Amino acids slow muscle breakdown during exercise
BCAAs include the amino acids leucine, isoleucine, and valine, which are found in dairy foods and meat. Some athletes use supplements containing BCAAs to boost strength and endurance.
Past research has found that BCAAs can help prevent muscle breakdown during prolonged exercise, but the exact amount needed to obtain this effect is not clear, Dr. Keitaro Matsumoto of Otsuka Pharmaceutical Company in Saga, Japan and colleagues note.
To identify the most effective dosage, Matsumoto and his team had four men and four women complete three 20-minute cycling sessions, pedaling at half their maximum intensity, with a 15-minute break between each session.
During the first exercise session, volunteers consumed a drink containing 2 grams of BCAAs and 0.5 gram of arginine, or a placebo beverage, 10 minutes into their workout. Arginine is another type of amino acid believed to boost the release of growth hormone and insulin.
Two weeks later, study participants repeated the experiment, and those who originally consumed the BCAA-arginine drink switched to placebo and vice versa.
Blood concentration and muscle absorption of BCAAs rose when the exercisers took the supplement, the researchers found, while muscle protein breakdown was reduced.
The findings suggest that taking BCAA just before exercise can effectively slow the protein break-down triggered by endurance exercise at a modest intensity, Matsumoto and colleagues note. However, they conclude, more research is needed to determine if adding arginine to BCAA will enhance its muscle-protecting effects.
SOURCE: International Journal of Sports Medicine, June 2007.
Copyright © 2007 Reuters Limited.