The Story Behind Running and Side Stitches

Jason Fitzgerald
by Jason Fitzgerald
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The Story Behind Running and Side Stitches

Whether you’re a new or experienced runner, there’s a good chance you have experienced the unpleasant, sharp pain of a side stitch. They can come on unexpectedly and, at times, are painful enough to force you to take a walking break mid-run, or worse yet, mid-race.

But what exactly are side stitches and what can you do about them? While some questions surround the exact science of side stitches, the good news is there are a variety of ways to minimize or prevent them.


The medical term for a side stitch is ETAP or exercise-related transient abdominal pain. Research shows side stitches impact approximately 70% of runners. Surprisingly, they are also common in a seemingly unrelated sport: horseback riding. The study suggests they tend to occur in activities that involve repetitive movement with your torso in an extended position, one of the few links between running and riding.

Side stitches typically produce a sharp, stabbing pain on one side of your abdomen (right more often than left), usually right below your rib cage. They can be mild or severe, and often arise without warning. Sometimes the abdominal pain is accompanied by pain at the tip of your shoulder, possibly due to referred nerve pain.


While there are a number of theories about why side stitches happen, there are exceptions to all of the possible explanations that make it difficult to pinpoint one exact cause.

Here are some potential reasons:

1. Diaphragmatic “tugging”: Your diaphragm is made of muscle and connective tissue and separates your chest and abdominal cavities. This theory proposes that side stitches are caused when an overly full stomach “tugs” on your diaphragm. The vertical impact of running pulls organs downward during activity, tugging on ligaments and creating irritation. Running with a full stomach and not allowing adequate time for digestion can lead to increased side stitches.
2. Sugar concentration: The concentration of sugar in pre- and mid-run drinks has a direct correlation to side stitches. Sugary fluids caused more side stitches, while those with a lower sugar concentration were less likely to do so.
3. Diaphragmatic ischemia: Ischemia simply means reduced blood flow to an area. In a high-intensity sport like running, blood is diverted away from the diaphragm to skeletal muscles, and it was initially thought this diversion led to side stitches. This theory has become less accepted over time, however, since lower intensity sports (like riding) also experience side stitches.
4. Postural changes: Changes in posture can come from the way you run (excessively arching your back while running downhill, for example), or it can come from other defects that you have no control over (scoliosis or other curvatures). This can irritate either the spine itself or the nerves that connect to your torso, causing abdominal pain.


While the science may vary on what causes side stitches, most of us only want to know how to get rid of them. Though you may have to experiment to see what works best for you, there are a number of preventative measures as well as mid-run techniques.

If you are a new runner, know side stitches often become less frequent over time. Long-time runners are less likely to experience them, so keep training.


  • Train consistently to allow your body to adapt to the stresses of running.
  • Strengthen your entire core (not just your abs) as this is known to help reduce the occurrence of side stitches.
  • Plan your pre-run meals so you don’t eat too much too close to a run. Large meals may need up to three hours to fully digest.
  • Avoid sugary or carbonated drinks, as these can exacerbate side stitches.
  • Warm up thoroughly before workouts to allow your body to ease into harder efforts.
  • Practice diaphragmatic (belly) breathing rather than using your chest muscles.


  • Side stitches are uncomfortable but harmless. Continue running and refocus if you are able. Sometimes they dissipate on their own.
  • Massaging or putting pressure on the painful area can be helpful to make it dissipate more quickly.
  • Expand your diaphragm in opposite pattern of what you usually do — try giving a strong, forceful exhalation while running when the foot on the opposite side of the pain hits the ground. Since pain occurs more often on the right, you’ll want to push all the air out of your lungs as your left foot hits the ground.
  • If you can’t keep running through the pain, stop and walk briefly with slow, deep breaths.


If you suffer from side stitches, fear not! Though it can be challenging to figure out the precise cause of this frustrating problem, the techniques above should help to make them a thing of the past.

About the Author

Jason Fitzgerald
Jason Fitzgerald

Jason is the founder of Strength Running, a USA Track & Field certified running coach and 2017’s Men’s Running’s Influencer of the Year. Learn more about how he can help you run faster.


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