This presentation will show how an understanding of biomechanics has modified the service action in an attempt to improve ball speed while at the same time reducing the load on selected body areas. Topics covered will include: - The use of elastic energy and muscle pre-load on subsequent contraction (approximately 20% enhancement of performance in actions such as external followed by internal rotation of the upper arm).3 The problem with this is that muscle has a greater potential to be injured when it is being stretched. Training programs must therefore address this issue using pulleys and "elastic band" type training - The use of coordinated movement of body segments in velocity generation. The removal of one segment, such as shoulder rotation in the service action (accounts for » 10% of racket velocity at impact) means that other segments must "make-up" for this loss. This additional stress may lead to injury. - The use of long axis rotation about the upper arm and forearm in velocity generation (Figure 1). Elliott et al.2 showed internal rotation of the upper arm accounted for » 40% of the racket-head speed at impact. This action must therefore be an integral part of both off- and on-court training if an effective serve is to be developed in an injury free environment. - The development of proximal (trunk) segment angular momentum to assist more distal segment motion. The importance of trunk end-over-end and forward rotations is an integral part of high velocity serving.1 The end-over-end (right-over-left shoulder for a right-handed player) rotation of the shoulders also places the shoulder joint in an ideal position both for performance enhancement and injury reduction at impact. Matsuo et al.5 in baseball showed that an abduction/adduction angle of 90-110o at the shoulder not only produced the highest ball velocity but also created the lowest shoulder and elbow loading. In the serve the fact that the ball is impacted marginally to the left of the front-foot (right-handed player) necessitates a tilted trunk to permit the end-over-end shoulder rotation and the appropriate shoulder angle shown in Figures 1 and 2.
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