Why Some Athletes Lose Control of Their Bowels During Races

For endurance athletes, the fear of an unexpected bathroom emergency is not as unusual as it may seem.

Australian Hyrox competitor Joanna Wietrzyk recently brought the issue into the spotlight after suffering bowel incontinence during a race in Beijing. Despite the incident, she went on to win the competition before later apologising and withdrawing her result.

Her experience, however, is part of a much wider problem affecting endurance athletes around the world.

Researchers estimate that about 60 per cent of endurance athletes experience some form of gastrointestinal symptoms during training or competition. Other sports-medicine estimates suggest the figure could be as high as 90 per cent.

The symptoms can range from bloating and stomach cramps to nausea and diarrhoea. In more severe cases, athletes can lose control of their bowels during competition.

The condition is often referred to as “runner’s trots” or runner’s diarrhoea, although it is not limited to runners. Marathon competitors, ultramarathoners, triathletes, race walkers and athletes taking part in high-intensity events such as Hyrox can all experience digestive problems.

Why does extreme exercise affect the gut?

There is no single explanation.

During intense exercise, the body directs more blood towards working muscles. Blood is also sent towards the skin when the body needs to cool itself, particularly during hot-weather events.

That leaves less blood available for the digestive system, potentially affecting the gut’s ability to move and absorb food and fluids normally.

The problem can become more noticeable when athletes consume large amounts of sports drinks, energy gels and bars during prolonged exercise.

Running adds another challenge.

The repeated up-and-down movement involved in running can physically jostle the intestines, while prolonged weight-bearing exercise can place additional stress on the digestive system.

This is one reason cyclists may tolerate large amounts of food and fluid during endurance events better than runners.

Dehydration and sensitivity to particular foods or nutrition products can also contribute. Researchers have also examined the possible role of the connection between the brain and the gut, including the body’s hormonal response to physical and psychological stress.

Heat can make matters worse by increasing the body’s need to send blood to the skin for cooling.

It is not necessarily poor fitness

Although embarrassing, gastrointestinal problems during extreme exercise are not necessarily evidence that an athlete is badly prepared or unfit.

Some of the world’s most experienced competitors have experienced similar problems.

Marathon runners, race walkers and triathletes have all been forced to deal with urgent bowel movements during major competitions, sometimes in full view of spectators and television cameras.

The problem has also been documented in sports medicine for decades and is believed to have affected athletes since ancient times.

Can athletes prevent it?

The risk can be reduced, although it cannot always be completely eliminated.

One of the most important strategies is to train the gut.

Athletes are encouraged to practise eating and drinking during training sessions in the same way they expect to do during competition. This allows the digestive system to gradually adapt to processing carbohydrates and fluids while the body is exercising.

Trying unfamiliar foods immediately before or during a major event can increase the risk of problems.

Athletes should also pay attention to hydration, heat exposure and the foods that appear to trigger their symptoms.

Keeping a simple record of meals, drinks, exercise intensity, weather conditions and digestive symptoms can help identify patterns and personal triggers.

Some research suggests that consuming carbohydrates during prolonged exercise may support the gut, while other approaches, including lower-fibre diets, have also been investigated. However, evidence for some dietary strategies remains limited, meaning what works for one athlete may not work for another.

Sports researchers therefore recommend an individual approach rather than a single solution for everyone.

Most exercise-related gastrointestinal symptoms are temporary and do not pose a long-term health risk.

However, frequent, severe or worsening symptoms should not simply be accepted as part of competitive sport. Athletes experiencing persistent problems should speak with a healthcare professional.

For endurance competitors, the lesson is simple: the gut is part of the performance system too — and, like the muscles, it can be trained.