Pretty much every cat I've known have what I call "Kitty Psychotic Moments", where all will be quiet and they will suddenly go running to the other end of the house at top speed (and usually run back a moment later), or leap in the air, or some other sudden unexplained burst of physical activity.
My best explanation is that when you sleep 19 hours a day, there is a lot of pent up energy, and some times that pent up energy just has to vent.