Ever wonder what happens inside your muscles following weight training? Resistance training causes stress in the muscle fibers, leading to a breakdown of proteins. In response to this overload, the muscle fibers repair themselves and respond by enlarging, which is called muscle hypertrophy. The fibers enlarge in order to handle the next stressor.

Amino acids are the building blocks of protein. Of the 20 amino acids, only three cannot be manufactured by the body and must be supplied by the diet. These branched-chain amino acids (BCAAs)—leucine, isoleucine, and valine—are essential to protein synthesis and in the prevention of protein degradation. BCAAs assist with muscle recovery by stimulating protein synthesis. In addition, they maintain levels of muscular glycogen, an energy-producing carbohydrate. Though they’re found in all protein-containing foods, the largest amounts of BCAAs are in red meats and dairy products.

BCAAs Improve Muscle Memory

The average person can obtain adequate amounts of BCAAs through a balanced diet. However, individuals who engage in routine strenuous exercise have higher total protein requirements and, therefore, have higher BCAA requirements. This is especially true of strength and endurance athletes. Furthermore, persons who are dieting will often have deficiencies in their protein stores. This is detrimental for the strength athlete who needs to retain muscle mass. BCAA supplements appear to have their greatest efficacy in improving muscle recovery in strength athletes such as weightlifters and bodybuilders, thus allowing greater strength and muscle mass gains. The non-athlete requires 15 to 30 mg of BCAAs per pound of body weight per day. Although the exact requirement for athletes is still being studied, doses averaging 6,000 mg per day have been used in studies.

To achieve maximal effect, BCAAs are typically administered following exercise. There are no reported adverse effects with acute intake of BCAA supplements up to doses of 30,000 mg per day; however, no additional benefits could be supported at these high amounts. BCAA supplementation is not recommended for individuals with amino acid metabolism disorders, for pregnant women, or for those with a history of adverse reactions to components found in supplements. Prolab BCAA Plus, AST Sports Science’s BCAA 4500, and Universal Nutrition BCAA 2000 are among the supplements available that contain adequate supplies of BCAAs in recommended proportions.

Current Research

BCAA supplementation is being studied extensively. It is widely used in burn victims to increase the rate of healing. Because of impaired protein metabolism, patients with severe liver failure are at risk for muscle wasting and brain deterioration. Current studies look promising that BCAAs can improve muscle mass and prevent brain deterioration in patients with advanced-stage liver cirrhosis. It is known that athletes who are engaged in prolonged activity eventually develop increasing levels of serotonin through a complicated enzymatic pathway that includes BCAAs. Because serotonin is a known mood stabilizer, it has been hypothesized that this leads to a feeling of fatigue during prolonged exercise, thus reducing performance. Studies are under way to determine if BCAA supplementation may decrease this effect and improve athletic performance.

Although there are no known adverse interactions with medications, thoroughly read the labels of the BCAA supplement and check with your health-care provider prior to use.

—Marie President, M.D.