Having a dog run 10mph will not be in better shape, he will have better endurance but that's about it. Running on a mill is easier than jogging on the street, so in all actuality road work is the best form of running you can do, the pads on the dog usually don't allow for extreme distances... But they're easy ways around it. As in MMA, the more well rounded the competitor, the harder to beat. With that said, a emill may give you wind, but you will sacrifice in other areas, this I am certain.