The first contact with this annoying phenomenon that affects 70% of runners is well known: we have all had it since childhood. Remember the carefree games in the park and the runs you used to take? Do you also remember how suddenly you would get a twinge under your right diaphragm?
“It’s the spleen,” they said. You were told by friends and parents, you were told later by the coach or gym teacher. Indeed: then no one told you anymore because, when it happened to you, you knew exactly what it was.
The curious thing is that science has not yet come up with an unambiguous and comprehensive explanation of why this happens. What is even more curious is that the spleen has nothing to do with it: anatomically the pain is in that region but the spleen is not causing it (also because it is on the opposite side). What happens then?
A matter of peritoneum
The most accepted theory explains that the pain is caused by irritation of two membranes: the parietal and visceral peritoneum. The former is in direct contact with the diaphragm (which helps inflate and deflate the lungs) while the latter envelops the internal organs. During running, these two membranes rub against each other, become irritated and thus create pain.
The “mechanical” explanation seems inapposite, but in reality it is now little accepted by science. Indeed, how do you explain that not all runners suffer from it? After all, we all have peritoneum, right? And how is it then related to speed? In fact, if you remember correctly, you always experienced this discomfort as the speed at which you ran increased, so–according to this logic–the more experienced and faster runners should always suffer from it.
However, it could be something else: perhaps it is the ligaments that bind the internal organs that become irritated during sports activity, or diaphragmatic ischemia. All are variously plausible hypotheses, although the one that is most credited today is another.
New abdominal perspectives
The new research comes from Old Dominion University in Norfolk, Virginia. Published in the. Clinical Journal of Sports Medicine, it involved 168 runners starting with a novel approach: in fact, the researchers’ thesis was that the causes may be psychological in nature.
The research subjects were asked about numerous details: from eating habits to whether the pains occurred before or after meals, on an empty stomach, whether they suffered from gastrointestinal discomfort, how they slept, and whether they suffered from stress or otherwise.
The two most important findings were that both runners who had a history of gastrointestinal disease or sleep disorders did not suffer from this type of “upper-abdominal” pain. So neither digestion nor sleep seemed to be the cause.
Instead, what those who suffered from it had in common was a high level of stress and anxiety. By the way, the results were confirmed by other observations, namely that both young and experienced runners and older runners did not suffer from it, at least only as long as they did not suffer from anxiety or stress. When this happened, in other words, it did not matter whether one was little or much trained or simply used to running: many people who fell within the critical stress and anxiety response framework also manifested these pains.
What’s the cause then?
The research-aside from not being based on a large number of subjects-has, if anything, demonstrated the association between psychological condition and side stitches (let’s not call it spleen pain anymore). What does it mean? It means that these pains almost always occur in individuals suffering from anxiety and stress but this does not mean that anxiety and stress are necessarily their cause.
(via Trail Runner Mag)