Above: Image © Izf, iStockphoto.com

You've run just about 5 km when all of a sudden, you're clutching your side in pain and your impressive stride turns into a hunched power-walk...you've been stabbed by a side stitch! Not to worry — even those hot shot runners with short shorts probably suffer a side stitch every once in a while! Side stitches, otherwise known as runner's cramps, are a common obstacle to achieving runner's high, that amazing feeling induced by a good run.

Did you know? A side stitch is caused by the pull of abdominal organs such as the liver and stomach on the diaphragm.

By understanding the science of the side stitch though, you can minimize your chances of having one come between you and that personal best half marathon time or that runner's high.

The stabbing pain in the side is caused by a pull on the diaphragm, the muscular membrane that stretches across the bottom of the ribcage to separate the thoracic cavity (lungs and heart) from the abdominal cavity (liver, stomach, intestines, etc.). As you run, the liver and stomach on the right side of the body bounce and therefore tug on the ligaments that connect them to the diaphragm.

Did you know? You might feel pain on the right side because the liver (the second largest organ after the skin!) and stomach are located on the right side of the body.

A little pull on the diaphragm causes so much fuss because it plays a key role in respiration. The diaphragm works like a dome-shaped air pump: as you inhale and draw air into the lungs, it lowers to contract, and as you exhale and expel air from the lungs, it rises to relax. This movement is controlled by the phrenic nerve, which originates in the neck. As a result, the diaphragm spasm is often accompanied by pain in the neck and shoulder region. The up and down motions of the diaphragm also explain why runners who exhale as they step their right foot down are more likely to suffer from side stitches.

The liver, the second largest organ after the skin and among the heaviest, and stomach, which are located on the right side of the body, tug the most on the diaphragm. So inhaling as your right foot hits the ground and exhaling as your left foot hits the ground is a way to minimize your chance of a side stitch.

Did you know? There are ways to relieve the pain of a side stitch and also to prevent one from stabbing during your run.

Other tips for decreasing the risk of a side stitch during exercise include:

Limit eating and drinking two to three hours before exercise (a full stomach = more pull) Stay hydrated with water though! (prevents other muscle cramps) Strengthen core muscles (flat, strong tummy muscles aren't just good for looks!) Gradually increase exercise intensity (keeps breathing more relaxed and controlled) Run on soft surfaces

Although the pain can be excruciating, a side stitch is not believed to cause any permanent damage to the body. If a side stitch hits though, there are ways to relieve the pain:

Stop or slow your pace until the pain subsides Use your hand to push the stomach in and up (right side) the ribcage and deeply exhale (eases the ligaments pull on the diaphragm) Belly breathe: push your belly out like a balloon on the inhale, relax on the exhale (allows the diaphragm to lower fully, reducing the stress on it)

Whether for first place glory in a marathon or just runner's high, these tools to understand, prevent and deal with side stitches are the keys to a happy diaphragm and a good run.

Learn More!

Side stitch - Wiki

Side Stitch - How Stuff Works

Article - Runners World

Alison Palmer has a BSc in Chemistry from the University of British Columbia and is currently completing an MSc in Chemical Biology at McGill University, where she modifies DNA to make it do tricks. She loves to talk and write about science, and hopes to pursue a career in science journalism.

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