Athlete's public mishap highlights common
Australian athlete Joanna Wietrzyk's incident at a Hyrox race spotlights exercise-induced gastrointestinal syndrome, a condition affecting up to 90% of
Australian athlete Joanna Wietrzyk apologized after soiling herself during the Hyrox fitness race in Beijing. Her case, while dramatic, shows a widespread issue in endurance sports known as runner's diarrhoea or exercise-induced gastrointestinal syndrome.
About 60% of endurance athletes report some type of gastrointestinal symptoms during training or competition. According to Kayla Henningsen, a PhD candidate at Monash University, the American Medical Society for Sports Medicine estimates that prevalence could be as high as 90%. Symptoms range from mild bloating to nausea, diarrhoea, and, in rare cases, loss of bowel control.
A common, if hidden, problem
High-intensity events like marathons and Hyrox create perfect conditions for gut distress. Wietrzyk is far from alone in her experience. The 1998 London Marathon winner, Catherina McKeirnan, suffered several bouts of diarrhoea during her race. In 2005, Paula Radcliffe was publicly seen relieving debilitating stomach pains near the finish line of the London Marathon.
More recently, US athlete Taylor Knibb won the 2024 Dubai T100 triathlon despite an incident during the race. Men are not immune either. French race walker Yohann Diniz experienced severe stomach pain, with blood and possibly diarrhoea dribbling down his leg, during the 50km event at the 2016 Olympics. He still finished eighth.
Why the gut rebels under stress
The scientific literature has recorded gut problems related to exercise for a century. Professor Ricardo Da Costa from Monash University notes it likely plagued athletes even in the ancient Olympics. Understanding why is complex and cannot be pinned to one cause.
Exercise diverts blood to skeletal muscles, affecting the digestive tract's motility and absorptive ability. "Events in the heat make the problem worse," says Professor John Hawley from Australian Catholic University. Blood is diverted to the skin for cooling. Prolonged weight-bearing exercise for 90 minutes or more, like running, produces more severe symptoms than cycling due to the vertical impact. Henningsen calls this the "mechanical jostling of the intestines." Dehydration and food intolerances are other triggers.
Training and managing the gut
From a sports physiology perspective, these gut problems highlight the stress of extreme exercise. These events are not necessarily a sign of poor preparation or poor fitness, Henningsen states. While risk can be reduced, it may not be completely eliminated.
Prevention strategies include avoiding unfamiliar foods before competition, staying hydrated, managing heat, and gradually adapting the gut to tolerate carbohydrates and fluids during exercise. The gut is an 'athletic organ' and can be trained, Hawley explains. He advises athletes to practise their race-day nutrition in training.
Henningsen agrees. Treat your gut like any other part of your performance system and train it accordingly, she says. She recommends keeping a record of foods, fluids, and symptoms to identify personal patterns. Research reviewed by Da Costa's team suggests ingesting carbohydrates during prolonged exercise may help, and proteins like glutamine may support gut integrity. Evidence for low-fibre or gluten-free diets remains unclear.
Fortunately, Hawley notes that most gastrointestinal symptoms are mild, transient, and pose no long-term health risk. Henningsen offers a final caution, advising athletes to see a healthcare professional if symptoms are frequent, severe, or worsening. Persistent issues should not simply be accepted as part of the sport.
