I tend to mess up verbal clues, saying tire when I mean tunnel, etc, so I try to use verbals for encouragement and speed and for more complicated maneuvers (back for a back side, out or with me to distinguish between two close obstacles.)
In my last class we did something similar to Jovi's run silent, we did run without arms, keeping your hands in your pockets or behind your back. It amazing how much you can do with just your shoulders and feet.
Jerry