What about a "punching" bag? Fill up an old pillowcase (or not old
) with scrunched newspaper. Tie the end together and hang it from a doorway or something like that. Then let them bag at it with their hands and wooden spoons. Obviously it needs to be supervised carefully and perhaps just a one person at a time game.
Indoor obstacle courses? When they get good at it having timed races to see who can complete it the fastest.