The sharp, localized pain experienced in the side of the abdomen during running is formally known as Exercise-Related Transient Abdominal Pain (ETAP), commonly called a side stitch. This sensation, which can range from a mild ache to a severe, stabbing discomfort, is a frequent complaint among athletes, with approximately 70% of runners reporting an episode within a year. While generally harmless and temporary, ETAP is a significant hindrance to performance, often forcing a runner to slow down or stop entirely.
Physiological Mechanisms Behind the Pain
The most widely accepted explanation for a side stitch involves irritation of the parietal peritoneum, the sensitive membrane lining the abdominal wall and the underside of the diaphragm. The repetitive, jarring motion of running causes friction between this lining and the internal organs, especially when the stomach is full. The phrenic nerve supplies sensation to the parietal peritoneum and has branches that innervate the shoulder tip, explaining why pain sometimes radiates to that area.
Another contributing factor is the mechanical stress placed upon the visceral ligaments, which anchor abdominal organs like the stomach and liver to the diaphragm. The high-impact, vertical movement of running pulls these organs downward, creating tension on the ligaments. This stress is often felt more acutely on the right side, as the liver, the body’s heaviest organ, is situated there.
Shallow or improper breathing patterns during high-intensity exercise can also contribute to the issue. When breathing is shallow and rapid, the diaphragm does not fully descend, which can lead to localized fatigue or spasm in the muscle. Improper breathing affects the mechanics of the diaphragm and the stress placed on surrounding structures.
Less frequently, the pain may originate from nerve root irritation in the thoracic spine. Since the nerves that supply the abdomen are connected to those exiting the spine, compression or irritation in this area can be perceived as pain in the side.
Dietary and Hydration Triggers
Eating a large meal too close to exercise increases the volume and weight of the stomach contents. This full state exacerbates the downward tugging on the visceral ligaments during the repetitive impact of running, intensifying the stress on the abdominal lining.
Foods that are high in fat or fiber require more time and energy for digestion, redirecting blood flow away from working muscles. This delay in gastric emptying means the stomach remains distended for longer, increasing the pressure and friction on the parietal peritoneum. It is generally suggested to avoid large meals for at least two hours before a run.
The type of beverage consumed is also a strong trigger, particularly hypertonic drinks, such as sugary sodas or certain sports drinks. These fluids have a high concentration of dissolved particles, which slows the rate at which fluid leaves the stomach. This delayed gastric emptying results in a full, sloshing stomach that significantly increases the mechanical irritation of the abdominal lining during movement.
Prevention and On-the-Run Relief
Preventing side cramps begins with strengthening the muscles that stabilize the torso. A strong core, particularly the deep abdominal muscles, helps hold the internal organs in a more stable position. This stabilization reduces the excessive vertical movement of the viscera, mitigating the strain on the visceral ligaments and the parietal peritoneum during running.
Proper warm-up routines prepare the diaphragm and surrounding muscles for exertion. Establishing a deep, consistent breathing pattern from the start is a proactive strategy. Runners should focus on diaphragmatic breathing, where the abdomen expands and contracts with each breath, rather than relying on shallow chest breathing.
A structured breathing technique involves coordinating the breath with the foot strike rhythm. For instance, maintaining a three-step inhale and two-step exhale pattern forces a deeper, more rhythmic engagement of the diaphragm. This full use of the diaphragm can reduce the likelihood of muscular fatigue and spasm while promoting spinal stability.
If a sharp pain begins mid-run, the immediate action should be to slow the pace or stop entirely. While standing or walking, apply gentle but firm pressure with two fingers directly on the painful area, pressing slightly upward toward the ribs. Maintain this pressure for about ten seconds while focusing on deep, slow breaths.
A specific stretch can help alleviate the acute discomfort. If the stitch is on the right side, raise the right arm overhead and gently bend the torso away from the pain, stretching the muscles on the affected side. This maneuver helps to stretch the diaphragm and the abdominal muscles, which can provide rapid relief. Once the pain subsides, resume running slowly, maintaining a focused, deep breathing pattern.