Interrelationship between physical activity and branched-chain amino acids.

Entrez PubMed: "Gleeson M.

School of Sport and Exercise Sciences, Loughborough University, Leicestershire, England, UK. m.gleeson@iboro.ac.uk

Some athletes can have quite high intakes of branched-chain amino acids (BCAAs) because of their high energy and protein intakes and also because they consume protein supplements, solutions of protein hydrolysates, and free amino acids. The requirement for protein may actually be higher in endurance athletes than in sedentary individuals because some amino acids, including the BCAAs, are oxidized in increased amounts during exercise compared with rest, and they must therefore be replenished by the diet. In the late 1970s, BCAAs were suggested to be the third fuel for skeletal muscle after carbohydrate and fat. However, the majority of later studies, using various exercise and treatment designs and several forms of administration of BCAAs (infusion, oral, and with and without carbohydrates), have failed to find a performance-enhancing effect. No valid scientific evidence supports the commercial claims that orally ingested BCAAs have an anticatabolic effect during and after exercise in humans or that BCAA supplements may accelerate the repair of muscle damage after exercise. The recommended protein intakes for athletes (1.2 to 1.8 g . kg body mass(-1) . d(-1)) do not seem to be harmful. Acute intakes o"

It's interesting to see that they found no scinetific support of the fact that BCAAs are strongly anti-catabolic due to the simple reason that they are very easily utilized as a source of energy. As a natural bodybuilder I know from a personal experience that it's absolutely worth taking those especially during the precontest dieting period while deficient on calories as they really do a great job in supplying the muscle tissue with the critically needed calories and spare it from being used for energy itself. So, since it works for me I am not really convinced that BCAAs don't do the job. I will continue to take them as this is a must in the sport of natural bodybuilding.