{{Short description|Intense pain on the side of the diaphragm that usually occurs when running}} A '''side stitch''' (or "stitch in one's side") is an intense stabbing abdominal pain under the lower edge of the ribcage that occurs during exercise. It is also called a '''side ache''', '''side cramp''', '''muscle stitch,''' or simply '''stitch''', and the medical term is '''exercise-related transient abdominal pain''' ('''ETAP''').<ref name=MortonCallister2000>{{cite journal|last1=Morton|first1=Darren P.|last2=Callister|first2=Robin|title=Characteristics and etiology of exercise-related transient abdominal pain|journal=Medicine & Science in Sports & Exercise|date=February 2000|volume=32|issue=2|pages=432–438|pmid=10694128|doi=10.1097/00005768-200002000-00026|doi-access=free}}</ref> It sometimes extends to shoulder tip pain, and commonly occurs during running, swimming, and horseback riding. Approximately two-thirds of runners will experience at least one episode of a stitch each year. The precise cause is unclear, although it most likely involves irritation of the abdominal lining, and the condition is more likely after consuming a meal or a sugary beverage. If the pain is present only when exercising and is completely absent at rest, in an otherwise healthy person, it does not require investigation. Typical treatment strategies involve deep breathing and/or manual pressure on the affected area.
== Causes == The precise cause of ETAP is unclear. Proposed mechanisms include diaphragmatic ischemia (insufficient oxygen); stress on the supportive visceral ligaments that attach the abdominal organs to the diaphragm; gastrointestinal ischemia or distension; cramping of the abdominal musculature; ischemic pain resulting from compression of the celiac artery by the median arcuate ligament under the diaphragm; aggravation of the spinal nerves; or, most likely, irritation of the parietal peritoneum (abdominal lining).<ref name=MortonCallister2000/><ref name=MortonCallister2015>{{cite journal |last1=Morton |first1=Darren P. |last2=Callister |first2=Robin |title=Exercise-Related Transient Abdominal Pain (ETAP) |journal=Sports Medicine |date=January 2015 |volume=45 |issue=1 |pages=23–35 |doi=10.1007/s40279-014-0245-z|pmid=25178498 |pmc=4281377 |s2cid=18088581 |doi-access=free }}</ref>
Although the diaphragm is mostly innervated by the phrenic nerve, and thus could explain referred pain to the shoulder tip region, the main evidence against diaphragmatic ischemia is that ETAP can be induced by activities of low respiratory demand, such as horse, camel, and motorbike riding, where ischemia of the diaphragm is unlikely. In a study using a fluoroscopic technique, diaphragmatic movements during an ETAP episode have been shown to be full and unrestricted.<ref name=MortonCallister2015/> In another study, researchers analyzed flow-volume loops from subjects who were experiencing ETAP and found no compromise in any measures of breathing, suggesting that the diaphragm is not implicated directly in the causation of ETAP.<ref name=MortonCallister2006>{{cite journal |last1=Morton |first1=Darren P. |last2=Callister |first2=Robin |title=Spirometry Measurements During an Episode of Exercise-Related Transient Abdominal Pain |journal=International Journal of Sports Physiology and Performance |date=December 2006 |volume=1 |issue=4 |pages=336–346 |doi=10.1123/ijspp.1.4.336|pmid=19124891 }}</ref>
Some have proposed that this abdominal pain may be caused by internal organs (like the liver and stomach) pulling downwards on the diaphragm,<ref name=Collins09>{{cite book|last1=Collins|first1=Andrew|title=On Running on Lessons from 40 Years of Running.|date=2009|publisher=Authorhouse|location=Bloomington, IN|isbn=978-1-4389-3624-6|page=148|url=https://books.google.com/books?id=xovMmC_USRYC&pg=PA148|access-date=12 October 2015}}</ref> but this hypothesis is inconsistent with its frequent occurrence during swimming,<ref name=MortonCallister2000/> which involves almost no downward force on these organs.
Frictional irritation of the parietal peritoneum has been suggested as a cause of ETAP.<ref name=MortonCallister2000/> The parietal peritoneum is the outer layer of the peritoneum that adheres to the abdominal wall and underside of the diaphragm. Because the portion of the peritoneum that underlies the diaphragm is innervated by the phrenic nerve, it could explain the shoulder tip pain.<ref name=CappsColeman1922>{{cite journal |last1=Capps |first1=Joseph A. |last2=Coleman |first2=George H. |title=Experimental Observations on the Localization of the Pain Sense in the Parietal and Diaphragmatic Peritoneum |journal=Archives of Internal Medicine |date=1 December 1922 |volume=30 |issue=6 |pages=778–789 |doi=10.1001/archinte.1922.00110120097004|url=https://zenodo.org/record/1499042 }}</ref><ref>{{cite journal |last1=Jackson |first1=S. A. |last2=Laurence |first2=A. S. |last3=Hill |first3=J. C. |title=Does post-laparoscopy pain relate to residual carbon dioxide? |journal=Anaesthesia |date=May 1996 |volume=51 |issue=5 |pages=485–487 |doi=10.1111/j.1365-2044.1996.tb07798.x|pmid=8694166 |s2cid=35371138 |doi-access=free }}</ref><ref>{{cite journal |last1=Narchi |first1=P |last2=Benhamou |first2=D |last3=Fernandez |first3=H |title=Intraperitoneal local anaesthetic for shoulder pain after day-case laparoscopy |journal=The Lancet |date=December 1991 |volume=338 |issue=8782–8783 |pages=1569–1570 |doi=10.1016/0140-6736(91)92384-E|pmid=1683981 |s2cid=22742711 }}</ref> The parietal peritoneum traverses the entire abdominal wall, which could account for the widespread distribution of ETAP; the tension in the parietal peritoneum is increased with torso extension; children have a proportionally larger peritoneal surface compared to adults, which could explain the increased prevalence of ETAP in younger individuals;<ref name=MortonCallister2015/><ref>{{cite journal |last1=Esperanca |first1=Manuel J. |last2=Collins |first2=David L. |title=Peritoneal dialysis efficiency in relation to body weight |journal=Journal of Pediatric Surgery |date=April 1966 |volume=1 |issue=2 |pages=162–169 |doi=10.1016/0022-3468(66)90222-3}}</ref> and pain arising from the parietal peritoneum relieves quickly on removal of the stimulus,<ref name=CappsColeman1922/> similar to what is observed for ETAP when activity is ceased.<ref name=MortonCallister2006/> After a meal, distention of the stomach could increase friction between the visceral and parietal layers of peritoneum,<ref name=MortonCallister2000/> and sugary beverages could provoke ETAP due to slower emptying of the stomach.<ref>{{cite journal |last1=Morton |first1=Darren Peter |last2=Aragón-Vargas |first2=Luis Fernando |last3=Callister |first3=Robin |title=Effect of Ingested Fluid Composition on Exercise-Related Transient Abdominal Pain |journal=International Journal of Sport Nutrition and Exercise Metabolism |date=April 2004 |volume=14 |issue=2 |pages=197–208 |doi=10.1123/ijsnem.14.2.197|pmid=15118193 |hdl=10669/75841 |hdl-access=free }}</ref> In fact, the fluid in the peritoneal cavity is highly responsive to osmotic gradients between it and its vascular supply.<ref name=MortonCallister2015/>
In the absence of a clear cause, any treatment techniques are uncertain. Typical strategies involve deep breathing and/or manual pressure on the affected area.<ref name=MortonCallister2015/>
==Occurrence== Side stitches occur in every level of athletes from school-aged children, weekend exercisers, or elite athletes, although they are more common in younger people. Activities that use upper body twists, like running, swimming, and horseback riding, report this affliction more often. Approximately two-thirds of runners will experience at least one episode of a stitch each year.<ref>{{cite news |last=Wetsman |first=Nicole |url=https://www.popsci.com/what-is-side-stitch/ |title=When you get a stitch in your side, what's really going on? |work=Popular Science |date=2017-10-20 |url-status=live |archive-url=https://web.archive.org/web/20171113205307/https://www.popsci.com/what-is-side-stitch/ |archive-date=2017-11-13 |access-date=2019-08-02 }}</ref>
==See also== * Precordial catch syndrome
==References== {{reflist}}
==Further reading== * {{cite journal |journal=Sports Medicine |volume=32 |issue=6 |year=2002 |pages=261–269 |title=The human spleen during physiological stress |author1=Stewart |author2=McKenzie |doi=10.2165/00007256-200232060-00002 |pmid=11980500 |s2cid=24607294 }} * {{cite journal |journal=Clinical Nuclear Medicine |year=2010 |volume=20 |issue=10 |pages=884–887 |title=The effect of exercise on normal splenic volume measured with SPECT |vauthors=Otto AC, Rona du Toit DJ, Pretorius PH, Lötter MG, van Aswegen A |doi=10.1097/00003072-199510000-00005 |pmid=8616992 |s2cid=37316332}} * {{cite journal |journal=Journal of Applied Physiology |volume=74 |pages=1024–1026 |year=1993 |title=Spleen emptying and venous hematocrit in humans during exercise |vauthors=Laub M, Hvid-Jacobsen K, Hovind P, Kanstrup IL, Christensen NJ, Nielsen SL |issue=3 |doi=10.1152/jappl.1993.74.3.1024 |pmid=8387068}}
==External links== * {{cite web |url=https://www.brianmac.co.uk/stitch.htm |title=Stitch |first=Brian |last=Mackenzie |website=Sports Coach |year=1999}}
{{DEFAULTSORT:Side Stitch}} Category:Abdominal pain Category:Ailments of unknown cause Category:Physical exercise