Myofascial Pain Syndrome Support Group
Myofascial Pain Syndrome (or MPS) is a term used to describe one of the conditions characterized by chronic pain. It is associated with and caused by "trigger points" (TrPs), sensitive and painful areas between the muscle and fascia. The symptoms can range from referred pain through myofascial trigger points to specific pains in other areas of the body. It may be related...

On a slightly cynical note I had a chiropractor that used to do stuff like that and I ended up going every week for a while and was in such a state afterwards I needed lots of a different therapy to put me right! The chiro was a bit, shall we say, 'over enthusiastic' with her adjustments. Just a thought.
http://en.wikipedia.org/wiki/Active_Release_Technique