Often called the building blocks of protein, amino acids play a critical role in the development and maintenance of human cells, all of which contain varying amounts of protein. Amino acids fall into two categories: essential and nonessential. The human body cannot synthesize the former, which must be supplied through dietary intake, while the latter can be produced within the body. Amino acids and the proteins they form help to build and maintain muscle tissue.
Identification
Essential amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, tryptophan and valine, according to the Reference Guide for Amino Acids. Of these, isoleucine, leucine, methionine and valine play the most significant role in the promotion of muscle growth and the prevention of muscle loss during times of physiological stress. Alanine, arginine, aspartic acid, cysteine, cystine, glutamic acid, glutamine, glycine, ornithine, proline, serine, taurine and tyrosine all fall into the category of nonessential amino acids that the body can synthesize through essential amino acids or the breakdown of proteins, according to MedlinePlus. Most of the nonessential amino acids work in combination with their essential cousins to promote muscle tissue development.
Food Sources
The essential amino acids -- those you must supply through dietary intake -- occur naturally in most protein-rich foods, as well as some plant-based foods. Good food sources include certain meats, eggs, cheese, milk, grains, vegetables and nuts, according to MedlinePlus.
Features
Three essential amino acids --- isoleucine, leucine and valine --- make particularly significant contributions to the promotion of new muscle tissue growth and the protection of existing muscle tissue. Because of their chemical structure, these three are called branched-chain amino acids, or BCAAs. They speed muscle recovery after the stress of strenuous exercise, according to VitaminStuff.com. Although all three convert to glucose, essential for energy, leucine makes the transformation most rapidly, helping to prevent the body's cannibalization of muscle tissue for energy.
Key to Muscle Growth
In "Men's Health TNT Diet," authors Jeff Volek and Adam Campbell contend that the key to muscle growth is storing new protein faster than the body breaks down existing protein. This can be accomplished by slowing the rate at which protein is being broken down, increasing protein synthesis or, ideally, both. One of the best ways to stoke the body's synthesis of protein is to keep blood levels of amino acids elevated, either through consumption of foods rich in amino acids or supplements.
Supplements and Timing
Bodybuilders and others interested in the promotion of rapid muscle growth often use amino acid supplements, which are widely available in health food stores and fitness centers. However, not all consumers know that timing is key to maximizing the benefits that such supplements provide. In a study published in the February 2000 issue of the "Journal of Applied Physiology," a team of University of Texas researchers found that the greatest benefit could be achieved when such supplements were taken 1 to 3 hours after a resistance training session. In their conclusion, they said that taking 6 g of essential amino acids along with carbohydrate increases muscle protein synthesis, thus promoting muscle anabolism.
References
- Reference Guide for Amino Acids: Amino Acids Overview
- MedlinePlus: Amino Acids
- VitaminStuff: Leucine
- "Men's Health TNT Diet"; Jeff Volek and Adam Campbell; 2008
- "Journal of Applied Physiology"; An Oral Essential Amino Acid-Carbohydrate Supplement Enhances Muscle Protein Anabolism After Resistance Exercise; Blake B. Rasmussen, et al.; February 2000
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