Badminton is a racket sport like tennis, except that a bird (also called shuttlecock, shuttle, or birdie) is used rather than a ball. Because of the extreme power and speed, a smash is probably the most exciting moment in a game.
Form of Smash
Below is an illustration of smashing and the energy flow:
○2: Energy slowly transmits through the leg upwards.
○3: Hold the arm back to maximize the distance the wrist travels before hitting the bird. Energy transmits to the hip and body weight shifts to the left foot.
○4: Swing the arm as quickly as possible and twist the wrist to further enlarge the linear speed of the racket. Energy transmits from the hip to the wrist and body weight completely lies on the left foot. (The twisting in this part will be further discussed below)
○5: After hitting, relax and let the arm finish the swing and end up at the side of the body. This allows the energy be consumed by the body, not the wrist or elbow, so that the energy left will not hurt the joints.
Starting from ○3 in Fig. 1, there is twisting associated. Fig. 2 illustrates the direction of the waist twist. The body should be twisted such that the direction the chest faces is perpendicular to where the bird comes. When a bird comes and one starts to smash, take the shoulder joint as the pivot and initiate the twist while holding forearm relaxed. Then an intersection stage will be reached . At the intersection stage the palm should face to the left (for right handers). Right afterwards, take the elbow as the pivot and twist the forearm as well as stretching the forearm such that 1) the whole arm is straight and fully stretched; and 2) the palm faces to the front. Lastly press the wrist to make the bird go downwards. The twists all contribute to the final velocity of the racket head. This whole process is like slashing a whip. When the slashing begins, energy transfers from the handle to the whip tip and the energy explodes on the target. Body rotation is the process of slashing and energy transfers from the waist to the shoulder, arm, forearm, wrist, and racket head.
When the bird hits in this region, the force will be more equally spread than when it hits outside of the region.
As Fig. 5 shows, if the point of contact is outside the sweet spot (colored red in Fig. 4 and Fig. 5), the force exerted by the bird will not equally spread and thus will cause the racket to tilt. As the bird is not hit perpendicularly, some power of the racket will be lost. Also because the bird is very light, such a small tilt will ruin the aim. And that’s why in badminton a single centimeter matters.
Excluding those made of aluminum alloy that mainly aim to be strong and unbreakable for the very beginners, at present the most common rackets are made of carbon fiber. These rackets vary in structure in a micro view. However, for people who are not professionals, it is very hard for them to feel the difference in power and control. The length of the racket plays another minor role. Rackets have length of 664mm or 674mm . The 10mm longer one will give you more power because the leverage is longer. However this effect is too tiny compared to the original length of the racket: a 1.5% (10/664) increase in length will not result in a significant difference. In addition, the material of the string is the same as the material of the racket: it matters but nonprofessional people can barely feel it. Therefore, among all these features, only the center of gravity of the racket and the string tension will give a considerable effect and they will be discussed below.
Racket’s Center of Gravity
The center of gravity can be measured by holding the racket using only one finger and slowly moving the finger along the shaft until the racket is leveled. This should be done without the string for better accuracy.
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