It would be one thing if all they were up against was cutting-edge, chemistry lab wizardry, but dishwasher crystals and contact lens fluid?
Athletes will go to mind-bending lengths in search of a competitive edge – and to cover up the various misdeeds that provide it.
A decade ago, at a time when Lance Armstrong was terrorizing the rest of the Tour de France peloton, that sometimes meant riders craftily altering a urine sample with a dash of protease – an enzyme found in many household soaps and cleansers.
By dabbing powder on one's fingers and then urinating on them during a drug test, traces of synthetic erythropoietin – or EPO, a hormone that bolsters endurance – melted away.
Other approaches weren't quite as low-tech: urine replacement through a catheter, masking substances, blood and muscle-boosting drugs that were not yet commercially available.
In the international cops-and-robbers game that pits bodies such as the World Anti-Doping Agency against a sophisticated and surprisingly vast netherworld of unscrupulous chemists and exercise doctors, it is accepted that dope cheats are generally a step or two ahead.
But the testers are making steady progress – the protease dodge, for example, hasn't worked for years.
Among the biggest recent advances: Testing for human growth hormone, one of the more prevalent performance-enhancing substances, is now more refined than ever.
And there is promising research on a test for gene doping, where it is theoretically possible to alter an athlete's genetic code to increase red blood cell production or muscle mass.
The main weapon in the battle against performance-enhancing substances in cycling and athletics – where their use has been rampant for decades – is the biological passport.
The theory underpinning it is mostly statistical: Longitudinal analysis reveals more about an athlete's body than intermittent testing, so blood chemistry is monitored over time.
Earlier this year, the International Association of Athletics Federations banned veteran Portuguese distance runner Helder Ornelas for doping with only his blood profile as evidence; you don't need to test positive any more to get caught.
At the London 2012 Games, anti-doping authorities partnered with pharmaceutical giant GlaxoSmithKline to unleash a testing regime that WADA head John Fahey called the most stringent in Olympic history – it nabbed nine athletes, including gold-medal winning women's shot-putter Nadzeya Ostapchuk.
But no test is foolproof.
An article published this month in the British Journal of Medicine acknowledged the existence of techniques that skirt the current testing procedures, some researchers have suggested there are as many as 100 undetectable EPO variants.
And the practice of micro-dosing – a series of small courses of testosterone, EPO, corticosteroids or growth hormones – is notoriously difficult to detect.
Minnesota-based physiologist Dan Zeman, who has written on how people evade positive results, said there's an ever-evolving variety of chemicals to disguise banned substances."You're looking for the masking agent, not the drug," he explained. "It's really a cat and mouse game of what to look for in the blood and urine."
Every time an agency such as WADA discovers and bans a technique – such as saline infusions to thin suspect blood, or a new substance such as AICAR, a slimming drug that dilates blood vessels, or SARM, which mimics testosterone – a substitute is quickly found. "There's an awful lot of money for coming up with ways to get across the finish line first," Mr. Zeman said.
Antoine Vayer, a former team official for Festina, a cycling team dissolved after a doping scandal in the late 1990s, speculated in the French newspaper Le Monde that Mr. Armstrong likely managed to avoid positive results through a mix of subterfuge and careful use of micro-dosing.
"He was just better at it than the others," Mr. Vayer told the paper.