How to Prevent and Stop Exercise-Related Transient Abdominal Pain (ETAP): The Runner’s Guide to Stitches

All runners, from the novice to the very experienced, will at some point have felt that nagging pain in their sides: the dreaded ‘stitch’. 

And it doesn’t matter how great your legs feel or how much energy you’ve got left; when a stitch – also known as ‘exercise-related transient abdominal pain’ — kicks in, it feels like there’s nothing else to do but grimace and try to run through it.

But luckily, that’s not always the case. In this guide, we’re going to take a look at what causes a stitch when you’re running, explore how to prevent stitches when running, and share some actionable guidance on how to provide relief from a stitch when they do crop up.

What is exercise-related transient abdominal pain (ETAP)?

Exercise-related transient abdominal pain – more commonly known as a ‘stitch’ – is something that almost every runner will experience at some point in time. 

However, despite a 2014 study suggesting that 70% of runners experience a stitch at least once per year, debate continues over exactly what causes a stitch during running.

Common symptoms of stitches

Stitches are characterised by several uncomfortable and often painful symptoms. 

You’re likely to experience sharp stabbing sensations, cramping, and a feeling of ‘pulling’ and/or tightness. It’s usually just below your ribs (although some runners report feeling pain in their shoulders), and more often than not occurs on one side of the body.

What causes a stitch while running?

Frustratingly, stitches are unpredictable and can crop up seemingly out of nowhere – even on those runs when you’re feeling super fit, and you’re gliding through the miles. 

And, despite increased research into ETAP, there’s still much debate about exactly what causes a stitch while running.

However, there are three main theories.

Theory 1: Stitches are caused by parietal peritoneum irritation

The most popular theory is that stitches are triggered by irritation of the outer layer of the peritoneum (the double-layered membrane which wraps around the abdominal cavity). 
Some scientists think that, during exercises with repeated up-and-down motion and consistent torso twisting (like running or swimming), friction occurs between the two layers, leading to irritation and pain in the parietal layer (the outermost layer of peritoneum, which attaches to the abdominal and pelvic wall). 

This friction is likely to increase if you have an inefficient running technique or a weak core.

Theory 2: Stitches are caused by fatigue in the diaphragm

Another working theory is that a side stitch while running is caused by fatigue or cramping in the diaphragm, the muscle that sits just below your lungs and helps you breathe in and out. 

However, there is no definitive answer as to how this results in that all-too-familiar pain.

Some scientists believe that it’s because running causes the diaphragm to expand and contract more frequently and vigorously than normal, leading to muscular discomfort – just like you’d experience in any overworked muscle.

Others believe taking rapid, shallow breaths while running limits the amount of oxygen reaching the diaphragm through the bloodstream, causing painful cramps. 

And there is also evidence to suggest that cramping in the diaphragm can be caused by eating too close to your run. 

When you eat, blood is redirected to your digestive organs to help you digest that food. If this process is occurring during your run, it can restrict blood flow to your diaphragm, potentially causing cramping and spasms that present as a stitch.

Theory 3: Stitches are caused by spinal stress or nerve irritation

This theory suggests that a combination of poor posture, a weak core, and repeated impact during running can stress the spine and irritate nerves around the ribs and abdomen, leading to a stitch.

How to prevent stitches when running

With no conclusive answer to exactly what causes a stitch, you might think that trying to prevent a stitch when you’re running is little more than guesswork. 

However, trial and error and the sharing of best practices between professional athletes and amateur runners have resulted in a range of actionable strategies and techniques.

Fueling and hydration techniques

Studies have found that high-sugar drinks can cause stitches, so avoid fruit juices, fizzy drinks, or sugary sports drinks pre-run, and stick to good old water instead.   

And take small, regular sips of water in the hours leading up to your session, rather than guzzling large amounts in one go; a little-but-often approach to hydration will help reduce bloating, decreasing the likelihood that your stomach will press on the lining of your abdominal cavity and irritate the parietal peritoneum. 

Try not to eat large amounts of food before you run, particularly fatty or fibrous foods, which take longer to digest. While your body is working to break them down, it reduces the flow to the diaphragm, leading to the spasms we mentioned earlier. 

Instead, fuel yourself with light, easy-to-digest snacks like bananas and cereal bars, which provide sustained, slow-release energy.

Improving your core strength and stability 

As there is some evidence suggesting that weak trunk muscles could increase the likelihood of developing a stitch while running, you should add core strengthening to your training programme.

Movements like planks, bicycle crunches, and kettlebell farmers' walks are some of the best core exercises for runners. 

These can easily be done at home or in the gym, or, if you can find a nice dry patch of grass, you can even tag them on to the end of your runs; so there’s no excuse not to include these in your programme.

Adding just a few minutes of core training into your routine two or three times a week can make a big difference to your technique, strengthening your trunk muscles, diaphragm, and core cylinder to reduce the likelihood of developing stitches.

Use diaphragmatic breathing

Shallow, rapid breathing is sub-optimal for running: it means the diaphragm is almost permanently contracted, and restricts oxygen and blood flow throughout the body.
Instead, try to master the art of diaphragmatic breathing, or ‘belly breathing’. Focus on taking deeper, slower breaths that cause your belly to expand, rather than your shoulders to go up and down. This will allow your diaphragm to move efficiently without being constantly contracted, boosting the flow of oxygenated blood throughout your body.

Belly breathing does take a bit of practise, so to master it, make sure you maintain a steady, rhythmic pattern – such as inhaling for three steps and exhaling for two. Alternate which foot lands on the exhale to avoid uneven stress. 

Warm-up properly (and start your run slowly)

When you’re just popping out for a quick run, it’s often tempting to forego your warmup.

However, taking the time to prepare your body action will benefit you massively, both in terms of the number of muscle strains and niggling injuries you get and the likelihood that you’ll suffer from a stitch. 

Going straight into a race-pace session can lead to irregular, shallow breathing – which, as we know, is a recipe for disaster when it comes to stitches.

Instead, take the time to do a full running warmup, including some mobility and activation work, followed by a few minutes of brisk walking. Then spend 5-10 minutes jogging at an easy tempo before ramping up to your full session pace. 

How to stop a stitch while running

There’s nothing worse than being taken down by a side stitch, especially when you’re in full flow and hitting your pace mile after mile.

But knowing what to do next will determine whether you can carry on or have to abandon your run and return home.

Firstly, you need to slow down, either to a very gentle jog or a walk. We know it’s frustrating, but trying to run through a stitch will only make the pain worse.

Once you’ve reduced the tempo, there are a few tried-and-tested techniques that will quickly get you back on track.

Reset your breathing

Reset your breathing pattern by taking a deep breath in as far as you can, then exhale sharply. Do this for 3-5 breaths. 

Then return to diaphragmatic breathing, focusing on the 3:2 ratio: breathe in for three steps, then out for two more.

Once the pain has fully subsided, gradually increase your pace again. Don’t immediately return to running flat-out; the stitch will come right back.

Stretch your back and abdomen

Take a few moments to come to a complete standstill, then stretch your back and torso to help relieve any built-up tension which could be causing diaphragmatic spasms:

• Raise your arms above your head and gently bend to your sides; first away from the stitch, then towards it.

• Then bend forward (be careful to do this slowly so you don’t get too much of a headrush, as you’ll likely be out of breath from running).

• Finally, interlink your hands behind your head and steadily arch your back.

Remember to keep practising your deep belly breathing while performing all of these stretches.

Repeat this routine slowly and carefully until the stitch has gone, and then slowly up the tempo until you’re back in your full flow.

Apply manual pressure

Many runners find they do this technique almost instinctively – it’s like a reflex.

However, most just grab the painful area, hold on for dear life, and keep hobbling through their run, which isn’t the most effective method.

Instead, try pinpointing the exact location of the pain and pressing it with two or three fingers. Then, using your diaphragmatic breathing, exhale and increase the pressure of your fingers, pressing inward and slightly upward. 

Repeat this for a few breathing cycles and, once you’ve massaged your stitch away, you can gradually get back to your run.

Warning signs of non-typical stitches

For the most part, a stitch is nothing to worry about. It’s a normal, albeit frustrating,  part of being a runner, and once it’s subsided, you can carry on with your session.

However, some painful conditions can feel like a stitch but are more serious and require professional advice. Seek medical help if you have:

• Pain in your side that is sudden, severe, or stabbing and doesn’t improve when you slow down and follow the above techniques.

• Extreme pain spreading to your shoulders, chest, or back.

• Shortness of breath, dizziness, or faintness.

• Nausea, vomiting, or sweating.

• Pain that occurs even when you’re not exercising.

• Pain that lasts several hours or even days.

These symptoms could be indicative of more serious conditions, such as a ruptured muscle or ligament, a hernia, a gallbladder issue, appendicitis, kidney stones, or even a heart condition. Runners experiencing these symptoms should seek advice from their GP to ensure proper diagnosis and treatment.

Follow our tips to manage stitches effectively

We’d love to tell you that you’ll never experience a stitch again after reading this guide, but unfortunately, we can’t; they’re an unpredictable phenomenon that even the cleverest of scientists haven’t been able to agree on. 

However, there is tangible evidence that combining long-term strategies (such as strengthening your core) with more immediate techniques, such as effectively managing your food and drink intake pre-run, can help limit the likelihood of developing stitches.

And, if the worst does happen and you are struck down with a stitch while running, you’ve now learned three easy, actionable tactics to get you back up and running in no time.