A stitch in your side is a sharp, localized pain in your abdomen that strikes during physical activity. Doctors call it exercise-related transient abdominal pain, or ETAP. It most commonly hits just below the ribs on one side, though it can occur anywhere across the abdomen. About 27% of participants in a 14 km community running event reported experiencing one during the race, with runners (30%) affected nearly twice as often as walkers (16%).
What Causes the Pain
The leading explanation involves two thin layers of tissue called the peritoneum that line your abdominal cavity and wrap around your organs. During exercise, these layers can rub against each other, creating friction and irritation that produces that familiar stabbing sensation. Think of it like two sheets of tissue paper sliding against each other when there isn’t enough lubrication between them.
This friction theory helps explain why the pain is so well-localized. Unlike a general cramp that radiates through a muscle, a stitch tends to hit one precise spot. It also explains a quirk that surprises many people: a side stitch can sometimes trigger referred pain in the tip of your shoulder, because the nerves serving the peritoneum also connect to the shoulder region.
Who Gets Stitches Most Often
Side stitches are far more common in younger athletes. The frequency drops with age, though researchers aren’t entirely sure why. Activities that involve repetitive torso movement are the biggest triggers. Running and swimming top the list, but horseback riding, cycling, and even brisk walking can bring one on.
Your posture plays a surprisingly large role. A study of over 150 subjects found that people with increased thoracic kyphosis (a more rounded upper back) experienced stitches more frequently. The curved posture may increase mechanical stress on the abdominal tissues during bouncing or rotational movements.
How Food and Drinks Affect Your Risk
What you eat and drink before exercise is one of the most controllable risk factors. Concentrated, sugary beverages are particularly problematic. In a study comparing sports drinks during high-intensity intermittent exercise, the more concentrated drink (with 8% carbohydrate and higher osmolality) produced significantly more side ache symptoms than a less concentrated 6% version. The higher sugar concentration appears to draw fluid into the gut and increase irritation in the abdominal lining.
Plain water or lightly flavored, lower-sugar sports drinks are less likely to provoke a stitch. Eating a large meal too close to exercise is another well-known trigger. Allowing two to three hours between a full meal and vigorous activity gives your stomach time to empty and reduces the mechanical load on the tissues around your organs.
How to Stop a Stitch Mid-Exercise
You don’t necessarily have to stop completely, but slowing your pace gives the muscles around your chest and abdomen a chance to relax. Pair the slowdown with slow, deep breathing: inhale fully, then exhale as slowly as you can. Repeat several times. This rhythmic breathing helps reduce the tension contributing to the pain.
Two physical techniques can speed relief:
- Press into it. Push your fingers firmly but gently into the painful spot while bending your torso slightly forward. Hold this until the pain starts to fade.
- Stretch the area. Raise the arm on the same side as the stitch overhead, then lean gently away from the painful side. This lengthens the abdominal muscles and can release the tension pulling on the irritated tissue.
Most stitches resolve within a few minutes using these techniques. If you’re a runner, some coaches suggest exhaling when the foot opposite to your stitch strikes the ground, which may alter the mechanical forces through your torso just enough to ease the irritation.
Preventing Side Stitches
Because stitches are tied to mechanical irritation, prevention comes down to reducing the forces acting on your abdominal lining. A proper warm-up that gradually increases intensity gives your body time to adjust. Strengthening your core muscles can also help stabilize your torso and reduce the bouncing that contributes to peritoneal friction.
Pay attention to your posture, especially if you tend to hunch forward when fatigued. Keeping your upper back relatively upright during exercise may reduce your susceptibility. On the nutrition side, avoid high-sugar drinks during exercise and give yourself adequate time after eating before you train hard. If you need to hydrate during a workout, stick with water or a diluted sports drink rather than a concentrated one.
When Side Pain Is Something Else
A true exercise stitch has a clear pattern: it starts during activity, stays in one spot, and fades within minutes once you slow down or stop. Pain that doesn’t fit this pattern deserves attention.
Abdominal pain that persists after you stop exercising, gets progressively worse, or comes with additional symptoms like fever, nausea, vomiting, bloating, or the inability to pass gas could point to something more serious. Conditions like appendicitis, kidney stones, and diverticulitis can all produce sharp abdominal pain that might initially feel like a stitch. Lower abdominal pain accompanied by vaginal bleeding, back pain, or lightheadedness could signal an ectopic pregnancy.
Sudden, severe abdominal pain that doesn’t respond to rest or the relief techniques above warrants immediate medical evaluation, particularly if it’s your first time experiencing it or if the quality of the pain feels distinctly different from a typical stitch.