Causes of Side Stitches During Exercise

Understanding Exercise-Related Transient Abdominal Pain (ETAP)

A man exhausted from jogging

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Most exercisers have experienced a side stitch—also known as a side cramp, side sticker, or side ache—at one time or another. In the medical community, this is referred to as exercise-related transient abdominal pain (ETAP) and is thought to affect as many as 60% of people who are physically active.

When a side stitch occurs, sudden, sharp or stabbing pain is usually felt on the right lower abdomen, just below the ribs. Though it rarely requires medical treatment, the pain can be severe enough to stop you in your tracks and may even compromise your performance.

Side stitches are especially common among runners, swimmers, and horseback riders.

Side Stitch Causes

While there is no definitive explanation as to what causes a side stitch, researchers have proposed a few different theories to explain this phenomenon.

Pre-Exercise Food Choices

Many scientists believe that the foods we eat prior to exercise are the primary cause of ETAP.

For example, one study 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 intake can trigger side stitches, including milk, protein bars, and high-protein shakes.

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.

Age, Sex, and Physical Condition

Age also appears to play a role in the risk of ETAP, with older adults less prone to side stitches than children, adolescents, or younger adults. Research has also found that exercise-related side pain is more common in female athletes.

A person's body mass index does not not appear to influence whether they develop side stitches. However, physical condition might have some impact, with ETAP more prevalent in athletes who are less experienced.

Body Mass Index (BMI) is a dated, biased measure that doesn’t account for several factors, such as body composition, ethnicity, race, gender, and age. 


Despite being a flawed measure, BMI is widely used today in the medical community because it is an inexpensive and quick method for analyzing potential health status and outcomes.

Repeated Trunk Movements

ETAP is closely associated with repetitive movements in which the torso is extended. This would explain why side stitches can affect runners and horse riders whose upper bodies are placed under rapid, repetitive stress.

It is thought that the friction between abdominal tissues and the stretching of ligaments and muscles trigger spasms and inflame nerve endings. This results in side pain.

When You Exhale

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). This causes the diaphragm to lift at the same time that the liver drops, stretching the peritoneal ligaments and potentially triggering ETAP.

Exercise Form

A 2016 study found that having a forward head posture may increase one's risk of side stitches. A 2017 study further noted that ETAP increases when the body's vertical form is displaced while running, particularly when it reduces the angle of the neck, trunk, and hips.

Studies like these highlight the importance of using proper form when engaging in exercise. When the body is aligned, it can reduce a person's risk of developing these sometimes painful side stitches.

According to research published in the journal 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.

Side Stitch Prevention

With a few precautionary measures, you may be able to prevent side stitches during exercise.

  • 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. A 2014 study found that strengthening your trunk muscles may reduce your risk of exercise-related abdominal pain. Incorporate core muscle work into your training regularly to build up this area.
  • 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.

Treating Side Stitches

If you develop a side stitch when exercising, stop and place your hand on the right side of your belly. Push 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.

6 Sources
Verywell Fit uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  5. Khoshaftar-Yazki N, Hakakdokht E, Mohajeran ES, Chakan S. Comparison of spinal abnormalities between two groups of clients with exercise related transient abdominal pain (ETAP) and without the side stitch. J Rehab Med. 2016;5(2):193-200.

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By Elizabeth Quinn, MS
Elizabeth Quinn is an exercise physiologist, sports medicine writer, and fitness consultant for corporate wellness and rehabilitation clinics.