The use of performance-enhancing drugs among athletes competing in the Olympic Games is not new—as early as 1904, American runner Thomas Hicks was given doses of strychnine during the marathon at the Summer Olympics in St. Louis, Missouri. He ended up winning the race after the first-place finisher was disqualified for completing part of the marathon by car. Today—thanks in part to large television audiences and massive commercialization, which have instilled in many viewers an idealistic picture of the Olympic athlete—there has been a significant crackdown on the use of performing-enhancing substances. Leading the fight against drug use in sports is the World Anti-Doping Agency (WADA), an organization established in 1999 under an initiative led by the International Olympic Committee. Over the years, WADA’s Prohibited List—a compilation of substances banned from sport—has grown to include not only more drugs but also additional methods of doping, including gene doping. The following is a survey of the major groups of banned substances and methods (as of 2016).
Anabolic agents
Anabolic agents, which include anabolic steroids and selective androgen receptor modulators, are substances that stimulate muscle growth. Examples include stanozolol, which is among the steroids most widely abused by athletes, and zeranol, a fungal-derived nonsteroidal estrogenic compound sometimes given to livestock to promote growth. Steroids such as stanozolol, which are exogenous (not normally made by the body), are easily detected in urine. However, endogenous anabolic steroids, which occur naturally in the body, are more difficult to detect. Determining whether an athlete is augmenting levels of a natural substance is usually done by calculating ratios and by comparing those numbers with average values.
Peptide hormones and growth factors
Included in WADA’s list of prohibited peptide hormones and growth factors are substances that stimulate the growth of tissues such as muscles, tendons, and ligaments or that enhance the oxygen-carrying capacity of blood, the body’s utilization of energy, or the body’s ability to recover. Specific examples include agents such as erythropoietin (EPO) and FG-4592, which increase the number of red blood cells in the circulation and thereby increase the oxygen-carrying capacity of hemoglobin, and insulin-like growth factor 1 (IGF-1), which can enhance muscle growth and regeneration. EPO, a hormone naturally produced by the kidneys, and FG-4592, an experimental drug, can be detected in the urine. Other prohibited substances in this group, however, including growth hormone and IGF-1, are more difficult to detect. Although present in urine, such substances occur at extremely low levels or lack criteria for abuse.
Beta 2-agonists
Beta 2-agonists are bronchodilators, which means that they relax smooth-muscle constriction and open the airways of the lungs. Many individuals take beta 2-agonists therapeutically for conditions such as asthma. The presence of these substance in unusually high amounts in the urine is considered an abnormal finding by WADA.
Hormone and metabolic modulators
Agents in this group include substances that modify the effects of hormones in the body or alter the body’s metabolism. Examples include antiestrogens, which athletes may take to prevent visible signs of anabolic steroid abuse (e.g., breast growth, baldness, infertility), and AICAR, which enhances fat utilization and mitochondria production in muscle. Elevated urine levels of prohibited substances in this category is reason for suspected abuse.
Diuretics and masking agents
Diuretics increase the flow of urine, in the process diluting and potentially masking the presence of other prohibited performance-enhancing substances. Diurectics can also alter the pH of urine and thereby prevent the urinary excretion of acidic and basic drugs. Examples of diuretics and masking agents include furosemide, chlorothiazide, and desmopressin. These substances can be detected in urine.
Other prohibited substances and prohibited methods
WADA’s Prohibited List also includes stimulants, narcotics, alcohol, cannabinoids, glucocorticoids (anti-inflammatory drugs), and beta-blockers (which block the effects of epinephrine). Alcohol and some beta-blockers are prohibited only in certain sports, while several beta-blockers are also prohibited out of competition in sports such as shooting and archery.
Among prohibited doping methods are the manipulation of blood, the tampering with (or attempted tampering with) of samples, and gene doping. In gene doping cells, genes, and genetic elements are manipulated with the express purpose of enhancing athletic performance. An example is repoxygen, a segment of DNA that was developed to stimulate the production of EPO. Repoxygen was developed by a pharmaceutical company originally as a form of gene therapy for severe anemia. It remains unclear whether repoxygen or any other form of gene doping has ever been used by an athlete.