Armature IK Causing Heavy Distortion I've been trying to figure what's wrong with what I'm doing for a long time now.
The IK moves how I want it to, but...you can see what happens with the attached image.
.blend file: file
This looks like a mesh binding problem. You should make sure your mesh's scale is applied, and then attach the mesh to the skeleton or rig more closely. You should go into weight paint mode and make sure the vertices farther down the chain aren't being influenced by the object you're manipulating.
Good luck.