Exercise is widely promoted in public health policy as being good for our mental and physical health and usually it is.
In our relatively sedentary 21st century existence, exercise is seen as a way for people to strengthen their musculoskeletal and cardiovascular health and as a means to prevent and manage non-communicable diseases such as diabetes, obesity and heart disease. Exercise also encourages people to get out into their community, to enjoy their environment and maybe join others in group exercise activities.
While every bit of exercise does accrue health benefits in this way the duration and intensity of exercise can be very important and for some people the strain of exercise may compromise the function of the gastrointestinal tract and lead to gastrointestinal symptoms.
Now known as “exercise induced gastrointestinal syndrome” it’s symptoms can affect the upper intestinal tract such as heartburn, reflux, nausea and vomiting or lower GI tract such as bloating, flatulence, diarrhoea, abdominal pain and cramping.1
There has been a lot of research recently around the effects of endurance and ultra-endurance exercise, on the gut health of athletes as more of them report the gut health problems they are facing. There is also a growing awareness that some people may have a greater pre-disposition than others to gut health problems which may be aggravated by untoward exercise strain.2-4
One common example of this is “Runner’s Trots”, when sometimes athletes experience an overwhelming need to defecate while running.
Diarrhoea, along with other signs of gastrointestinal distress caused by the physical motion of exercise, affects athletes involved in endurance and long distance running and cycling, events, especially those lasting more than 2 hours in hot or humid conditions at high intensity (i.e>60% VO2 max).1
There are several reasons attributed to this occurring:
- Heat stress, when blood is directed away from the gut to skeletal muscles and the body’s peripheral circulation, can have the effect of impairing gastric emptying times, reducing the ability to digest and absorb nutrients and the gut lining can be left more permeable and prone to inflammation and injury1, 5.
- The jarring action of running jolts the GI tract organs against the abdominal wall which may increase the sense of urgency and need for the athlete to break for a toilet stop.
- The body position of the athlete during exercise may cause discomfort. Cyclist (especially if adopting the hunched ‘aero’ position) and rowers may find their confined space in the boat, compresses their abdomen, increasing the urge to defecate compared to other athletes.
- Female athletes are more likely to experience exercise induced gastrointestinal syndrome than males.
- Some individuals with recurrent symptoms of this syndrome may have a greater predisposition to its occurrence.
- Feeding during exercise when the gastrointestinal tract may already be compromised may be a risk factor for some athletes.
While these symptoms are very individual they can be stressful and interrupt an athletes ability to train and temporarily alter the absorption of key nutrients. So if this is affecting you let’s consider some of the dietary factors that may help to alleviate some of the problems.
- Avoid dehydration and also drinks with a high carbohydrate concentration (>10%) such as energy drinks or fruit juice. Sports drinks with a lower 4-8% carbohydrate concentration or water are preferable.
- Carbonated drinks (including sparkling mineral water) can increase bloated feelings and abdominal pain, so are best avoided.
- Avoid eating main meals too close to the event allow 2-4 hrs before eating and exercise.
- Mind the type of foods that you eat pre-event. High fat and high protein foods delay emptying of the stomach which can cause gastro-intestinal upset. While normally an athlete may eat good sources of dietary fibre day to day, on event days and in 2 days pre-event more refined forms of carbohydrate may sit more comfortably in the gut. Do practice this before adopting for main events.
- People with gut related medical problems, such as Coeliac disease, Irritable bowel syndrome, Lactose or fructose intolerance as well as some people with allergies, may find that exercise compounds their symptoms. Affected athletes may need to refine their meal plans with a Sports Dietitian.
- The adoption of gluten free diets by non-coeliac athletes is so far not supported by blinded control study however some athletes may benefit from the short- term use low FODMAP diets to reduce exercise induced gastrointestinal symptoms.6
- Research to improve nutrient absorption during endurance events has found gut training using carbohydrate can help.
This information is just some of the topics covered in my new book “How to grow an athlete- from playground to podium” out soon.
If this topic is relevant to you, a friend or family member and you would like personal help then contact me, for a nutritional assessment and advice that could aid your performance and reduce health risks.
- Costa, R.J.S., Snipe, R.M.J., Kitic, C.M., Glibson, P.R., ‘Systematic review: exercise-induced gastrointestinal syndrome – implications for health and intestinal disease’, Alimentary Pharmacology and Therapeutics, 2017, 46(3), 246–65.
- Costa RJS, Snipe R, Camões‐Costa V, Scheer BV, Murray A. The impact of gastrointestinal symptoms and dermatological injuries on nutritional intake and hydration status during ultramarathon events. Sports Med‐Open. 2016; 2: 1‐ 14.
- Jeukendrup AE, Vet‐Joop K, Sturk A, et al. Relationship between gastro‐intestinal complaints and endotoxaemia, cytokine release and the acute‐phase reaction during and after a long‐distance triathlon in highly trained men. Clin Sci. 2000; 98: 47‐ 55
- Stuempfle KJ, Hoffman MD. Gastrointestinal distress is common during a 161‐km ultramarathon. J Sports Sci. 2015; 33: 1814‐ 1821.
- van Wijck K, Lenaerts K, Grootjans J, et al. Physiology and pathophysiology of splanchnic hypoperfusion and intestinal injury during exercise: strategies for evaluation and preventions. Am J Physiol. 2012; 303: G155‐G168.
- The FODMAP Diet ‘Shepherd Works’, https://shepherdworks.com.au.
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