Side cramps, or “stitches,” are a common occurrence in runners, walkers, and people beginning a strenuous aerobic exercise program or workout. Symptoms are described as a fleeting sharp cramping or catching pain in the side of your chest wall or abdomen. They occur with running or exertion and resolve with rest.

Like muscle cramping in general, “stitches” do not pose any serious health risk. There are no definite answers to what causes them, but there are some theories.

In general, stitches will stop occurring as you get more fit. They are believed to be caused by inefficient blood flow, a phenomenon that improves with regular training. They should become less frequent and are likely to disappear if you are running several times a week.

Many runners find stitches to be breathing related, occurring with heavy breathing. In these instances, stitches are likely tiny muscle cramps in the diaphragm or intercostal muscles – all muscles used to breathe. These kinds of stitches resolve with gentle shallow breathing and rest. Putting your arms over your head and lying down should stop the pain quickly. If you do not want to interrupt your run, try leaning to the side of the pain, breathing through pursed lips, and slowing down the rate of breathing.

In regards to meal timing, after you eat, blood flow gets directed to your stomach, liver and intestinal system, “stealing” it from your breathing muscles. If breathing muscles are not well trained, they are more susceptible to the low blood flow and can cramp and cause pain. Poor sleep, dehydration or poor nutrition may make you more prone to recurrence.

Some “stitches” are thought to be gas trapped in your bowels. They could also be a symptom of irritable bowel syndrome, colitis, or hernia. If the pain is persistent, or is associated with bowel movement changes, you should see a doctor to make sure your electrolytes, gastrointestinal system, and overall health are not in jeopardy.