The sudden, sharp discomfort felt in the side during physical activity is common for many athletes and casual exercisers. This temporary sensation is formally known as Exercise-Related Transient Abdominal Pain (ETAP). Up to 70% of runners report experiencing this pain annually. While generally harmless, a stitch can force a person to slow down or stop completely, making it a frustrating barrier to performance. Understanding the mechanisms behind ETAP is key to managing this shared experience.
Defining the Side Stitch
The pain associated with a stitch is localized to the mid- to upper-abdomen, frequently along the lower edge of the ribcage. Although it can occur anywhere, it appears more often on the right side. The sensation ranges from a dull ache or cramping feeling to an intense, sharp, or stabbing pain.
This discomfort is transient, meaning it lasts for a short duration and is directly related to physical activity involving repetitive torso movement, such as running or horseback riding. In some instances, the pain may radiate upward to the shoulder tip, known as referred pain. This results from the shared nerve pathway between the diaphragm and the shoulder region, providing an anatomical clue to the stitch’s origin.
Leading Theories on the Cause
The exact cause of ETAP remains a subject of ongoing scientific discussion. One prominent theory centers on irritation of the parietal peritoneum, a thin membrane lining the abdominal cavity that is highly sensitive to friction and pressure. This irritation is thought to be caused by the repetitive mechanical jostling of internal organs during high-impact activities.
This mechanical stress links closely to the theory of visceral traction. This theory suggests that the jarring motion pulls on the ligaments connecting abdominal organs, like the stomach and liver, to the underside of the diaphragm. A full stomach, especially one containing large volumes of fluid or hypertonic (sugary) drinks, adds weight to these organs, increasing the strain on the supportive ligaments. The increased tension then irritates the parietal peritoneum, particularly where it is innervated by the phrenic nerve.
Diaphragm and Posture Hypotheses
A separate hypothesis involves the diaphragm muscle itself, suggesting the pain is caused by a spasm or insufficient blood flow (ischemia). During intense exercise, blood is preferentially shunted to the working limb muscles, potentially reducing the supply to the diaphragm. Shallow or irregular breathing patterns may also contribute to this muscle fatigue or spasm. Poor posture, such as a slouched running form, can compress the abdominal area and may aggravate localized nerve irritation in the spine.
Stopping and Preventing Stitches
Immediate relief from a stitch involves reducing activity and targeted pressure or stretching. When pain strikes, slow your pace or stop exercising altogether to reduce mechanical stress on the abdomen. While standing or walking, focus on deep, controlled belly breathing to fully engage and relax the diaphragm.
Immediate Relief Techniques
You can apply gentle but firm pressure directly to the painful area, pressing inward and upward while taking slow, deep breaths. Another effective technique is to stretch the affected side by raising the arm overhead and bending the torso away from the pain. Holding this side bend for 20 to 30 seconds helps stretch the abdominal musculature and underlying connective tissues.
Prevention Strategies
Preventing ETAP requires attention to pre-exercise habits and core stability. Avoid consuming large meals or high-volume drinks within one to two hours before a workout, as a full stomach exacerbates visceral traction. Limit hypertonic beverages, such as high-sugar juices and sodas, as they slow gastric emptying and increase abdominal pressure. Implementing a consistent warm-up routine and focusing on deep, rhythmic breathing can reduce the risk of diaphragm fatigue. Strengthening the core muscles provides better support for the torso and internal organs, reducing internal movement and strain. Incorporating exercises like planks and bird dogs helps stabilize the trunk and maintain better posture.
When Pain Needs Medical Attention
In nearly all cases, an exercise-related side stitch is a temporary and benign condition that resolves quickly upon stopping or slowing down. However, any abdominal pain that is severe, prolonged, or accompanied by other symptoms should be evaluated by a healthcare professional. Pain that continues for hours after exercise, or pain that occurs even when you are at rest, warrants medical attention.
Symptoms that are not typical of a stitch are red flags that could indicate a more serious underlying condition. These include:
- Fever
- Nausea
- Vomiting
- The presence of blood in the stool
A doctor can help rule out other potential causes of abdominal discomfort during exertion, such as muscle strains, issues with reduced blood supply to the bowel, or pre-existing digestive disorders. Consulting a physician is prudent if ETAP is recurrent, unusually intense, or prevents participation in your sport.