In this lesson, we continue our explanation of the role of the shoulder in the acceleration stage of a stroke. We use the forehand as a model, but the explanation applies to all strokes. Below is a Shockwave video of Allison Bradshaw's forehand at Charlottesville that provides the context of our discussion.

Below left is an isolated look at her shoulders during the takeback stage. Note how they are flexed in preparation for executing the stroke. Below right is an annotated figure showing the accelerate to strike stages superimposed. The time interval for this transition is 1/30 second.

There are three points of interest in the annotated photo. First, the ball has traveled only a short distance during the time the racquet started its acceleration until slightly after contact with the ball. Second, the racquet head has been rotated over 45 degrees into the path of the ball during this time. This rotation is primarily from the upper arm. Third, during this time, the butt of the racquet has traveled about the same distance as the ball.

The first key point is that the upper arm rotation occurs as a direct result of using the shoulder to drive the butt of the racquet forward. The upper arm rotation does not occur by proactively rotating the arm. It is nearly an unconscious motion, for which the brain usually does not provide sensory feedback. If you proactively rotate the upper arm, you will likely overrotate the racquet and shank the ball or hit off center.

The second key point to note is that the short distance the butt has traveled indicates how forcefully the shoulder has "jabbed" the butt forward to accelerate the racquet. The shoulder cannot extend the jabbing force over a very long interval; hence, it must be timed to strike the ball at maximum racquet velocity. If you accelerate before the ball is in close range, the racquet will have slowed down so much that the ball may dribble off your racquet. As a result, you may feel that the stroke has no power and give up on it too soon.

Notice that in this illustration the butt has been accelerated upward as well as forward to produce topspin.