I recently wrote about how the mass of the entire arm pushes and lifts the ball on the forehand.
When you increase body mass into and through the ball, you increase the force of the shot. While the mass of the arm driving the ball
is crucial to power tennis, there is an even larger mass moving through the ball - the torso.
I just filmed Andy Murray from this overhead view - and it gives us an extraordinary picture of how
he rotate his torso into - and through - the ball. Watch how the double bend remains passive as the
torso rotation rotates this hitting structure into, and through, the ball. Focus your eyes on
Murray's shoulder line and watch how his shoulders start perpendicular to the net and rotate until
they are parallel to the net. You can even see him rotate his torso THROUGH contact as
the shoulders continue to rotate, powerfully adding
body mass through the ball.
In the Hingis clip, we see the same thing. She doesn't "swing" her racket at the ball at all. Instead she
locks into a double bend and uses torso rotation (and a lifting of the arm) to get the racket to contact.
The torso rotation and the double bend give weight and power to her forehand by maximizing body mass into the ball.
Think of torso rotation as the "engine" that powerfully drives your forehand. The racket and arm should never
get ahead of this massive source of power.