7*-
My main training partner and I incorporate all kinds of locks into our push hands practice, but we work into them gradually.
-We start with fixed footwork and practice the basic redirections and work uprooting one another.
We practice uprooting one another without using musclar force (that is force that is discconnected from the movement of the whole, so no jerking, pushing, etc... ONLY GUIDING your partner) This way as soon as someone uses muscle you can feel it for sure!
-After we both have felt GOOD uproots we move on to switching arms and taking steps.
-After that we move into a more free sparring stage where the basic redirections start combing with joint locks including wrist, elbow and shoulder. At this point if either of us experiences pain we tap immediatly on our partner. Things are still done slow and flowing.
Have you seen that Dong style tai chi push hands video that's out there? That guy is smooth. I'll see if I can find the link. Or search Dong style push hands video or something.
Anyways, we've successfully incorporated chi na into pushhands for a couple years now, its's not very hard. I can shoot video of it if you want.
Dave