Neuromodulation Physical Therapy The pelvic floor musculature performs an important role in the tonic support of the pelvic viscera provided by a preponderance of slow-twitch (type I) fibers. In addition, fast-twitch (type II) fibers within the lavator ani provide active periurethral muscle contraction with increased intra-abdominal pressure. An increase in pelvic floor muscle tone occurs during bladder filling via a guarding reflex, accompanied by bombardment by unmyelinated C-fiber afferents with an increased somatic efferent stimulation of the pelvic floor muscles during vesical distention. In IC patients, the result is high-tone pelvic floor muscle dysfunction. High-tone pelvic floor muscle dysfunction has also been known as coccygodynia, tension myalgia, levator ani spasm, and levator syndrome.