An Australian athlete’s uncontrolled bout of diarrhea during a Hyrox World Cup event in Beijing last weekend has thrust a rarely discussed but surprisingly common issue into the spotlight: exercise-induced gastrointestinal distress, colloquially known as “runner’s diarrhea.”
Joanna Wietrzyk continued competing with soiled legs and shoes, forcing other participants to run on mats contaminated with fecal matter before organizers replaced them. The incident, while striking, is far from unprecedented in elite sport.
A Recurring Problem in Elite Athletics
Swedish athlete Mikael Ekvall earned the viral nickname “bajsmannen” (roughly “poop man”) after completing a half-marathon in 2008 while suffering severe diarrhea. He reportedly ran nearly ten kilometers with intense intestinal cramps.
The phenomenon extends well beyond professional athletes. Medical research indicates the issue is widespread among recreational runners as well.
“An epidemiological study conducted among runners reported a 26% incidence of diarrhea and nearly 54% of cases of fecal urgency among marathon participants,” noted Dr. Gérald Gremion in the Swiss Medical Review.
The Physiology Behind the Problem
Multiple factors contribute to gastrointestinal distress during exercise, beginning with reduced blood flow to the digestive system.
“During physical exertion, the body redirects blood to the muscles to supply them with maximum oxygen. The blood flow normally irrigating the digestive system can be reduced by 70-80%, disrupting its normal metabolism,” explained Isabelle Morin, a nutritionist at La Clinique du Coureur.
High temperatures compound the problem further. According to John Hawley, a professor at the Australian Catholic University, blood is also “diverted to the skin to cool it and maintain body temperature” in addition to fueling muscles.
Running-specific mechanical factors play a role as well. “The pounding of the ground transmits mechanical waves to the viscera, resulting in increased intestinal transit speed, which can cause fecal urgency,” noted Dr. Gremion.
Aggravating Factors
Sports-specific nutrition products can intensify symptoms. According to Dr. Gremion, these include sports drinks and carbohydrate-concentrated gels.
Beyond physiological causes, numerous other factors can trigger episodes of fecal urgency, including medical conditions, treatments, or simply competition stress, as the digestive system is “highly connected to the nervous system,” Morin pointed out.
Prevention Strategies
Health professionals offer several recommendations to prevent mid-race emergencies:
- Use the bathroom before the start
- Limit fiber-rich and gas-producing foods (broccoli, beans, cabbage) several days before important races
- Avoid coffee on race morning
- Steer clear of high-carbohydrate drinks and foods during exertion
- Gradually train your body to eat during exercise if fueling is necessary
- Hydrate properly without “drinking beyond your sensation of thirst”
“Remember to test your nutritional routine multiple times in training. The golden rule remains: never try anything new on race day,” Morin concluded.
