Mind & Body

Side Stitches May Be Caused By An Organ You've Never Heard Of

What causes that cramp in your side during exercise? It turns out that scientists don't actually know. There have long been two prevailing theories. The first is that it comes from a cramp in your diaphragm, the muscle that enables your lungs to fill with air. This may seem likely on its face, but it doesn't hold up when you think about the fact that side aches are a common ailment of horseback riders, who aren't breathing heavily when it happens. The second theory is that the pain comes from a jostling of your organs during excessive movement. This doesn't really hold up either, as anyone who has had a side stitch can tell you it's in a single area, not all over.

Many experts are turning to another theory: irritation of the parietal peritoneum. You may have never heard of this membrane, which lines your abdominal and pelvic cavity, but scientists—including the authors of a 2003 paper in the British Journal of Sports Medicine—think it's the most likely culprit of that mid-workout pain. Irritated by excessive movement? Check. Causes pain in a single area? Check. This organ also explains the other causes of side stitches, such as exercising after a large meal (a full belly puts pressure on the membrane), and fatigue in the middle of a long workout session (tired core muscles can make you slouch, and a slouching spine can irritate the membrane). The case isn't closed on the side-stitch mystery, but the parietal peritoneum is definitely the biggest suspect. Find out more about the science of workout woes with the videos below.

What's Causing That Stitch In Your Side?

It's a mystery, but science has some theories.

Key Facts In This Video

  1. A stitch is known as a exercise related transient abdominal pain. 00:26

  2. When exercising, you may become dehydrated, which means there is less fluid in between the layers of the peritoneum, resulting in pain. 01:37

  3. Working out to strengthen your core should reduce movement in your abdomen while exercising. 02:02

What Happens When You're Dehydrated?

Examine all the things that happen when you haven't had enough water.

Does Stretching Actually Help?

The answer: sometimes.

Key Facts In This Video

  1. The degree to which stretching affects athletic performance depends on the sport or activity. 00:18

  2. There's little evidence to suggest that stretching before or after an activity will decrease muscle soreness. 00:43

  3. Warming up before exercising can increase your muscles' potential for strength and power during the workout. 01:21

Written by Ashley Hamer October 3, 2016

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