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Alex "IronDoc" McDonald: Amino Acids Before, During and After Exercise
By Alex M. McDonald, MD
4/13/2009 |
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It has been known for some time that carbohydrates are essential to endurance exercise, before, during and after to main blood glucose levels as well as restore muscle glycogen in order to fuel the next training session. However, more recently Amino Acids (AA), particularly Branch Chain Amino Acids (BCAA), have become a popular nutritional topic. Products from reputable companies, such as Base Performance Nutrition, have began producing powders and supplements that contain amino acids. What exactly are amino acids, what role do they play in nutrition as it pertains to endurance athletics and what does this mean practically for an athlete.
Amino Acids are the building blocks of protein. A protein molecule is a long string of hundreds to thousands of amino acids strung together. The order of amino acids dictate the shape of the protein and as a result, dictates the function of the protein. Many common diseases illustrate the importance of amino acid. For example Cystic Fibrosis, a lethal genetic disease, results from a change in a single amino acid among hundreds which alters the protein just enough so that it is unable to perform its intended function. Lastly, and most interestingly, amino acids are also involved in numerous metabolic pathways that affect exercise metabolism. Branch Chain Amino Acids (BCAAs) are a few amino acids with a specific structure that make them slightly unique in their function.
There are 36 different amino acids, many of which the body can produce on its own by breaking down the nutrients a person's diet (obtained thru various forms of dietary protein), reorganizing it and building the necessary amino acids it requires. However, there are 9 “essential” amino acids that the body is unable to produce and these must be obtained in the diet in order to maintain health. Lastly, there are “conditionally essential” amino acids which the body is able to produce, however, under periods of heavy stress the body’s ability to produce these amino acids is not be able to keep up with demand. As a result, under circumstances of heavy training stress, these amino acids become essential as well and must be obtained in the diet.
The amount of protein an athlete requires has been a popular topic among the scientific community and there is a general consensus that endurance athletes' daily protein requirement is between 0.55-0.73g per pounds of body weight, 1.5-2 times the requirement of the average population. If an athlete does not consume enough protein they could slow tissue growth and/or recovery from training and potentially set themselves up for injury. On the other hand, ingesting more protein than necessary to maintain protein balance during training does not promote greater gains in strength or fat-free mass.
More recently, research has focused on the effects of amino acid and protein consumption in relation to training. Consuming amino acids results in easier digestion and potentially better absorption into the body as compared to whole proteins. As a result, a lot of research focused on consuming protein before and during exercise examines amino acids specifically. There is literature that indicates consuming protein with carbohydrates, before and after exercise, limits muscle damage and increases the body’s ability to repair damage caused by training. In theory this will hasten recovery and allow for training at a higher, more consistent level. This in turn raises the question, can consuming amino acids during exercise help prevent muscle damage and gain any ergonomic advantage?
It is important to keep in mind that metabolism during exercise, particularly prolonged exercise can be very different than at rest and it cannot be surmised that a certain result at rest will also be true while the body is under the demands of exercise. There is some evidence that indicates consuming certain amino acids while exercising results in increased release of growth hormone, which may provide an athletic advantage. Other research has measured lower level of ammonia and creatine kinase (indirect measures of muscle damage) in the blood while consistently consuming certain amino acids while exercising. It was important to note that these changes were only observed if the amino acids were consumed regularly over weeks, not just at a single point in time. At this point it remains unclear if amino acids during training significantly affects body composition, strength, and/or muscle growth.
Branch Chain Amino Acids (BCAA’s) have also been examined in the context of exercise with mixed results; there are two primary theories. The first is similar to the above stated, that consumption of BCAA during exercise decrease muscle damage. There have been several studies which have demonstrated lower perceived soreness after exercise and higher maintained muscle strength after daily training. However, other studies have not supported this information. It should be noted that these studies have not shown that BCAA have any negative consequences on athletics.
The second is slightly more interesting in that it had been hypothesized that BCAA limit the release of hormone and neurotransmitters that may cause feelings of fatigue during exercise. BCAA might also improve physical performance; during exercise in the heat or in a competitive race when the central component of fatigue is assumed to be more pronounced than in a laboratory experiment. However, there are other studies which seem to disprove this theory, indicating that further research is required.
Lastly, BCAA have been shown to have a beneficial effect on the immune system, particularly after heavy and/or intense training. In particular the BCAA Glutamine has been shown to help bolster any hit the immune system takes after heavy training.
The bottom line is that consuming amino acids, which are readily available for absorption, and sufficient dietary protein are an important part of pre and post exercise recovery to keep athletes healthy. Possibly more importantly, adequate protein and amino acids make it possible for an athlete to be able to train consistently day after day, which is where real fitness gains are made. Base Performance Nutrition makes a great blend of an amino acid powder designed to be mixed with a beverage and consumed before, during and/or after training as well as a Recovery Activator supplement with glutamine for post workout. The consumption of amino acids during exercise is a new field of research and there are some indications that this practice can limit muscle damage and may even improve athletic performance. Athletes wishing to consume amino acids during training should begin experimenting with low levels and titrate upwards as their body tolerates.
The field of sports medicine and sports nutrition is vast and new research and evidence is being discovered daily. However, amino acids are not a passing trend and are an important part of the puzzle for athletic success.
Alex M. McDonald, MD is a professional triathlete, coach and a member of the Timex Multisport Team. His interests lie in coaching endurance athletes, sports medicine and exercise physiology. He obtained his MD degree from the University of Vermont. Prior to medical school, Alex graduated from Connecticut College in 2003 with an emphasis on both the biological and social sciences. He currently lives and trains in Durham, NC.
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