Anti-doping technology has vastly improved over the years, particularly with advances like the biological passport, which monitors fluctuations in the athlete's blood over time rather than trying to detect any one particular substance.

But when you look at the actual numbers, the worldwide proportion of drug tests that are positive is only about 1 to 2 percent, ProPublica reporter David Epstein says, and that figure hasn't changed in years – putting dopers and anti-dopers in a bit of a "technological lockstep."

So why has drug testing always been a step behind?

At least part of the reason is because regulators don't want to catch athletes unfairly, Epstein tells ProPublica's director of communications Nicole Collins Bronzan. There's a high burden of proof, much like our criminal justice system, but setting such wide parameters in the biological passport means there's a lot of room to dope without getting caught. And a lot of room for marketers to take advantage.

Epstein and Bronzan recall a recent trend where athletes were using deer antler spray to increase performance. "There's insulin-like growth factor, IGF, in deer antlers which is one of the reasons they grow so quickly. So the marketing leap is this is one of the fastest growing substances on earth so if we take the [deer antler] velvet and grind it down and put it in a supplement, it'll make your muscles grow, too," Epstein says. "There's no evidence that deer insulin-like growth factor works in humans in the first place" but beyond the marketing spin, these supplements have really taken hold because there's no valid test to distinguish between IGF taken from an outside source and what your body naturally produces.

Making more accurate, commercially-available tests remains important, Epstein says, but intelligence gathering and investigation may prove to be more effective. Just look at the Tyson Gay case. "It's been controversial that Tyson Gay got a short suspension for his positive test, only one year, but that really shows that anti-doping authorities are really viewing intelligence gathering as the new frontier so they're willing to bargain the way the FBI does with the mafia – to let some people give information in exchange for reduced sentences."

Catch this week's podcast episode on iTunes, SoundCloud and Stitcher. You can also read all of Epstein's sports science reporting here.