SEE: Why runners sometimes can't hold in their poo

Last year French Olympic athlete Yohan Diniz had an incredibly hard time during his 50km race. The unfortunate athlete had blood and faeces running down his legs for most of the latter part of the race. Runner's gut Despite the challenges Yohan Diniz persevered and at one stage inserted a sponge into his shorts in order to soak up the blood and faeces, and pushed through the discomfort to complete the race. What the French athlete was experiencing at the Rio Olympics is known as runner's gut or ‘trot’. Runners and walkers are more likely to experience it than other athletes. The symptoms generally manifest as grumbling, stomach pain or cramps, bloating and diarrhoea. It is understandable that people who experience irritable bowel symptoms when they run or walk can experience a lot of anxiety. And apart from the embarrassment, the disruption can also hinder their performance. Possible causes of runner's gut Dehydration Dehydration increases the risk of nausea, vomiting, diarrhoea and other gastrointestinal problems during exercise. Always be well hydrated when you start exercising; this will reduce the risk of problems associated with dehydration during sports events. Highly concentrated carbohydrate drinks Drinking fluids with a high carbohydrate concentration (greater than 10% – e.g. soft drinks, fruit juice and energy drinks) can cause diarrhoea and gut issues during exercise as they draw extra water into the gut. Standard sports drinks (4–8% carbohydrate) are less likely to cause gut upset. Reduced blood flow to the gut The blood supply to your gut gets redirected to other muscles working during your training. The decrease in blood flow to your gut can cause stomach ache, nausea, vomiting and diarrhoea. Timing of the last meal before exercise Not leaving sufficient time for your food to digest before start training could be a cause of runner’s gut. The waiting period between eating and going for a run/walk varies for everyone, but the general rule is to wait 2-4 hours after eating. The type of food eaten just before exercise Stomach related medical conditions such as coeliac disease, irritable bowel syndrome, lactose intolerance and fructose malabsorption could become worse during strenuous activity. If you enjoy a leisure run, don't let the possibility of getting runner's gut put you off, as the problem tends to affect professional athletes more than amateurs or recreational runners.