an amino acid that does not occur in proteins but is found in the muscle tissue of vertebrates both in the free form and as phosphocreatine; supplies energy for muscle contraction
"After adding creatine to his post-workout shake, he felt a noticeable boost in strength during his next set."
An amino acid, 2-(carbamimidoyl-methyl- amino)acetic acid, which naturally occurs in vertebrates and helps to supply energy to muscle and nerve cells.
"After the doctor explained that creatine is an amino acid found in our bodies that boosts energy for muscles and nerves, I decided to add a supplement to my daily routine before my intense workout."