Why does my side hurt when I run? If you are having the same experience, it may very well be a side stitch. And, you’re not the only one. Approximately 70% of runners report experiencing a side stitch.

A side stitch is exercise-related transient abdominal pain. It typically occurs in the upper abdomen, with right side pain being more common than left side pain.

Read on to find out more about why your side hurts when you run and what science has to say about this common condition.

What Is a Side Stitch?

A side stitch is an abdominal pain you feel when running or performing other exercises such as sit-ups. Side stitches are also common while riding on horseback.

For some people, side stitches feel like stabbing pain. For others, they feel more like stomach cramps or stomachaches.

A side stitch can affect a new or beginner runner as well as professional athletes. However, the latter may be more aware of the potential triggers, which allows them to better predict and prevent the pain.

What Causes Side Stitch?

Before we delve further into what causes your side to hurt when you run, it’s important to note that the mechanism responsible for side stitch pain is not yet fully known.

Doctors and researchers theorize that side stitches may be caused by diaphragmatic ischemia or blood movement to the diaphragm, the major muscle responsible for respiration.

According to another theory, side stitches may occur when the abdominal or pelvic cavity lining becomes inflamed due to movement. This theory claims that gravity tugs at the ligaments in your abdomen when you run or exercise, causing the lining to become irritated.

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Irritation of the spinal column is yet another potential explanation. According to this theory, running puts stress on a spinal nerve that runs to the diaphragm. The grounds for this is that putting manual pressure on the vertebra of the upper spine can replicate side stitch pain.

Side stitches have also been linked to age, sex, or physical condition, with younger runners and females being more likely to experience it. It has also been associated with gastrointestinal disease, pre-exercise food choices, and running form.

However, while these theories may bring us closer to a full understanding of the causes of the condition, none fully explain the occurrence of side pain across different categories of runners.

According to the Cleveland Clinic, an imbalance of electrolytes in the body may also contribute to a side stitch. Electrolytes are essential nutrients like sodium, potassium, and calcium. The link between them and muscle cramps during running or intense exercise is well documented.

The good news is that even if the cause of side pain may remain shrouded in mystery for now, you can prevent a side stitch and all the pain and annoyance that come with it.

How to Prevent Side Stitch?

With a few preventive measures, you can make the most of your runs by reducing the risk of side pain. None of these methods is infallible, but they can certainly help.

Bear in mind that side stitch triggers could be different for different people. So you may want to put into practice different preventative methods until you discover the one that works for you best.

Foods to Avoid

Before going for a run or exercising, avoid high-fat and high-fiber foods. These foods take longer to digest, giving your stomach more work to do.

Also, you want to avoid drinking sugary beverages and high-carb drinks as research indicates these increase the risk for a side stitch.

Do Not Run on a Full Stomach

Following from the previous point, you want to avoid running on a full stomach, which may put further strain on your abdominal area. 

Be mindful of food before a run. Eat a light breakfast at least an hour before you lace your shoes or put it off after your run.

Hydrate Properly

Stay hydrated while running or exercising to prevent muscle cramps and electrolyte depletion. According to the same study cited above, drinking low-carb sports drinks is less likely to trigger a side stitch.

Tip: You can make your sports drink by adding still water, lemon juice, a small pinch of salt, and, optionally, a natural sweetener like stevia. Just make sure you take a running bottle with you.

Slow Down

Don’t push yourself too much too soon. Shift down a gear if you feel the stitch pain appearing. Take a break if needed. Pain while running is often a signal your body sends you to take it easier.

Breathe Deeply

Breathe through your mouth as you run. Exhale slowly, being aware of your breathing. This simple breathing technique can help ensure you take in enough oxygen, which your muscles need to keep running.

You can also practice belly breathing before you run and as you move. Focus on breathing with your abdomen rather than with your chest.

Control Your Breathing

Breathing well can help you avoid a side stitch, so try to breathe evenly, not too fast or too slow. Count and focus on your breathing as you run, making sure you breathe deeply. 

Pre-Stretch Your Abdominal Muscles

Always warm up before you run, and pay special attention to your abs. Stretch with side torso twists and other similar exercises.

Get Strong Abs

Perform lower back and abdominal exercises regularly. Incorporating these exercises into your workout routine will strengthen your abs, which may reduce the risk of side stitches.

Practice Good Posture

You may have heard this a million times before, but it’s worth repeating—run tall, with your body well aligned.

Running with your head forward increases the risk for side stitches, according to this study.

Maintaining a good posture for your upper body is the key to making your abdomen work more easily as you run. Focus on your core.

Gradually Increase Your Fitness Level

Slow and steady is the way to go to improve as a runner as well as to mitigate the risk of side stitches and common injuries like the runner’s knee.

Increase mileage gradually by 10 to 15% every week or according to your running plan. Don’t go beyond that even if you feel you can handle it.

How to Treat a Side Stitch?

We’ve looked at ways to prevent a side stitch. But what if you’re kinda having one even as you read this? Getting a side stitch now and then is okay and nothing to worry about. There are ways to deal with it. Here are the most effective:

  • Stop moving and apply pressure to the area with your fingers. Do it gently, feeling the spot where it hurts.
  • Try bending your upper body forward as you apply the pressure.
  • Take a deep breath and exhale the air slowly.
  • Raise the arm on the affected side and lean toward the opposite side. Remain stretched for 30 seconds and then repeat on the other side.
  • Drink some water to stay hydrated. Even better, take in some electrolytes. Having a running supplement at home can prove useful.

A side stitch is usually nothing to worry about. Yes, it may slow you down, but it will usually go away within minutes.

In the end, to reduce your risk of side stitches, combine preventive measures and make sure you’re properly hydrated and nourished.

And if you do happen to get a side stitch now and then, don’t worry—most runners do!

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Written by

Chris Zibutis

Chris Zibutis is the Head Running Coach and founder of Joggo – that one person on earth who loves interval runs.  He holds a degree from Copenhagen Business School and is an avid runner – having participated in numerous marathons and triathlons, Chris brings substantial fitness and running experience to the Joggo team.