Men get it, too, but unfortunately, it’s more common in women. In fact, one survey of marathoners found that a whopping 74 percent of female runners report hearing nature’s call while racing, and 68 getting diarrhea during or soon after. Runners’ trots likely have something to do with the jostling of intestines that goes on during a run, which, combined with the diversion of blood from the intestines to the muscles, can cause GI problems. Dehydration only makes matters worse. To forestall an unplanned pitstop, be sure to drink extra water and reduce your intake of high-fiber foods before going on a long run.