Public mishaps involving loss of bowel control during high-intensity sports have long been a source of embarrassment for competitors, yet these incidents are far more common than the general public assumes. The recent experience of Australian athlete Joanna Wietrzyk at the Hyrox games in Beijing has brought renewed attention to the phenomenon known as runner’s trots, or runner’s diarrhoea. Wietrzyk won the fitness race, but her performance was marked by the visible presence of faecal matter on her legs, an incident that has prompted broader discussions regarding the physical toll of extreme exercise.
Data suggests that between 60% and 90% of endurance athletes report some form of gastrointestinal distress during training or competition, according to Kayla Henningsen, a PhD candidate researching exercise gastroenterology and extremes physiology at Monash University. Henningsen notes that symptoms range from mild bloating and cramping to nausea, diarrhoea, and in rare cases, a loss of bowel control. High-intensity events such as marathons, ultramarathons, and Hyrox create the ideal conditions for such distress.
The history of professional athletics is marked by several notable public instances. In 1998, London Marathon winner Catherina McKeirnan navigated the course while battling diarrhoea. Paula Radcliffe, the 2005 London Marathon winner, was caught on camera relieving herself near the finish line, later blaming the incident on her consumption of gluten-free pasta and grilled salmon. In 2024, US athlete Taylor Knibb won the Dubai T100 despite having to relieve herself during the race, famously asking a camera operator to avoid filming her. Men are not immune; TikTok celebrity Davis Clarke soiled himself during the 2024 Boston Marathon to avoid a time-consuming toilet stop. During the 2016 Olympics, French world record-holder Yohann Diniz suffered from stomach pain and diarrhoea during a 50km race walk, yet still finished in eighth place. Additionally, Swedish runner Mikael Ekvall Mikael Ekvall earned the nickname “bajsmannen” (poop man) after completing a 2008 half-marathon with diarrhoea running down his leg.
The biological mechanisms behind these issues are complex and were only significantly studied in the 1980s and 90s. Prof John Hawley from the Australian Catholic University explains that exercise diverts blood flow from the digestive tract to skeletal muscles, which compromises the gut's motility and absorptive capacity. This effect is worsened when athletes consume drinks, gels, and bars during prolonged, weight-bearing exercise. Heat exposure further exacerbates the problem by redirecting blood to the skin for cooling, which leaves the gut vulnerable. Henningsen describes this as the “mechanical jostling of the intestines,” noting that the vertical impact of running is more taxing than non-weight-bearing activities like cycling. Other factors, such as the gut-brain axis, hormonal stress responses, and microbiome changes, may also contribute to the issue.
Experts emphasize that these occurrences are not necessarily signs of poor fitness or preparation. While the risk may not be completely eliminated, preventative strategies include avoiding unfamiliar foods before events, staying hydrated, managing heat exposure, and gradually adapting the gut to tolerate carbohydrates and fluids. Hawley suggests that the gut is an “athletic organ” that can be trained to tolerate nutrient loading, advising athletes to practice their competition-day fueling during training. Henningsen recommends keeping a record of foods, fluids, and symptoms to identify patterns. While some evidence suggests that carbohydrates, proteins like glutamine, and low-fibre or gluten-free diets might help, the findings remain inconclusive. Fortunately, most gastrointestinal symptoms are transient and pose no long-term health risks.
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).
Da Costa’s team refers to the gut-brain axis possibly directing performance stress to the gut – potentially through the hormonal stress response and/or the microbiome – among other factors including altered pH.
