Why Do Marathon Runners Poop Their Pants?
To be an endurance runner is to leave a trail of sacrifice behind you.
When it comes to appreciating the athletic capacity of the human body, few activities can match a marathon. Runners pound the pavement for 26.2 miles with graceful, gazelle-like strides to overcome the physical and mental challenges of endurance.
Their movements can almost look like ballet. Until they poop in their shorts.
Some athletes call it a runner's trot. Others call it gingerbread man. This is the sudden and explosive need to empty the bowels in the heat of a race. Marathon history is littered with these fecal footnotes. During the 1982 World Ironman Championships in Hawaii, Julie Moss pooped her pants in front of 20 million viewers watching ABC's Wide World of Sports. In the middle of the 2005 London Marathon, Paula Radcliffe had to repeatedly pause and let her bowels empty in front of the crowd and television cameras. Countless runners in training or regional competitions have undoubtedly suffered the wrath of the Gingerbread Man.
The problem is so widespread that at the New York Marathon in 2017, two spectators carried handmade signs. One read "Don't Poop Your Pants!" The other, held aloft by a child, read "Nobody Poops".
Athletes in other sports have reportedly dealt with in-game mud, but most attribute it to food poisoning or illness. In the marathon, constant physical exertion is often blamed.
"It has to do with the fact that during periods of physical stress, the body diverts blood away from organs that are not critical at that moment," Michael Dobson, a colon and rectal surgeon at Novant Health in Charlotte, North Carolina, told Mental Floss in 2021. "For endurance athletes, you're diverting blood away from the intestines and towards the muscles. Lack of blood flow to the intestinal tract can cause many disruptions in normal function. As a result, it causes irritation in the intestinal tract. This can result in the evacuation of bowel movements.
When a runner's leg muscles work overtime, less blood goes to the intestines. This causes an inflammatory response in the intestinal lining, which can lead to ischemic colitis or temporary inflammation. That's when problems start to arise.
"Even without a big meal, the body continues to secrete liters of fluid a day in the intestinal tract," Dobson said. "When there are stressors involved, it causes these things to flow down the pipes." 
Last Line of Defense
People can have bowel problems without having to soil themselves. What causes runners to poop that they cannot ignore is that they lose control of both the internal and external sphincter muscles at the end of the anal canal. When there is enough waste, the involuntary muscle that usually holds the poop outside the pants relaxes. The outer voluntary muscle is the last line of defense, but the runner cannot tighten it.
"It's really hard to keep the muscle voluntarily closed when someone in the middle of a strenuous physical activity is doing other activities with other muscles in the legs and pelvis," Dobson said. "You can't control the muscle when you're using the muscle."
That's when you start to doubt what you ate last time. But according to Dobson, there's not much you can do before a race except limit your solid food intake or avoid Taco Bell.
Given that 60 percent of marathoners face gastrointestinal issues at some point, wouldn't it make sense to wear protection like an adult diaper? "I don't know the benefit of it," Dobson said. "Accidents are still going to happen. Now you have something heavy and wet in your hand. A wet diaper. There's nothing on the market that's going to make it better instead of just evacuating it. It might be more uncomfortable to run with a heavy and wet garment. It would be restrictive." It would also cost the sport one of its rites of passage. "I remember an ultra-marathoner once telling me it was a badge of courage," says Dobson. "You're not in the club until you shit your pants in an ultra marathon."
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