my youngest has had a shoulder muscle injury a few months ago which is now all fine and healed but seems reluctant to use the full extent of his reach, have been told to trot him down hill to stretch his front out and improve his reach, anyone heard this, would it work??

Not heard of that myself but have you thought about swimming?  My boy has recently had an op on his leg so he was holding it up even when it was much better through habit I believe / stiff!  He went for 10 swimming lessons and is fab now, we are going to continue for fun swims now as he loved it so much.

There are pools designed esp for dogs ;)

As said hydrotherepy will work wonders I would think.  Also general trotting will work.  Have one boy who wouldn't drive out behind and I took him jogging 3-5 times aweek for 5KM at a time and he got alot better.  stoped now as too much work for me but will start again in january to get him ready for crufts!

thanks for that, not sure how he would take to swimming :-o , will keep up with the trotting and see if this combined with training for this upcoming working season improves his movement.