A player who is in correct defensive position and ready to quickly respond to the play
should always remain in motion, shifting weight and "moving the feet" (vibrating).
A stationary player who is maintaining court position should be constantly shifting weight
from one leg/foot to the other by raising the heel of each foot in turn in an alternating
left-right-left-right sequence. The heel is raised only a few centimeters (approx. 1-5) while the
rest of the foot remains on the ground still supporting some of the player's weight.
The lifting of the heels and shifting of weight (vibrating) is executed quite rapidly - up to 5 times
per second. When a player is more relaxed and waiting on the play, the vibrating can be
executed at a slower pace (perhaps 2 times per second) but as the player anticipates an imminent
play and a required response, the pace should be quickened up to the maximum rate.
This reduces the time it takes the player to begin to move quickly into any given new
position as required in reaction to the ongoing play.
This technique is similar to the foot-shuffling/weight-floating technique tennis players use when
preparing to receive service.
Upon analysis, we see that the first action of a person beginning to bolt (move) in any direction
is to take an "initial step" in the opposite direction with one leg, shift weight onto it, and push-off
with it, thus propelling the body in the desired direction.
The vibrating technique aims to ensure that in the moments before decision, the player is
almost always in the process of taking (or about to take) the right "initial step" to begin moving.