Biomechanics III – The Principle of Conservation of Impluse

The Perfect Optimum Swing

In tennis the point of impact when the force of the racket take action on the ball. It causes the ball to change its direction and speed. The perfect optimum swing of the racket against the ball is obtained when the ball strike the “sweetspot” of the racket. This must then be supported by a good balance in the body of a tennis player.

For maintaining a good balance on the court three main factors are responsible :

  • Head position
  • Upperbody position
  • Foot position

The Head Position

The inner ear is the organ of balance(vestibule). A high and quiet head position provides a great body stability. The more the head is tilted in a certain position, the more the position of the body becomes unstable. Hence when the tennis player executes his groundstrokes on the court, he/she needs to have a straight head when he/she hits the ball.


The Upper Body

Is the heaviest body part of the human body. It usually represents 43 – 46 percent of the total weight of the body. For head is 6.94 percent, for arms 4,94 percent and for the legs 19,86 each. This proportion of weights indicates that any strong inclination of the upper body, besides moving the center of gravity of the body, will lead to instability of the position. During the time when a tennis player hits the ball, it is necessary to keep the upper body in a high position.


The Lower Body

In tennis, support points, are always represented by the player’s legs. The closer the legs are, with both the support surface being smaller and easier and more often the center of body weight, it can reach beyond this support surface. In this case the balance on the court is immediately lost. That is why it is useful and absolutely necessary that the legs are in a position as far as possible, not just in the basic position but to each groundstroke. When the support surface is enlarged, the center of gravity of the body can move during the groundstroke wide enough inside this surface, without coming out of its surface. As a result the stability of the body is maintained in any game situation. The distance between the legs should be in principle, at least equal to the width of the shoulders.

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