Hand and Arm Rotation

After racket face angle and shoulder rotation,
the third variable across the grips styles
on the modern forehand is hand and arm rotation, one of the most complex and confusing
technical elements in understanding and teaching the game.

This hand and arm rotation is sometimes described as the "windshield wiper"
effect. In general, the more extreme the grip, the more total rotation of the hand
and arm in the forward swing.

Agassi demonstrates the forward internal
rotation of the arm, the so-called
windshield wiper effect, the source of much of the variation-and
confusion–in the modern forehand.

But individual players also have the ability to vary this
rotation from ball to ball, depending on the circumstances. They increase
the amount of the rotation to increase spin, to create short angles, to deal
with low balls, and when they hit on the run.

They also vary the speed of the rotation. You can actually see the change by counting frames in the high speed footage. Sometimes the speed of the hand and arm rotation increases by a third or more. But the ability to vary the hand rotation can work the other way as well. Sometimes you’ll see players with extreme grips…