Strokes and Strategies For Tennis

D. Analysis of Power –

The energy imparted to the ball can be defined as the equal and opposite reaction to the energy supplied by the racquet. Newton's Law defines the energy in the racquet as the mass times the velocity squared. Obviously, the racquet head speed is the most important factor, since it is squared.

This racquet head speed can only be increased, from a practical standpoint, by a longer stroke that provides more time to accelerate. Beginners usually tend to just push the racquet. Obviously, this will never provide much racquet head speed. In fact, the harder that you push, the slower the ball goes because pushing harder slows down the racquet head. This becomes very apparent when attempting to serve the ball. Nobody's arm is strong enough to achieve any pace on the ball this way. The racquet must be swung, not pushed.

Relative to the ball, the velocity of the player, moving forward or running across the court, is added to the speed of the swing. That explains why a ball hit while running forward will carry further than one hit while standing still. This must be taken into consideration when hitting the ball. Some players always try to stop their forward motion by planting their feet the instant before hitting the ball. This is not always possible. Therefore, it is better to practice just taking this extra force into consideration when hitting the ball on the run.

When examining the mass component, some proportion of the weight of the arm swinging the racquet must be considered, depending on the firmness of the grip. To eliminate the variability of this weight, the player should always squeeze the grip on the racquet just prior to hitting the ball.

Next, if the body is moving, some proportion of the weight of the body must be added or subtracted depending on which direction the body is moving. That is why a ball hit off of the back foot (body moving backward) will not have much power. It is very important to have the body moving forward at the time of impact. Always hitting the ball out in front of the body will help to insure this.

Another very useful method of adding body weight to the racquet while remaining in one place, is to twist the body into the ball. This is, in effect, hitting the ball with the body. This can add very significant power to the stroke and is particularly useful because there is usually not sufficient time for a really long stroke. Tennis is a sideways game. If at all possible, you should get sideways to the approaching ball in order to twist into the stroke for power. Sometimes, there isn't time and the advanced player must learn to hit open stance. You should be careful that this doesn't become a lazy habit.