Q&A: Bloating after running. Fizzy drinks and the gut. Probiotics and gender.

Welcome back to our weekly Q&A Wednesday. We had our first community online live event earlier this week and it was really enjoyable! We covered some common gut health problems, touching on bloating, IBS, and abdominal pain. There were loads of really great questions asked by the audience, so I’ve typed up a few of the answers and thought I’d share them here. Don’t worry if your question hasn’t been answered yet, the Q&As publish every week.

The first question (why do I get bloated with running?) is available to all subscribers. There are further questions behind the paywall (about the effects of fizzy drinks on our gut, and about whether men and women should have different probiotics).

If you have any questions that you would like to be answered in future weeks, please do submit them here.

Medical Disclaimer. Although I’m a doctor, I can’t replace your registered doctor. As such, the information in this newsletter is for information purposes only. It is not intended to be a substitute for medical advice, diagnosis or treatment. Always seek the advice of your qualified healthcare provider for any medical conditions, and never disregard professional medical advice because of information you have found in this newsletter. The publisher and authors of this newsletter assume no responsibility for any adverse effects that may result from the use of the information contained herein.

Q. I struggle with bloating after running, is there a reason for this?

• Anon

A. Great question! Yes, there are a few reasons that explain your bloating after running and the good news is there are some things that you can try out to help reduce your symptoms. The question is about running, but the answer applies to other high intensity sports.

The first culprit is gulping down water or your isotonic drink, due to your extreme thirst during or just after exercise. And because you’re so breathless, your swallowing technique is all out of sync as well. Everybody takes in a little air with every single swallow that we take usually, but if we drink too quickly, we’ll take in a large amount of air (called aerophagia)! Some air will often come straight back up as a belch, and the rest will pass down and travel through the intestines, to exit later at the other end. The solution here is obvious - try to drink more slowly and take smaller sips. This will reduce the amount of air that enters your digestive system, and so reduce your bloating after running.

The next culprit is… swallowed air, again. But this time it’s the gulping down of too much air as you breathe, just because of the breathlessness caused by the intensity of your running (and not related to drinking). There’s not much that you can do about this, but anecdotally it does improve as you become more experienced at running and get physically fitter. In addition, trying to control your breathing can help (but this can be tricky to master). Diaphragmatic breathing is a technique that can help reduce aerophagia (and acid reflux too) - watch this video to learn more about diaphragmatic breathing. This shorter video also includes the technique (both videos are from good, reputable hospitals).

This next cause is a bit more obvious - running too soon after you’ve eaten. There is no hard and fast rule for how long to leave between a meal and exercising. It depends upon the amount of food and drink consumed, the intensity of the planned exercise, and how quickly your body can process the meal. For a small snack it should be possible to engage with intensive exercise immediately. If you have a large meal, then gentle exercise such as an after dinner walk can be undertaken immediately (something I really recommend highly, for quite a few reasons including blood sugar control) but leaving 2-3 hours until exercising intensely is a reasonable yardstick.

And just the act of intensive exercise can drive the feeling of bloating. The hormone cortisol is produced by the adrenal glands, just above the kidneys, and strenuous exercise is one of the things that stimulates its production. Cortisol helps us train harder and better. (In fact cortisol has been given a bad reputation recently because of its involvement in “chronic stress” but the simple fact is that without cortisol we’d die within 24 hours). This cortisol surge causes water retention, which can lead to a bloating feeling in some people. If you are new to running, or have had a long time out of it, this symptom may be more severe. The trick here is to start your return to running gently, with slow pace and short distance and gradually build up, so that your body has time to adapt.

Finally, if you find that you’re bloated at other times but that it’s worse after running, then it may be related to something in your diet, and the act of exercise may be just “stirring up the gas”. Read our recent article on bloating for more about this.

I hope that this has been useful, and I would stress that running is a great activity. It can help boost mood, improve the function of the heart and lungs, reduce our risk of cancer and improve our blood sugar control. It also often reduces bloating! It does this by improving bowel function and reducing constipation, which is a major cause of severe bloating (we have a full review of constipation coming up in the next few weeks).