Gastric Distress? Dont Stress…

Posted on 18/04/2019

Runners Stomach. Whether it”s hopping from side to side in the queue for the gloriously gross port-a-loo at the weekend 10km race, or needing to find the nearest rock off the trail to crouch near and hope no-one sees, we’ve all been there probably more than we would like to admit. It’s not glamorous, during a training run it could just be uncomfortable and will result in a less effective session. During a race, though, it can be a disaster and ruin your chances of snagging that PB or podium position.

What is runny guts – I mean runners gut? And what steps can we take to avoid it?

Basic Digestion

Let’s start at the beginning. When you eat, your stomach and small intestine have to break down the food into absorbable elements and nutrients, and how quickly this occurs is influenced by the macronutrient mix, fiber content, fluidity, acidity, and meal size.

Macronutrients are digested at different rates with carbohydrates been digested fastest, fats slowest and protein somewhere in between. For example: if you ate some watermelon on its own, it would be digested and absorbed quickly due to it being a simple carbohydrate, with average fiber content and high sugar and water content. Add it to some yoghurt, or peanut butter (trust me on this – I’ve tried it, it’s good) it will be digested and absorbed slower due to adding a protein and/or fat.

In order for the watermelon and yoghurt to be digested, blood flow is directed to the digestive tract to help things along, and various hormones are secreted in a well-orchestrated symphony.

So, what changes when you run?

First, and foremost, blood is diverted away from your stomach and sent to your pumping muscles, meaning its less of a symphony and more like a grade 3 music class, with everyone thumping their instruments to a different beat. Your stomach, like any other muscle in your body, needs adequate blood flow. When the blood flow is restricted the stomach is not going to digest the food as easily as it would during a resting state.

Secondly, more of those hormones that help digest food is secreted while running which can result in anything from cramping and gas to nausea and diarrhea. Lastly, you’re bouncing around in there which makes it harder for your digestive tract to keep things in tune. So basically – the harder you’re working, the more likely you are to experience runners’ gut.

So what do we do then?

Hydration! Hydration! Hydration! Being hydrated is critically important. Dehydration can result in constipation and if you can’t empty the tank prior to running, the chances of the poop hitting the fan during the run (semi-literally) are increased significantly. Being dehydrated also means you’re further reducing the availability of blood to your stomach and you’re less likely to absorb what you take in. Say hello to undigested food sitting in your tummy, making cramping, bloating or gas an inevitability.

Overloading your stomach with exceedingly concentrated fluids or gels is also something to be aware of. Your body can only absorb so much at once and when you overload it, it results in water being drawn into the concentrated environment in your intestines (you learned about osmosis at school right?). We all know where that leads – a one-way pit stop to nowhere you want to be.

Timing of food intake is also important and based on the individual. Whilst you may be able to guzzle down a smoothie and protein bar 10minutes before going for your morning run, the next person may need to eat 3 hours in advance to prevent gastric distress. It’s all about what works for you here. If you know lactose doesn’t work for you before a run, don’t eat it, or eat it well enough in advance (+3hours). If a fiber-rich meal gets your gut going, rather opt for lower fiber options. Choose options that are moderate to low in protein and fat – you don’t want to slow things down too much – so a higher carbohydrate meal is preferable.

Runners are also notorious coffee fiends and often can’t even think about a run without their fix. But be weary – caffeine is a stimulant and if you’re prone to having a sensitive gut then be cautious of timing and figure out the best time pre-run to have it. Also, ensure you experiment with caffeinated gels/food during a training run. Figure out how much and what works for you prior to using them in races to prevent an on-the-go bowel movement.

Quick Tips

I know this seems like a lot, but here are some ‘cheat sheets’ of things to avoid/try to prevent the runs on a run.

Possible Triggers

  1. Dehydration
  2. Timing and consistency of your intake
  3. Nerves, adrenaline, excitement
  4. Caffeine
  5. Lactose
  6. Pushing yourself past your current fitness level

Possible Methods of Combat

  1. Simple, well tolerated and known foods (don’t be dumb, don’t try what you don’t know when it comes to race day. Experiment beforehand)
  2. Time and volume are proportional (i.e. longer time = bigger volume and more protein/fats. Shorter time = smaller volume, more simple carbohydrates)
  3. If it’s a reoccurring problem – keep a journal to jot down what you ate and drank prior to running to identify potential triggers
  4. Avoid things with non-nutritive sweeteners (sorbitol, xylitol, mannitol) and chewing gum as these can have laxative/bloating effects

Most importantly is to figure out what works for you. We all have different bodies that function differently under certain conditions. Don’t leave your nutrition up to chance, experiment before any big events to ensure you nail that race and don’t get down with the dumps.


Pre Run Snack Ideas

Small snacks (30-60min pre-run)

  • Rice crackers with low-fat cottage cheese or hummus and honey – all the above provide a good source of carbohydrates with minimal protein/fat and fiber.
  • Low-fat yoghurt with berries – the yoghurt and berries both provide a good source of low fiber carbs, with some fat and protein from the yoghurt for satiety.
  • Peanut butter and banana – banana is a good source of potassium, electrolytes, and carbohydrates. Peanut butter also provides a good dose of carbs and fats, keeping this relatively easy to digest pre-run. Stick it on some toast or crackers for extra carbs if you’re heading out for a longer session (opt for a lower fibre bread/cracker)
  • Fruit and Nut bar/Date balls – dried fruits/dates are a great high energy snack, paired with nuts and you’ve got a powerhouse of energy boosting foods.
  • Small muffin/banana bread – make them yourself so you can control the amount of added fats and sugar, but a small muffin/slice of banana bread pre-run has a good dose of easily digested carbohydrates. Kelly Woolf has a pretty killer banana bread recipe you should give a go!

Larger snacks/meals (60+ mins pre-run)

  • Avocado Toast – Avo is a great source of energy and healthy fats to combat post run inflammation, and the toast a good source of carbohydrates.
  • Fruit and Nut butter smoothie – fruit packs a nutrient dense carb punch with heart-healthy fats and carbs from the nut butter. Add a small serving of yoghurt if you’re able to tolerate that for an added protein and carb punch and have some extra time before the run.
  • Oats with fruits and nuts – oats, while higher in fiber, is a great source of energy and paired with inflammation-fighting fruit and healthy fats from some nuts you’ve got the perfect pre-run meal. Make it with half milk/half water or stir in your favourite protein powder if you have some time to kill before the run to keep to satiated and help with post-run recovery.
  • Granola with milk/yoghurt/nut milk – granola has a reasonable amount of fiber and a good dose of carbs (especially if it has raisins/dried fruit in it). Paired with protein and carb-rich yoghurt/milk for post-run recovery and you got a powerhouse pre-run meal. This Ginger Molasses Granola recipe from Run Fast Eat Slow is great to whip up for pre-run, post-run, pre-bed (basically anytime) snacking. Packed with nutrients and minimal added sugar you can have your cake and eat it too!
  • 3 Ingredient Pancakes – banana, oats, eggs (and salt, but that doesn’t count), these are a great option for a sweeter treat with a good whack of protein to keep you full and help prevent post-run muscle breakdown. Add some peanut butter if you’re going on a long run for some extra fuel and staying power.


If you have any advise from one runner to another, or any two cents to add – please feel free to comment below!

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