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Remember that time you got diarrhea during a marathon and barely made it to the port-a-john? How about those long runs when you gulped water and immediately wanted to vomit? Turns out you’re in good company: Gastrointestinal (GI) distress significantly impacts a large number of elite athletes, and it may be even worse for those who aren’t in peak condition.
There are countless theories on the Internet about why running can wreak havoc on the GI system. A lot have little basis in science, and some chat-room tips (pre-race enema, anyone?) aren’t so wise. We went to the experts for insight and smarter solutions to tummy trouble.
The main reason for runners’ upper GI problems (acid reflux, vomiting) and lower GI distress (cramping, diarrhea) is that the gut simply shuts down after a lot of exertion.
“About 88 percent of blood is shunted away from the GI tract to the working muscle groups. When you shut down the blood flow, it causes high physiologic stress,” explains David Nieman, director of the Human Performance Lab at Appalachian State University in North Carolina. “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.”
That stress also leads to poor absorption of water and fuel: When blood is diverted to the muscles, your stomach empties more slowly. In some cases, stomach contents, including acid, can come back up, says Keith Roach, MD, an associate clinical professor at Weill Cornell Medical College in New York City.
Stop Upper GI Distress
Let’s start with some tips to relieve acid reflux, nausea and the feeling that your water or fuel “just sits” in your stomach. Here’s what Dr. Roach, who is also a competitive triathlete, suggests:
- Start with the obvious. Avoid foods that can trigger acid reflux (tomatoes, caffeine and common offenders) and eat a few hours before you exercise.
- Gulp, don’t sip. Instead of sipping on your run, take 1-2 cups of water at water stops. It may improve absorption, and it’s easy to experiment with.
- Consider medication. Talk to your doctor about medications that can improve gut motility—meaning they will make your stomach and intestines “squeeze more and push things forward. Either of these can potentially can help your body absorb more food and water,” Dr. Roach says. “They’re not my first choice, but a serious athlete may want to consider giving one a shot for his or her A event for the year.”
Other health experts recommend avoiding gels or sports drinks if your gut is touchy. (Sports drinks may not be helping you anyway; in a study published in PLoS One, Nieman and his colleagues found that they were no more effective than bananas in boosting athletic performance.
Halt Runner’s Trots
Sometimes runners get diarrhea because their guts are in overdrive—usually before a race, when nerves play a major role. Far more distressing: Hitting mile 16 and feeling the warning cramp that actually makes you look forward to stepping in a fetid plastic outhouse. That’s what we mean by runner’s trots, and physiologic stress is often to blame.
A common solution is to slash fiber intake before a long run or race. Krista Austin, PhD, owner of Performance & Nutrition Coaching in San Diego, tells her athletes reduce their fiber intake to about 10 grams per day during race week—swapping brown rice for white, crunchy peanut butter for creamy, etc. She sometimes suggests taking 800 milligrams of magnesium, which can have a laxative effect, two days before a race.
Another approach is to follow the constipating BRAT diet (bananas, white rice, apples, white toast) the day before a race—and skip the laxative. “By inducing some diarrhea, you’ll lose fluid and salt. Unless you really know what you’re doing by putting them back in, you’re going to mess up your electrolyte level something fierce,” Dr. Roach says.
Consult with your physician before incorporating any new practices into your diet and/or routine to make sure they are a right fit for your system.
Hope Cristol is the director of content for Sharecare.com, a freelance writer and a slow-and-steady marathoner.