Creatine

Acording to science, creatine supplementation can be of benefit to power athletes, but not to endurance athletes.

For a normal person (someone not doing intense workouts) they can increase the creatine stored in muscles by 20% through supplementation, where after a few days of supplement it gets passed out in the urine.

Clearly then, creatine is of benefit in recovery after very intense workouts, where creatine has been depleted.

In addition, supplementation with 20g of creatine for 5 days before high intensity workouts showed an improvement in scientific studies. Interestingly it was noted that taking caffeine negated the benefits of the creatine supplementation.