Photo by Sean Gallup/AP

Read one particular way, the history of cycling is a history of riders doing all they can to stretch past the natural limits of the human body. Cheating has been at the very heart of cycling since its inception and riders have tried, at various points throughout the sport’s history, strychnine, EPO, cocaine, wine, horse tranquilizers, blood bags, cortisol, and even tiny hidden motors. Now we come upon a new frontier: poop. The future of cycling is shit.

The madwoman behind “poop doping” is Lauren Petersen, a postdoctoral microbiologist at the Jackson Laboratory for Genomic Medicine. Petersen has been racing bikes all her life, but as she told The Scientist earlier this month, she’s struggled with chronic Lyme disease since her teen years. She finally rid herself of the disease in 2013, but the intense course of antibiotics she took had ravaged her system and left her with chronic fatigue and stomach problems.

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Eventually, she learned that her microbiome (the colony of microbes in her body) was dangerously unbalanced and was not functioning as it should. She was not breaking down any food, and she learned that she was not eligible for a potentially beneficial fecal transplant. So she simply did one herself. As she said, it was a fairly dangerous DIY procedure and it wasn’t fun, but it worked better than she thought it could:

In February 2014, with the support of her family, she recruited a donor and did it herself. “I just did it at home. It’s not fun, but it’s pretty basic. It costs like six bucks to do.” (The $6 being for the drugstore enema kit.)

The do-it-yourself solution worked. “Within two months I was a new person,” Petersen says. “I had no more fatigue. I could ride my bike hard three days in a row, no problem.” She started racing four months after her fecal transplant, and was winning races at the pro level soon after that. “Everything changed,” Petersen says.

Petersen’s donor was a fellow elite cyclist, and after analyzing the sample and those of other riders, she discovered an unusually high prevalence of the bacterium Prevotella, which helps synthesize amino acids that help in muscle recovery. Petersen’s analysis of her friends’ craps also showed an abundance of M. smithii, which performs a complementary function. The science is complicated, but in short, a healthy amount of both bacteria types in one’s gut means you can more efficiently process food and then deal with debilitating byproducts like carbon dioxide and hydrogen.

“The more a person trains, the more likely they are to have Prevotella,” says Petersen. “In my sampling, only half of cyclists have Prevotella, but top racers always have it... it’s not even in 10% of non-athletes.”

Petersen is now studying the contents of several more cyclists’ butts and trying to determine what specific role the two bacteria play in a complicated environment with hundreds of variables. Theoretically, she has to isolate Prevotella and M. smithii, show that they can boost performance safely, then find a better delivery system than a $6 enema bag. There might be a whole host of interconnected physiological reasons why elite cyclists perform better, and while the abundance of two specific bacteria is compelling, it’s far from hard-and-fast proof. Isolating two variables in the vast and complex microbiome will take years of study. Petersen’s positive experience as a patient doesn’t guarantee that fecal transplants from elite cyclists will work for everyone, or that Prevotella and M. smithii alone will make someone a better rider. Right now, this is all theoretical and in the process of getting tested.

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Deadspin reached out to Petersen about the potential hazards of poop doping, and she said that the need for rigorous testing means it will be years before anyone can poop dope. Her team is working on the best way to grow Prevotella, and they will soon move to testing on mice.

We don’t know yet (about safety concerns). Prevotella is a pretty hard little bacteria to grow outside the human gut but we’re trying - and will move into mouse-model experiments in the near future to measure both beneficial effects and look for any detrimental ones. It will be at least a few years before these special athlete microbes will be available. A lot of work needs to be done to ensure they are safe - and effective.

Despite the hurdles in front of her, Petersen assured Bicycling magazine last week that bacterial doping will be “coming soon.”