Runner’s tummy: what to do if you get the runs on a run

11th October, 2023

So why do runners get tummy troubles?

Ever had tummy troubles during or after a run? If you’re a runner, you may have experienced the dreaded “runnner’s stomach” – the uncomfortable and sometimes painful digestive issues that can pop up during or after a run. 

Whether it’s cramps, bloating, diarrhoea, or nausea, a troublesome tummy can be frustrating and disrupt your exercise routine. If you’ve felt the effects, you’re not alone. It’s estimated to affect up to a whopping 90% of runners. 

There are several reasons for these symptoms – as well as the physical jostling itself, it can often be down to your body diverting the blood flow away from your digestion to where your muscles need it most. This can lead to a more permeable or “leaky” gut. 

If you’re not properly hydrated, this can also contribute to constipation and cramping, while fuelling with high-fibre or high-fat foods too close to a run can give you some digestive discomfort. Stress can also be a factor, and if you have any existing tummy troubles like IBS, running can be a trigger. 

Is it IBS? 

One study investigated tummy troubles among 430 endurance athletes (think marathons and triathlons) and found that over 56% of the athletes experienced at least one gut symptom during training or during a competition. 

While only 2.8% of them had been diagnosed with irritable bowel syndrome (IBS), the researchers found that actually 9.8% of them met the criteria for IBS. This shows that most athletes who suffer from IBS haven’t been diagnosed, and even more experience troublesome tummy symptoms. 

The take-home message: if you’re experiencing symptoms, it could be well worth looking into IBS and trying out our top tips. 

How to reduce the runs while running

The good news is there are several things you can try to keep your tummy happy while you’re pounding the pavement: 

1. Drink up 

Drink plenty of fluids before, during, and after your run to avoid dehydration. When you’re dehydrated, your body tries to save its water by taking it away from your tummy. And this can lead to gut symptoms. For a long run, aim to drink enough water regularly (without downing it too quickly!) and take your time to figure out the right amount of fluid for you. 

2. Mind your meals 

High-fibre and high-fat foods can take longer to digest, so try avoiding these just before a run. Instead, go for easy-to-digest carbs like toast or a banana.  

What about FODMAPs?

FODMAPs are types of carbs that are highly fermented in your tummy (you can read more about those here). Some initial studies suggest avoiding high-FODMAP foods in the short-term before a run can help you reduce the risk of runner’s tum. So it might be worth missing out on FODMAP foods like garlic, onion and beans temporarily. Just remember to reintroduce those tummy-loving foods afterwards! 

3. Test the timing 

Some runners find running in the morning on an empty stomach is easy on their tummies, but others find a small snack before running helps. Experiment to see what suits you. For most of us, giving your tummy time to digest your food by eating at least 2-3 hours before going for a run is a good idea. 

4. Watch the caffeine 

It might seem like a good idea to down a caffeinated energy drink right before the off, but caffeine stimulates your gut to move, which might cause a sudden need to go, after you go! Instead, opt for smaller, more regular hits of caffeine throughout the race or try getting your caffeine from matcha, which reduces some of the side effects of caffeine due to the presence of l-theanine.  

5. Make time for mindfulness 

Feeling the pre-race nerves? Stress can have a big impact on your tummy and can trigger trouble like bloating, nausea and diarrhoea. You might even notice that you need to use the toilet more frequently before a big race! Try practicing stress-busting techniques like deep breathing, meditation, or yoga to calm those nerves for peak performance and a happy gut. 

Want to know what supplements can help runner’s tummy? 

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