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Interest in extraordinary athletic achievement fuels the modern day science of performance enhancement in sports. The desire to improve athletic performance in a scientific manner is a relatively recent development. At one time, the focus on maximizing human physical and mental potential centered on the importance of manual work and military service. The role of sport was inconsequential, except for its potential in improving ­military preparedness.92 Today, “sports doping” refers to the use of a prohibited xenobiotic to enhance athletic performance. The word doping comes from the Dutch word doop, a viscous opium juice used by the ancient Greeks.28

Controversy surrounding the systematic use of performance enhancing xenobiotics by the participating athletes has marred many sporting events. Since the International Olympic Committee (IOC) began testing during the 1968 Olympic games, prominent athletes have been sanctioned and stripped of their Olympic medals because they tested positive for banned xenobiotics. However, from a public health perspective, the use of performance-enhancing drugs among athletes of all ages and abilities is a far more serious concern than the highly publicized cases involving world class athletes. The majority of studies on the epidemiology of performance enhancing xenobiotics have investigated androgenic anabolic steroid use. Androgenic means masculinizing, and anabolic means tissue building. An anabolic process stimulates protein synthesis, promotes nitrogen deposition in lean body mass, and decreases protein breakdown. Studies of high school students document that 6.6% of male seniors have used anabolic steroids, and 35% of these individuals were not involved in organized athletics.31 Others find rates of androgenic steroid use in adolescent athletes range from 3% to 19%.101,114,170,226,231,232 Of the 243,193 samples analyzed by accredited laboratories for the presence of banned performance enhancing xenobiotics in Olympic and non-Olympic sports, 2% had positive findings. The majority of these findings are specific for anabolics and stimulants.


Performance enhancers can be classified in several ways. Some categorize performance enhancers according to the expected effects. For example, some xenobiotics increase muscle mass, whereas others decrease recovery time, increase energy, or mask the presence of other xenobiotics. However, one xenobiotic may have several expected effects. For example, diuretics may be used to mask the presence of other xenobiotics by producing dilute urine, or they may be used to reduce weight. Clenbuterol is an anabolic xenobiotic, but it also is a stimulant because of its β2-adrenergic agonist effects. Depending on the xenobiotic, it is used either during training to improve future performance or during competition to improve immediate results.28

According to the 2013 World Anti-Doping Agency (WADA) World Anti-Doping Code, a xenobiotic or method constitutes doping and can be added to the Prohibited List if it is a masking xenobiotic or if it meets two of the following three criteria: it enhances performance, its use presents a ...

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