Side Stitches: Possible Causes and Research-backed Treatment and Preventive Methods

Side stitches are a very common problem among runners.  Though they are typically nothing more than an occasional nuisance, in some people, they can cause serious disruptions in training or racing.

As we’ve seen in previous articles, if an injury or condition that’s detrimental to running performance is common enough, there’s likely to be at least a handful of scientific studies on it that can help us gain a better understanding of what’s going on.  Fortunately, this is the case for side stitches as well.

Possible causes of side stitch

A side stitch classically manifests as an aching, stabbing, or sharp pain your abdomen, just below your ribs.  It’s usually localized to one side, and occasionally will be accompanied by pain at the tip of your shoulder on the same side.

A few survey-based studies on runners and other athletes who develop side stitches in an athletic event have established that eating a large meal or drinking concentrated, sugary fluids like fruit juice close to the time of the competition will increase your risk of developing a stitch.  But perplexingly, being older and training more often seem to confer a protective effect.

Diaphragmatic ischemia

The actual cause of side stitches is still uncertain.  There are a few competing ideas, all of which have some evidence to support them.  Traditionally, it was though that ischemia, or a decrease in bloodflow, to the diaphragm (the muscle which expands your lungs and allows you to breathe) causes localized irritation and pain.

This purported cause also explains why certain foods or fluids seem more prone to cause side stitches: more blood required by the stomach for digesting certain foods or liquids would pull away more blood from the diaphragm.  But several studies have provided evidence against this theory of “diaphragmatic ischemia.”

A 2006 study by two researchers at Avondale College in Australia measured the actual breathing patterns of athletes suffering from side stitches during exercise.  Twenty eight athletes were recruited, all of which had a history of developing side stitches during training.  Several respiratory variables associated with lung function and breathing were measured, then the athletes completed a treadmill run.  Fourteen developed a side stitch, while the others were able to complete the test without pain.  After the test, the athletes all had their lung function measured again, and the researchers compared the function of the pain-free athletes to that of the ones suffering from a side stitch.

While the athletes with a side stitch showed a small decrease in lung power during exhalation, the authors concurred that the magnitude of this difference was not likely to affect performance.

Further, the fact that they detected no difference in inhalation strength—which is primarily governed by the diaphragm—implies that poor blood flow to the diaphragm was not a major causal factor.  If it were, the researchers would have expected to see some limitations in the strength or power of the blood-starved diaphragm.  And bloodflow shouldn’t be disrupted significantly in high-impact but low-intensity sports like horseback riding, yet one study found that side stitches affect up to 62% of horse riders.

Irritation on the ligaments and abdominal pain

A different explanation for side stitches is irritation or “tugging” on the ligaments and the membrane which hold and connect all of the various muscles, bones, and organs inside the abdomen.

As the theory goes, impact during activity pulls the organs in your abdomen downwards, tugging on the ligaments in the upper abdomen and eventually creating irritation.  This would explain why consuming a meal (regardless of its contents) too soon before running can bring on a side stitch, and it explains why side stitches are common in running and horse riding, but are rare in cycling.  However, there are a few phenomena which don’t fit into this theory either.

For one, varying the concentration of sugars in fluids consumed immediately before or during exercise has a measurable effect on your risk of developing a side stitch.

This was demonstrated in a 2004 study which used 40 athletes with a history of side stitches during exercise.  On separate occasions, each subject was given a controlled amount of weakly-flavored water, a sports drink, fruit juice, or no fluids at all.

After ingesting the fluid, the subjects completed a treadmill run and reported any abdominal pain.  The fruit juice, with its high concentration of sugar, was much more likely to cause a side stitch than any of the other conditions.  And the sports drink, which had a medium concentration of sugar, appeared to cause more severe side stitches than no fluids at all (though less so than the fruit juice), though this finding just escaped statistical significance.

Second, side stitches affect up to 75% of swimmers, whose sport does not involve up-and-down jolting of the abdomen.  So vertical tugging can’t fully explain the origin of side stitches either!

Irritation of the spinal column

Finally, a third line of reasoning connects side stitches with irritation of the spinal column.  In a 2004 report, D. P. Morton and T. Aune (authors of several of the papers cited here) described how, in nine out of 18 runners seen at their clinic, the pain from a side stitch incurred during a workout could be readily reproduced by applying manual pressure to the vertebrae along the upper spine.   Morton and Aune also cited two studies which found that kyphosis (or “roundback”), a condition where the upper spine is more sharply curved than normal, is related to an increased risk of suffering from side stitches.

Crucially, this spinal theory also explains the sometimes-observed pain at the tip of the shoulder—both the nerve that runs to the diaphragm and the nerve that runs to the tip of the shoulder originate from the same vertebrae.

Further, it also can explain why runners, horse riders, and swimmers experience high rates of side stitches, but cyclists do not: running and horse riding involve vertical jolting of the spine, while swimming involves rotational twisting, both of which could put stress on the upper spine.  Cycling, however, involves comparatively little spinal stress.

Ultimately, this final explanation has its own holes as well: why do pre-race meals and sugary fluids seem to bring on side stitches more often and more severely? Why don’t all people with side stitches have reproducible pain when putting pressure on the upper spine?

Suggested preventive and treatments methods

Unfortunately, the cause (or causes) of side stitches have yet to be completely fleshed out.  Like many things in athletics, the roots of side stitches are likely more complex than one single factor.  On the bright side, we can glean some useful information from the science we’ve reviewed.

  • If you have a history of side stitches, take note of what you eat and drink before you start your workout. Giving yourself more time after eating might stave off a stitch, and avoiding concentrated sugary drinks before and during exercise should help as well.
  • Case studies suggest that stretching the stomach, deep breathing, and contracting the abdominal muscles while bending forward can all help alleviate a side stitch.
  • If you have chronic side stitches, it may be worth having a physical therapist or chiropractor examine your spine to see if dysfunction there could be exacerbating your side stitches.

As more research on side stitches is done, we should move closer to fully understanding how the diaphragm, the ligaments and membranes of the abdomen, and the spinal column all affect side stitches.

Until then, you’ll have to experiment with some of the techniques listed above to help you get over your side stitches.

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References

1. Morton, D.; Callister, R., Factors influencing exercise-related transient abdominal pain. Medicine & Science in Sports & Exercise 2002, 34 (5), 745-749.
2. Morton, D.; Callister, R., Spirometry measurements during an episode of exercise-related transient abdominal pain. International Journal of Sports Physiology and Performance 2006, 1 (4), 336-346.
3. Morton, D.; Callister, R., Characteristics and etiology of exercise-related transient abdominal pain. Medicine & Science in Sports & Exercise 2000, 32 (2), 432-438.
4. Morton, D.; Callister, R.; Richards, D., Epidemiology of exercise-related transient abdominal pain at the Sydney city to Surf community run. Journal of Science and Medicine in Sport 2005, 8 (2), 152-162.
5. Morton, D.; Aragón-vargas, L.; Callister, R., Effect of ingested fluid composition on exercise-related transient abdominal pain. International Journal of Sport Nutrition and Exercise Metabolism 2004, 14 (2), 197-208.
6. Morton, D.; Aune, T., Runner's stitch and the thoracic spine. British Journal of Sports Medicine 2004, 38, 240-243.
7. Muir, B., Exercise related transient abdominal pain: a case report and review of the literature. Journal of the Canadian Chiropractic Association 2009, 53 (4), 251-260.
8. Plunkett, B.; Hopkins, W., Investigation of the side pain "stitch" induced by running after fluid ingestion. Medicine & Science in Sports & Exercise 1999, 31 (8), 1169-1175.

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