The desire to win is a built-in component of competitive sports. Indeed, many athletes believe winning is everything. This philosophy leads individuals to succumb to using performance-enhancing drugs, such as anabolic steroids, human growth hormone (hGH), amphetamines, cocaine, caffeine and ephedrine, and to engage in practices such as blood doping to improve their performance.

According to the U.S. Anti-Doping Agency (USADA), the independent national anti-doping organization for Olympic, Paralympic and Pan American sport, “performance-enhancing drugs have the ability or potential to drastically alter the human body and biological functions, including the ability to considerably improve athletic performance in certain instances.”

But despite their perceived benefits, some of these drugs can also be extremely dangerous and, “in certain situations, deadly,” adds the agency. As a result, organizations such as the USADA and the World Anti-Doping Agency, or WADA, continuously conduct research on doping tests and education and outreach programs to boost awareness and stop athletes from turning to doping.

WADA was established in 1999 to promote, coordinate and monitor the fight against doping in sports in all its forms. Since 2004, WADA has been publishing an annual list of prohibited substances, such as steroids and stimulants, and methods, such as blood and gene doping, that identifies and classifies drugs and techniques used in and out of competition (i.e., during training) for particular sports.

In the effort to stop the abuse of such drugs in sports, medical experts use doping tests to identify which substances and techniques both professional and amateur athletes may be using.

Scientists employ one or more of several main methods to test athletes for banned substances. Doping tests commonly screen bodily fluids, such as urine, blood, saliva and sweat, for drugs. Because urine is easy to collect, freeze, store and test for drugs and their related metabolites (by-products from metabolic reactions in the body), it’s one of the most commonly examined fluids. “Drugs and their metabolites are generally present in higher concentrations in urine than in other tissues or fluids because of the concentrating function of the kidneys,” write Gary I. Wadler, MD, and Brian Hainline, MD, in their book Drugs and the Athlete, a seminal work on doping.

“Blood and urine testing both play an important role in an effective anti-doping program,” says Annie Skinner, USADA’s communications director. “There are some substances and methods that can only be detected in blood, for example, the use of exogenous human growth hormone [hGH not produced by the body]. But there are other substances that are more easily detected in a urine sample.”

For saliva testing, doctors swipe inside an athlete’s mouth with a swab for a sample. This doping test can also be used to detect amphetamines, marijuana and cocaine.

In 2015, researchers at the University of Waterloo in Canada developed a sensitive test that uses a test strip with a special coating that extracts drug molecules from saliva. According to scientists, this coating can be applied to any surface; currently, researchers are working to develop easy-to-use saliva test strips in the form of a gum or lollipop.

Although screening an athlete’s sweat or hair for signs of drug use is much less common, these testing methods can also detect many of the same banned substances within a particular time period.

Doping tests screen for the presence of a wide range of drugs, including amphetamines, heroin, crack cocaine, methamphetamines, ecstasy, also known as MDMA or “molly,” ketamine, PCP, human growth hormone and synthetic drugs, such as erythropoieitin, or EPO, which was designed to treat anemia in people suffering from chronic kidney disease and other illnesses that cause a drop in red blood cell count.

Athletes who use EPO can increase the oxygen-carrying capacity of their blood, thus improving physical performance during competition. In 2013, EPO was one of the banned substances championship cyclist Lance Armstrong admitted to having used in competition; as a result, he was stripped of the Tour de France titles and prize money he received for winning the race seven years straight, from 1999 to 2005.

Any athlete who participates in an elite event, such as the Olympics, can be tested for drugs on WADA’s Prohibited List. Substances that are prohibited always—in and out of competition—include anabolic agents, peptide hormones, growth factors, related substances and mimetics (imitator drugs), beta-2 agonists, hormone and metabolic modulators, diuretics and masking agents. The always-prohibited methods include manipulating blood and its components (e.g., plasma), tampering with doping samples, administering intravenous infusions or injections not associated with legitimate medical care and manipulating gene therapies to enhance sports performance.

In addition, the list prohibits the in-competition use of stimulants, narcotics, such as oxycodone; cannabinoids, such as cannabis, hashish and marijuana; and glucocorticoids, such as hydrocortisone.

Several factors make different types of doping tests accurate and reliable: matching the testing method with how long ago the doping substance was used, eliminating opportunities for tampering with the test sample, and connecting the amount of the doping substance detected to the drug’s ability to enhance performance.

“Science plays a crucial role in the fight for clean competition,” says Skinner. “The WADA-accredited laboratories use cutting-edge science to detect the use of performance-enhancing drugs and methods,” Skinner explains. “The anti-doping science community is actively involved in researching and monitoring new drugs being developed so that accurate testing methods can be created to detect them before they are used in the athlete community.”

In recent findings, researchers shone a spotlight on the pharmaceutical industry’s unplanned production of the latest generation of doping agents that will challenge anti-doping scientists: drugs designed to combat muscle-wasting diseases.

“As these companies are developing new drugs and methods to help treat diseases, those same substances and methods may also be inappropriately used to try and enhance athletic performance,” Skinner says.

But she also stresses that USADA and WADA have forged relationships with these companies to prepare for these latest challenges. “Working with our partners at pharmaceutical and biotech companies can help us to prevent the abuse of these medications and to develop new testing methods.”