RunInsight

What is that stitch in your side?

Nearly every runner, from beginner to experienced marathoner, has felt that sharp, sudden pain under the ribs at least once. Commonly called a "side stitch" (on the left) or sometimes linked to the liver area (on the right), its technical name is ETAP (Exercise-related Transient Abdominal Pain).

Although extremely annoying, it is rarely a sign of something serious, but it can ruin a workout or a race if you don't know how to manage it quickly.

Main causes

Although science is still debating the exact origin, the most accepted theories include:

• Peritoneal irritation: Friction between the membranes lining the abdominal cavity.
• Shallow breathing: A diaphragm not working at full capacity can become stressed.
• Nutrition: Running too soon after a large meal or drinking very sugary beverages.
• Posture and core: Weak abdominal muscles can make pain more likely.

How to make it pass quickly

If pain hits during a run, don't panic. Here are three essential steps:

1. Pressure technique: Press your fingers firmly on the exact spot of pain while exhaling deeply.
2. Sync your breathing: Try exhaling when the foot opposite the painful side hits the ground.
3. Slow your pace: Don't stop abruptly, but ease off noticeably until the stitch fades.

Long-term prevention

To keep it from coming back, work on core stability. Plank exercises and diaphragmatic breathing are your best allies. Also wait at least 2–3 hours after a full meal before lacing up your running shoes.

Conclusion: listen to your body

A side stitch is a warning signal. If pain persists or worsens, don't push through: walk, breathe, and wait for it to pass. With time and training, these episodes become increasingly rare.