The branched-chain amino acids consist of three essential amino acids: leucine, isoleucine and valine. They are considered “essential” because they cannot be synthesized in the body from other amino acids and must be supplied in the diet. From a bodybuilding standpoint, the BCAAs are the primary muscle aminos because they metabolize primarily in muscle. One of them, leucine, turned out to be a major player—perhaps the most important amino acid—in relation to increased muscle protein synthesis. One of the advantages of whey protein supplements is that they contain a large amount of naturally occurring BCAAs—about 26 percent.
Studies of BCAAs pertaining to resistance training, which includes bodybuilding, have yielded variable results. Some identify definite anabolic effects from extra BCAA intake, but others find few or no effects. There is, however, no argument concerning the importance of taking essential amino acids after training. Their effects are so potent that a postworkout dose of a mere six grams is enough to boost muscle protein synthesis.
The BCAAs also appear to lower elevated cortisol during and after intense workouts. Cortisol is a steroid hormone released from the adrenal cortex under conditions of stress, including intense exercise. It is the major catabolic hormone in muscle, since it helps break down muscle amino acids, which are then sent through the blood to the liver, where they are converted into glucose for energy purposes. Your success in making muscle and strength gains depends on having the right balance of anabolic hormones, such as testosterone and growth hormone, and cortisol. When you tip the hormone ratio toward the anabolic side, you make gains.
The primary amino acids in muscle affected by elevated cortisol are the BCAAs and glutamine. The theory is that by increasing your intake of BCAAs and, to a lesser extent, glutamine, you provide the substrates that help preserve muscle aminos, thus creating an anabolic effect in muscle.
One situation in which cortisol is likely to rise is during what exercise physiologists call “overreaching.” That’s a temporary phase of overtraining marked by an increase in training volume, such as the number of sets and reps you do, or a significant increase in intensity, such as working every set to complete muscular failure. The body—more exactly the brain—interprets dramatic changes in training style as increased stress, and the response is a boost in cortisol synthesis and release.
Bodybuilders commonly overreach during precontest training. They go on food restriction, significantly reducing calories and carbohydrates to lower their bodyfat. They also make training changes, which usually involve more volume, frequency and intensity. The idea is to maintain as much previously developed muscle as possible while simultaneously burning bodyfat to the max to achieve more muscular definition. The problem is, unless you’re also using pharmacological assistance, such as anabolic steroids, the increase in training coupled with the decreased food intake and the rise in cortisol that results can quickly develop into a catabolic scenario. So if BCAAs can oppose the negative effects of overreaching, can they help maintain a more anabolic profile under high-stress conditions?
When cortisol rises, it dampens immune response, which can result in an increased risk of opportunistic infections, such as colds and flu. While the body normally has the immune capacity to cope with infections, the high-stress rise in cortisol interferes with that protection. A bodybuilder preparing for a contest cannot afford to be hampered by an illness. Getting the flu, for example, can rapidly cause a catabolic scenario in the body, which must use all its resources to combat the virus that caused the flu. When you restrict food intake and nutrients, the catabolic effect is significantly amplified. If the BCAAs can blunt the effects of cortisol at that time, the immune response to the infection would be enhanced. Or the immune system may be strong enough—without the interference of the cortisol—to curtail the infection before it takes hold.
You still need to know the amount of BCAAs to take for maximum anabolic and protective effects, especially during periods of overreaching or more intense training. Several studies have examined that question. One found that you need a minimum of 20 milligrams of leucine per kilogram of bodyweight. In a 200-pound bodybuilder that would mean a daily minimum dose of 1,800 milligrams of leucine. That figure, however, pertains to someone taking in a normal amount of protein, not someone involved in intense training.
Another study followed 10 previously trained sprinters and jumpers while they trained intensely over a five-week period. The athletes’ resting levels of leucine dropped by 20 percent, isoleucine by 21 percent and valine by 18 percent during the intense training, which points to an increased need for BCAAs under intense training conditions. The athletes’ total serum amino acids dropped by 19 percent, even though they were getting 1.26 grams of protein per kilogram of bodyweight, which is more than the suggested 0.8 grams per kilogram suitable for sedentary people. The suggested requirement for BCAAs under hard training conditions is 60 milligrams of leucine, 50 milligrams of valine and 20 milligrams of isoleucine per kilogram of bodyweight.
A recently published study suggests that you can still derive benefits from smaller doses of BCAAs, particularly in terms of decreased muscle breakdown after training and a rise in anabolic hormones, along with more control of cortisol.1 Eight college-age men who had at least a year of weight-training experience but who hadn’t trained for six months were randomly assigned to either a BCAA group or a placebo group. They took the supplements for three weeks, followed by a fourth week in which they continued taking the supplements but also engaged in an intense training regimen purposely designed to produce overreach. The amino acid supplement used in the study was rich in BCAAs but in amounts significantly less than what previous studies had determined would yield anabolic effects. In addition, the subjects also were not allowed to have more than 0.8 grams of protein per kilogram of bodyweight, the suggested intake for average people.
Despite the modest dose of BCAAs, the subjects who got the supplement had lower cortisol and higher testosterone than those in the placebo group. In addition, creatine kinase, an enzymatic marker of muscle damage, was also significantly reduced when the subjects took BCAAs. These results suggest that even relatively modest doses of BCAAs can have a significant anabolic effect in muscle because of blunted cortisol, with testosterone counts maintained.
The results were limited because there were only eight subjects; still, they suggest that BCAAs may be more potent in some ways than was previously believed. The authors also indicate that the proper dose of BCAAs depends not only on training volume and intensity but also on body size. Larger people need to take more BCAAs to get the same effects as smaller people get with lesser doses.
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1 Sharp, C.P.M., and Pearson, D.R. (2010). Amino acid supplements and recovery from high intensity resistance training. J Stre Cond Res. 24(4):1125-1130.