Interesting read. I work my dogs on a flirt stick to help build muscle and fitness when twisting, it's amazing what this exercise can take out of them, My bitch when she 1st started on it, after 1/2 mins was done. I have built her up over time and she can now happily go for 10 mins on the flirt, however like anything, i think it's everything in moderation. She trains on the stick normally twice a week, and has free running everyday, jump training, ball retrieve and swims 3 times a week. I do all this with her not so she's fit to work, but purely to keep her mentally and physically stimulated