In September 2026, Australian athlete Joanna Wietrzyk made headlines after losing control of her bowels during HYROX Beijing, yet continued to the finish and won the event.¹ Much of the public debate centred on hygiene and competition rules. G-Health poses a question that goes beyond one athlete: why can bowel control suddenly become so difficult when the body or mind is under pressure?
The Sudden Need to Go Is More Common Than You Think
Bowel control problems are far more common than most people realise. A major 2024 analysis brought together 80 studies involving 548,316 adults. It estimated that faecal incontinence affects 8% of adults worldwide, roughly one in twelve.2
A complete bowel accident sits at the extreme end of the picture. Sudden urgency, cramps and loose stools are much more familiar. They can strike during a hard run or workout, but also before an examination, interview, flight or public presentation. Physical effort and emotional pressure reach the gut through different routes, and several triggers may arrive at the same time.
Why Exercise Can Suddenly Upset the Gut
During strenuous exercise, the body prioritises blood flow to working muscles. In hot conditions, more blood is also directed towards the skin to release heat. Blood flow to the digestive system can therefore fall, especially when exercise is long, intense or combined with dehydration. This may temporarily disturb digestion, absorption and the gut barrier.3,4
Exercise can also change the way the digestive tract moves. The stomach may empty more slowly while the lower bowel becomes more urgent or unpredictable. Running, jumping, burpees and lunges repeatedly move the abdomen, while heat and fatigue can make symptoms more likely.3
Food and drink matter too. A large meal shortly before exercise activates the normal signal that encourages the bowel to make room after eating, known as the gastrocolic reflex. High-fat meals, excess caffeine, concentrated sports gels and foods that already upset your stomach can add another trigger. An important event is therefore a poor time to test an unfamiliar breakfast, drink or supplement.3
Why Pressure Can Suddenly Upset Your Bowels
You do not need to be an athlete to recognise the feeling. Some people develop cramps, loose stools or an urgent need to find a toilet whenever they are anxious, rushed or facing an important moment.
Part of the explanation lies in the constant two-way communication between the brain and gut through nerves, hormones and chemical signals. This connection is known as the gut–brain axis. When you feel threatened or under pressure, the body moves into a heightened state of alert. Those signals can change bowel contractions, affect the movement of fluid through the gut and make normal internal sensations feel much stronger.5
For one person, the response may stop at butterflies in the stomach. For another, it may become pain, diarrhoea or a sudden dash to the toilet. This helps explain why the problem can appear before an examination or interview even when there has been no strenuous exercise at all.
Why Loose Stools Are Harder to Hold
Bowel control depends on more than how quickly the gut is moving. The final part of the bowel must store the stool, the nerves must recognise that it has arrived, and the pelvic floor and ring of muscle around the anus must hold it until a toilet is available. Stool consistency matters as well.6
A formed stool may still create urgency, but it is generally easier to hold than loose or watery stool. Liquid stool moves more freely and can leave less time to react. Helping loose stools become better formed can therefore be part of managing bowel leakage.
Gel-forming fibre such as psyllium can hold water and help loose stools become more formed. One study found that adults taking psyllium experienced fewer episodes of bowel leakage than those who did not receive it.7 Research reviews also describe its ability to normalise stool form.8
But here is the catch: fibre is not one single ingredient. Psyllium forms a soft gel, while other fibres may behave very differently—especially if you suddenly eat much more than usual. The answer is not to load up on any fibre you can find, but to choose suitable types and build them up gradually.
What May Help Before a Demanding Day
No routine can control every bowel reaction, but removing avoidable triggers may lower the chance of several problems arriving together. Before a race, examination or other high-pressure event:
- prioritise sleep and allow enough time to eat and use the toilet;
- choose familiar meals and avoid foods or drinks that you know can upset your stomach;
- be sensible with caffeine, particularly if it normally stimulates your bowel;
- hydrate steadily instead of drinking a large volume at the last minute;
- do not try an unfamiliar supplement on the day, especially one that may loosen stools or stimulate bowel movement; and
- use slow breathing or another familiar relaxation method to reduce the stress signals reaching the gut.
Athletes who need food and fluid during prolonged exercise can also practise their planned intake during training. This form of ‘gut training’ may improve tolerance, gastric comfort and nutrient absorption under exercise conditions.9
The Same Pressure but Different Guts
Two people can face the same race, heat or stressful situation, yet only one suddenly needs a toilet. Willpower is only part of the story. The difference may also depend on how unsettled the gut was before the pressure began, how watery the stool becomes and how well the bowel maintains control when challenged.
Sometimes exercise or stress is only the final push. A gastrointestinal infection can irritate the gut lining and increase fluid in the bowel. Antibiotics can disturb the usual microbial community and may temporarily leave stools looser or less predictable.10 IBS and certain food sensitivities can make bowel sensations and contractions more reactive. Ongoing intestinal inflammation can also interfere with normal fluid absorption and requires medical assessment.
This is where gut resilience becomes relevant. A more resilient gut has a better chance of keeping stools formed, maintaining steadier bowel habits and recovering when diet, stress, infection or medication disturbs it.
Support the Gut Microbiome Over Time
The microorganisms living in the intestine help break down components of food, produce useful substances, interact with the gut barrier and compete with incoming microbes.11 A well-supported microbial community forms part of the digestive environment that helps the gut cope with change and recover afterwards.
A varied diet remains the foundation. It supplies different fibres and plant compounds, while regular meals, adequate sleep and stress management help keep bowel routines more predictable. Two further parts of that routine deserve attention: adding live friendly bacteria and providing fibres that gut microorganisms can use.
Add Live Friendly Bacteria (Live Probiotics)
Foods commonly described as probiotic-rich include yoghurt labelled as ‘live’ or ‘containing live cultures’, kefir and some unpasteurised fermented vegetables such as kimchi or sauerkraut. Fermentation alone does not guarantee live microorganisms, because heating or pasteurisation after fermentation may remove them.
Being alive matters. After live friendly bacteria are swallowed, they must pass through stomach acid, bile and the rest of a demanding digestive environment. Some will not survive the journey. One approach is to provide an adequate amount so that enough remain viable; another is to choose foods or supplements with a protective food matrix or formulation designed to help more of the microorganisms reach the intestine alive.12
The important words are adequate amount and survival, not simply the largest number of bacteria or the longest list on the front of a pack. For someone who wants additional dietary support, a clearly formulated supplement can offer a convenient and consistent source of live friendly bacteria. Again, this is a routine built over time, rather than an emergency solution taken just before a demanding day.
Feed Gut Microbes with the Right Fibres
Introducing live friendly bacteria is one part of the picture; feeding the microorganisms already living in the gut is another. Prebiotics are substances that selected gut microorganisms can use in a way that benefits health.13 Familiar examples include inulin and fructooligosaccharides, or FOS. Xylooligosaccharides, known as XOS, are another type used in selected food formulations.
Onions, garlic, leeks, asparagus and chicory provide inulin-type fibres. Oats, barley, beans, apples, citrus fruit and slightly green bananas provide other fermentable fibres and resistant starches that different gut microbes can use.14 Ingredients such as XOS and resistant dextrin are more commonly found in selected fibre-enriched foods and food supplements.
Different fibres support gut resilience in different ways. Gel-forming fibres can help bind water and shape loose stools. Prebiotic and other fermentable fibres nourish the microbial community, which produces useful substances that interact with the colon and gut barrier. Whole plant foods usually provide a mixture of fibres, so variety matters more than relying on one ingredient alone.
Do Not Try to Fix Your Gut at the Last Minute
Gut resilience is built during ordinary days, not on the morning of a race, examination or important presentation. Suddenly increasing prebiotic dietary fibre, adding unfamiliar probiotic-rich foods or starting a new supplement may cause wind, bloating or a change in bowel habits: the very problems you were hoping to avoid.
Increase fibre gradually, drink enough fluid and notice how your own bowel responds. Introduce live friendly bacteria and other supplements during ordinary weeks, when you have time to observe any change. Keep the meals, drinks and routine before an important event familiar and predictable.
When to Speak to a Health Professional
An occasional urgent dash after coffee, nerves or a hard workout may have an obvious trigger. Repeated bowel leakage deserves proper medical attention. Speak to a GP if urgency or incontinence keeps returning, disrupts daily life or is accompanied by blood in the stool, persistent pain, fever, symptoms that wake you at night or unexplained weight loss. Bowel incontinence can involve the bowel, rectal sensation, pelvic floor, sphincter muscles or nerves, and diet is only one part of the assessment.6
Takeaway
Exercise and psychological pressure can both unsettle the bowel. Changes in blood flow, heat, physical movement, food, caffeine and gut–brain signalling may combine to create sudden urgency. If the stool becomes loose or watery, it is also harder to hold.
Some preparation happens on the day: rest, familiar food, steady hydration, sensible caffeine intake and enough time for the toilet. The longer-term work is to support more predictable stools and a steadier digestive environment. A varied diet provides the foundation, while probiotic-rich foods, suitable live friendly bacteria supplements and fibres used by gut microorganisms can form part of a consistent routine.
References
Giddings A. Hyrox athlete competing covered in faeces sparks huge debate: but it’s becoming normal. Metro [Internet]. 2026 Sep 14 [updated 2026 Sep 15; cited 2026 Sep 17]. Available from: https://metro.co.uk/2026/09/14/this-hyrox-athlete-competed-covered-faeces-becoming-normal-29603418/amp/
Mack I, Hahn H, Gödel C, Enck P, Bharucha AE. Global prevalence of fecal incontinence in community-dwelling adults: a systematic review and meta-analysis. Clin Gastroenterol Hepatol. 2024;22(4):712-731.e8. doi:10.1016/j.cgh.2023.09.004.
Costa RJS, Gaskell SK, Henningsen K, Jeacocke NA, Martinez IG, Mika A, et al. Sports Dietitians Australia and Ultra Sports Science Foundation joint position statement: a practitioner guide to the prevention and management of exercise-associated gastrointestinal perturbations and symptoms. Sports Med. 2025;55(5):1097-1134. doi:10.1007/s40279-025-02186-6.
Costa RJS, Snipe RMJ, Kitic CM, Gibson PR. Systematic review: exercise-induced gastrointestinal syndrome: implications for health and intestinal disease. Aliment Pharmacol Ther. 2017;46(3):246-265. doi:10.1111/apt.14157.
Leigh SJ, Hindmarch CCT. The impact of acute and chronic stress on gastrointestinal physiology and function: a microbiota-gut-brain axis perspective. J Physiol. 2023;601(20):4491-4538. doi:10.1113/JP281951.
Assmann SL, Keszthelyi D, Kleijnen J, Anastasiou F, Bradshaw E, Brannigan AE, et al. Guideline for the diagnosis and treatment of faecal incontinence: a UEG/ESCP/ESNM/ESPCG collaboration. United European Gastroenterol J. 2022;10(3):251-286. doi:10.1002/ueg2.12213.
Bliss DZ, Savik K, Jung HJG, Whitebird R, Lowry A, Sheng X. Dietary fiber supplementation for fecal incontinence: a randomized clinical trial. Res Nurs Health. 2014;37(5):367-378. doi:10.1002/nur.21616.
McRorie JW Jr, McKeown NM. Understanding the physics of functional fibers in the gastrointestinal tract: an evidence-based approach to resolving enduring misconceptions about insoluble and soluble fiber. J Acad Nutr Diet. 2017;117(2):251-264. doi:10.1016/j.jand.2016.09.021.
Jeukendrup AE. Training the gut for athletes. Sports Med. 2017;47(Suppl 1):101-110. doi:10.1007/s40279-017-0690-6.
Dethlefsen L, Relman DA. Incomplete recovery and individualized responses of the human distal gut microbiota to repeated antibiotic perturbation. Proc Natl Acad Sci U S A. 2011;108 Suppl 1:4554-4561. doi:10.1073/pnas.1000087107.
Ducarmon QR, Zwittink RD, Hornung BVH, van Schaik W, Young VB, Kuijper EJ. Gut microbiota and colonization resistance against bacterial enteric infection. Microbiol Mol Biol Rev. 2019;83(3):e00007-19. doi:10.1128/MMBR.00007-19.
Hill C, Guarner F, Reid G, Gibson GR, Merenstein DJ, Pot B, et al. Expert consensus document: the International Scientific Association for Probiotics and Prebiotics consensus statement on the scope and appropriate use of the term probiotic. Nat Rev Gastroenterol Hepatol. 2014;11(8):506-514. doi:10.1038/nrgastro.2014.66.
Gibson GR, Hutkins R, Sanders ME, Prescott SL, Reimer RA, Salminen SJ, et al. Expert consensus document: the International Scientific Association for Probiotics and Prebiotics consensus statement on the definition and scope of prebiotics. Nat Rev Gastroenterol Hepatol. 2017;14(8):491-502. doi:10.1038/nrgastro.2017.75.
Slavin J. Fiber and prebiotics: mechanisms and health benefits. Nutrients. 2013;5(4):1417-1435. doi:10.3390/nu5041417.