The deep front line fascial train passes through and surrounds the pelvic floor. This fascia extends from tibialis posterior in the lower leg up to diaphragm and into scalenes in the neck.
The fascial network is continuous and very little in known about its functional relationship to muscle tension and less is known about changes that may occur during pelvic floor rehabilitation, (exercises) and surgery.
Meyers a well known fascail train expert and myofascial therapist believes that fascia is a highly adaptive structure that can change in response to forces placed through the body. We do know that fascia is made mostly of elastic tissue and has no contractile elements like muscle. We can also demonstrate fascia is able to lengthen or tighten, depending on loads applied.
Lets argue that a weak pelvic floor, which is essentially bowl shaped, deepens. This deepening potentially stretches the fascia over time, maybe 1-2 years. Which then leads to less support through the pelvic floor for the pelvic organs. Strengthening the pelvic floor leads to reduced stretch of the pelvic fascia.
Therefore we could assume that those that get some relief from their pelvic pain by lying down, especially if the pelvis is higher than the shoulders, may get relief from long term pelvic floor strengthening routines.
We could also assume that some of the pelvic pain may be due to altered tension of the pelvic fascia.