The Athlete’s Guide to Probiotics

Some of the challenges runners faced in the 140-day Race Across USA earlier this year were to be expected: traversing 8,000-foot mountain passes, popping countless blisters, and dealing with accumulating fatigue while covering the vast 3,098-mile distance between Huntington Beach, California, and the Chesapeake Bay in Maryland. Others, not so much, like the arrival every few weeks of sample-collection kits packed in dry ice, which racers were required to fill up with their own feces and FedEx back to a lab at the University of California at San Francisco within 24 hours.

“You’re focused on your daily routine,” recalls Bryce Carlson, a Purdue University anthropologist who both competed in the race and coordinated the research project with fellow runners, “and now you’re being asked to poop on command.”

The project’s goal was to study how the grueling race affected the athletes’ microbiota, the trillions of bacteria that live in and on each of us. It’s well established that microbes play a crucial role in digestion, immune function, and even brain chemistry, but only recently have scientists begun to explore how and why they might affect physical performance, too. And vice versa.

The microbiota of an elite athlete, it turns out, may be quite different from that of a sedentary person. Last year, Irish researchers compared the gut microbes of 40 professional rugby players with nonathlete controls and found that the rugby players had, on average,

twice the microbial diversity. It’s unclear whether it was training, diet, or something else that accounted for the difference, but a recent study on mice at the University of Calgary suggests . . .  reader_3