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Title

Biomechanical Factors for Consideration in the Development of the Serve:

Abstract

The development of an efficient service action requires an understanding of stroke mechanics, combined with a coaching approach to develop service efficiency. In this presentation a developmental sequence will be provided for service mechanics, with on-court examples.

Keywords

Service mechanics, stroke development, biomechanics, coaching

Summary

Biomechanical Factors for Consideration in the Development of the Serve:
Theory and Practice
Professor Bruce Elliott, School of Sport Science, Exercise and Health,
The University of Western Australia, Australia
Dr Machar Reid, Sports Science Manager, Tennis Australia, Australia

This presentation will discuss mechanical aspects of the serve from a theoretical perspective coupled with practical on-court interventions to develop each aspect. While different coaches will have varying approaches to serve development, each mechanical aspect of the motion discussed below must be addressed somewhere in the learning process.
1. Rhythm: This is a key feature of all efficient service actions. Children learning to serve in a modified game format, with an appropriately scaled racket and ball, should strive to achieve service rhythm. While this rhythm may be achieved in a variety of teaching approaches (neither leg action nor trunk involvement; reduced swing path), it is one of the first ‘building blocks’ needed to create an efficient service action. This aspect of the action will also be involved with the development of an efficient ‘ball toss’ and creation of a hitting position with the front arm extended upwards. The role of the wrist to develop service power in this rhythmical swing will also be explored.
2. Development of a throwing action: Selected aspects of throwing technique, related to future service development will be discussed both theoretically and practically. Each aspect will be linked with the service mechanics presented below.
3. Trunk (hip and shoulder alignments) rotation during the backswing: Once a player has developed a rhythmical swing, tactical considerations such as more power or more disguise (with reference to ball direction) may be addressed. Young players may now increase the displacement of the racket in the backswing by rotating both the hip and shoulder alignments (trunk rotation). Mechanically, it is desirable to teach that the shoulder alignment should be rotated more than the hip alignment in a horizontal plane (creating a horizontal separation angle), even at an early age. The level of the separation angle may increase as part of the normal development process. Shoulder and hip alignment tilt (vertical separation angle) are also part of the development of trunk rotation during the backswing.
4. Foot positions: Having developed rhythm and hip/shoulder rotations it is then mechanically logical to ensure that the back foot is appropriately placed with respect to the back hip. This step in the learning process is important as it links with the development of ‘leg drive’ and ‘shoulder-over-shoulder’ trunk rotation (discussed below).
5. The creation of leg-drive: Some young players commence serving with a ‘leg drive’, however, many children do not, so this action should be introduced (irrespective of foot-up or foot-back techniques) when the above service characteristics are in place. Remember:
• Young players should commence with less knee flexion than is commonly seen in mature players. Children may start with modest levels of knee flexion (~20º) and then build this to the ~70º knee flexion recorded for adult performers.
• The racket position, ‘down behind the back’, will often be reduced for players without any ‘leg drive’, so do not expect the same backswing position for children, who do not have any ‘leg drive’. Young players may compensate for this lack of ‘downwards drive’ by dropping the racket-head by extending at the wrist - this should be avoided.
6. Development of trunk rotation in the forwardswing - in all three planes (twist, forwards and shoulder-over-shoulder). With the appropriate foot placement, leg drive and ball placement (see comments below re shoulder internal rotation), creation of the important shoulder-over-shoulder trunk rotation will generally occur naturally. The role of twist axis rotation in service development will be discussed from a practical perspective.
7. Development of shoulder internal rotation, the key feature in the development of racket speed in the ‘power serve’: Mechanically this form of shoulder rotation will be achieved by:
• Movement of the ball toss for a right-handed player from a 1 o’clock position to one more aligned with the front foot (12 o’clock).
• Shoulder-over-shoulder rotation.
• Purposeful practise of internal rotation at the shoulder joint - this may be commenced at an early age, if an appropriate racket and ball are being used.

When shoulder internal rotation should be introduced into the teaching sequence is a question with no real answer. It can be taught relatively early in the learning process, however, it certainly will not achieve its ultimate goal of dramatically increasing racket speed until the factors discussed in point 7, as well as muscle strength have been appropriately developed. Variability: The role of variability will be discussed across all levels of service development. What factors, such as toss height relative to stature, should be held constant across the development spectrum and when should variety be introduced into the service action (direction and spin) with respect to the points above.

The coordination of the above features will provide the young player with the best opportunity to develop an effective serve. Good mechanics, while reducing the potential for injury, also provide the best opportunity to serve consistently with power.

Title 2º

Biomechanics: Trunk Rotations in the High-Performance Tennis Serve

Abstract 2º

Biomechanics typically addresses 2 major issues in sport; performance enhancement and injury reduction. In this paper I will discuss the way energy flows through the trunk, from the lower limbs to the racket-arm, in the most efficient manner.

Summary 2º

What is the role of the ‘legs’ in preparing for this flow of energy? They must:
• Create forces that drive the hips upward - particular emphasis on the back leg drive, although it is accepted that the front leg will always produce more total force.
• Position the back foot such that the drive assists the hip-over-hip rotation.
The trunk, as it is driven upward by the legs rotates in three different ways (shoulder-over-shoulder, forward and twist). Each of these is briefly described below during the ‘swing to impact’:
1. Shoulder-over-shoulder rotation - the key movement at the start of the drive phase of a high-performance serve for all but very tall players. While both hip joints elevate, the back hip is driven or rotated higher than the front (it has a higher vertical velocity) to begin this hip alignment rotation. This rotation is caused by a combination of; back leg drive, action from trunk musculature and natural trunk rotation in the shoulder-over-shoulder rotation.
2. Forwards trunk rotation occurs prior to impact, at much the same time as the trunk also moves about its twist axis.
3. Forward rotation is a key feature of the follow through, which if performed with vigour, will produce an arabesque of the back leg.
Players, who only rotate forward about the twist axis, will often; lack hitting-height and the ability to hit up to the ball. Vision in both video format and picture sequences will be used to clearly demonstrate the above movements. A more detailed explanation of the role of trunk rotations in the serve is outlined in the book ‘Technique Development in Tennis Stroke Production’ recently published by the ITF.

Dinner

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CV

Name

Bruce

Surname

Elliott

Curriculum vitae

Professor Bruce C. Elliott PhD, FACHPER, FISBS, FAAKPE.
Professor Elliott is the senior biomechanist and Head of the School of Sport Science, Exercise and Health, at the University of Western Australia. Generally considered a world’s leader in research into biomechanics and tennis stroke production he has recently co-edited the ITF publication Biomechanics of Advanced Tennis. He has published over 180 articles in refereed journals, as well as over 50 book chapters or books all in the general area of sports science.

He was the keynote speaker at the 1st World Congress on Racket Sports, the 3rd World Congress of Medicine and Science in Tennis and the last four ITF Worldwide Coaches Workshops (2001 - Thailand; 2003 - Portugal; 2005 – Turkey; 2007 - Paraguay). He was the organiser of the applied research Projects at the Sydney 2000 Olympics, one of which was on shoulder loading in the tennis serve.

He is the past president (2003-2005) of the International Society of Biomechanics in Sports and sits on the Coaching Advisory Panel of Tennis Australia. In 1999 he was honoured with the Award of Merit by the Western Australian Sports Federation and in 2003 the Professional tennis Registry gave him the Stanley Plagenhoef Sport Science Award for “his lifetime contribution to tennis” and the Australian Government awarded him their Centenary Medal for service to sport policy and research development for sport”. The University of Western Australia presented him an award for Excellence in Research Supervision in 2006 and Teaching in 2008.

Conditions

I agree with ITF Worldwide Coaches Conference 2009 conditions

History

Member for

1 year 14 weeks