The first time stomach issues wrecked a long run, I assumed I’d picked up a dodgy takeaway. Then it happened again. And again.
So, I did what any modern hypochondriac would do: consulted Dr. Google. The good doctor confidently diagnosed me with everything from weak pelvic muscles to the gut-jarring trauma of my own footstrikes. Running forums were even better (or worse, depending on how you feel about unsolicited advice), suggesting everything from pre-run enemas to dry bagels for nausea. Unsurprisingly, none of this had any actual research behind it. (Though here’s a fun fact I didn’t need but now can’t forget: between a quarter and half of elite athletes suffer gastrointestinal distress that really cramps their style. You could read more about that here, but honestly… please don’t.)
Determined to get some real answers, I called in the big guns: David Nieman, PhD, director of the Human Performance Lab at Appalachian State University. According to Nieman, the reason runners suffer both upper GI issues (think acid reflux and vomiting) and lower GI distress (cramping and diarrhea) is pretty straightforward: after enough exertion, the gut just packs it in.
“About 88 percent of blood is shunted away from the GI tract to the working muscle groups,” Nieman explained. “When you shut down the blood flow, it causes high physiologic stress. That leads to the body’s high production of stress hormones and cytokines (inflammatory proteins). You have a GI tract that reflects the stress that your body’s going through.”
So charming, isn’t it?
As for how to deal with it, Nieman wasn’t exactly bursting with good news. His advice? “Keep calm; eat a pre-race meal about an hour before; go easy on the fiber.” But even that’s no guarantee. The man ran 58 marathons and never figured out how to stop his own acid reflux mid-race. “I would actually vomit up acid,” he admitted. And with that, he more or less retired from competitive running.
Research also shows dehydration (guilty) and going full goblin-mode on carbs during exercise (also guilty) can trigger gut issues. Krista Austin, PhD, owner of Performance & Nutrition Coaching and a former physiologist for the U.S. Olympic Committee warns against overloading on high-glycemic carbs like sports drinks and energy gels.
“They don’t empty from the gut very well. Instead they saturate the gut with carbohydrates, and you eventually start to get that GI distress,” she said.
Her solution? A low-glycemic product called SuperStarch from Generation UCAN. Worth trying, though you should know she also consults for the company, which makes swallowing that advice just a little harder.
Nieman isn’t a fan of sports drinks either. “Essentially sugar water,” he calls them and his research backs it up. In one study, he and his colleagues found sports drinks were no better than bananas at boosting athletic performance. Bananas might have won that nutritional smackdown, but before you go filling your running belt with them, it’s worth mentioning that the study was funded by Dole Foods. Yes, really.
Both Nieman and Austin suggest cutting back on fiber before a big race, but Austin is a bit more tactical about it. Three days out, she has her athletes reduce fiber to around 10 grams a day, brown rice becomes white, crunchy peanut butter turns creamy, and bran flakes are swapped for good old corn flakes.
She’s also got one more trick up her sleeve for those truly plagued by pre-race gut anxiety: magnesium supplements. “To fully empty the colon, I have some of my runners take about 800 milligrams of magnesium two nights before the race. It will help them kind of push everything out,” she says. And, as a bonus, magnesium also doubles as an antacid which feels like the universe’s way of apologising.
Of course, even perfect preparation won’t always save you from a catastrophic run… or, worse, a catastrophic case of the runs. So, here’s one final piece of hard-earned wisdom for the newbies out there: always bring toilet paper. Even if you don’t need it, someone at that grim late race portaloo almost definitely will. And trust me, that makes you a hero.