Stop zombies sprinting?

[Chilton]

Not that i know of, however, you may be able to do something creative with draggable boxes and the like so the player can create obstacles - Placing a stack of boxes in front of a door for example, wont stop them, but theyll slow down to push through it.
Of course, make sure the player cant make any permenant barriers, just things to slow them down. They will go around movable boxes for example, but cant go through them.