The role of amino acids in skeletal muscle health and sarcopenia: A narrative review.

The skeletal muscle is the largest organ present in the body and is responsible for mechanical activities like maintaining posture, movement, respiratory function, and support for the health and functioning of other systems of the body. Skeletal muscle atrophy is a condition characterized by a reduction in muscle size, strength, and activity, which leads to an increased dependency on others for movement, an increased risk of falls, and a reduced quality of life. Various conditions like osteoarthritis, osteoporosis, and fractures are directly associated with increased muscle atrophy. Additionally, numerous risk factors, like aging, malnutrition, physical inactivity, and certain disease conditions, through distinct pathways, negatively affect skeletal muscle health and lead to muscle atrophy. Among various determinants of overall muscle health, the rate of muscle protein synthesis and degradation is an important parameter that eventually alters the fate of overall muscle health. In conditions of excessive skeletal muscle atrophy, including sarcopenia, the rate of muscle protein degradation usually exceeds the rate of protein synthesis. The availability of amino acids in the systemic circulation is a crucial step in muscle protein synthesis. The current review aims to consolidate the existing evidence on amino acids, highlight their mechanisms of action, and assess their roles and effectiveness in enhancing skeletal muscle health.