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What is a Side Stitch and Why Won’t It Go Away?

By: Rick

If you run, you’ve likely experienced a side stitch. If you haven’t, consider yourself lucky! A side stitch is a cramp-like sensation occurring toward the bottom of the rib cage area and usually on the right side of the body. The sensations can range from slightly annoying to a more severe stabbing-type pain.


The nerdy name for a side stitch is ‘Exercise-Related Transient Abdominal Pain,’ or ETAP, for short. While there are many theories out there as to the exact cause, no one singular cause for ETAP has been identified.

Of the many theories, below are some of the more common ones:

  • Lack of electrolytes
  • Increased blood flow to spleen/liver
  • Stretching of ligaments associated with the diaphragm
  • Shallow breathing
  • Excessive back flexion (rounding of the back)

Some runners also experience pain in the shoulder (usually right-hand side) when running. This is thought to be referred pain from the diaphragm via the phrenic nerve.

While ETAP is not dangerous, it likely causes frequent breaks to stretch, reduced pace or even cessation of a run.


While some people seem more susceptible than others to ETAP, below are five things that may help:

  1. Strengthen inner-core musculature (deep core muscles)
  2. Gradually increase running mileage and intensity
  3. Increase fitness level
  4. Get a proper warm-up
  5. Pay attention to pre-run hydration/food intake to see if there is a correlation with ETAP


As noted above, when ETAP occurs, common ways to reduce or eliminate it is to slow down, stretch, stop running and to focus on deep breathing.

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Muir, Brad (2009-12-01). “Exercise related transient abdominal pain: a case report and review of the literature”. The Journal of the Canadian Chiropractic Association. 53 (4): 251–260.

Morton, DP; Callister, R (September 2010). “Influence of posture and body type on the experience of exercise-related transient abdominal pain.”. Journal of science and medicine in sport / Sports Medicine Australia. 13 (5): 485–8.

Plunkett, BT; Hopkins, WG (August 1999). “Investigation of the side pain “stitch” induced by running after fluid ingestion.”. Medicine and science in sports and exercise. 31 (8): 1169–75.

Morton, DP; Callister, R (2000 Feb). “Characteristics and etiology of exercise related transient abdominal pain.”. Medicine and science in sports and exercise 32 (2): 432–8.

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About Rick

Rick Prince is the founder of United Endurance Sports Coaching Academy (UESCA), a science-based endurance sports education company. UESCA educates and certifies running, ultrarunning, nutrition, cycling and triathlon coaches worldwide on a 100% online platform.

Categories:Coaching, Running, Triathlon