Most athletes will have experienced the dreaded “runner’s tummy” but how might we reduce the chances of suffering with it?

With spring marathons likely the focus for many distance runners right now, the dreaded “runner’s tummy” is sure to be something many readers of AW will have suffered with recently. There is nothing worse when halfway through a run a battle begins between tummy, legs and brain.

Crippling stomach cramps can appear out of nowhere. How many of you have been out on a run when suddenly you have needed a quick dash behind the nearest bush? It’s amazing that it almost always happens when and where you don’t want it to. The end result is usually a hobble back home and bent-over double with discomfort. As well as being embarrassing, it can also be a massive hindrance to achieving your training and competition goals.

Gastro-intestinal (GI) problems are experienced by many athletes and can be presented in ways, such as diarrhoea, cramps, vomiting, nausea and GI bleeding to name but a few. So, what can we do to reduce the chance of it happening? The research is limited, but the causes and recommendations on minimising its occurrence can be made to susceptible individuals.

Why does it happen?

It is known that high-intensity exercise causes a redistribution of blood flow away from the gut to the working muscles and skin. This lack of blood flow (GI ischemia) is thought to be the main contributor to GI symptoms. In addition, hormonal changes, increased GI motility (contraction of the muscles that mix and propel the contents in the GI tract), altered absorption and mechanical bouncing are all postulated to cause GI distress. Although very individual, manipulation of dietary intake and correct feeding strategies could play a part in improving and minimising symptoms.

Which food causes problems?

Food sensitivity is very individual and those that suffer from GI stress while running may find a variety of foods trigger their symptoms. More commonly, foods high in fibre and fat have been found to aggravate the gut during intense running. In normal day-to-day training, high-fibre foods are vital for a healthy gut. However, fibre is not easily digested and slows gastric emptying. As a result, foods high in fibre such as granary bread, bran-based cereals and fruit and vegetables can all contribute to gut problems during an intense training session or in a race.

In the same way, foods high in fat could slow gut transit and could therefore be another potential culprit. High concentrated levels of carbohydrate ingested during exercise is a commonly reported trigger to GI discomfort while undiagnosed intolerances like lactose could be an underlying trigger to runner’s tummy.

Reducing runner’s tummy

» Keep a food and symptoms diary. This may help you identify any trigger foods causing your problems. Also, trialling ingestion food and drink during intense training sessions is vital to assess tolerance.

» Follow a low-fibre diet 24-48 hours before a race. Eating refined carbohydrates such as white bread, pasta and rice and also limiting the amount of fruit and vegetables 24-36 hours before you race can also help reduce gut problems.

» Avoid foods high in fat on the day of racing or intense training.

» Keep hydrated. Although many runners feel that drinking while running may aggravate their gut, dehydration can be equally detrimental. Running and drinking is not easy, but if you practise this during training, maintaining hydration should contribute to a more settled gut.

» The gut is trainable, so practise consuming carbohydrate while exercising. In events lasting longer than 2hr 30min if consuming multi-transportable carbohydrates (glucose:fructose or maltodextrin:fructose), absorption can be as high as 90g/hr. However, tolerance levels will differ between individuals and therefore must be practised well in advance of the event.

» Ensure your main meal is no less than three hours before an event or session. You may want something small to eat an hour before you race, but you will need to practise to find out what you can tolerate.

» If you suspect a lactose intolerance consult a dietician. Plenty of lactose-free alternatives are available in supermarkets. You will need to check, though, with a healthcare professional to ensure you are getting enough calcium. Don’t eliminate any food group without consultation.

» Don’t stress! If you are an individual predisposed to runner’s tummy, the anxiety it can cause, coupled with pre-race nerves can have you lining up for the portaloos time after time. Try relaxation and self-talk techniques and perhaps try a light run before your event to get your bowel moving before your event.

» Alexandra Cook BSc P.g. Dip RD is a sports dietitian and a club runner with Thames Hare & Hounds. Alexandra Nutrition is a private dietetic and nutrition consultancy covering Lincolnshire, Rutland and Leicestershire (