If you have stepped into a gym, you have probably heard the rattling of cup shakers and seen fatigued people slamming down a concoction of drinks. Chances are likely they are drinking a supplement containing branched-chain amino acids.
Also shortened to BCAAs, branched-chain amino acids are special amino acids denoted for their “branched-chain” chemical structure: leucine, isoleucine, and valine.
Here’s a closer look at what BCAAs have to offer and why they’re so popular among athletes and bodybuilders.
Why Drink BCAAs?
A more appropriate question would be, “Why wouldn’t you drink them?”
Unlike other essential amino acids, branched-chain amino acids are “oxidized primarily in the skeletal muscle.” This means they are more readily available to directly and indirectly improve physical performance.
Exercise triggers BCAA catabolism. Consequently, researchers believe BCAA requirements may be higher in physically active individuals.
One cross-over study administered a mixture containing 5 g BCAAs to several young, healthy female and male test subjects. The subjects were unaccustomed to regular exercise and underwent compound leg exercises to fatigue over several weeks.
For female test subjects, muscle soreness was higher on day 2 and day 3 during the placebo trial. However, after supplementing with the BCAA mixture, subjects reported peak soreness only occurred on day 2 and “was significantly lower than that which occurred following the placebo trial.” Researchers note delayed onset muscle soreness (DOMS) occurring during days 3-5 in female subjects was markedly lower during the BCAA trial.
For male test subjects, DOMS also peaked on day 2 and was generally lower in the BCAA trial but failed to reach statistical significance. Researchers believe this is because the male test subjects’ body mass required more BCAAs. However, it is said muscle soreness during a certain 5-day period was lower in both sexes during the BCAA trial compared to the placebo.
Speed Protein Metabolism
Although all branched-chain amino acids are beneficial to exercise and performance, leucine often steals the show. Leucine is special in its ability to promote muscle protein synthesis. This optimized synthesis results in more muscle fibers and stronger muscles.
Studies show leucine amplifies protein synthesis by optimizing protein activity involved in mRNA translation.
Leucine is considered unique in its metabolic regulatory roles. However, its benefits are most noticeable in the absence of the branched-chain aminotransferase (BCAT) enzyme because leucine’s skeletal muscle benefits are buffered by this enzyme.
Branched-chain amino acid use isn’t limited to the gym. Although more research is required to confirm findings and efficacy, branched chain amino acids are studied for their ability to improve mood and mania.
In one study, 25 subjects with mania were given 60 g BCAA or a placebo over a 7-day period. Results show the BCAA mixture led to lower mania ratings in the first 6 hours of treatment. The study says a “persistent advantage” resulted from BCAA supplementation.
Boost Immune System
Because exercise is physically demanding on muscles and central nervous system, athletes often are subject to increased sickness and infection. These facts may all influence glutamine levels, an amino acid known for its immune function benefits. Glutamine levels fall as a result of prolonged exercise and high intensity workouts.
BCAAS are considered nitrogen donors for glutamine synthesis. Research reveals 6 g BCAA for 2-4 weeks and an additional 3 g dose 30 minutes before a long-distance run “prevented the 24% fall in the plasma glutamine concentration observed in the placebo group.” The BCAA dose also modified immune response to exercise.
Increase Power Output
Once again, leucine outshines its counterparts and has been shown in a clinical study to influence power output.
Untrained men were given 4 g isolated leucine while undergoing a workout program over a 12-week period. Researchers noted the test subjects experienced greater power output from the leucine group without notably influencing lean mass or fat mass. The untrained participants who supplemented leucine “demonstrated significantly higher gains in total 5-RM strength… and 5-RM strength in 5 out of 8 exercises.”
Look For the Ratio
A generally accepted and studied BCAA dose for improving muscle fatigue and promoting protein synthesis is formulated in a 2:1:1 ratio (leucine: Isoleucine: valine). However, this doesn’t necessarily mean other ratios are ineffective, just unstudied. Most BCAA sports supplements adhere to this ratio, so it shouldn’t be hard to find an affordable product that suits your needs.
-  Yoshiharu Shimomura, et al. “Nutraceutical Effects of Branched-Chain Amino Acids on Skeletal Muscle.” J. Nutr. February 2006 vol. 136 no. 2 529S-532S
-  Anthony JC, et al. “Signaling pathways involved in translational control of protein synthesis in skeletal muscle by leucine.” J Nutr. 2001 Mar;131(3):856S-860S.
-  Layne E. Norton and Donald K. Layman. “Leucine Regulations Translation Initiation of Protein Synthesis in Skeletal Muscle after Exercise.” J. Nutr. February 2006vol. 136 no. 2 533S-537S
-  Scarna A, et al. “Effects of a branched-chain amino acid drink in mania.” Br J Psychiatry. 2003 Mar;182:210-3.
-  Walsh NP, et al. “Glutamine, exercise and immune function. Links and possible mechanisms.” Sports Med. 1998 Sep;26(3):177-91.
-  Bassit, R. A., Sawada, L. A., Bacurau, R. F., Navarro, F., Martins, E., Jr, Santos, R. V., Caperuto, E. C., Rogeri, P. & Costa Rosa, L. F. (2002) Branched-chain amino acid supplementation and the immune response of long-distance athletes. Nutrition 18:376-379
-  Ispoglou T, et al. “Daily L-leucine supplementation in novice trainees during a 12-week weight training program.” Int J Sports Physiol Perform. 2011 Mar;6(1):38-50.
-  Yoshiharu Shimomura, et al. “Exercise Promotes BCAA Catabolism: Effects of BCAA Supplementation on Skeletal Muscle during Exercise.” J. Nutr. June 1, 2004 vol. 134 no. 6 1583S-1587S