Higher tissue levels of amino acids translate into increased protein synthesis as shown by a number of studies using both oral amino acids and amino acid infusions.1, , , , 2 3 4 5
For example, one study by using femoral arterio-venous catheterization and quadriceps muscle biopsies, measured muscle protein synthesis and breakdown, and amino acid transport during intravenous infusion of an amino acid mixture in young and elderly subjects.6 Peripheral amino acid infusion significantly increased amino acid delivery to the leg, amino acid transport and muscle protein synthesis, independently of the age of the volunteers. Despite no change in protein breakdown during amino acid infusion, a positive net balance of amino acids across the muscle was achieved
For example, one study by using femoral arterio-venous catheterization and quadriceps muscle biopsies, measured muscle protein synthesis and breakdown, and amino acid transport during intravenous infusion of an amino acid mixture in young and elderly subjects.6 Peripheral amino acid infusion significantly increased amino acid delivery to the leg, amino acid transport and muscle protein synthesis, independently of the age of the volunteers. Despite no change in protein breakdown during amino acid infusion, a positive net balance of amino acids across the muscle was achieved