Try doing the pot. I am working on this with my dogs right now. We just started Sunday and I can already tell a difference in the way they use their back legs. Also you can lay a ladder on the ground and have the dog walk through it and work towards running through the rungs.
Karly - GSD 10/16/12
Alta Tollhaus Farrell "Briggs" - GSD 03/24/13
Cats - Cricket, Mickey, Spartacus, Tiger, Josie, Ashton, Lily, Drake, Cooper, Tucker & Hank