A couple of things I've used during testing:
Sing "My Bonnie Lies Over the Ocean" with the class. Every time they hear a "b" they change position: if they are sitting, they stand, and vice versa. It's fun when you get to the "bring back, bring back, oh bring back my Bonnie to me" part and their heads are bobbing like buoys in the ocean! We then try to do it faster and faster. I haven't used "Looby Loo" or things like that, but they'd probably work, too.
Play "Simon Says" but use stretching/exercise things. For example, tell them to try to touch the ceiling without having their feet leave the ground. Or have them try to touch both of the opposite walls of the classroom at the same time. I also use jumping jacks, hopping, etc. but I don't worry too much about who gets "out"--the purpose is to get them moving and oxygenated and ready for the next sub test.
Are you in Michigan, by any chance? We're practicing this week, too, for our MEAP tests in October. We can't do any official practicing two weeks before the test, so today is "it" for us. The poor kids--two weeks "off" and then we start with this again. Wonder when we're going to have time to teach the curriculum?