Why Do We Get a Stitch When Running? What Researchers Know About Side Pain

Oct 13, 2026 · 4 min read · Sourced and fact-checked

The short answer: A running stitch is called exercise-related transient abdominal pain. About 70 percent of runners report it in a year, and a 2014 review says its exact cause is still not settled.

That sharp pain in your side during a run is common, and science is still working out why it happens.

What it is

A 2014 review in the journal Sports Medicine calls it exercise-related transient abdominal pain, or ETAP, commonly known as a stitch. It is especially common in activities with repeated torso movement and the torso held upright or extended, such as running and horse riding. The review says about 70 percent of runners report it in the past year, and in a single running event about one in five participants can be expected to get it.

What it feels like

The pain is usually felt on the sides of the mid abdomen along the lower rib edge, although it can occur anywhere in the abdomen. The review says it can also come with pain at the tip of the shoulder. It tends to be sharp or stabbing when severe, and cramping, aching or pulling when milder.

Who gets it

According to the review, it is most common in young people but is unrelated to sex or body type. Well-trained athletes are not immune, although they may get it less often. Eating makes it worse, and drinks with high sugar or salt concentration, called hypertonic drinks, are especially likely to set it off.

What may cause it

The review lists several theories: reduced blood flow to the diaphragm, strain on the ligaments that connect the abdominal organs to the diaphragm, gut blood flow problems or swelling, cramping of the abdominal muscles, pressure on an artery in the abdomen, irritation of spinal nerves, and irritation of the parietal peritoneum, the membrane lining the abdominal cavity. Of these, the authors say irritation of the parietal peritoneum best fits what is known, but more research is needed. The cause is not fully settled.

Possible ways to prevent it

The authors say management strategies are largely anecdotal. Commonly suggested ideas include avoiding large amounts of food and drink for at least two hours before exercise, especially hypertonic drinks, improving posture in the upper back, and strengthening the core or wearing a supportive broad belt. They describe relief techniques during an episode as equivocal, meaning the evidence is unclear.

A note

A stitch is generally harmless, but chest pain, pain that does not ease after you stop, or pain with other worrying symptoms needs a doctor. This is general information, not medical advice.

Sources

Exercise-Related Transient Abdominal Pain (ETAP), Sports Medicine, 2014 review (published September 3, 2014): https://pmc.ncbi.nlm.nih.gov/articles/PMC4281377/

Facts checked: October 13, 2026.