An amino acid composition comprises alanine, arginine, aspartic acid, glutamic acid, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, and glutamine. The amino acid composition of the present invention has such an effect that it can improve the action of promoting the process wherein the body fat is converted into the energy required for the physical exercise during and/or after the anoxic motions performed under an extremely high load.