Branched-Chain Amino Acid Plus Glucose Supplement Reduces Exercise-Induced Delayed Onset Muscle Soreness in College-Age Females

Supplementation with branched-chain amino acids (BCAAs) has been used to stimulate muscle protein synthesis following exercise. The purpose of this study was to determine if supplementation with BCAAs in combination with glucose would reduce exercise-induced delayed onset muscle soreness (DOMS). Using a double-blind crossover design, 20 subjects (11 females, 9 males) were randomly assigned to either BCAA ( ) or placebo ( ) groups. Subjects performed a squatting exercise to elicit DOMS and rated their muscle soreness every 24 hours for four days following exercise while continuing to consume the BCAA or placebo. Following a three-week recovery period, subjects returned and received the alternate BCAA or placebo treatment, repeating the same exercise and DOMS rating protocol for the next four days. BCAA supplementation in female subjects resulted in a significant decrease in DOMS versus placebo at 24 hours following exercise ( ). No significant effect of BCAA supplementation versus placebo was noted in male subjects nor when male and female results were analyzed together. This gender difference may be related to dose per body weight differences between male and female subjects. 1. Introduction The-branched-chain-amino-acids-(BCAAs)-leucine, isoleucine, and valine are three of the nine amino acids that are essential for human protein synthesis. The BCAAs are similar in structure and are catabolized via the same metabolic pathway, resulting in breakdown products that feed directly into the Krebs cycle to resynthesize adenosine triphosphate (ATP) [1]. The BCAAs account for 35% of the essential amino acids found in skeletal muscle protein [2]. During exercise, skeletal muscle mitochondria will metabolize BCAAs through a two-step process. The first involves the transamination of the BCAA to an alpha-keto acid by the enzyme branched-chain amino transferase (BCAT). The BCAAs in the alpha-keto acid form remain in the tissue amino acid pool. From there, these alpha-keto acids can either be further catabolized by branched-chain alpha-keto acid dehydrogenase (BCKD) to form products which feed into the Krebs cycle or are used to resynthesize muscle protein [3]. The BCKD complex is thought to be the rate-limiting step in BCAA catabolism and is activated through dephosphorylation [1]. However, BCKD activity is relatively low in skeletal muscle due to increased activity of a BCKD-kinase deactivating enzyme in this tissue. Therefore, the BCAAs that are catabolized to alpha-keto acids during exercise are preferentially used to resynthesize skeletal muscle protein