Running a marathon is a monumental challenge, with athletes covering up to 60,000 steps, burning over 3,000 calories, and losing litres of sweat. While dehydration, electrolyte imbalances, and heatstroke are well-known risks, another common issue is runner's diarrhoea, affecting up to 96% of endurance runners.
Runner's trots involve urgent diarrhoea, cramping, and a strong urge to defecate. In most cases, it is manageable with fluid and electrolyte replacement, but severe instances may show blood in stool, indicating possible mechanical bowel damage from the jostling of running.
The exact cause is unclear, but several factors contribute. During exercise, blood is diverted from the gut to the heart, lungs, and muscles, potentially irritating the gut lining and affecting gut bacteria. Diet also plays a role; high-protein, high-fat, and high-fibre foods can increase gut activity. Caffeine and certain carbohydrates, like lactose and high-fructose fruits, may worsen symptoms by speeding digestion and causing fermentation.
Psychological factors, such as anxiety, may also trigger runner's diarrhoea, similar to irritable bowel syndrome. To avoid it, runners should eat a familiar, low-fibre breakfast, such as a plain bagel or rice cereal, and avoid new foods on race day. Fruits like strawberries and bananas are safer choices.
Timing is crucial: eat 2-3 hours before the race to allow digestion. Hydration with water and electrolytes is essential, as both are lost through sweat. Small, regular sips of water or sports drinks can help maintain balance without overloading the stomach.
