That Sharp Side Stitch Isn't About Fitness — It's About Timing

Here's the good news: if you get that sharp stabbing pain under your ribs when you run, it has almost nothing to do with your fitness level. Researchers call it ETAP — exercise-related transient abdominal pain — and it hits about 70% of runners at some point every year, from beginners to elites. So no, you're not weak or out of shape. You just haven't dialed in a few unglamorous details yet.

The science points to three main culprits. First, what's in your stomach: eating or drinking too close to your run, especially anything high in sugar or very concentrated (hypertonic), pulls fluid into your gut and irritates the lining around your organs — that's the likely source of the pain. Second, posture: slouched shoulders and a collapsed chest cavity restrict how your diaphragm moves, and that mechanical stress seems to trigger stitches too. Third, a weak or under-engaged core means less stability for your trunk with every stride, which adds strain to the same area.

None of this is dangerous. A stitch is uncomfortable, not harmful, and it almost always passes within a few minutes.

What actually helps: give yourself a solid two-hour buffer between eating and running, and skip sugary sports drinks or juice right before you head out — water is safer close to run time. If a stitch hits mid-run, slow down, take slow deep breaths from your belly instead of your chest, and try pressing your fingers into the painful spot or bending forward slightly at the waist. Most runners find relief within a minute or two.

Long-term, working on posture (think tall spine, open chest) and basic core strength — planks, dead bugs, anti-rotation work — seems to reduce how often stitches show up in the first place.