The Law of Muscular Slingshots
The basic idea of coaches and players, as well as the simplistic biomechanics of loops and swings in tennis shots (serve, forehand and backhand) are derived from the concept of a simple physical pendulum. An arm with a hand holding a racket has been seen as a more-or-less single rigid body, with no more than 3 degrees of freedom (DOF). And really, if you have a robotic arm with only 3 DOF, and you want to hit a ball with it, then you need to have a loop; and, even more, if you want to hit the ball hard, you need to have a big swing. That is absolutely true. In a language of modern biomechanics, “its phase space is a simple circle.” That is how we originally got our current loops – to play “nice tennis”, and swings – to be able to “hit hard”. In particular, you need a big swing as you want to use all the potential energy of the racket’s weight, so, as a preparation for the shot (say, forehand), you lift the racket–head as high as possible along the circle (that is, above your head). This is the common picture behind all loops and swings in tennis. Although simple to understand, it is not as easily implemented, which is where the many expensive lessons on the court come in. This system has produced thousands of young tennis players, hitting the ball in virtually the same way, with the same distinguished tennis movements: loops and swings.
KeywordsMuscle Spindle Eccentric Contraction Concentric Contraction Sweet Spot Plyometric Training
Unable to display preview. Download preview PDF.