Another Study on BCAA's

[hotasice2003]

Exercise Promotes BCAA Catabolism: Effects of BCAA Supplementation on Skeletal Muscle during Exercise

Yoshiharu Shimomura, Taro Murakami, Naoya Nakai, Masaru Nagasaki and Robert A. Harris

Abstract
Branched-chain amino acids (BCAAs) are essential amino acids that can be oxidized in skeletal muscle. It is known that BCAA oxidation is promoted by exercise. The mechanism responsible for this phenomenon is attributed to activation of the branched-chain -keto acid dehydrogenase (BCKDH) complex, which catalyzes the second-step reaction of the BCAA catabolic pathway and is the rate-limiting enzyme in the pathway. This enzyme complex is regulated by a phosphorylation-dephosphorylation cycle. The BCKDH kinase is responsible for inactivation of the complex by phosphorylation, and the activity of the kinase is inversely correlated with the activity state of the BCKDH complex, which suggests that the kinase is the primary regulator of the complex. We found recently that administration of ligands for peroxisome proliferator-activated receptor- (PPAR) in rats caused activation of the hepatic BCKDH complex in association with a decrease in the kinase activity, which suggests that promotion of fatty acid oxidation upregulates the BCAA catabolism. Long-chain fatty acids are ligands for PPAR, and the fatty acid oxidation is promoted by several physiological conditions including exercise. These findings suggest that fatty acids may be one of the regulators of BCAA catabolism and that the BCAA requirement is increased by exercise. Furthermore, BCAA supplementation before and after exercise has beneficial effects for decreasing exercise-induced muscle damage and promoting muscle-protein synthesis; this suggests the possibility that BCAAs are a useful supplement in relation to exercise and sports.

http://www.nutrition.org/cgi/content/full/134/6/1583S

[hotasice2003]

© 2006 American Society for Nutrition J. Nutr. 136:538S-543S, February 2006



Amino Acid Mixture Improves Training Efficiency in Athletes1,2

Masaru Ohtani*,3, Masaaki Sugita and Kimiaki Maruyama**

* Sports Science for Health and Activities, Department of Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan; Department of Health and Physical Education, Mie University, Tsu City, Japan; and ** Department of Life Science, Meiji University, Kawasaki, Japan


3 To whom correspondence should be addressed. E-mail: Ohtani@k.u-tokyo.ac.jp .
This review discusses some of the beneficial effects of a dietary amino acid supplement on muscle function, fatigue, and recovery in exercising athletes. The supplement, a mixture of amino acids that included the branched-chain amino acids, arginine and glutamine, was studied chronically at several daily dose levels for extended periods of time (10, 30, and 90 d). Outcome variables included physical measures of muscle strength, fatigue and damage, and blood indices of muscle damage and oxygen-carrying capacity. One beneficial effect of the amino acid supplement was a quicker recovery from the muscle fatigue that followed eccentric exercise training. A dose-response study of the amino acid mixture at 2.2, 4.4, and 6.6 g/d for 1 mo showed that at the highest dose, indices of blood oxygen-carrying capacity were increased and those of muscle damage were decreased at the end of the trial. When the amino acid mixture was given for 90 d to elite rugby players during training at a dose of 7.2 g/d, a blood-component analysis indicated improvements in the oxygen-carrying capacity of the blood. Together, the studies suggest that the amino acid supplement contributed to an improvement in training efficiency through positive effects on muscle integrity and hematopoiesis.