The ideal metabolic scenario for gaining muscle size and strength is to have the amount of muscle protein synthesis exceed that of muscle catabolism, or breakdown. Various nutrients contribute to protein synthesis, particularly essential amino acids. Of the eight essential amino acids, the most potent in terms of aiding muscle protein synthesis are the branched-chain aminos: leucine, isoleucine and valine. Recent research shows that of the three, leucine appears to be the key amino in that process. One reason that whey protein supplements are so popular is their rich BCAA content, which can comprise more than a quarter of all the amino acids contained in whey.
Other studies suggest that leucine undergoes several metabolic alterations, producing by-products that may be even more potent than leucine. One example is HMB. Beta-hydroxy beta-methylbutyrate is known as a “downstream” metabolite of leucine because it’s produced by two enzyme reactions with leucine.
Several years ago researchers at the University of Iowa found that HMB showed potent effects in spurring muscle gains in animals. They later replicated the initial animal results with human subjects and determined that three grams of HMB per day in divided doses worked the best. As with many exercise science studies, most of the human-based studies of HMB involved untrained college students. Nearly all of them gained muscle and strength after supplementing with HMB. Later studies, however, showed that more advanced trainees didn’t seem to make similar progress when using the same dose as beginners.
Further research found that HMB helped older people retain muscle and also seemed to help those who returned to training after a layoff. Today it’s considered an anticatabolic supplement, although precisely how it works still isn’t clear. In a new study, scientists from Finland looked at another leucine metabolite, known as alpha-hydroxy-isocaproic acid. HICA, like HMB, is a downstream metabolite of leucine, and it’s found naturally in fermented foods, such as cheeses, wines and soy sauce. Isolated-cell studies show that HICA has anticatabolic effects in muscle. For one thing, it inhibits the activity of enzymes that break down muscle and connective tissue.
The Finnish scientists tested HICA on 15 young male soccer players, average age 22.1 The study had a four-week, double-blind design. Players got either a placebo or HICA and underwent an intensive training period that featured both extended soccer practice sessions and weight training one to two times a week. The subjects in the HICA group got 500 milligrams three times a day for a month, while those in the placebo group drank a beverage containing only a carbohydrate. The researchers wanted to see whether HICA would help prevent delayed-onset muscle soreness, the type that peaks a day or two after intense training and usually indicates severe muscle damage.
In a previous unpublished study, the same researchers had found that wrestlers who used HICA had few or no symptoms of muscle soreness, despite engaging in intense training sessions that lasted 1 1/2 to 2 1/2 hours. In the study with soccer players, using HICA increased whole-body lean mass, especially in their legs. While the supplement didn’t spur any increase in performance measures, the athletes using HICA felt much milder muscle soreness than those in the placebo group. They gained more muscle in their legs, the primary muscles involved in both the soccer and the weight training they did. On the other hand, the gain in lean mass was only 400 grams compared to 150 grams in the placebo group. All the athletes were already eating a high-protein diet. That those taking the HICA gained slightly more muscle mass than those in the placebo group suggests that HICA does appear to boost gains beyond what comes from eating a high-protein diet alone. You can bet that HICA will start showing up in supplements aimed at bodybuilders. Since the Finns hold a patent for that purpose, any companies interested in incorporating HICA in their products will have to license it from them.
What about BCAAs themselves—do they also favorably affect muscle soreness after training? That was the focus of another new study.2 Twenty-four untrained men were randomly assigned to either a BCAA group or a placebo group. They all did 12 sets of 10 reps of eccentric knee extensions using a weight equal to 120 percent of one-rep concentric maximum. Eccentric contractions, or negatives, involve a lengthening of muscle, usually by lowering the weight, and are known to be the primary cause of muscle damage and soreness. The subjects took BCAAs 30 minutes before exercise, 1.5 hours after exercise, between lunch and dinner and prior to going to bed. For two days after the workout they took the supplement four times between meals. It contained 3.5 grams of leucine, 2.1 grams of isoleucine and 1.7 grams of valine. The placebo consisted of sweetened water. The total intake of BCAAs was 29.2 grams a day.
As expected, negative muscle contractions caused a loss of muscle function after the workout. Taking BCAAs didn’t prevent that, but it did decrease muscle soreness at 48 and 72 hours after the exercise, when the pain usually peaks. Still, the authors note, it takes large doses for BCAAs to be effective in preventing post-training muscle soreness. They also note that since the subjects were untrained men, the findings may not apply to those who have more training experience. On the other hand, the researchers do suggest that BCAAs may be good for preventing excess muscle soreness in beginners and those returning to training after a layoff.
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1 Mero, A.A., et al. (2010). Effects of alpha-hydroxy-isocaproic acid on body composition, DOMS, and performance in athletes. J Int Soc Sports Nutr. 7:1.
2 Jackman, S.R., et al. (2010). Branched-chain amino acid ingestion can ameliorate soreness from eccentric exercise. Med Sci Sports Exerc. 42(5):962-70.