by Jim Stoppani, Ph.D. Bodybuilding . com


Longtime followers of mine should be well-versed in the benefits of branched-chain amino acids (BCAAs), which are the three essential aminos leucine, isoleucine, and valine. However, given that different supplements contain different ratios of these three critical aminos, there’s a lot of confusion about which ratio of BCAAs is best. Before we dive into that discussion, here’s a quick branched-chain primer.

BCAAs are called branched-chain amino acids because of their structure. Each one has a forked outcropping that resembles a branch. In addition to being special for their structure, they are also special for numerous other reasons.

BCAAs aid in energy and even fat loss, but the main benefit of BCAAs is their ability to boost muscle growth. After all, that’s the number one goal for most of us. When it comes to building muscle, BCAAs are the most critical amino acids. Of the three, leucine is the MVP. Leucine plays one of the most critical roles in growth signaling.

Leucine acts much like a key to the ignition of a car. The car, in this case, is a muscle cell or fiber. The ignition turns on the process of muscle protein synthesis (MPS), which builds up the muscle protein that leads to more muscle growth. In more “science-y” terms, leucine activates a complex called mTOR, which ramps up muscle protein synthesis and therefore muscle growth.

Research suggests that people who add extra leucine to their post-workout protein and carbs experienced significantly greater muscle protein synthesis than those just getting protein and carbs. Because leucine is so critical for muscle growth, you want to make sure you use a BCAA product that has more leucine than its counterparts, isoleucine and valine.

I recommend you go with a BCAA product that uses a 2:1:1 ratio of leucine to isoleucine and valine. Many products bump up the ratio much higher in favor of leucine, with some coming in at an 8:1:1 ratio and some hitting a 10:1:1 ratio. Many people assume that, given leucine’s critical role in muscle growth, a BCAA product with a 10:1:1 ratio is five times better than one with a 2:1:1 ratio. But, before you go spend your hard-earned cash on these supposedly superior BCAA products, hear me out.

The most critical time to take BCAAs is around your workouts, whether you take them before, during, or after. (And yes, that’s in addition to the BCAA-rich protein shake you should also be drinking.) One reason for this is that you want ample leucine to instigate muscle protein synthesis. It’s this fact that leads many people to assume that the highest ratio is best.

Some products even suggest you should forego the other two BCAAs and just take leucine. That is a big mistake. To back it up, one study pitted leucine by itself against all three BCAAs in a 2:1:1 ratio. Scientists from Baylor University gave college-aged men either a leucine supplement, a 2:1:1 BCAA supplement, or a placebo before and after a leg workout. They discovered that while leucine increased MPS after the workout better than the placebo did, the BCAAs increased protein synthesis even better than leucine and the placebo. That’s one reason for sticking with a 2:1:1 ratio (or something close to it) when supplementing with BCAAs.

Another reason to use a 2:1:1 BCAA supplement is to increase energy and lessen fatigue. BCAAs are used directly by muscle fibers as a fuel source. This is especially true during intense exercise, such as weight training. Numerous studies suggest that supplementing with BCAAs before exercise promotes muscle endurance. More importantly, the BCAAs help reduce fatigue during workouts. And this comes down to the role that valine plays in the body.

During exercise, tryptophan is taken up by the brain in large amounts. Tryptophan is converted in the brain to 5-hydroxytryptamine (5-HT), better known as serotonin. Having higher serotonin levels during exercise signals the brain that the body is fatigued. This leads to a reduction in muscle strength and endurance. Valine competes with tryptophan for entry into the brain. Typically, valine wins.

This means that when you take the BCAA valine before and/or during workouts, less tryptophan gets into the brain to get converted to serotonin. This allows your muscles to contract with more force for a longer time before getting fatigued. In other words, you can crank out more reps in the gym, recover quicker between sets, and maintain better strength and endurance in the later portion of your workouts. Valine can also help you to stay more alert and keep your brain sharper during the day when you aren’t working out.

For these reasons, I recommend sticking to a 2:1:1 ratio of leucine to isoleucine and valine when supplementing with BCAAs before, during, and/or after training.

If you are interested in maximizing fat loss, there’s yet another reason why a 2:1:1 ratio is best. This is where the BCAA isoleucine comes in. Isoleucine appears to play a major role in providing BCAAs their fat-burning benefits.

Japanese researchers discovered that mice given isoleucine while eating a high-fat diet gained significantly less fat than mice not getting supplemental isoleucine. This was due to isoleucine’s ability to activate special receptors, known as PPAR, that increase fat-burning and inhibit fat storage. PPAR works to increase the activity of genes that encourage greater fat-burning in the body while decreasing activity of genes that normally increase fat storage. This leads to a greater ability to burn fat with less chance of storing it.

It turns out that using a BCAA supplement that has a much ratio higher than 2:1:1 can work against you for energy, fat loss, and even muscle growth. Some high-ratio BCAA products provide only 500 mg or less of valine and isoleucine. Steer clear of these. That amount is not enough to keep you energized and blunt fatigue during your workouts. It may not be enough to maximize muscle protein synthesis and the resulting muscle growth.

My advice is to stick with BCAA products that use a 2:1:1 ratio providing at least 1 gram of isoleucine and 1 gram of valine per dose. But, if you’re looking for optimal gains, your best bet is to get in at least 3 grams of leucine per dose. It’s the suggested minimum amount you need to optimize mTOR activation and maximize muscle protein synthesis.

I recommend you take in 5 g of BCAAs at a 2:1:1 ratio (so you get 3 g leucine, and over 1 g of isoleucine and valine) about 30 minutes before your workouts.

Follow that workout with another dose of at least 5 g of BCAAs. Here again, a 2:1:1 ratio is good. Even a 3:1:1 ratio, which will give you a bit more post-workout leucine to initiate protein synthesis, will work well. Just be sure that you’re getting at least 1 g of isoleucine valine after your workouts, along with at least 3 g of leucine.

Keep in mind that this should be in addition to pre- and post-workout shakes, or one large protein shake that you sip on before, during, and after the workout. This will bump your BCAA content up a bit, but don’t worry: You still need those free BCAAs from a BCAA supplement to truly maximize energy and muscle growth.

Stoppani, J., et al., Consuming branched-chain amino acid supplement during a resistance training program increases lean mass, muscle strength and fat loss. Journal of the International Society of Sports Nutrition 2009, 6(Suppl 1):P1, 2009.

Anthony, J. C., Yoshizawa, F., Anthony, T. G., Vary, T. C., Jefferson, L. S., & Kimball, S. R. (2000) Leucine stimulates translation inititation in skeletal muscle of postabsorptive rats via a rapamycin-sensitive pathway. J. Nutr. 130: 2413-2419.

Crozier, S. J., Kimball, S.R., Emmert, S. W., Anthony, J. C., & Jefferson, L.S. (2005) Oral leucine administration stimulates protein synthesis in rat skeletal muscle. J. Nutr. 135: 376-382.

Crowe, M. J., et al. Effects of dietary leucine supplementation on exercise performance. Eur J Appl Physiol. 2006 Aug;97(6):664-72.

Bolster, D. R., Crozier, S. J., Kimball, S. R., & Jefferson, L. S. (2002) AMP-activated protein kinase suppresses protein synthesis in rat skeletal muscle through down-regulated mammalian target of rapamycin (mTOR) signaling. J. Biol. Chem. 277: 23977-23980.

Koopman R, Wagenmakers AJ, Manders RJ, Zorenc AH, Senden JM, Gorselink M, Keizer HA, van Loon LJ. (2005) Combined ingestion of protein and free leucine with carbohydrate increases postexercise muscle protein synthesis in vivo in male subjects. Am. J. Physiol. Endocrinol. Metab. 288(4): E645-653.

Coburn, J. W., et al. Effects of leucine and whey protein supplementation during eight weeks of unilateral resistance training. J Strength Cond Res 2006 May;20(2):284-91.

La Bounty, P., et al., The effects of oral BCAAs and leucine supplementation combined with an acute lower-body resistance exercise on mTOR and 4E-BP1 activation in humans: preliminary findings. Journal of the International Society of Sports Nutrition, 5(Suppl 1):P21, 2008.

De Lorenzo, A., et al. Effect of acute and chronic branched-chain amino acids on energy metabolism and muscle performance.Diabetes Nutr Metab. 2003 Oct-Dec;16(5-6):291-7.

Blomstrand E.A role for branched-chain amino acids in reducing central fatigue. J Nutr. 2006 Feb;136(2):544S-547S.

Gomez-Merino, D., et al. Evidence that the branched-chain amino acid L-valine prevents exercise-induced release of 5-HT in rat hippocampus. Int J Sports Med. 2001 Jul;22(5):317-22.

Paddon-Jones, D., et al. Amino acid ingestion improves muscle protein synthesis in the young and elderly. Am J Physiol Endocrinol Metab. 2004 Mar;286(3):E321-8.

Tipton, K. D., et al. Postexercise net protein synthesis in human muscle from orally administered amino acids. Am J Physiol. 1999 Apr;276(4 Pt 1):E628-34.

Mourier, A., et al. Combined effects of caloric restriction and branched-chain amino acid supplementation on body composition and exercise performance in elite wrestlers. Int J Sports Med 1997 Jan;18(1):47-55.

Cota, D., et al. Hypothalamic mTOR signaling regulates food intake. Science. 2006 May 12;312(5775):927-30.

Donato, J., et al. Effects of leucine supplementation on the body composition and protein status of rats submitted to food restriction. Nutrition 22(5):520-527, 2006.

Nishimura, J., et al. “Isoleucine Prevents the Accumulation of Tissue Triglycerides and Upregulates the Expression of PPAR{alpha} and Uncoupling Protein in Diet-Induced Obese Mice.” J. Nutr., March 2010, in press.

Source: http://www.bodybuilding.com/fun/ask-…-of-bcaas.html


Be Sociable, Share!

Leave a Reply

* Copy This Password *

* Type Or Paste Password Here *