What are signs of irritable bowel syndrome?

Irritable bowel syndrome is a functional disorder without a known cause.  Empirically it is known that useful medications modify autonomic neural function.  My clinical research has discovered a group (N=20) of male extreme sport enthusiasts who suffer from IBS.  The unifying clinical finding was that they all had sacroiliac joint (SIJ) injury and hypermobility (subluxation) disorder (diagnosed via criteria published in the Occupational Disabilities Guidelines).  I speculate that SIJ hypermobility stimulates the pelvic presacral plexus & contained parasympathetic nerves that innervate the colon, inducing colon spasm and evacuation.  IBS highly correlates with fibromyalgia, which is likewise common in persons with SIJ subluxation disorder. The reason for a "spectrum of disorder" for fibromyalgia is that the cause, pelvic girdle instability due to pelvic ligament laxity, manifests differently in individuals & genders.  The body musculoskeletal tower is constantly stressed by gravity & a body tilted above an unstable pelvis incurs widely ranging chronic muscle spasm leading to varying densities of painful trigger points. The delicate female pelvis is more easily injured & women have an higher incidence of Joint Hypermobility Syndrome (inherited trait) that contributes to pelvis instability.  Female pelvices are subject to varying intensities of permanent injury related to frequency of childbirth.  In both sexes, severity of fibromyalgia symptoms is a function of musculoskeletal deconditioning & upper body mass borne by an unstable pelvis.  On a Pain Board at Quora.com I discusses these dynamics, which are the true cause of fibromyalgia.  I also discuss my study of male extreme sport enthusiasts who have IBS.