Why Do You Get a Side Stitch When Running?

What causes a side stitch when you run?

A side stitch—known clinically as exercise-related transient abdominal pain (ETAP)—is a sharp, cramping pain usually felt just below the ribcage, more often on the right side. It happens when breathing mechanics, posture, and the repetitive up-and-down motion of running put strain on the diaphragm and the ligaments that anchor your internal organs. It's extremely common: surveys of distance runners have found that up to roughly 70% report experiencing at least one stitch at some point, making it one of the most frequent reasons a beginner drops to a walk mid-run.

Researchers haven't settled on one confirmed mechanism. Leading theories point to: (1) irritation or fatigue of the diaphragm, the muscle sheet that drives breathing, (2) tension on the peritoneal ligaments connecting the diaphragm to the stomach and liver, which get tugged with every stride's vertical motion, and (3) reduced blood flow to the diaphragm during shallow, rapid breathing. All three point to the same practical takeaway: how you breathe and how much your torso moves both matter more than any single "cause."

How do breathing rhythm and posture affect side stitches?

Shallow, unsynchronized breathing and a hunched running posture both raise the odds of a stitch, because they change how much your diaphragm and abdominal organs get jostled with each stride.

Most runners settle into a locomotor-respiratory coupling pattern, exhaling on the same foot strike every time—for example, always breathing out as the right foot lands. Some research suggests this repeated one-sided loading concentrates strain on the liver and its supporting ligaments, and that runners who deliberately vary or synchronize their breathing, such as a 3:2 or 2:1 step-to-breath ratio that alternates which foot you exhale on, may reduce stitch frequency. The evidence is still preliminary, but switching up your breathing pattern costs nothing and is a reasonable first thing to try.

Posture matters too. A hunched, forward-leaning torso compresses the abdominal cavity, giving the diaphragm and stomach less room to move and shortening each breath. Runners who slouch forward, especially as they fatigue, often notice discomfort intensify. Standing tall—ears over shoulders, chest open, a slight forward lean from the ankles rather than the waist—gives the diaphragm more room to work and appears to ease abdominal discomfort during effort. If you tend to collapse forward as you tire, the same postural drift that contributes to a stitch often shows up as excess vertical bounce; see how to stop bouncing when running for drills that address both.

Does hydration or meal timing cause side stitches?

Yes—what and when you eat or drink before running is one of the most consistently reported triggers in surveys of runners with recurrent stitches.

Large meals within 1-2 hours of a run, high-sugar or high-osmolality sports drinks (concentrated carbohydrate solutions), and gulping a large volume of fluid right before heading out all increase stomach distension and osmotic load in the gut, which has been linked to higher ETAP rates in several runner surveys. Practical adjustments commonly recommended by coaches and clinicians:

How do you stop a side stitch while running?

The fastest way to stop a stitch is to slow down, deepen your breathing, and gently press or stretch the affected side—most stitches ease within a minute or two once pressure comes off the area.

Technique How to do it Why it may help
Exhale on the opposite foot If pain is on the right, exhale as the left foot strikes Shifts diaphragm loading away from the strained side
Press and bend Press two or three fingers into the painful spot and bend slightly forward Reduces tension on the peritoneal ligaments
Slow to a walk Drop pace or walk for 60-90 seconds Lowers jostling and breathing rate
Deep belly breathing Inhale slowly through the nose, expand the belly, exhale fully through pursed lips Increases diaphragm range of motion and blood flow
Reach and lean Raise the arm on the painful side overhead, lean away from that side Stretches ligaments and intercostal muscles on that side

If a stitch is severe, doesn't ease within a few minutes of walking, or comes with chest pain, dizziness, or breathlessness out of proportion to your effort, stop running and treat it as a medical symptom rather than a routine stitch.

Does your running form make side stitches more likely?

Excess vertical bounce and hard downhill impact both increase how much your torso and organs move with each stride, and that extra jostling is one of the more consistent stitch triggers in runner surveys.

If you already know you have a bouncy stride, the same mechanics that waste energy on the way up and down can aggravate a stitch on the way down; working on cadence and vertical oscillation, as covered in how to stop bouncing when running, can reduce both problems together. Downhill sections carry a similar risk for a different reason: the extra impact loading that can strain the knees on descents (see how to run downhill without hurting your knees) also shakes the abdominal organs more with each footstrike, which may be why stitches show up more often on hilly or downhill courses.

Building better trunk and hip control through strength and plyometric work can help some runners tolerate impact and breathing demands more comfortably over time; see plyometrics for runners for a structured starting point. None of this guarantees a fix—stitches have multiple contributing factors—but reducing unnecessary torso movement is one of the few form-related levers with a plausible mechanism behind it.

If you want a quick read on your current cadence or how much vertical bounce you have, a tool like StrideIQ can estimate those from a short phone video, which is a reasonable starting point for spotting a bouncy stride, though it isn't a substitute for an in-person gait assessment if pain persists.

Worth noting: a side stitch is unrelated to the tightness some runners feel in their lower legs. If you're also dealing with tight calves after runs, that's typically a separate mechanical issue—see why do my calves get tight when running for causes specific to that.

What can't form and breathing fixes tell you about abdominal pain?

Breathing adjustments, posture cues, and meal timing address the common, benign version of exercise-related abdominal pain—they can't rule out other causes, and they aren't a guaranteed fix even for a typical stitch.

The evidence behind breathing-pattern changes and posture cues for reducing stitches is still limited and mostly observational; they help some runners and not others, and no single technique works for everyone. A short phone-video form check, including tools like StrideIQ, can flag cadence and rough bounce but can't diagnose the cause of abdominal pain or assess internal organs, ligaments, or diaphragm function.

See a doctor promptly, rather than trying to run through it, if abdominal or chest pain is severe, doesn't resolve with rest, radiates to the arm or jaw, comes with nausea, sweating, or lightheadedness, or occurs on every run regardless of what you eat or how you breathe. A physiotherapist or sports medicine doctor can also help if stitches are frequent enough to limit your training, since a recurring pattern is often easier to identify in person than from general advice online.

Frequently Asked Questions

Are side stitches dangerous?

Usually not. A typical side stitch is a benign, self-limited cramp that resolves within a couple of minutes once you slow down or adjust your breathing. See a doctor if the pain is severe, doesn't ease with rest, or comes with chest pain, dizziness, or breathlessness out of proportion to your effort.

Will getting fitter make side stitches go away?

Many beginners notice fewer stitches as their cardiovascular fitness and breathing efficiency improve over weeks to months of consistent running, but this hasn't been proven as a direct cause-and-effect relationship in research, and fit runners still get stitches.

Why do I only get a stitch on some runs and not others?

Stitch frequency tends to track with variables like how recently and how much you ate, how fast you're running, how much fluid you drank beforehand, and how hilly the course is—so a bad-stitch day is often a combination of several of these, not one fixed cause.

Does core strength help prevent side stitches?

It's plausible: better trunk stability may reduce excess torso movement and improve breathing mechanics, but this hasn't been directly proven for stitch prevention specifically. It's still a reasonable general strength goal for runners.

How long does a side stitch usually last?

Most stitches ease within one to a few minutes once you slow your pace, deepen your breathing, and stretch or press the affected side. If it lingers well beyond that or keeps returning, treat it as a signal to check in with a clinician rather than pushing through.

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