Influence of Exercise on Protein and Amino Acid Metabolism

Abstract

The sections in this article are: General Aspects of Amino Acid and Protein Metabolism in Muscle Amino Acid Transport and the Free Amino Acid Pool Outline of the Metabolism of Amino Acids in Muscle in Relation to Exercise Interrelationship of BCAA , Alanine, and Glutamine Metabolism The Purine Nucleotide Cycle in Muscle Amino Acid Catabolism and Gluconeogenesis from Amino Acids in Liver and Kidney Training Effects on the Capacities of Muscle Enzymes of Amino Acid Metabolism The Effects of Contractile Activity on Ammonia Production and its Relation to the Free Amino Acid Pool Alterations of Muscle and Blood Amino Acid Concentrations during Exercise Production and Consumption of Amino Acids by Muscle during Exercise Effects of Training on Amino Acid Metabolism during Exercise Interrelationships between Working Muscle and the Viscera during Exercise Protein Turnover During Exercise Effects of Acute Contractile Activity on Protein Turnover Postexercise Alterations in Muscle Protein Synthesis Effects of Habitual Exercise on Whole‐Body Protein Turnover Effects of Immobilization and Disuse Collagen Turnover in Muscle Physical Activity and Protein Requirements Outstanding Questions

Effects of protein and amino acid supplementation on muscle protein metabolism in relation to exercise

“…As described above, protein and amino acid breakdown is promoted during exercise. It has been confirmed that muscle protein synthesis increases during the resting recovery period after exercise 4,41) , and that this increased protein synthesis lasts for at least 2 days after exercise 41,42) . This suggests that nutrient intake after exercise should effectively increase protein synthesis.…”

“…Furthermore, muscle contains 3-5 g of free amino acids, which play an active role in protein metabolism 4,5) . Therefore, proteins and amino acids are very important nutrients to sustain or increase skeletal muscle mass in humans.…”

“…There are 3 major protease systems in muscles: 1) the lysosome system, 2) the ATP-dependent ubiquitinproteasome system, and 3) the Ca 2+ -dependent protease system 4) . Among these systems, the lysosome system is known to be activated by acute exercise.…”

“…1). Numerous types of amino acids, in excess, are catabolized in the liver, whereas some amino acids (Leu, Ile, Val, Ala, Asp and Glu) can be directly oxidized for energy production in muscles 4,5) . Branched-chain amino acids (BCAAs: Leu, Ile and Val) are typical amino acids that are catabolized in muscles, but not the liver, and Ala and Glu (particularly Glu/Gln) act as transporters of amino groups from the muscles to liver.…”

“…It is generally recognized that protein requirements increase with intensive exercise, although there is no consensus. However, as intensive exercise promotes protein and amino acid breakdown during exercise and protein synthesis after exercise, it is recommended that athletes increase protein intake by 1.5 to 2-fold during intensive exercise training periods 4,8) .…”