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A side stitch — that sharp, stabbing pain under your ribs during a run — is one of the most common and annoying problems runners face. They’re particularly common in beginner runners, but they affect experienced runners too, especially at higher intensities or in hot weather.
The good news: they’re almost entirely preventable once you understand what causes them.
What Causes a Side Stitch?
The exact mechanism is still debated in sports medicine, but the leading theory involves the phrenic nerve and the diaphragm. During running, the diaphragm works hard with each breath. The diaphragm is supported by ligaments that also attach to abdominal organs (particularly the liver, on the right side — which is why side stitches are more common on the right). When you breathe and run simultaneously, tension on these ligaments can irritate the phrenic nerve, causing the characteristic sharp pain.
Supporting factors:
– Eating too close to running — a full stomach pulls down on the diaphragmatic ligaments
– Running too fast too soon — higher breathing rate increases diaphragm demand before it’s warmed up
– Upright or hunched posture — reduces breathing efficiency and increases diaphragm stress
– Shallow breathing — breathing from the chest rather than the belly reduces oxygen efficiency and increases diaphragm fatigue
– Dehydration — some evidence links inadequate hydration to increased stitch frequency
How to Prevent Side Stitches Before You Start
Don’t eat in the 2 hours before a run (for stitch-prone runners).
This is the single most impactful prevention measure. Solid food takes 2–4 hours to leave the stomach; running with food in your stomach pulls on the ligaments that support your diaphragm. If you need to fuel before a run, stick to liquids or easily digestible snacks (a banana, not a meal) at least 1.5–2 hours before.
Warm up gradually.
Jumping from zero to hard pace immediately stresses the diaphragm before it’s ready. Even 5 minutes of easy jogging before increasing your pace gives your breathing system time to adjust.
Breathe from your belly, not your chest.
Belly breathing (diaphragmatic breathing) is more efficient and puts less strain on the muscles around your lower ribs. Practise it before a run: breathe in so your belly expands first, then your chest. When you run, your breathing should feel low and full rather than shallow and rapid.
Stay hydrated — but not over-hydrated.
Being dehydrated increases stitch frequency. Drinking a large amount of water immediately before running also increases stitch frequency. Aim to be well-hydrated going into a run without drinking significant volumes in the 30 minutes before you start.
The Breathing Rhythm Technique
There’s an evidence-based breathing pattern associated with lower stitch frequency: the 3:2 rhythmic breathing pattern, where you inhale for 3 footfalls and exhale for 2 footfalls (so each exhale doesn’t always fall on the same foot).
The theory: exhaling consistently on the same foot (typically the right) synchronises diaphragm contraction with ground impact on that side, amplifying the stress on the right-side diaphragmatic ligaments. Alternating the exhale foot reduces this.
Try it on your next run: count your steps, breathing in for three and out for two. It takes a few runs to feel natural, but many runners report a significant reduction in stitches once they adopt it.
How to Get Rid of a Stitch Mid-Run
If one develops during a run, try these in order:
1. Slow down or walk.
Reducing your pace lowers your breathing rate and reduces the diaphragm stress. Most stitches resolve within 1–2 minutes of slowing to a walk. If you’re racing and don’t want to stop, slowing slightly for 30–60 seconds is less costly than trying to run through it.
2. Deep belly breathing.
Deliberately slow your breathing and breathe deeply — focus on filling your belly on each inhale. This relaxes the diaphragm and reduces the tension on the phrenic nerve.
3. Exhale pressure.
Try exhaling forcefully against pursed lips (as if you’re blowing out a candle). Some runners find this releases the diaphragm spasm.
4. Press into the stitch.
Apply firm pressure with your fingers directly on the stitch location and hold for 10–15 seconds while taking a deep breath. This technique has anecdotal support among many runners and often works faster than breathing techniques alone.
5. Raise your arm on the stitch side and stretch.
Reaching your arm overhead on the affected side while exhaling stretches the ligaments and can release the stitch. Often combined with bending slightly away from the stitch side.
When Stitches Are More Than a Stitch
Occasional stitches during runs are normal, particularly in early training. If you experience pain that:
– Doesn’t resolve within a few minutes of slowing or stopping
– Is severe enough to double you over
– Radiates to your shoulder or jaw
– Returns persistently every run regardless of what you do
…these are not typical exercise-related stitches and warrant medical assessment.
Summary
Side stitches are almost entirely a prevention issue for most runners:
- Don’t eat solid food within 2 hours of running — the biggest single cause of stitches for most people
- Warm up gradually — 5 minutes of easy pace before pushing harder
- Practice belly breathing — deeper, lower breathing reduces diaphragm stress
- Try 3:2 rhythmic breathing — alternates the exhale foot to reduce repetitive stress on the right side
- Mid-run: slow down, breathe deeply, and press into the stitch — most resolve within a minute or two
Next read: Running form tips to improve efficiency