Editor’s Note (02/08/18): Scientific American is re-posting the following article, originally published August 5, 2016, in light of the 2018 Winter Games which begin on February 9 in PyeongChang, South Korea.

When the 2016 Summer Olympics begin in Rio, one group of athletes will be conspicuously absent: The Russian track and field and weight lifting teams. Their absence will be felt: In London in 2012 the team took home a total of 82 medals. But it’s unlikely that they will be missed.

The Russian athletes were at the center of a state-sponsored doping program that was revealed over the past year. Investigators found a vast and intricate system of cheating, centered on a lab in Moscow that was responsible for drug testing athletes who reside and compete in Russia. Positive tests were covered up by lab workers, and blood and urine samples from athletes who were using banned performance-enhancing drugs (PEDs) were secretively swapped out for “clean” specimens, with the help of state intelligence agents.

The program involved athletes in sports as different as wrestling to sailing, and for all of them, the staple was the same: a literal “cocktail” of steroids, washed down with Chivas Regal scotch to lessen the chances of detection (vermouth for the women). What was most surprising, to seasoned observers, was their choice of drugs. The key ingredient of the cocktail was something called Oral Turinabol, a potent derivative of testosterone that, as it turns out, already had its own lengthy Olympic pedigree.

Oral Turinabol was the key ingredient in the last known state-sponsored Olympic doping program, which propelled East German athletes to gold medals in the 1970s and 1980s. Since then drug testing in sports has become much more widespread and much more precise, with tests for hundreds of specific compounds. In order to compete, athletes must give up their privacy, notifying officials of their whereabouts every single day of the year, so they can be located for on-the-spot, out-of-competition testing overseen by the World Anti-Doping Agency, or WADA. Something as potent and notorious as Oral Turinabol should have been wiped out long ago. Yet there it was, being swilled down like Red Bull by athletes who went on to win multiple medals at the Sochi Winter Olympics alone.

It seems reasonable to ask: Have we made any progress against doping in sports?

Well, yes and…not really. One the one hand, WADA-accredited labs processed an astounding 186,073 blood and urine samples in 2014, the most recent year for which figures are available. Slightly less than 1 percent of those came back with an “adverse” or “atypical” finding, jargon for a positive or suspicious result. That translates into a large number of positive tests—but contrast that figure with the 29 percent of athletes at a major international meet who, when promised anonymity by researchers, admitted to using PEDs. Clearly, plenty of cheaters are getting away with it.

Source: World Anti-Doping Agency 2014 Anti-doping Testing Figures Report

Graphic by Amanda Montañez

One reason is that the dopers remain about five to 10 years ahead of the testers. Consider the example of recombinant erythropoietin, or EPO, a potent hormone that boosts red blood cell count (and, thus, aerobic endurance). The drug had been in use for more than a decade before a reliable test was introduced in 2000, at the Sydney Olympics. Yet tests, clearly, have not stopped its use. In 2014 57 athletes tested positive for EPO, according to WADA. Anecdotal evidence, however, suggests it may be far more pervasive; because the drug only remains in the athlete’s system for a matter of hours, low doses are very difficult to detect.

The sad truth is that athletes continue to test positive for many of the same things that they have been using historically: amphetamines and other stimulants, becoming popular in the 1950s; anabolic steroids in the ‘70s and ‘80s; EPO and human growth hormone from the ‘90s to the present. Anabolic agents remain the most widespread class by far, with over 1,400 positives in 2014 across all sports. That number includes some 76 athletes who returned positive tests for that 40-year-old standby, Oral Turinabol—which was taken off the market, but like many other doping drugs, is just a few clicks away on the Internet.

In a way, although this seems like bad news—even in the era of frequent, random drug testing athletes still used easily detectable substances—there’s also a kernel of good news. A decade ago Oral Turinabol was only detectable within five to seven days after ingestion. Now the window of detection is more like five or six months. Drug testing has improved across the board, making it more difficult than ever to get away with cheating—which is why the Russians seemed to think they needed such a systemic, officially sanctioned cheating program. As such, the Russian doping scandal reveals that, contrary to appearances, drug testing has been at least somewhat successful: To get away with doping now requires the complicity of an entire state-run drug-testing lab. Whether other countries have followed Russia’s example is an unanswered question; disturbingly, the drug-testing lab responsible for the Rio Olympics lost its WADA accreditation earlier this year before being reapproved on the eve of the Games.

In this guide to Olympic doping, we break down the most commonly used doping methods, explaining how they work, analyzing their ease of detection and revealing which ones benefit performance—and which ones have little or no evidence of performance benefits. (Such as: human growth hormone.) We also investigated the ways in which athletes, as always, are pushing the boundaries and adopting new and “improved” methods of cheating.

The difference is that now, unlike prior decades, the testers are not that far behind—as we saw in January, when tennis superstar Maria Sharapova tested positive for a substance called meldonium, a heart-failure drug that had just been added to the list of banned substances. (And for which, by the way, there is minimal evidence of any benefit performance.) To pick another example, WADA has announced that it has developed a test for gene doping, in which athletes could inject themselves with specific genes to improve muscle-building or endurance—in spite of the fact that, to date, there has been no known successful use of gene-doping techniques.

“Test methods have become substantially more comprehensive and sensitive, allowing us to monitor and detect such compounds faster and longer than assays 20 to 30 years ago,” says Mario Thevis, a forensic chemist at the Center for Preventive Doping Research in Cologne. “On the other hand, the breadth of drugs in development is enormous, and hence we must at least consider the scenario that not one or two new classes of drugs and methods of doping are today's or tomorrow's challenge, but 10 or 20 additional ones.”

ANABOLIC STEROIDS

Anabolic steroids are hormones that help increase muscle mass and strength. They include testosterone as well as its synthetic derivatives such as nandrolone, stanozolol and oxandrolone, which have been tweaked to enhance their ergogenic effects (as opposed to androgenic).

Illustration by Tami Tolpa

Results

Steroids increase muscle mass and strength and they also help speed recovery, enabling more intense training. Weight lifters use cycles of steroids, combined with intense training, to bulk up; they are also popular among sprinters and jumpers. But anabolics are extremely popular across the entire spectrum of Olympic sports (faster, higher, stronger). They have been found in athletes ranging from cyclists and rugby players to fencers and target shooters.

Detection

By far the most common prohibited substance found in athletes, anabolics comprised nearly half of all positive tests in 2014, according to WADA figures. Another 13 percent of positives were for diuretics or other masking agents, intended to flush the drugs from the athlete’s system. Traditional urine tests look for changes in the normal steroid profile, such as the ratio of testosterone to epitestosterone. Those have been supplemented by more sophisticated carbon-isotope tests that are able to distinguish endogenous from exogenous steroids. Unfortunately, the effects of steroids last much longer than the drugs themselves, so the newest generation of tests focuses on detecting long-term metabolites (LTM) of anabolic agents.

Evolution

Small peptides known as selective androgen receptor modulators, or SARMs, increase the sensitivity of muscle cells to natural steroid hormones—with fewer undesirable side effects than traditional steroids. Although not yet approved for human use, SARMs are readily available on the Internet.

BLOOD DOPING (AKA OXYGEN-VECTOR DOPING)

Hormones including recombinant erythropoietin (EPO) as well as blood transfusions that increase red blood cell count

Illustration by Tami Tolpa

Results

More oxygen to muscles equals more power, less fatigue and faster performances. To pick one example, Lance Armstrong relied on both EPO and blood transfusions to win the Tour de France seven times. Blood doping and EPO are both highly effective, hence their popularity, particularly among endurance athletes such as runners and cyclists. Blood doping is also suspected to be prevalent in soccer, among other sports.

Masking and Detection

A direct urine test for EPO was introduced in 2000, at the Sydney Olympics. Since then many athletes have reverted to the older method of blood-doping via transfusion, which remains undetectable. Others have tried “microdosing” with EPO, injecting smaller doses of the drug that clear the body in a few hours, making detection unlikely while still conferring some performance benefits. (Because the half-life of recombinant EPO is only a few hours, the “window” for a positive test is short.)

New types of EPO tests are being developed that are more sensitive; one promising new method looks for changes in RNA that persist long after the drugs themselves are gone from the athlete’s body. Homologous blood transfusions (that is, from another person) are detectable via DNA screening, but there is still no reliable test for autologous blood transfusion. Researchers are looking into methods that might discern changes in cell structure that result from freezing the blood.

Another way to detect blood doping is via the “biological passport,” adopted by WADA in 2009, which tracks blood parameters such as hematocrit and hemoglobin on a longitudinal basis, looking for changes indicative of possible doping. Especially telling is the “off-score,” the ratio of hemoglobin to reticulocytes, or immature red blood cells; the ratio increases when blood is withdrawn and infused, making blood doping easier to detect indirectly.

Evolution

In recent years, athletes including cyclists have used drugs called HIF stabilizers (hypoxia inducible factor), an emerging class of kidney-disease drugs that stimulate the body’s own production of EPO by activating genes to express EPO. Many HIF stabilizers, such as argon and xenon, are detectable in blood tests, but cobalt chloride does the same thing and is more difficult to detect.

STIMULANTS

The oldest doping method, stimulants such as Benzedrine (amphetamines), showed up in the 1936 Olympics. The category also includes lower-grade stimulants such as ephedrine and even caffeine, which was on the banned substances list until 2003. Athletes may now enjoy their triple espressos, but cold medicine containing pseudoephedrine remains a no-no above a certain concentration.

Illustration by Tami Tolpa

Result

Athletes on stimulants feel like they have more energy and alertness. They help quicken reaction times, which is why they have been a favorite with baseball players as well as cyclists and runners. But stimulants also interfere with the body’s own heat-regulation systems, and have been implicated in the deaths of a handful of professional cyclists on very hot days.

Masking and detection

Traditional amphetamines are relatively easy to detect because they have been used for so long and the tests are well established. Several athletes have been sanctioned for the presence of small amounts of pseudoephedrine in their systems that they insisted came from cold medicine.

Evolution

Modafinil, a drug used to treat narcolepsy and other sleepiness disorders, has been popular with athletes; as are various “designer” stimulants that are more difficult to find in tests.

GROWTH FACTORS

These include human growth hormone (hGH), as well as insulinlike growth factor (IGF-1) and other growth factors

Illustration by Tami Tolpa

Results

There is limited evidence that hGH directly improves athletic performance, but it does seem to help lower body fat percentage and is also used by athletes and others in order to aid recovery from injury, particularly to tendons and ligaments.

Detection and Evasion

A blood test for HGH was introduced in 2004, but the test is expensive and not particularly sensitive; also, injected hGH lasts no more than 20 hours in the body. In 2014 WADA-accredited laboratories returned a grand total of one hGH positive—out of thousands of samples.

Evolution

Oral GH “secretalogues” are small peptides that stimulate the natural production of growth hormone via the pituitary. More recently, a Russian scientist has developed a drug called “Full Size MGF,” a cousin to IGF-1 that is both potent and undetectable.

GLUCOCORTICOSTEROIDS AND BETA2 AGONISTS

These are two classes of medications used primarily by asthma patients. Glucocorticoids, a class of corticosteroids, include prednisolone, cortisone and dexamethasone; they are not the same as anabolic steroids, but are more like anti-inflammatories. Beta2 agonists include compounds such as salmeterol (marketed as Advair), formoterol and salbutamol.

Illustration by Tami Tolpa

Results

Although both categories of drugs are banned, their performance-enhancing benefits are controversial. Glucocorticoids have been known since the 1930s to improve muscle endurance, which is why they are banned. They are also used for recovery, enabling athletes to sustain greater volume and intensity of training. As for beta2 agonists, an analysis of 26 studies found no significant benefits to athletes but competitors still use them extensively (hence the large number of positive tests). The oral and injected forms of both are also thought to help build muscle mass, similar to anabolics, and are banned in and out of competition. The (more common) inhaled forms, however, are permitted for many athletes who have demonstrated a need for them and have received a therapeutic use exemption (TUE). Confused yet?

Detectability

Relatively easy to detect via urine test—but given that so many athletes already have TUEs for both kinds of drugs, it is difficult to determine whether their use is for legitimate purposes or boosting performance. The WADA has established daily use thresholds for many different drugs in each category but the limits are fairly high, and it is difficult to distinguish between systemic and inhaled forms of the drug.

Evolution

More and more athletes in endurance sports are obtaining use exemptions for these drugs, claiming they suffer from asthma. Surprisingly, many have a legitimate case: Some research suggests that long-term aerobic training, such as running or cycling, may indeed worsen or even induce asthma symptoms.

MECHANICAL DOPING

Rumored for years, the existence of mechanical doping—the use of concealed motors to assist a cyclist—was confirmed in January when a motor was discovered inside the tubes of a bike ridden by Dutch racer Femke van den Driessche at Cyclo-Cross World Championships.

Illustration by Tami Tolpa

Results

The lightweight, nearly silent motors can add between 60 and 250 watts of extra power, more than enough to make a difference on a steep climb.

Detectability

Van den Driessche’s motor was discovered via electromagnetic resonance, when officials became suspicious after seeing wires dangling from her bike. Cycling officials have also used infrared cameras set up at secret locations on racecourses. No motors were found during the 2016 Tour de France but investigations by French and Italian journalists using thermal imaging suggest that some riders continue to use the motors undetected. Van den Driessche received a six-year ban from competition, and ultimately retired from the sport.

Evolution

Instead of motors, some cyclists are allegedly experimenting with electromagnetic wheels, with magnets hidden inside carbon-fiber rims, which are capable of generating a 60-watt boost—not bad given that a Tour de France contender will average about 350 to 400 watts on a difficult Alpine climb.