I'm SO glad you started this post cause I was just signing on to ask the same question. My Cooper is 6 months and a bundle of PURE ENERGY!!! Since its so cold here I was thinking of trying him on the treadmill and now since I've read the posts I'm definately gonna give it a try. I just dont know what else to do with him in the puppy stage....hoping with more exercise he will lay off the biting/scratching etc a little.....hubby is getting a little fed up and so is the wall in his room. Time to go back to crating a little more I guess....any other suggestions?