Questions About BCAAs and Muscle Building

Amino Acids are the products of protein breakdown in the body. There are 20 kinds of amino acids in the human body, of which 8 are essential amino acids that need to be obtained from food. The branched-chain amino acids are three of the eight essential amino acids, namely leucine, isoleucine and valine. They are so named because of the branching structure on the side chain. Branched-chain amino acids also have a "tall" name, BCAA, which is actually the English abbreviation of branched-chain amino acids~

Most amino acids are catabolized in the liver, while branched-chain amino acids are metabolized in skeletal muscle tissue, and are amino acids that are oxidized for energy in muscle tissue. The key enzyme activity of branched-chain Amino Acid metabolism in muscle is strong, which makes branched-chain amino acid metabolism in muscle extremely fast. The branched-chain amino acid metabolism small molecules produced by metabolism not only act on skeletal muscle itself, but also participate in the homeostasis regulation of adipose tissue, cardiac muscle, liver and other tissues.

Compared with other amino acids, these three branched-chain amino acids can be transaminated and completely oxidized at a relatively fast rate, and the efficiency of their oxidation to generate ATP is also higher than that of other amino acids, per molecule of leucine, isoleucine, and valine. Complete oxidation, yielding 42, 43, and 32 molecules of ATP, respectively. During exercise, branched-chain amino acids are oxidized for energy and become an important source of energy for muscles.

The decomposition of branched-chain amino acids in muscles is extremely active, and the process of transamination and oxidation can be completed quickly, and the efficiency of oxidation to generate ATP is much higher than that of other amino acids. At rest, 14% of the total energy consumption of human skeletal muscle is provided by the oxidation process of branched-chain amino acids. When the body is in a state of exercise, the secretion of hormones that promote catabolism in the body increases, the enzymatic activity of oxidatively decomposing branched-chain amino acids, and the energy of skeletal muscle. The utilization efficiency is improved, so that the catabolism of branched-chain amino acids is further strengthened, and it becomes an important energy source for the body during exercise.

The increase of plasma free branched-chain amino acids can improve the absorption and utilization efficiency of the muscles. Timely supplementation of branched-chain amino acids before exercise or during long-term exercise can provide energy supply to the body in time. And the energy supply through branched-chain amino acids can not only avoid the absorption of the liver and be rapidly utilized by the skeletal muscle, but also in the branched-chain amino acids, except for leucine, which is a ketogenic amino acid, the other two amino acids can be used in the process of gluconeogenesis in the liver. Glucose is produced or stored in the form of glycogen, thereby reducing the consumption of glucose and glycogen. From the perspective of energy supply, supplementation of branched-chain amino acids can enhance exercise capacity and prolong exercise time.

A sports nutritionist from a provincial sports team also said that in the training of athletes, a certain amount of branched-chain amino acid supplements are usually given before training.

If you want to gain muscle, it is generally described as reducing protein decomposition, increasing protein synthesis, and realizing that protein synthesis is greater than decomposition.

The three amino acids in branched-chain amino acids have different roles in protein metabolism. Among them, leucine has a greater effect on promoting the synthesis of skeletal muscle protein. First, leucine acts as a substrate for glutamine. Glutamine can not only transport nitrogen, but also be used to synthesize protein, thereby promoting muscle growth.

At the same time, leucine can promote protein synthesis through hormone-dependent and hormone-independent pathways. Hormone dependence mainly means that supplementation of branched-chain amino acids can stimulate protein synthesis by promoting the secretion of insulin and IGF-1. Hormone-independent mainly means that leucine promotes protein synthesis by promoting polypeptide chain synthesis, which can increase the level of leucine tRNA, which is a key substance for protein synthesis.

In addition, β-hydroxy-β-methylbutyric acid (HMβ), a metabolite of leucine, is a regulatory signal for protein synthesis, which can reduce the degree of muscle damage and reduce protein decomposition, and promote a positive nitrogen balance in the body.

When we do high-intensity, fast-paced anaerobic exercise in the gym, the duration is short and we get tired quickly. Numerous studies have found that exercise-induced central fatigue is closely related to the metabolism of certain amino acids, especially the metabolism of aromatic amino acids. Both branched-chain amino acids and aromatic group amino acids are transported across the blood-brain barrier by the same carrier, and aromatic group amino acids and branched-chain amino acids compete for binding to the carrier. For example, tryptophan, as an aromatic amino acid, its metabolite serotonin is an important cause of central fatigue. When the intake of branched-chain amino acids increases, it can competitively inhibit the decomposition of tryptophan, thereby achieving the purpose of delaying fatigue.

Anaerobic metabolism will produce a large amount of lactic acid, and the accumulation of lactic acid will cause local muscle soreness, affect the muscle contraction ability, and then affect the body's exercise ability. Supplementation of branched-chain amino acids can accelerate the recovery of blood sugar after exercise, prevent the sharp drop in blood sugar level after exercise and inhibit the production of lactic acid, reduce the accumulation of lactic acid in skeletal muscle, and delay the generation of fatigue.