COMPONENT 2: THE SERVING ARM

As stated previously, the legs provide a push-like motion in the kinetic chain and carries energy through the body until it reaches the wrist of the serving arm. Novice tennis players initially learn to use a push-like movement in the serving arm to gain accuracy, however as they progress to the elite level, players learn to use a throw-like pattern to create ball speed (Blazvich, 2012, p.198). (refer to Images 4 and 5 for differences in beginner and advanced serving techniques).

The acceleration of an object is proportional to the net force acting on it and proportional to the mass of the object (Blazvich, 2012, p. 45). Newton’s second law of motion understands that we need to apply a force to something to change its state of motion. In the case of the tennis serve, the tennis ball needs to be measured in terms of its inertia (the propensity for an object to remain in its present state) and a force needs to be applied to the tennis ball to overcome its inertia and be accelerated.

Angular momentum must be increased to increase force production. Blazvich (2012, p. 79) demonstrated that to increase the momentum the moment of inertia needs to be decreased and this can be achieved by either reducing the objects mass or keeping the mass close to the centre of rotation. This is why younger tennis players (with smaller muscle mass) tend to hold the racquet further down the handle and junior tennis racquets have shorter leavers.

Image 4: Novice server

 

Image 4: Elite serve (Novak Djokovic)