MAT is an interesting way of relieving pain conditions, that I believe is related to osteopathy. I have had the luck to work with an excellent practitioner. A session includes both getting your muscles to work more efficiently and a home work component of simple isometrics to lock in what you have gained. Session results can be mixed, usually I felt good afterwards, with issues partially resolved. Sometimes I felt lighter and a particular pain was gone. Overall progress can be slow and usually requires a number of sessions, with some muscles needing to be activated again, or other underlying/related muscles still needing work. Years of postural habits, whether due to injury or just life style, cannot miraculously be unwound in just a session or two.
I really like this approach, as it is based on retraining the brain- simplistically said, reminding it that a particular muscle is supposed to do a particular task. MAT it has given me a lot of hope and good results.
Here is the info from the professional organization with a list of practitioners as well: www.muscleactivation.com