand et al. concluded that BCAA supplementation reduces rate of perceived exertion (RPE) and mental fatigue during prolonged exercise and improves cognitive performance after exercise. This study also suggests that in some situations, BCAA supplementation may improve physical performance, such as during exercise in the heat or in actual competitive races where central fatigue may be more pronounced than in laboratory experiments. (2)
- Another study performed in 2004 by Blomstrand et al. looked at the mental and physical effects of BCAAs given to subjects during a marathon. Mental performance was improved when the BCAA supplement was ingested during the race, and the running performance improved for the “slower” runners (3.05-3.30 hours). However, there was no significant effect on the performance of the “faster” runners (<3.05 hours). (3) This shows a positive relationship between BCAA ingestion and performance enhancement for a runner.
- In 2005, the Journal of Nutrition held a symposium entitled, “Branch Chain Amino Acids and Exercise” at the International Society for Sports Nutrition. The symposium addressed how ingestion of amino acids might affect physical performance and influence central and physical fatigue. There was much evidence proposed at the symposium that indicates that amino acids might, in fact, have a positive effect on prolonged exercise. (5)
However, other researchers say that most studies show no effects of BCAA supplementation on performance, such as prevention of fatigue during prolonged exercise. Two recent studies support these conclusions:
- For example, in 2004, Watson et al. reported no beneficial effects of BCAA supplementation consumed before and during prolonged cycling to exhaustion at 50 percent V02max in the heat, on performance time, heart rate, and core or skin temperature. (6) The same year, Cheuvront et al. also reported similar findings with subjects exercising in the heat, noting no significant effect of BCAA supplementation on time-trial performance, cognitive performance, mood, perceived exertion, or perceived thermal comfort. (4)
- Further, in 2005, during an amino acid workshop, Michael Gleeson of the Academy for Nutritional Sciences said:
“No valid scientific evidence supports the commercial claims that orally ingested BCAAs have an anticatabolic effect during and after exercise in humans or that BCAA supplements may accelerate the repair of muscle damage after exercise.” (6)
Does amino acid supplementation work?
Evidence exists on both sides of the argument. Therefore, the only related, sure thing an endurance athlete can do is ensure that he or she ingests the recommended 1.2-1.4 grams of protein per kg each day [values that are about 150-200 percent of the current United States Recommended Dietary Allowances (RDA)]. This amount has been verified and agreed upon by the American College of Sports Medicine, the American Dietetic Association and the Dietitians of Canada in their recent joint position stand on nutrition and athletic performance.
Research sources and for more information:
(1) Aminovital.com. Muscular Nutrition for Peak Performance: An Amino Supplement for the Action in Your Life. Ajinomoto, 2002. Obtained from the World Wide Web at: http://www.aminovital.com/ewhat.html
(2) Blomstrand, E. Amino acids and central fatigue. Amino Acids 20: 25-34, 2001.
(3) Blomstrand E, Hassmen P, & Ekbolm B. (2004) Administration of branched-chain amino acids during sustained exercise — effects on performance and on plasma concentration of some amino acids. European Journal of Applied Physiology 63:2, 83-88.
(4) Cheuvront, S., et al. Branched-chain amino acid supplementation and human performance when hypohydrated in the heat. Journal of Applied Physiology 97:1275-82, 2004.
(5) Fenstrom J, Wolfe R. (2006) Branch-chained amino acids in exercise: Introduction to symposium on branch-chained amino acids in exercise. Journal of Nutrition. American Society for Nutrition. 136: 524S.
(6) Gleeson, Michael. (2005) Interrelationship between Physical Activity and Branched-Chain Amino Acids. 4th Amino Acid Assessment Workshop, The American Society for Nutritional Sciences. The Journal of Nutrition, 135:1591S-1595S.
(7) Institute of Medicine. (1999). The Role of Protein and Amino Acids in Sustaining and Enhancing Performance. Committee on Military Nutrition Research. National Academy Press: Washington, DC. Page 53.
(8) Watson, P., et al. The effect of acute branched-chain amino acid supplementation on prolonged exercise capacity in a warm environment. European Journal of Applied Physiology 93:306-14, 2004.
Photo courtesy of Pacific Health Laboratories.
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Tags: amino acids, amino vital, anticatabolic, BCAA, BCAA supplements, BCCAs, branch chain amino acids, branched chain amino acid, branched chain amino acids, College of Sports Medicine, Dietitians of Canada, energy source, essential amino acids, krebs cycle, lactic acid, lactic acid build up, non essential amino acids, protein, RDA, Recommended Dietary Allowances, supplementation, supplements
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The Final Sprint
Fat does not contribute to lactic acid. http://home.hia.no/~stephens/lacthres.htm
Also, lactic acid does not actually exist in the human body under most conditions including exercise. Lactic acid almost immediately becomes the salt form, lactate. The lactate buffers hydrogen ions and is a useful fuel substrate.
The case for BCAAs seems weak to me; the best evidence supports a role in neurotransmitters and maybe a role in perception of effort. My recommendation (and I am not selling a product) is that BCAAs will not do any harm, but carbohydrate should still be the focus.
March 17th, 2007 at 12:28 amSam,
March 23rd, 2007 at 4:50 pmYou’re right that fat doesn’t produce lactic acid. Mistake on my part. What I meant to say is that it produces citric acid. However, the ACSM does say that endurance athletes need more protein in their diets than regular people. I agree that carbs should be the focus, but I have to agree with the published material that protein definately needs to be supplemented in the diet, especially for competitive endurance athletes.
Am thinking of useing “amino vital”jel product as london marathon race buildup/race day supplement.Have already used it in training with no ill effects but not on race day.Am “ok “standard masters marathoner,any suggestions/advise would be appreciated for next week’s event.
THANK’S,DAVE…
April 16th, 2007 at 7:32 am