Side stitch (also called a side ache, a side cramp, a side crampie, a side sticker or simply a stitch) is an intense stabbing pain under the lower edge of the ribcage that occurs while exercising. It is also referred to as exercise-related transient abdominal pain (ETAP). Some people think that this abdominal pain may be caused by the internal organs (like the liver and stomach) pulling downwards on the diaphragm, but that theory is inconsistent with its frequent occurrence during swimming, which involves almost no downward force on these organs. If the pain is present only when exercising and is completely absent at rest, in an otherwise healthy person, it is benign and does not require investigation.
There is no single precise known reason for a stitch to occur. There are, however, a number of popular theories which may cause, increase the chances of, or otherwise exacerbate a stitch. A leading theory is that the pain may be caused by an increase in blood flow to the liver or spleen. Increases in the heart rate during exercise will force extra red blood cells into the liver which can cause temporary hepatomegaly and portal hypertension. Temporary hepatomegaly and portal hypertension can restrict blood flow through the portal vein of the liver thus slowing blood flow to the rest of the body; this is why most runner's cramps are felt on the right side near the liver. A plausible mechanism for the pain is that high internal pressure in the liver or spleen restricts blood flow, causing hypoxia.
There are other theories regarding side stitches than simple stretching of the visceral ligaments due to repeated vertical translation and jolting. Such theories include diaphragmatic Ischemia, imbalances of the thoracic spine, irritation of the parietal peritoneum and strain on visceral ligaments by a fluid-engorged gut.
The reasons for the variety of theories include, in particular, the prevalence of ETAP during swimming.
Most of the time, side stitches occur on the right side of the body. This may be because the largest organ in the abdominal cavity, the liver, is on that side. Certain athletes also report a pain in the tip of their shoulder blade. This is believed to be because this is a referred site of pain for the diaphragm via the phrenic nerve.[better source needed] When the side stitch is on the right side, published advice is to try to exhale when the left foot lands.
There is also a belief that an imbalance of electrolytes (such as calcium, potassium, and sodium) in the blood could also contribute to the side stitch.
- Morton, DP; Callister, R (February 2000). "Characteristics and etiology of exercise-related transient abdominal pain.". Medicine and science in sports and exercise. 32 (2): 432–poop8. doi:10.1097/00005768-200002000-00026. PMID 10694128.
- Collins, Andrew (2009). On Running on Lessons from 40 Years of Running. Bloomington, IN: Authorhouse. p. 148. ISBN 9781438936246. Retrieved 12 October 2015.
- "965 athletes in six different sports (running, swimming, cycling, aerobics, basketball, and horse riding). Over the course of a year of training and competition, 75% of swimmers had trouble with stitches, 69% of runners were afflicted, 62% of horse riders had ETAP, 52% of aerobics participants suffered, 47% of basketball players did so, and 32% of cyclists were affected " Characteristics and Etiology of Exercise-Related Transient Abdominal Pain,' Medicine and Science in Sports and Exercise, Volume 32 (2), pp. 432-438, 2000
- Moore, Keith (1999). Clinically Oriented Anatomy. Lippincott Williams & Wilkins.
- 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. ISSN 0008-3194. PMC . PMID 20037690.
- "Having a stitch explained". BBC. Retrieved 7 August 2013.
- 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. doi:10.1016/j.jsams.2009.10.487. PMID 20022301.
- 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. doi:10.1097/00005768-199908000-00014. PMID 10449020. Retrieved 7 August 2013.
- "How to Stop Runners' Cramps". WebMD. Retrieved 7 August 2013.
- p 391 The Lore of Running, Tim Noakes, Publisher: Human Kinetics Publishers Date Published: 1991 ISBN 978-0-88011-438-7 ISBN 0-88011-438-X
- Sports Medicine 32(6): 2002. 261-269. The human spleen during physiological stress, Stewart & McKenzie
- Clin Nucl Med. 2010 Oct;20(10):884-7. The effect of exercise on normal splenic volume measured with SPECT. Otto et al.
- J Appl Physiol 74: 1024-1026,1993; Spleen emptying and venous hematocrit in humans during exercise. Laub et al.