Creatine

a nitrogen-containing organic acid prevalent in vertebrate muscle and nerve cells and facilitating cellular energy supply

Description
Creatine occurs in muscle, generally as phosphocreatine, in urine, sometimes as such but generally as creatinine. Urine creatine levels are elevated in muscular dystrophy and other diseases. Documented ergogenic benefits of creatine administration include enhanced performance in all-out exercise of up to 30 seconds' duration and facilitated recovery from repeated bouts of intense exercise.