The sharp, temporary pain that strikes below the ribs during exercise is formally known as Exercise-Related Transient Abdominal Pain (ETAP), but is more commonly called a side stitch. This localized discomfort often feels like a stabbing or cramping sensation and is a frequent complaint, particularly among runners. While a side stitch can abruptly interrupt a run, it is generally considered a benign condition that resolves quickly upon stopping or slowing down.
The Science Behind the Pain
The most widely supported theory attributes the side stitch to irritation of the parietal peritoneum, a thin membrane that lines the abdominal wall and the underside of the diaphragm. This tissue is richly supplied with nerves, making it highly sensitive to friction or tension. During the repetitive, jarring motion of running, stress on this membrane triggers the sharp, localized pain.
Mechanical stress is increased when abdominal organs, such as the liver and stomach, tug on the ligaments that connect them to the diaphragm. This downward pull is intensified by a full stomach or colon, which adds weight and strain to the supporting structures. Because the liver is the heaviest organ and resides on the right side, stitches frequently occur on the right side of the mid-abdomen.
The diaphragm, the primary muscle responsible for breathing, sits directly beneath the parietal peritoneum. Shallow and rapid breathing during intense running prevents the diaphragm from fully descending. This places greater strain on surrounding ligaments and limits the movement of abdominal organs. Shallow breathing also reduces lubricating fluid within the peritoneal cavity, increasing friction between the layers of the peritoneum.
Stopping a Stitch When It Strikes
When a side stitch begins, the immediate priority is to reduce the tension and mechanical stress causing the irritation. Slowing your pace to a brisk walk or stopping entirely instantly lessens the jarring motion on the abdominal organs and supporting ligaments. This change allows the body to re-establish a more controlled breathing pattern and reduces strain on the peritoneal lining.
Applying firm, direct pressure to the painful area with your fingers or the palm of your hand helps relieve the discomfort. Simultaneously, focus on deep, controlled breathing, aiming to push the air into your belly rather than your chest. Try a specific rhythmic breathing technique: forcefully exhale when the foot opposite the side of the pain strikes the ground. For instance, if the stitch is on the right, exhale as your left foot lands.
Stretching the side where the pain is located can also provide rapid relief by lengthening the diaphragm and the abdominal wall. While standing, raise the arm on the affected side over your head and bend your torso away from the stitch. Hold this position for 20 to 30 seconds to gently stretch the musculature and release tension from the ligaments supporting the abdominal contents.
Adjustments for Long-Term Prevention
Proactive changes to nutrition and breathing habits are highly effective in reducing the frequency of side stitches. Avoid consuming large meals or foods high in fat or fiber within one to three hours of exercise, as they delay gastric emptying. This leaves the stomach distended for longer, increasing the weight and pull on the visceral ligaments during the run.
Training the diaphragm through conscious, deep belly breathing, also known as diaphragmatic breathing, is a powerful preventative measure. Practice inhaling deeply so that the abdomen visibly expands, and focus on slow, complete exhalations. This practice strengthens the diaphragm and ensures that the muscle is fully engaged and relaxed during the repetitive stress of running.
Another helpful breathing strategy is to synchronize your breath with your foot strikes, using a rhythmic pattern like a 3:2 ratio—inhaling for three steps and exhaling for two. A strong, stable core is equally important, as robust abdominal muscles minimize the vertical movement and jarring of the internal organs. Maintaining an upright posture with an engaged core while running also reduces stress on the abdominal lining. A dynamic warm-up that includes gentle torso twists and side bends before starting a run can also help prepare the abdominal muscles and diaphragm.