I've found something which has been helping me with retraining exercises that I thoght you might be interested in. This applies to the left fretting hand.While trying to play softly but fast I find the sensation of the string on the guitar is enough to remind me of the dystonia sensation enough to distract me and make me use more force than necessary. As an experiment, I took one of my unused guitars and removed all the strings from it.
I tried the same exercises on it and to my surprise I found that I had a lot more fluidity and freedom without the "distraction" of the string pressure. Basically I fret the notes as if would be playing the exercise. The right hand is optional although you can play air guitar with it if you want to simulate the picking action.
After practicing this way for some time, I find that when I go back to the regular instrument my hands are a lot more relaxed and flexible.
I am going to be doing this as part of my regular practice routine from now on since it seems to be helping...
