But the improvement in the male swimmers' speed became apparent only after almost two weeks of taking creatine. The body uses phosphocreatine during high-intensity exercise, when the muscles need a quick burst of energy. Phosphocreatine restores ATP, a compound that serves as fuel for muscles. Creatine and its derivative, phosphocreatine, occur naturally in the human body. Phosphocreatine is a high-energy compound necessary for muscle contraction.
Some people take synthetic forms of creatine in hopes of enhancing muscle performance.
After it is ingested, stores of both creatine and phosphocreatine in the muscle can increase. The study appeared in a recent issue of the International Journal of Sport Nutrition . Leenders and her colleagues evaluated the performance of 18 men and 14 women who were members of Ohio State's swim team. Half of the men and half of the women took creatine. Each athlete who took creatine was paired with a swimmer of the same gender who received a placebo.