It’s never good when the biggest success of race day is making it to the toilet in time before there’s an accident! I’m talking about the pervasive problem that is the dreaded Gastrointestinal (GI) distress associated with endurance events.
Nausea, vomiting, stomach cramping and diarrhoea has been noted in 37-47% of runners participating in races ranging between 67-161km in distance. Nausea and vomiting are some of the main reasons for racers dropping out of ultra endurance events, and the second most common cause of reduced racing performance among athletes who finished the race!
This is an unfortunate inevitability for many ultra endurance competitors, but in order to minimise the effects, do not exceed 100g of carbs per hour of racing. Your body can metabolise around 100g of carbs per hour, so exceeding this level will lead to GI distress. The impact associated with running also stimulates the bowel, so getting the dietary side of things right is crucial!
Stuempfle, K, J., Hoffman, M, D., & Hew-Butler, T. (2013). Association of Gastrointestinal Distress in Ultramarathoners With Race Diet. International Journal of Sport Nutrition and Exercise Metabolism. 23, 103-109.