In one study, 155 women with sarcopenia, aged at least 75, either took an amino acid supplement with or without exercise, only exercised, or only received health education.
The amino acid supplement contained 1,260 mg of leucine, 420 mg of lysine, 315 mg each of valine, isoleucine and threonine, 210 mg of phenylalanine, and 165 mg of other amino acids, twice per day.
After three months, while the health-education group had not improved, all three other groups could walk faster compared to the start of the study.
The two exercise groups—with and without amino acid supplementation—had greater muscle mass. But only the amino acid-exercise group also increased knee-extension muscle strength.