There’s a long history of athletes pooing themselves mid-race – why, and how can you avoid it?

Since the ancient Olympics, athletes like Hyrox competitor Joanna Wietrzyk have experienced runner’s diarrhoea. What does the science say about extreme exercise’s ‘mechanical jostling of the intestines’?

Soiling yourself in public sounds like a bad dream. But the Australian athlete Joanna Wietrzyk has now apologised for doing just that at the Hyrox games in Beijing on Saturday.

Wietrzyk won the fitness race but not before using communal equipment with faecal matter visibly running down her legs – and muddying Hyrox’s reputation.

Apologies aside, Wietrzyk’s unfortunate case of runner’s trots, or runner’s diarrhoea, is far more common than many people realise, throwing a new light on the ominous rows of portable toilets stationed along the course of a fun run and the knowing nods between runners as they pass them (or not).

About 60% of endurance athletes report some type of gastrointestinal symptoms during training or competition, according to Kayla Henningsen, a PhD candidate researching exercise gastroenterology and extremes physiology at Monash University. The American Medical Society for Sports Medicine estimates that the prevalence could be as high as 90% .

Severity varies considerably. “Symptoms can range from mild bloating and cramping through to nausea, diarrhoea and, in rare cases, loss of bowel control,” Henningsen says. “High-intensity events such as marathons, ultramarathons and Hyrox can create the perfect conditions for gastrointestinal distress, urgency or diarrhoea.”

Wietrzyk isn’t alone: other public mishaps published over the past three decades include the 1998 London Marathon winner, Catherina McKeirnan, who dodged cameras along the way while suffering several bouts of diarrhoea. Paula Radcliffe, the winner of the 2005 London Marathon, wasn’t so lucky; she was publicly caught relieving herself of debilitating stomach pains by the road near the finish line, blaming it on too much gluten-free pasta and grilled salmon the night before. In 2024 the US athlete Taylor Knibb won the Dubai T100 despite having to relieve herself during the race, uttering the immortal line to a camera operator : “I just shit myself … so can you not get my ass? Thank you.”

Although runner’s trots are more common in women, men aren’t immune. The TikTok celebrity Davis Clarke decided a toilet stop would impact his time so he crapped his pants during the 2024 Boston Marathon. In a 50km race walk at the 2016 Olympics, the French world record-holder Yohann Diniz suffered stomach pain and had blood and possibly diarrhoea dribbling down his leg before collapsing – then still managed to finish in eighth place.

Perhaps most cringeworthy episode afflicted a Swedish runner, Mikael Ekvall, who ran a half-marathon in 2008 withdiarrhoea running down his leg , earning him the viral nickname “bajsmannen” (poop man). He finished in 21st place despite 10km of severe stomach cramps.

The scientific literature has recorded gut problems related to exercise stress, known less colloquially as “ exercise-induced gastrointestinal syndrome ”, for the past century, according to Prof Ricardo Da Costa from Monash University and colleagues.