As we have mentioned in discussing the stages of the forehand, if the elbow is not contracted properly, and if the equal but opposite reaction is not accounted for, the elbow destabilizes during rotation, causing the elbow to move away from the body. The result is that the upper arm rotation then causes the racquet face to tilt downward, sending the ball short or into the net.

In the two leftmost figures below, we illustrate this sequence from an overhead view. The sequence is read from right to left. In the middle figure, the consequence of not holding the elbow in place as you rotate is that the elbow slings outward from the body, causing the racquet to tilt downward. As can be seen from the middle frame, the racquet face has begun to tilt sufficiently that the ball will fall short if hit at this point. In the far left frame, the racquet has turned down so severely that the ball will go into the net if struck at this point.

The solution is to counter the destabilizing effect of a high-speed rotation by contracting the elbow inward and even tilting the body at the waist to maintain stability of the racquet arm.

This sequence, when viewed as three steps from right to left, illustrates the consequence of rotating the body and arm together as a unit instead of as a sequence. In the figure at the far right, Becky illustrates a rotation motion in which the body will "sling" the arm forward. The result is that the elbow can be pulled away from the body by the force of the rotation, causing the racquet face to tilt downward as discussed above.

The solution to this problem is to first contract the elbow toward the body during, at most slight, initial rotation, and then speed up the rotation only after the elbow is in front of the body plane.