Side stitches plague up to 70% of runners annually, yet scientists still debate their exact cause. Researchers call this condition exercise-related transient abdominal pain, or ETAP. The leading theories involve breathing patterns irritating the phrenic nerve, disrupted blood flow around the diaphragm, or poor posture during running.
The pain typically strikes the lower ribs or upper abdomen and can force runners to stop mid-workout. Understanding what triggers it helps you prevent future episodes.
Three main factors appear to contribute. First, your breathing pattern matters. When you inhale as your right foot strikes the ground, your diaphragm contracts while your liver (on the right side) moves downward, creating tension on the ligaments supporting it. Second, eating too close to your run diverts blood flow to your digestive system, leaving less for your muscles and diaphragm. Third, weak core muscles and poor posture limit your diaphragm's mobility.
If a stitch strikes during your run, slow your pace immediately. Stretch by raising both arms overhead and leaning gently toward the opposite side of the pain. Apply light pressure to the cramped area while taking slow, deep breaths. Many runners find relief within a few minutes.
Prevention works better than treatment. Practice rhythmic breathing before you run, matching your breath to your footstrike pattern. Eat your last significant meal two to three hours before running. Skip sugary drinks shortly before exercise. Work on your core strength through planks, bridges, and rotational exercises. Stay consistently hydrated throughout the day, not just before runs. Gradually increase your mileage and intensity rather than jumping into harder workouts.
Proper running posture also reduces ETAP occurrence. Keep your shoulders relaxed, chest open, and spine neutral. Slouching restricts your diaphragm's movement and