In my "Master Principles" series, I begin with the concept of "Pull-Push" to describe professional strokes. There is, however, a second force at work that is equally, if not more, powerful. This second force is torquing, turning or rotating motions. Not only do these rotational motions apply tremendous force to an object, they also lead to Angular Momentum, which produces a rapid burst of acceleration while maintaining the integrity of the hitting structures. Here is what Wikipedia says about pull, push, and torquing forces:

Torquing, twisting, rotational forces can be found everywhere in professional tennis, but it wasn't until I started capturing footage at 300fps that I realized just how prominent these moves were. In fact, after studying much of my 300fps video, I'd say that rotational forces account for most of the strokes. The linear motions come down to pulls and pushes, which are combined with rotations and torques to lead to today's big power/spin game.

Tennis instruction is, unfortunately, mired in an almost 100% linear conception of tennis. We say to take the racket "straight" back. We say to "hit through four tennis balls". We say to "finish out towards the target". We say that the volley is a "forward punch". Even on the serve we say to "drop the racket in a backscratch postion and swing up to contact" (linear upward path) and that power comes from a "downward snap" of the wrist (linear downward). At the core of all these linearly conceived "tips" (all of which are flat out wrong or grossly oversimplified) is a conception of tennis that goes in a straight line - from takeback point A to finish point B.

This text is replaced by the Flash movie.

Becker is pronating his arm and hand into contact.

The huge problem here is that human bodies don't move very well in straight paths. Our bodies move most naturally, most powerfully, and most rapidly through rotational motions, through angular momentum, and through torque. So this linear approach to tennis that most teaching pros offer results in movements that are both unnatural and ineffective. They lead to strokes that look like what we saw in the pro tour in the 60's and 70's. Long linear swings that result in little power, little connection with the ball, and almost no integration of the body into the stroke. And that is why people who take lessons are so frequently stuck at awkward low levels - often for their entire lives.

This text is replaced by the Flash movie.

Frank Dancevic applies a torque to the ball by rotating his hand and arm clockwise as he pushes forward and lifts upward from the shoulder.

In my high speed footage (and even in the 60fps footage) you will see rotation, angular momentum, and torque occuring in all the strokes. We see the torso rotating 90 degrees or more into the ball on the forehand. We see the rainbow like path of the full windshield wiper motion on the forehand. We see the arm and hand twisting a full 180 degrees on the serve. We see the entire arm start to rotate from contact on in the one handed and two handed backhands. On the forehand volley we see the entire arm - from hand to shoulder - rotate inward from contact on. On all the ground strokes we see an "inside out" path of the racket into contact which generates angular momentum. This list goes on.

For a quick look at rotation, torques, and angular momentum in all the strokes, let's start with the serve - the most remarkable example of rotation and torque you can find in our game.