ProN8 | Badminton Biomechanics Introduction

This first video concentrates on the racket
arm, underpinning the introductory technical series. The aim here is to convey purpose. Hitting the shuttle fast invokes efficient biomechanics, and so smashes and clears using
a standard forehand grip are of particular interest. Here are the topics for the video. Consider striking a shuttle in a coronal plane that passes through the face. The point of contact for a smash is normally a little further forwards. The point of contact lies in a circular arc about 1m in radius centred at the racket shoulder. The lowest point is about about 1/2m above the racket shoulder, and extends to directly over the head of the player. As you may have seen from earlier videos, force is ultimately exerted on the shuttle in a smash by rotating the racket The arm acts as a
rotating drive shaft around the time of contact. The axis of pronation-supination forms part
of the axis for that drive shaft. When the hand is in the standard anatomical position,
the axis passes through the hand and between the middle and ring fingers. For efficient biomechanics, the hand holds the racket so that the axis of pronation-supination intersects the axis of the racket shaft. The grip is designed to facilitate fast rotation of the
racket. It does this by minimising the moment of inertia while maximising energy transfer. The main role of the wrist, in conjunction with the hand, is to hold the racket so that the axis of pronation-supination intersects the racket handle. It principally does this by extending to about 45 degrees. In addition, the wrist facilitates holding the racket at
90 degrees to the forearm by abducting. It does this to maximise the moment of inertia
of the racket face, which facilitates maximum force transfer into the shuttle. During some strokes, the wrist adducts just before the moment of contact. This allows the player
to extend their reach by an additional 50cm. After the moment of contact, the wrist abducts
again to restore the angle to 90 degrees. During the backswing the elbow is bent to
90 degrees. This serves to increase external horizontal rotation of the shoulder by maximising
the moment of inertia of the forearm. In the forward swing the elbow is moved into the
segment formed by the arc mentioned earlier. Once there, extension of the elbow transfers
energy into the forearm and aligns the axis of pronation-supination with the axis of rotation
of the upper arm. The shoulder plays a significant role in generating power, mainly by horizontal rotation. A key movement, known as hyper external horizontal rotation, pre-loads this rotation.
In order to get a clearer picture of the rotation we will consider arm movements that contribute
to it. The ready position for such a stroke is as follows: using a standard forehand grip,
abduct the shoulder to approximately 90 degrees and horizontally abduct it by about 45 degrees. Bend the elbow to approximately 120 degrees Laterally adduct the wrist so the racket points towards the shuttle too. and rotate the shoulder so the forearm points
towards the shuttle. Finally, this is the ready position. The backswing starts by externally horizontally
rotating the shoulder. Simultaneously, horizontally adduct the shoulder and extend the elbow until
the forearm is perpendicular to the upper arm. Supination of the forearm and medial
adduction of the wrist until the racket is perpendicular to the forearm also serve to
pre-load the shoulder rotation. Once the hyper external horizontal rotation reaches it’s
maximum, the forward swing begins. The forward swing starts by horizontal and lateral adduction
of the shoulder until the elbow is in the segment where the contact occurs. Internal
horizontal rotation of the shoulder starts shortly afterwards. Powerful shoulder rotation
continues until the end of the follow through.

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