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my foot work is ok (X) step but i belive the i'm not using my upper body. can anyone help me out.

i want to make a short joke so bad right now

: ) :

I don't know much on the whole subject, but one thing that has helped me lately is to make sure that my shoulder is turned. What I mean by "turned" is in relation to the plane of the upper body. In other words, I can turn my hips during the x-step, I can twist my lower torso in relation to the hips, and I can also turn (load up) my shoulder relative to my upper torso. During the throw, this amount of shoulder turn is pretty critical to me, since it increases my upper arm speed before the forearm extends.

For me, to excentuate the hip/shoulder turn, I face my butt towards the intended target when I am halfway through my x-step. This forces me to turn both my hips and shoulders.

one thing i've been doing lately that may work for you is to include a step around my body as part of my follow through.

if throwing right hand back hand this means letting your left leg swing around in front of your right leg after you've thrown (finishing sideways to your target). in reality, your momentum at the point of release is different if you are in the process of stepping around with your left leg. your mommentum will be going forward instead of around your body, and this is because stepping through will allow your hips to open up square so you will not be torquing the disc as much with your shoulders.
i've been having huge problems torquing the disc... releasing it too late, turned over, and out of control... not a smooth way to use my power. this happens when there's too much shoulder movement. allowing my follow through to include that step around with the left foot has brought the smoothness and control i've been seriously lacking and i'm throwing it MUCH better as a result.
i started off doing this with approach shots... from a stand still; throwing from my right leg planted and allowing my left leg to swing all the way in front of me. the control i achieved was great and i felt more comfortable adding some good snap... i was throwing it farther than i ever had not using a run up. and it was SO consistent and accurate!! then i started incorporating it into my run up and now i always step through when i drive... it's changed my whole game and is exactly what i needed to rid my self of embarrassing shanks that would sometimes be 45 degrees off target.

i think this may be the info you need regarding the relationship between hips and shoulders. if you already knew this stuff, appologies :)