Have you ever had your runner’s high burst by the sudden urge to run to the washroom? Congratulations, you’ve joined the club of endurance athletes suffering from exercise-induced digestive upset, not-so-fondly known as “runner’s gut.”
This condition refers to gastrointestinal distress during or immediately following exercise and can include symptoms like cramping, nausea, bloating, diarrhea and bowel urgency. Distance runners are notorious for digestive complaints, with some studies reporting 30 to 90 per cent prevalence in these athletes.
If you’re part of that statistic, fear not. Although there’s no cure for runner’s gut, understanding the root causes and corrective action can help prevent frequent flare-ups.
Causes of Runner’s Gut
There are a couple of factors that make runners more prone to gastrointestinal issues. Firstly, repetitive, high-impact sports, like running, causes jostling of the stomach and intestines. All the sloshing can contribute to symptoms like diarrhea or feeling the sudden urge to go.
Secondly, intense and prolonged exercise reduces blood flow to the digestive system which can cause injury to the lining of the intestinal tract, increasing gut sensitivity.
Unfortunately, not much can be done to mitigate these causes of runner’s gut; however, there are several nutritional factors that also increase your risk of trots.
Dehydration
Dehydration occurs when excessive fluid loss disrupts normal digestion. During exercise, sweating increases the risk of dehydration and losing more than two per cent of body weight in fluids can lead to nausea, vomiting, and diarrhea. Staying properly hydrated is essential for maintaining digestive and overall health.
Timing and Type of Pre-Workout Foods
Exercise temporarily slows digestion, so your body needs enough time to process food before activity. The type of food you eat also impacts digestion speed. High-fibre, fat, and protein-rich foods take longer to break down, whereas simple carbohydrates digest quickly, providing fast energy for workouts.
Hypertonic Solutions
Hypertonic solutions contain a high concentration of solutes, such as sugar or salt. When consumed in large amounts, they pull water into the gut from surrounding tissues, potentially causing bloating, cramping, diarrhea, and worsening dehydration.
Other Considerations
Anxiety can significantly affect digestion through the gut-brain axis. Pre-workout nerves trigger stress hormones that influence gut movement, leading to nausea, cramping, diarrhea, or constipation. Managing stress and choosing easily digestible
foods can help prevent digestive discomfort before exercise.
Practical Tips to Reduce Your Risk of Digestive Upset
- Start exercise hydrated
Athletes should always keep a water bottle with them to promote good hydration. Sipping throughout the day helps your body better absorb the fluid better than chugging large amounts in one sitting. Most people can benefit from aiming to drink five to 10 millilitres per kilogram of body weight four hours before exercise, and another three to five millilitres per kilogram of body weight two hours before exercise, if you have not urinated or only produced small amounts of dark urine. - Modify your pre-workout meal
Before training, focus on higher carb and moderate protein meals that you tolerate well. If you are prone to stomach upset, a good rule of thumb is to leave two to four hours between your pre-workout meal and exercise. Toast with peanut butter and honey, oatmeal with cinnamon and banana, or a smoothie with fruit are examples of meals to have two to four hours before training. If consuming food less than 90 minutes before exercise, focus on simple carbs that will digest quickly such as dates, saltine crackers, or rice cakes with jam or honey. - Avoid very high carbohydrate drinks
Fruit juices, soft drinks, and energy drinks tend to be hypertonic, meaning they have high concentrations of dissolved carbohydrate which draws water into gut, leading to diarrhea, dehydration, and bowel urgency. Opt for traditional sports drinks which are formulated to be hypotonic, making them ideal for hydration. - Develop a relaxation routine
Reduce anxiety-related digestive upset by using relaxation techniques before training. Guided meditation and visualization can also be powerful tools to help athletes feel calm and focused going into a training session or race. Reading, journaling, or watching TV are other great ways to relax before a workout. - Focus on variety
Some data suggests that people who eat a variety of plant foods have better gut health. While it’s recommended to avoid unfamiliar foods before training and races, expanding the variety of foods in your diet can support good gut health in the long term. Choosing different coloured fruits and vegetables, experimenting with new spices, and adding more plant-based protein to meals are easy ways to increase variety in your diet. - Training your gut
Our guts are adaptable, meaning we can build up tolerance to foods during exercise. More research is needed to give specific strategies for how to train your gut, but the key is to practice eating during your longer runs to help improve your body’s ability to absorb and use nutrients during exercise. Take it slow and experiment with different fuelling strategies until you figure out what works best for you.
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