Ok, i see what you think.
Yes, its probly really fun for the cat and the hamster gets exercise but its not humane in anyway. Think of it like this, say your little brother or older sister needs some exercise? What could you do, oh i know, lets lock them in an enclosed space with a lion! That ought to get rid of thoes few extra pounds, right? Wrong!
You wouldn't like it (well, maybe you would...), please don't do this, i am not sure what messed up parent is letting you behave like this but if i met them i would defintly throw water at them and tell them to wake up.
Sorry if i offended you, i hope you understand now that this hamsters life is of the same value as yours.