Administering an amino acid-containing composition, containing the following amino acids (1)-(9), whereinthe molar content ratio of each amino acid to the total content of the amino acids (1)-(9) falls within the following numerical ranges:(1) leucine 35-66%；(2) isoleucine 5.0-15%；(3) valine 5.0-15%；(4) threonine 7.0-14%；(5) lysine 8.0-16%；(6) methionine 2.0-10%；(7) histidine 0.1-3.5%；(8) phenylalanine 2.5-8.0%； and(9) tryptophan 0.1-2.0%,is effective for enhancing recovery from muscle fatigue.
