Causes of Side Stitches During Exercise

Understanding Exercise-Related Transient Abdominal Pain (ETAP)

A man exhausted from jogging

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Most runners have experienced a side stitch (also known as a side cramp, side sticker, or side ache) at one time or another during exercise. This sudden sharp or stabbing pain is usually felt on the right lower abdomen just below the ribs. It is especially common among runners and swimmers.

In the medical community, side stitches are referred to as exercise-related transient abdominal pain (ETAP), as they only occur during exercise and rarely require medical treatment. With that said, side stitches can be severe enough to stop you in your tracks and compromise your performance. With a few precautionary measures, you may be able to prevent or minimize the severity of side stitches during exercise.

Causes of Side Stitches

While there is no definitive explanation as to the cause of a side stitch, researchers have proposed two bodies of theory to explain the phenomenon: dietary-related causes and physiology-related causes.

Dietary Causes

Many scientists believe that the foods we eat prior to exercise are the predominant causes of ETAP. Interestingly, the volume of food eaten seems to have less of an effect than either the timing of a meal or the types of food eaten.

An early study conducted by the University of Newcastle in Australia found that the consumption of juices or beverages high in carbohydrates (11% concentration or greater) just before or during exercise increased the risk of ETAP.

By contrast, people who consumed water or low-carb sports drinks experienced fewer side stitches. It has also been proposed that excessive protein can trigger side stitches, including milk, protein bars, and high-protein shakes.

While age appears to play a role in the risk of ETAP—with older adults less prone to side stitches than children, adolescents, or younger adults—a person's sex or body mass index does not. Even well-trained athletes are not immune to ETAP.


Exercise, in and of itself, is not a risk factor for side stitches; neither is the intensity of the exercise. If anything, ETAP is closely associated with repetitive movements in which the torso is repeatedly extended. This would explain why side stitches can affect horse riders or off-track racers whose upper bodies are placed under rapid, repetitive stress.

The structures of the body affected by this stress may include the:

  • Diaphragm, the muscle layer situated between the abdominal cavity and lungs
  • Lumbar spine, an area located on the lower back
  • Parietal peritoneum, the soft lining of the abdomen and pelvic cavity that surrounds most of the internal organs
  • Peritoneal ligaments, the connective tissues that hold the internal organs in place

It is possible that the friction between the tissue layers, as well as the stretching of ligaments and muscles, can trigger spasms and inflame nerve endings of the spine and peritoneum. The parietal peritoneum is especially rich in phrenic and thoracoabdominal nerves which are extremely sensitive to pressure and pain.

With regards to running, the jarring of the torso typically occurs in rhythm to your breathing. Runners tend to exhale every two or four steps. While most exhale as the left foot hits the ground, some exhale on the right. It is the latter group that seems to be more prone to side stitches.

It has been theorized that exhaling on the right foot exerts greater pressure on the liver (which is also situated on the right just under the ribs), which causes the diaphragm to lift at the same time that the liver drops, stretching the peritoneal ligaments and potentially triggering ETAP.

Treatment and Prevention

Regardless of the cause, ETAP can affect an athlete's performance. Among runners especially, the problem is not insignificant.

According to research published in the Sports Medicine, 70% of runners experience at least one episode of ETAP each year, while one out of five runners will experience a side stitch during a running event.

Here are several ways to better cope with side stitches or possibly avoid them altogether:

  • Change your stride-breathing pattern. Most runners follow a two-to-one breathing pattern, taking one full breath for every two full strides. Consciously changing that pattern every now and then may reduce the stress placed on the abdomen and torso.
  • Eat and hydrate appropriately. Avoid heavy meals just before exercise, especially foods high in protein. When training, sip rather than chug fluids and avoid drinks with high concentrations of acid, sugar (carbohydrate), or sodium.
  • Focus on your core. Incorporate core muscle work into your training, including planks, side planks, and V-sits.
  • Practice belly breathing. Instead of breathing with your chest, learn to breathe with your diaphragm by extending your belly during inhalations and pulling in your belly during exhalation.

If you develop a side stitch when running or swimming, stop and place your hand on the right side of your belly, pushing upward as you inhale and exhale evenly.

Stretching may also help relieve the pain of a stitch. Raise your right arm straight up and lean toward the left. Hold for 30 seconds, release, and then stretch to the other side. If you continue to experience pain, see your doctor.

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  1. Morton D, Callister R. Exercise-related transient abdominal pain (ETAP). Sports Med. 2015;45(1):23-35. doi:10.1007/s40279-014-0245-z

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