The name Branched Chain Amino Acid, or BCAA, is the name given to the three amino acids leucine, isoleucine, and valine. They are called this due to their tree-branch like structure. These three amino acids are considered "essential" since they cannot by synthesized in your body, and therefore must be acquired through diet and supplementation.
When you look at the composition of human skeletal muscle tissue, about 35% of it is made up of the three BCAAs. These building blocks are essential in building new muscle, aiding in recovery, providing energy, and reducing soreness.
One of the main muscle building properties of BCAAs comes from the impact of leucine on the anabolic pathway mTOR. Without getting too scientific, this pathway basically senses how much leucine is present in your body. When there is a high concentration of leucine, this sensor lets your cells know that there is enough protein available to make new skeletal muscle, stimulating muscle protein synthesis. If the leucine concentration is low, this sensor basically stops muscle protein synthesis until there is enough protein available. Supplementing leucine in the form of BCAAs can help to keep this pathway activated, and keep your body in an anabolic state.
Not only do BCAAs help you pack on more lean muscle mass, they also allow you to keep the muscle mass that you already have. BCAAs are great at preventing muscle breakdown, or catabolism. Simply put, exercise is catabolic. As you exercise, your muscles are broken down for energy. If you supplement BCAAs, they can be used as energy so your body does not need to break down muscle tissue.
While BCAAs are a great way to help add some muscle mass to your frame, they are also incredibly useful when you are cutting down. As you cut calories and get leaner, your body tries to hang on to its body fat stores. This results in muscle tissue being broken down in order to use the amino acids for energy. This is the exact opposite of what we want to happen! When dieting and exercising, not only are you increasing the breakdown of muscle, but also slowing the rate of building new muscle, causing an overall loss in muscle mass.
Supplementing BCAAs while dieting can help to alleviate these issues and allow you to hang on to your hard earned muscle mass. The leucine in BCAA supplements helps your body stay in a muscle building state, so you aren't losing as much muscle mass. Also, the BCAAs can be used as energy while training, so your body does not need to break down muscle tissue. Simply put, the more BCAAs in your system, the less muscle that needs to be broken down for energy.
In addition to helping you maintain muscle mass while dieting, BCAAs can help to give you more energy during intense workouts. While exercising, tryptophan is converted into serotonin in the brain. This increase in serotonin can lead to an increased perception of fatigue. Luckily, BCAAs compete with tryptophan for absorption into the brain, thus reducing the production of serotonin. This can allow you to work out with more intensity, for an extended duration. As we all know, when dieting and training, we'll take every last bit of energy that we can get, and supplementing BCAAs can provide a nice boost.
Many people are skeptical that BCAAs are necessary to supplement. They argue that you can get all of the BCAAs you need from other protein sources, such as meat and whey supplements. While it is possible to get all of your BCAAs this way, it takes a lot longer to get them into your system and working for you. Free form BCAAs do not need to be broken down through digestion in order to get into your bloodstream like other protein sources do. This means that they can get right to work rebuilding muscle, providing energy, and activating muscle protein synthesis.