biomechanics serve itf coaching
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Coach Education Series Copyright © ITF 2007
Biomechanical principles for the
serve in tennis
ITF Coaches Education Programme
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Coach Education Series Copyright © ITF 2007
At the end of this session you will be able to
• Understand the mechanical factors which help producing a good serve
• Understand the theory behind advanced serving mechanics
• Analyse the service actions from a biomechanical perspective
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Coach Education Series Copyright © ITF 2007
Speed of serve1999 Wimbledon
• Sampras 218.8• Rudseski 215.6• Ivanisevic 215.6• Henman 214.0
• Williams 201.1• Novotna 180.2• Serna 173.8• Graf 17220
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Coach Education Series Copyright © ITF 2007
Service action main phases
• Backswing
• Forward swing
• Follow through
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Coach Education Series Copyright © ITF 2007
Phases of the backswing
– Leg drive / foot orientation– Trunk and shoulder rotation– Upper arm external rotation– Storage of elastic energy
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Coach Education Series Copyright © ITF 2007
Backswingfoot up & back techniques
• The foot up and foot back techniques are characterised by different considerations– Back foot just behind to allow hip rotation– Foot up: Better vertical drive– Foot back: Better preparation to the net
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Coach Education Series Copyright © ITF 2007
Backswingleg drive
• The racket should be down behind the back side
• It is better if the racket is away from the body than too close to it
• The body moves forward• Forward rotation of the trunk• Efficiency: If the body is taken off the ground
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Coach Education Series Copyright © ITF 2007
Backswingleg drive - hitting in the air
• An effective leg drive will not only affect the displacement of the racket but also will make hitting in the air
• Don’t teach hitting in the air• It is a natural consequence of the leg drive
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Coach Education Series Copyright © ITF 2007
Backswingright foot referred to left foot
• If, at impact, the back foot comes forward to be positioned in front of the front foot it will not allow the rotation of the trunk
• It is better to keep the back foot behind the front foot at impact
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Backswingshoulder and trunk rotation
• Rotation of the body
• Forward movement of the body
• Shoulder over shoulder
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Coach Education Series Copyright © ITF 2007
Backswingrotation of the body
• It is the less important of the 3 movements of the body
• 2 directions:– To the ball– Counter rotation
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Coach Education Series Copyright © ITF 2007
Backswingforward movement of the body• To impact• Rotation forward of the trunk• The racket shoulder is moving forward into
impact• 10-20% of the power of the serve comes from
this action
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Coach Education Series Copyright © ITF 2007
Backswingshoulder over shoulder movement
• Right shoulder over the left shoulder• Related to how high the ball toss is and to the
location of the ball toss• Free arm goes up• This movement differentiates good serves
from excellent ones
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Backswinglink of leg drive and trunk/shoulder
rotation
• Large forward rotation• What differences slow vs. fast serves is
the “cartwheel” rotation (shoulder over shoulder)
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Backswingtrunk and shoulder rotation
• Horizontal (rotation)• Vertical (shoulder over shoulder)
• There are movements you need to put the muscles of the arm in stretch
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Backswingexternal rotated position of the
shoulder
• Stored energy around the shoulder• It is different from the forearm• You don´t want the hand to be hyperextended
because it would create too much stretch on the forearm
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Backswingstorage of elastic energy
• Need to put muscles and tissues of the upper limb and shoulder on stretch
• Look at if the movements of the trunk allow for this stretch of the shoulder muscles and tissues
• The body movements should create this stretch
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Coach Education Series Copyright © ITF 2007
Backswinghow to store elastic energy
• Take the shoulder back• Use muscular effort• Plyometric training:
– do it better on soft surfaces– Box 1/2 metre– Amount of force: 4-5 times body weight on 2 legs
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Backswinguse of elastic energy: timing
• If the movement has a delay of 1 sec., 50% of the energy is lost
• The longer the delay, the more energy is lost• This does not mean that there should not be
or there is not a pause• The pause has to be shorter than 1 sec.
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Backswingbenefits of use of elastic energy
• Pre-loading of the muscle• 20% benefit of external followed by internal
rotation• I.e. Taking the arm back and then forward• 20% increase of power in the serve• Reduce 20% the muscular effort in the serve
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Phases of the forward swing
1. Co-ordinated action (kinematic chain))2. Upper arm internal rotation and arm
flexion3. Ball toss4. Impact alignment of hitting limb - trunk5. Racquet trajectory6. Foot landing sequence
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Forward swingco-ordinated swing
Leg Drive +Trunk rotation
Upper armElevation & flexion
Forearm extension +Forearm pronation +Upper arm internalrotation
Hand flexion
Shoulder speed
Elbow speed
Wrist speed
Racket speed
OptimalRacket Speed
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Forward swing co-ordination
• Flow together• Good rhythm• All should take place• Is the player using all the segments he can
use?• Females do not use shoulder over shoulder
as much as males do
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Coach Education Series Copyright © ITF 2007
Forward swingForearm extension
• Gives height• Pronation of forearm does not gives power
but realigns the racket face• It changes the angle
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Forward swingupper arm internal rotation
• It occurs very lightly• It participates completely in the follow through• Do not teach to finish the movement across
the body• It is detrimental to the speed
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Forward swingcontributions to racket speed at impact
• Leg drive 10%• Trunk flexion 20%• Internal rotation 30-40%• Hand flexion 30%
• This does not mean that there are parts which are less important in the serve
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Forward swing
• Wrist action following internal rotation is wrist flexion
• Shoulders are almost parallel to the net prior to impact
• Area of highest speed is just above the area of percussion
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Forward swingBall toss
• Should be considered as part of where is the trunk
• Not isolated, if not, it may be wrong• Types:
– Forward foot plane (B.Becker)– Facing plane (J. Newcombe)
• Don’t know which is better, easier for beginners to toss in front
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Forward swingBall toss location
• On the left foot• The upper limb is straight and the racket is
tilted• This permits a better shoulder rotation
(internal rotation of the upper arm)• Latissimus dorsi is the one which does much
of the work
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Forward swingMovement of the free arm
• Push the ball into the air• No Science involved on it• Keep it close to the body when the hand goes
down• Better movement of inertia
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Forward swingBall impact location
• Ball travels forward and left related to left toe• It is not hit on the right but on the left side of
the body
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Forward swingImpact alignment of the upper
limb - trunk
• If the shoulders are horizontal to the ground the alignment is incorrect
• If the shoulders are almost parallel to the ground the alignment is correct
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Forward swingUp and out hitting action
• Feel like the right shoulder is hitting out• This is affected by the leg drive• This movement can be helped by using a
“cue word” such as: “up and out”, “drive”
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Coach Education Series Copyright © ITF 2007
Forward swingUse of the whole body
• Just swinging with the upper body will not help your serve
• By using lower body the racket will move up and out to the ball
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Forward swingSpins
• Slice comes by putting the shoulders parallel to the net
• With the shoulder over shoulder movement the player can produce more topspin
• Flat serves do not exist
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Forward swingOther aspects
• Yandell (1998) found that there is not such thing as a flat serve in professional tennis
• The hitting action is up and out• In the serve you don’t hit through the ball• Landing foot:
– 95% Left - left– 5% Left - right
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Forward swingOther aspects (II)
• Don´t let the arm swing too far away from the body
• Apply the same principle as when the kids take the racket from the throat. They can rotate the racket better when the point of contact is closer
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Phases of the follow through
• Upper arm internal rotation
• Shoulder orientation
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Follow through
• Internal rotation plays a very large role• It takes the racket out of the body• Check shoulder orientation:
– Not horizontal– Better more vertical
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Follow through
• Check internal rotation and pronation
• Check the movement of the racket when it is finished
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Serveteaching tips
• Beginners: – Rhythm is the most important thing
• Intermediate: – Include leg drive, trunk rotation, etc..
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Angular momentumin the serve
• The body has to develop forward momentum about the X axis (trunk)
• As the trunk slows down, the arm gains momentum
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Appropriate service techniques for a more
powerful serve are result of
– Increased racket displacement– Increased segment rotations– Increased use of elastic energy– Rhythmical action about a stable base
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Summaryservice mechanics
• Get leg drive, trunk rotation, shoulder over shoulder to increase racket displacement
• Increase segment rotation but not with beginners
• With advanced players work on trunk extension
• Increase stretch to pre-load muscles• Rhythmical action