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.95 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.32,128
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 xenobiotics 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.35 Others find rates of androgenic steroid use begins at age 10 years old and ranges from 3% to 19% of all adolescents.102,114,156,174,229
Performance enhancers are classified in several ways. Some categorize performance enhancers according to the expected effects. For example, some xenobiotics increase muscle mass; others decrease recovery time, increase energy, or mask the presence of other xenobiotics. However, many xenobiotics frequently have several expected and unexpected effects. For example, diuretics are used to mask the presence of other xenobiotics by producing dilute urine, or they are 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 or for weight loss.32
According to the 2017 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 risk to the athlete’s health, and it is contrary to the spirit of sport1 (Table 41–1).
Some of the prohibited xenobiotics are used ...