think about your whole body as a skateboard deck. when the entire deck is intact and rigid, you get the strongest pop. if you break a bunch of the plys but keep skating it for shits and giggles, you can't pop it as well as a lot of the force is absorbed by the busted ass deck.
similarly, you can have strong legs but if your core (abs, back) is jelly soft you will be not be getting maximum efficiency out of your leg strength.
conclusion: pilates and tae bo, bro.