A leucine metabolite that can help add muscle

July 15, 2010

By Jim Stoppani, PhD


Of all the amino acids that make up protein, leucine has been established as the most anabolic. In recent years, scientists have begun to uncover the muscle-building effects of leucine metabolites, such as KIC and HMB (alpha-ketoisocaproate and beta-hydroxy beta-methylbutyrate, respectively). Now another leucine metabolite, HICA (alpha-hydroxyisocaproic acid), is also showing great promise for its effects on recovery from intensive training.

Leucine is considered to be a potent anabolic agent because it can activate cellular proteins that lead to muscle growth. Once leucine is broken down in muscle tissue, it forms a variety of related compounds (such as KIC and HMB). These compounds have also proven to be popular supplements, because studies have shown that they can decrease muscle breakdown while helping to increase overall strength and muscle mass. HICA, which is formed when leucine is completely broken down, has also been reported to inhibit muscle loss by blocking the action of certain catabolic compounds.

The first study to test the effects of supplemental HICA was performed with competitive wrestlers. Each wrestler was given 1.5 grams per day of HICA during six weeks of heavy training in their sport. By the end of that period, the wrestlers had added about two pounds of muscle to their frames. It may not sound like much, but the results are rather impressive considering that they were training up to five hours per day, a time period during which they would be expected to lose muscle. The wrestlers also reported significantly less post-training workout pain compared to the previous six weeks, when they were not receiving the supplement.

Based on the promising results of the preliminary study in wrestlers, researchers from Finland conducted a second study in soccer players. One group of athletes was given 500 milligrams of HICA three times per day; a second group received a placebo. All of the athletes participated in an intensive training program consisting of four practice sessions, one match and two weight-training workouts each week over four weeks

As reported in the original study, the athletes receiving HICA increased muscle mass — with almost one pound of muscle added to the legs alone. The placebo group lost muscle due to the high volume of training and energy expenditure. Postexercise muscle soreness was also significantly reduced in the HICA group compared to the placebo group. In addition to working by blocking muscle-damaging compounds, it is likely that HICA also worked by being converted back into the anabolic amino leucine.

Both studies used 500 mg of HICA three times per day, which appears to be an effective dose. However, HICA may be hard to find at your local supplement shop — or even online. With news of these studies and the coverage here in FLEX, you can expect that to change soon. In the meantime, be sure you are dosing with plenty of leucinerich branched-chain amino acids. Go with 5-10 g of BCAAs with breakfast, your pre- and postworkout shakes, and your nighttime meal. When HICA becomes more readily available, you can add 500-1,000 mg to your BCAA dosing.