Can exercise cause Gastrointestinal Symptoms?
3 minute read
Vicky is a Registered Performance Nutritionist, currently researching Gastrointestinal symptoms in athletes at the University of Westminster. We have previously heard from Vicky Newbold on effect exercise potentially has on gut microbiome diversity and gastrointestinal symptoms. So let’s find out more…
What are gastrointestinal symptoms?
Gastrointestinal (GI) symptoms can be described as either upper-GI symptoms (nausea, vomiting, upper abdominal bloating, belching, chest pain and heartburn) or lower-GI symptoms (flatulence, urge to defecate, lower abdominal pain, loose stools, diarrhoea and bloody stools). Many of us will experience symptoms such as bloating, belching and flatulence as part of the normal digestion and absorption of our food. However, when experienced frequently or with severity, these symptoms can sometimes accompany a more serious clinical diagnosis of IBS, IBD or Crohn's disease.
How can exercise cause gastrointestinal symptoms?
There are several ways in which exercise can cause these symptoms, the main mechanism is linked to the redirection of blood flow away from the digestive system and towards the working muscles. This can slow down the transit of food, causing GI symptoms and may in some cases lead to damage to the lining of your gut. This seems to occur particularly during high-intensity or prolonged exercise
Other factors which influence the extent of GI symptoms are the temperature of the environment and whether you are dehydrated.
If I’m healthy, but do have GI symptoms, is exercise still beneficial?
Gastrointestinal (GI) symptoms are frequently reported by elite endurance athletes. Some studies have shown that for athletes who experience GI symptoms at rest, they can be made worse by exercise. However, the opposite has been shown in non-athletic populations, so perhaps the total amount of training is a factor. However it’s not just the elite athletes who experience GI symptoms, in one study almost a third of recreational marathon runners reported GI symptoms during their race.
“Some studies have shown that for athletes who experience GI symptoms at rest, they can be made worse by exercise.”
Does the type of exercise influence GI symptoms?
High-intensity and long duration exercises can cause some unpleasant GI symptoms such as diarrhoea, stomach cramping, bloating, nausea, heartburn, flatulence and vomiting. The up and down jostling movement of running is thought to be a factor, although cyclists can also experience GI symptoms. Regular, light to moderate exercise appears to be beneficial for those with gastrointestinal disorders (related to the transit of food through the gut), helping to reduce build-up of gas and residues in the gut. Early studies indicate that moderate exercise may have an anti-inflammatory effect and may diminish some symptoms of IBD. There is also emerging research to support claims that yoga can help manage IBS symptoms, although better quality research is needed.
Is it just the type of exercise which could exacerbate GI symptoms?
No, adequate hydration appears to be key. The consumption of appropriate quantities of carbohydrate have helped to reduce GI symptoms during 2 hours of running. The type of carbohydrate can influence GI symptoms and there is growing evidence to support the use of short-term low FODMAP diets. The use of probiotics to reduce GI symptoms in runners is also an emerging area of research showing some promise
It appears that the response to exercise is highly individual. There is already a large body of research on this topic but it doesn’t have all the answers yet. Many of the studies have been on elite athletes who undertake intense training schedules and there is little understanding of how the psychological response to the stress of competing might also influence GI symptoms.
“Adequate hydration appears to be key”
If I am experiencing GI symptoms, what should I do when it comes to exercise?
Regular light to moderate exercise is less likely to exacerbate your symptoms
Avoid eating close to exercise, leave at least 1-2 hours before exercising
Avoid eating foods high in fat, fibre or protein in any pre-workout meal
Consider avoiding foods which are high in FODMAPs just before exercise
Aim for good overall hydration but don’t drink large quantities of fluid close to exercise
Speak to your GP if you have any concerns about your symptoms
Words by Vicky Newbold
Vicky is a AfN and SENr Registered Performance Nutritionist (ANutr, SENr) with an MSc in Sport and Exercise Nutrition. She runs her own nutrition consultancy practice and is also a Research Assistant at the University of Westminster.
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