Chapter 37 - An Overview of Branched-Chain Amino Acids in Exercise and Sports Nutrition

Abstract

Protein consumption as well as the effects of isolated amino acids have long been studied for their possible ergogenic effects on skeletal muscle mass and strength. This chapter discusses in detail the role of specific amino acids, namely the branched-chain amino acids (BCAAs), especially leucine, regarding their metabolism, the molecular pathways they activate in skeletal muscle and their physiological effects. Studies regarding the effects of protein and amino acids supplementation on gain of muscle mass and strength are discussed with an emphasis on the activation of key proteins (such as mTOR and p70S6k) that, once phosphorylated, are able to stimulate the initiation of protein synthesis. The effects of different sources of protein, dose and timing and their physiological effects are also discussed. The last section gives practical recommendations regarding amino acid and protein supplementation, their safety, as well as the possible side effects when amino acids are given under specific metabolic conditions.