Creatine occurs naturally in the body, helping to supply energy to working muscles, particularly initiating movements and activities of short durations. About half of this compound is made from other amoino acids, the same building blocks for protein, and the other half is from what you eat (i.e. vegetarian athletes should definitely be supplementing their diet!). About 95% of creatine is stored in skeletal muscle.
While creatine can have little to no effect in single effort work (1 repetition of a sprint or lift), the real value occurs in the ability to repeat these movements at high intensity. Therefore, it won’t necessarily make you faster on 1 run or jump, but your ability to run fast or jump high on your 10th rep would be improved.
While myths abound about the safety of creatine, it has been proven safe over and over again, even being prescribed to patients with diseases ranging from Parkinson’s to muscular dystrophy. There are claims that creatine users are more susceptible to cramps, muscle spasms, and even pulled muscles. However, a 3 year study showed creatine had no effect on the incidence of injury or cramping.