Stimulants is a generic term used to describe various substances that are ingested by athletes into the human body for the purpose of increasing alertness or general physical performance. Common stimulants that have been typically utilized by athletes in various disciplines are caffeine, amphetamines (including benzedrine, ephedrine and methamphetamine), and cocaine in its various forms.

Stimulants may be legally prescribed by a physician to counter medical conditions such as narcolepsy, a disorder where the subject sleeps uncontrollably, as well as certain brain dysfunctions occurring in children.

Caffeine is a mild stimulant that occurs naturally in numerous types of plants, the most common of which is coffee. Caffeine has been scientifically determined as effective in reducing fatigue in athletes, as well as having a role in the slowing the rate of glycogen depletion in the body in the course of endurance events such as the marathon, thus potentially increasing the efficiency of the athlete. Caffeine is also a powerful diuretic, reducing the body's ability to retain fluid during performance.

Amphetamines increase the heart and respiration rates, increase blood pressure, dilate the pupils of the eyes, and decrease appetite. These substances will tend to reduce fatigue over a short term period, as well as tending to increase the self confidence of an athlete during competition.

Cocaine is a powerful central nervous stimulator, manufactured through extraction from the naturally occurring coca plant. Although more commonly used as a recreational drug, it has been used by athletes seeking additional mental sharpness and concentration. A notable example of cocaine use in elite competition is that of Cuban high jumper Javier Sotomayor, the world champion who was stripped of a Pan American Games championship in 1999 after testing positive for cocaine.

All stimulants tend to be psychologically addictive, which will cause pronounced "down" periods when the athlete ceases taking the stimulant. Other side effects, which vary from person to person, include anxiety, blurred vision, sleeplessness, and dizziness. Abuse of amphetamines can cause irregular heartbeat and even physical collapse; a number of deaths in long distance cycling have been attributed to the abuse of stimulants.

All amphetamines and cocaine are banned substances in any amount if detected in the blood of an athlete at virtually any type of international competition. Caffeine is prohibited in amounts greater than 12 mcg/ml in athlete urine samples at Olympic competition, an amount approximately equal to the ingestion of eight cups of coffee in a two hour period.

SEE ALSO Caffeine; Doping tests; Ephedra.