Defensive back footwork skills such as speed shuffles, back pedals and hip turns were learned by athletes at Sports Fitness Hut's Speed And Power Camp. These footwork skills can also be used in other sports like baseball, soccer and basketball.
I played defensive back in college so I'm definitely an authority on the need for accelerating backwards, forwards, shuffling, etc. We practiced "running backwards at game speed" every day until it became a natural movement.
If you play a defensive position in your sport or transition to defense (as in basketball, lacrosse or soccer) then you need to train your body for backwards acceleration and other footwork skills. Many times, you may be running forward and need to adjust quickly into a back pedal, shuffle or hip turn to defend your opponent. Or, you could be in a stand-still position and need to quickly accelerate backwards in a defensive position.
There are exercises that you can practice to improve your backwards acceleration. As with all speed exercises, backwards acceleration practice should be done with "game-time effort." You also must keep your shoulders leaned forward in order to maintain dynamic balance and to be able to stop and go forward "on a dime."
Some common exercises to improve footwork are: back pedal, hip turn and run, hip turn and shuffle, hip turn and crossover, shuffle and run and continuous hip turns. Good hip drills are: hip twists, hip in outs , leg swings and hip flexions/extensions.