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Amino acids are the building blocks of protein. Of these, nine are considered essential. When a substance is said to be essential for the body it means without it you will die. Essential amino acids therefore are ones we cannot survive without. Likewise essential fatty acids are necessary for us to thrive.
Of the essential amino acids, three account for as much as 33% of muscle tissue:
Leucine: The amino acid leucine is the king of stimulating muscle protein synthesis! Leucine is one of the three branched chain amino acids (BCAAs), and is unique in its ability to stimulate skeletal muscle protein synthesis. In fact, leucine has a several fold greater impact on protein synthesis than any other amino!
Isoleucine: Isoleucine is an amino acid that is best known for its ability to increase endurance and help heal and repair muscle tissue and encourage clotting at the site of injury. This amino acid is especially important to serious athletes and body builders because its primary function in the body is to boost energy and help the body recover from strenuous physical activity.
Valine: Valine is a branched-chain amino acid (BCAA) that works with the other two BCAAs, isoleucine and leucine, to promote normal growth, repair tissues, regulate blood sugar, and provide the body with energy. Valine helps stimulate the central nervous system, and is needed for proper mental functioning.
Effects on Endurance Exercise
A well-known study showed BCAA supplementation worked to increase lactate threshold and exercise endurance. But it should also be noted these trials were not conducted solely on BCAA supplementation, but on BCAAs as well as a 4% carbohydrate solution. While an increase in lactate threshold was clear, no actual increase on performance came about in a controlled time trial!
But, just to throw a spanner in the works, other researchers found that a 3% carbohydrate and 1.2% BCAA drink significantly changed exercise performance, despite containing lower total calories and caloric content.
In further studies the researchers found that with carbohydrate supplementation alone the subjects were able to cover more distance in a controlled time trial, whereas there was no difference at all between distances covered in BCAA supplementation versus a placebo. However, the rate of perceived exertion did drop in the BCAA group, but no aerobic performance increase could be detected.
Resistance Training and BCAAs
When it came to resistance training, however, things were substantially different. Researchers found significant increases of testosterone levels in BCAA supplemented trainees following resistance training. These studies concluded that short-term BCAA supplementation may produce a net anabolic hormonal profile change – precisely what you’re after if you lift weights.