Not all performance enhancers are illegal or dangerous. Caffeine is proven to aid athletes by attaching to adenosine receptors in the brain, making hard efforts feel a little easier. The catch is that it doesn't work as well in regular coffee drinkers. Runners in the know wean themselves off coffee at least a week before racing and then pop a caffeine pill about an hour before the starting pistol is fired. Pills are preferable to coffee because they are less likely to necessitate midrace pit stops. The optimal dosage is 1.4 milligrams per pound of body weight. NoDoz and similar products contain 200 milligrams of caffeine per pill – about right for a 145-pound person.