Get access to everything we publish when you sign up for Outside+.
A side stitch is a turd in the punch bowl: it can ruin your trail-running party. Sometimes, it can even end your party altogether, forcing you to stop your run or DNF your race.
Strangely, side stitches are still a bit of a mystery. There is no consensus on why they happen, why they hurt so much and how to prevent them in the first place. However, combining research with longstanding athlete practice provides some answers.
What does a side stitch feel like?
Side stitches are generally characterized by sharp pain on the upper midsection just beneath the ribs on the right or left side (usually the right), though some athletes report them elsewhere on the abdomen. Some people can feel a similar pain just beneath one of their collarbones, which is likely related to nerve connections with the diaphragm.
At their worst, side stitches can persist as pain or lasting tightness for several days. At their most innocuous, they can go away in a few seconds.
What causes a side stitch?
Most theories about what causes side stitches relate to the diaphragm, the big breathing muscle that provides force to inflate and deflate the lungs. It is innervated by the phrenic nerve, which travels from the upper vertebrae in the neck, and is connected to ligaments from below.
Some ideas of what causes stitches are outlined in a 2015 review study in the journal Sports Medicine. One is that the jarring motion of running can cause the ligaments to pull at the diaphragm, creating the tell-tale pain on the upper abdomen. The jarring motion may also cause irritation in the parietal peritoneum, a thin membrane lining the abdominal cavity.
Another theory revolves around the rapid breathing from running, which, combined with impact forces, essentially pinches the diaphragm, causing reduced blood flow and/or irritation.
Others think that side stitches are primarily related to hydration and fueling status. Just like jumping in the ocean after a boardwalk hot dog, running too soon after a big meal or sugary drink seems to correlate with side stitches in studies of some runners. This could be because digestion of certain foods requires more blood to pump to the stomach and, hence, less blood flow to the diaphragm, or because a bolus of food and saliva in the stomach could increase pulling forces.
A final interrelated theory focuses on the upper spine. A 2004 report in the British Journal of Sports Medicine found that side-stitch pain could be recreated by applying manual pressure to the upper vertebrae. The spine-stress theory could explain why runners, horseback riders and swimmers get side stitches, but not cyclists, since biking doesn’t involve much spine movement.
Ultimately each of these theories acts as a possible factor in causing side stitches. All of them can play a role, but you can still have a side stitch without each present.
How can you prevent side stitches?
An ounce of prevention is worth a metric ton of cure, since side stitches can make running far less enjoyable. Theory and practice converge for several strategies for athletes who are desperate for answers.
1. Control your breathing with deep inhalations and complete exhalations. Side stitches are most common with shallower breathing, which is likely one reason why beginner runners get them more frequently. Prior to your runs, take a couple of minutes of deep breaths to stretch your diaphragm, and try to run with controlled breathing.
2. Stretch your abdominal wall. Some athletes I coach have had success with doing cobra pose from yoga a few times per day. Even better: do the full sun-salutation routine.
3. Lightly massage your diaphragm and the surrounding area. Knead the affected area like a ball of pizza dough you truly love. Diaphragm “massages” could increase blood flow and reduce tension around the diaphragm (at the very least, they are a good conversation starter).
4. Don’t eat in the two hours prior to running, preferably avoiding fatty and high-fiber foods, and fully hydrate at least an hour before, preferably with diluted sports drink or water. Sugary drinks and big meals correlate with side stitches.
5. Strengthen your core with front and side planks. Start with a minute or two front and side plank each day. Some athletes find that increased core strength reduces side-stitch risk (possibly by putting less stress on the upper spine).
6. Practice good posture while running. Some reports indicate that a curved upper spine can increase side stitch risk. When running uphill, think about keeping your spine straight while you lean from your ankles. Keep your neck in line with your spine when running at all times. And limit the twisting motion of your upper body.
How can you cure an existing side stitch?
No matter what you do, side stitches can be unavoidable for some people (I am one of the chronic sufferers). If you’re in the middle of a run or race and feel the dreaded stitch coming on, several strategies could help:
1. Control your breathing with deep inhalations and forceful exhalations when the foot on the opposite side of the stitch hits the ground. Usually, this means exhaling only on left footfalls for the more common right-side stitch. This breathing pattern has been used for decades by stitchers, possibly because it counteracts some of the force against the stressed diaphragm.
2. Slow down and provide light pressure on the abdominal wall. Some people find that manual pressure near the affected area can alleviate the pain. For a particularly difficult case on my team, we had success with an at-home binding that the athlete wore during runs (almost like Spanx for the stomach).
3. Slow down even more, practicing deep breathing, until you are jogging. If that doesn’t stop the stitch, take a few minutes to stop and regroup, lightly massaging the affected area, stretching and breathing deeply.
4. Experiment with mid-run nutrition, since some people think certain foods, dehydration and electrolyte deficiency exacerbate their stitches.
To put it simply, side stitches suck. But finding the prevention-and-cure combination that works for you can stop them from ruining your runs.
David Roche runs for HOKA One One and NATHAN, and works with runners of all abilities through his coaching service, Some Work, All Play.