Exercise-induced GI problems are different for everyone. It might mean bloating, wind, pain or diarrhoea. These are all symptoms that may also occur in Irritable Bowel Syndrome (IBS). These symptoms can cause anxiety and stress, as well as affect performance and recovery. This is very important at the elite level, where small changes can have a big impact on performance.
So, what causes exercise-induced GI problems in athletes?
Research has found that the main causes of GI symptoms in athletes are either physiological, mechanical or nutritional.
Physiological: During physical activity, blood is directed away from the GI tract to the working muscles. In intense exercise, up to 80% of your blood flow can be sent to other parts of the body. Something we call ‘motility’ also changes. This means that the muscles along your GI tract that help to push food down are not working as they usually would.
Mechanical: Your posture, or the impact of physical exercise on the body can cause GI symptoms. This is more common in runners than cyclists. The impact of pounding the pavement is possibly to blame.
Nutritional: We know that nutrition can have a big influence on the GI tract, athlete or not. Fibre, fat, protein and fructose are all linked with exercise-induced GI symptoms, and dehydration can worsen symptoms. Concentrated carbohydrate drinks often consumed by athletes can also cause symptoms.
It could be that symptoms are caused by a complex mix of all of the above!
Nutritional solutions to exercise-induced GI problems
Athletes may use a range of nutrition solutions to improve symptoms. These might be using a few types of carbohydrates, lower fibre and fat intake and staying hydrated. It may even mean using nutrients to stimulate a natural chemical called ‘nitric oxide’ in the intestine – which might increase blood flow to your GI tract and reduce symptoms. In addition, training the gut over time to accept more carbohydrate and fluid has also been shown to reduce GI symptoms in exercise.
So, athletes use many strategies to combat exercise-induced GI problems and perform at their best. But many athletes who struggle with GI symptoms fail to resolve it through common approaches. This is where FODMAPs come in.
A low FODMAP diet to treat exercise-induced GI symptoms
If you aren’t familiar with the term FODMAPs – it stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. These are types of carbohydrates that our bodies don’t absorb well. Due to this, they are fermented (broken down) by the large intestine. In most people this is not a problem – and even good for us! But in people with IBS, they are particularly poorly absorbed, and this might cause the symptoms mentioned earlier – diarrhoea, bloating, wind and pain, among others.
A low FODMAP diet is a common treatment for IBS management. In IBS, the poor absorption of FODMAPs increases fluid and gas in the colon, triggering GI symptoms. Given that physiological changes create a compromised gut environment during intense physical activity, it is possible that high intakes or leftover FODMAPs in the colon could trigger or amplify GI symptoms during or after exercise.
In short – very active people are more sensitive to GI symptom triggers like FODMAPs, because of repetitive stress on the gut.
What’s the research say?
Studies show that more than 40% of athletes adopt gluten-free diets to improve GI symptoms. Interestingly, it might be an unintentional decrease in FODMAPs that actually causes symptom improvement.. A recent study found that 78% of athletes had removed at least 1 high FODMAP food to reduce GI symptoms, with a promising 82.6% seeing improvement in their symptoms.
Get Advice!
Eating a low FODMAP diet can be challenging whoever you are. But for athletes, or even the dedicated daily exerciser, it can be even harder. Dietary elimination requires careful consideration. Inadequate intake of energy or nutrients can compromise performance and gut health. A low FODMAP diet for an athlete should be implemented with a dietitian experienced in sports and FODMAPs. Nutrition suitability, variety and quantity is essential for athletes!
Quick tips to avoid exercise-induced GI symptoms:
1. Stay hydrated
2. Avoid high-fibre foods before competition
3. Practice nutrition strategies BEFORE race day
4. Avoid aspirin and Nonsteroidal Anti-Inflammatory drugs (e.g. Nurofen)
Keep in mind that these are general tips – so if you are experiencing GI symptoms, seek help from an informed dietitian or doctor!
By: Ellie Wiltshire
IG: @el.wiltshire
Image sourced from Pinterest
References:
- Fell, J, Lis, D, Kitic, C, Ahuja, K, Stellingwerff, T 2017, FODMAP removal in athletes: An online survey of specific food avoidance and associated symptoms in athletes, vol. 20., no1, pp. 9-10
- Oliveira, E.P, Burini, R.C, & Jeukendrup, A 2014, Gastrointestinal complaints during exercise: prevalence, etiology, and nutritional recommendations. Sports Medicine (Aukland, N.Z), 44(Suppl. 1), 79-85. PubMed doi: 10.1007/s40279-014-0153-2
- Lis, D, Ahuja, K.D.K, Stellingwerff, T, Kitic, C.M, Fell, J 2016, Food avoidance in athletes: FODMAP foods on the list, vol. 41, no. 9, pp. 1002-1004
- Lis, D, Ahuja, K.D.K, Stellingwerff, T, Kitic, C.M, Fell, J 2016, Case study: Utilising a low FODMAP diet to combat exercise-induced GI symptoms, International Journal of Sport Nutrition and Exercise Metabolism, vol. 26, no. 5, pp. 481-487
- Oliveira, E.P 2017, Runner’s diarrhea what is it, what causes it and how can it be prevented?, Current opinion in gastroenterology, vol. 33, no. 1, pp. 41-46
- Sports Dietitian’s Australia (SDA), The low FODMAPs diet, SDA, viewed 16 July 2017, <https://www.sportsdietitians.com.au/factsheets/diets-intolerances/the-low-fodmaps-diet/>