This is a conditioning
drill I learned from a top college coach that improves quickness
and footwork for doubles net players.
The right-handed player waits at the center line in the deuce
court service box. Coach has a stopwatch. At the command of "go,"
the player shuffles from the center of the service box to the
inside alley line, and drops to the forehand volley position (stepping
forward with the left leg), then returns to the center stripe
and drops to the backhand volley position, and repeats until 30
seconds are up. Players should be able to do this 30 times in
30 seconds. Most won't, for quite a while.
Reverse this for left-handers.