In this discussion, we explain the third major technique of producing topspin. It is often referred to as the windshield wiper method because it has a motion similar to an automobile windshield wiper. The illustrations are for the acceleration and strike stages.

Below left is the start of the windshield wiper acceleration. Below right is a three-stage animation. The power of this technique arises from the use of the forearm to rapidly accelerate the racquet in a counterclockwise circular motion (relative to the player's position) at high speeds. The motion requires development of the strength of the forearm to be effective.

A key difficulty in this motion is interjecting the straight-line interval for the strike as the racquet approaches the ball. This is done both by lifting the racquet from the shoulder and by using a forearm joint contraction as the forearm rotation is progressing. Just before the strike, the shoulder can be used along with the legs to straighten out the racquet as the racquet head strikes the ball.

Note that the elbow is well out away from the body in order to have unobstructed and flexible execution of the motion.

Below left is the strike stage of the windshield wiper motion. Below right is the rollover illustrating the transition between it and the previous stage. To stabilize this motion and diminish any equal but opposite reactions, the player has taken a wide stance.

	Move your cursor over the image to see the transition

Below left is the position just after the strike. We show this position in order to convey the sense of circular acceleration that is produced by the windshield wiper technique.

	Move your cursor over the image to see the transition

The butt of the racquet is elevated in the figure on the left as compared to that on the right. This resulted from producing the straight-line interval during the strike stage.