Introduction
In Badminton research, the plyometrics training is not extensively researched. This chapter will note the importance of understanding the related factors leading to the idea of conducting this study. The review of the related literature for this study is presented into five main sections:
Physical Training in Sports
Physical Training in Badminton
Agility in Sports
Agility Contribution in Badminton
Plyometric Training in Improving Agility
Physical Training in Sports
Physical fitness is a very important factor affecting performance in sports. As in the preparatory phase of periodization plan for any training programme, the physical fitness is always the first to be developed before focusing into other training factors such as technical training, tactical training, and psychological training. Physical fitness contributes to sports performance. It serves as a foundation that leads to a higher possibility of succeeding in competitive arena of sports (Bompa, T. O. & Haff, G. G., 2009).
Many researchers have studied on various types of physical fitness training, such as balance training, agility training, sprinting training, resistance training, circuit training, interval training, and plyometric training.
Many studies found that physical training serve the purpose of improving various physical attributes, such as flexibility, functional performance, muscular control, muscular power, distance running performance, running economy, strength performance, explosive power, vertical jump, initial acceleration, speed, agility, and many other attributes.
Physical Training in Badminton
Badminton is a highly competitive dynamic sport. At elite level, it is suggest that badminton is characterized by repetitive efforts of alactic nature and great intensity which are continuously performed throughout the match. Badminton players are required to be able to move in multiple directions while smashing and receiving a shuttlecock with fast speed. The speed of a shuttlecock can be up to 421kph (Guinness World Record, 2009).
Badminton players are often required to perform speed, agility, flexibility, endurance, and strength capabilities at their limit. It is proposed by Badminton Association of England (2002) that the off-court type of fitness training for badminton can include strength training, aerobic training, speed and agility training, flexibility training, core stability training, and circuit training.
As an explosive sport, badminton performance can be enhanced from resistance training. Effective resistance training programme requires a systematic process of analysis, implementation and evaluation to ensure maximum adaptation and improvement. The prescription of resistance training methods can enhance badminton specific performance in jump smashes, lunges, and fast change of direction.
Agility in Sports
Agility is often considered an essential element for many sports and activities. It is an ability that involves a rapid whole body movement with changes of direction or velocity in response to a stimulus. In many competitive sports such as badminton, the players do not perform at their own pace and move, but are performing in response to the shuttlecock, the opponent, or the partners. As such, agility in badminton is not completely an independent factor.

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Little and William (2005) proposed that agility is a specific physical attribute that is fundamentally important to sports performance for three reasons. First, developing agility will provide a strong foundation for muscular control and motor skill function, thereby establishing overall performance in badminton. Second, good agility enable players to move fast in balanced and stabled manner, and this proper movement mechanics and this may reduce injury risk. Finally, as an athlete matures, a heightened ability to quickly change directions will enhance overall performance in both proactive offensive and reactive defensive circumstances.
According to Young and Farrow (2006) and Vescovi (2008), agility is important as many sports such as badminton performed on a court require high-speed total body movements. Many of these movements are in response to the motion of the shuttlecock, opponents, or partner. As such, fast movement is very important.
Deterministic model of agility performance
The multifactorial nature of agility has been represented by a deterministic model in Figure 2.1 which indicating the various factors contributing to performance.
Figure 2.1 is the model suggested by Young et al. (2002) which indicated that main factors determining agility. Agility can be affected by a few factors, such as visual scanning, anticipation, pattern recognition, knowledge, technique, straight sprinting speed, and leg muscles quality.
Agility
Perceptual and decision making factors
Change of direction speed
Straight sprinting speed
Technique
Pattern recognition
Anticipation
Visual scanning
Knowledge
Leg muscle qualities
Foot placement
Strength
Adjustment of strides to accelerate & decelerate
Power
Body lean & posture
Reactive strength
Figure 2.1 Deterministic model of agility performance.
Perceptual and decision making factors
According to Young et al. (2002), perceptual and decision making is one of the main factor affecting agility. The factors affecting perceptual and decision making included visual scanning, anticipating, pattern recognition, and knowledge.
Visual scanning is the ability to process visual information in the competitive environment. In a badminton match, as it is like other ball games, players are paying their visual focus on the trajectory of shuttlecock or ball, or movement of opponent. A common words of “eyes on ball”, this shows that the badminton players are applying the visual scanning on the shuttlecock and opponent to analyze what is the next step to move.
Anticipation and prediction in badminton match influences the movements of a player. From the visual information from visual scanning, badminton player process the information and start to anticipate the move of opponent and the shuttlecock. As the opponent tense up the body with great back swing, it is anticipated that the next move might be a smash; as the opponent remain relax and small actions of racket, it can be anticipated that the next move might be a soft drop.
Pattern recognition is the ability to recognize the patterns of play by the opponent. This happened when a player has specific playing habit or favourite shots. It happen as simple as an attacking badminton player has more smashes and a defensive player has more return in high shots. By understanding the pattern, badminton player can be more agile by narrowing the possibility of stimulus to be response.
Knowledge from experiencing different game play situations can help predict probable movements of opponent. When a player is out of position and the body is not in favourable position to return a shot, it is likely that the return will go to the front court rather than the back court. As such, a badminton player can be faster and more agile to react to the circumstance.
Change of directional speed
Young and Farrow (2006) also noted that agility is affected by the change of direction speed. Change of direction speed is influenced by the techniques, straight sprinting speed, and leg muscle quality.
Techniques to change direction and change velocity quickly are expected to be influenced by the position of the body while running. A forward lean is required to accelerate, a backward lean to decelerate and stop, and a sideward lean to produce a lateral change of direction. These body positions are necessary in order to produce forces to the ground to evoke reaction forces in the desired direction.
If a badminton player is ready to react and move to any direction in court, the ready stance of the body should be slightly knee bend, body leaning forward, and body weight more on toe than on heel (Badminton England, 2002). This ready stance enables the player to make quick adjustments to the running posture to execute a quick change of direction. Such quick adjustments of posture and positioning of limbs is clearly a skill that requires training.
Young et al. (2001) conducted a study where found that the straight sprinting speed was improved significantly after six weeks of straight sprint training, but had no gains in changes of direction test. The six weeks change of direction training had limited contribution to straight sprinting speed as well. These findings can be explained by training specificity, and suggest that athletes must train specifically with the movement patterns required in their sports.
Badminton requires a lot of sudden sprint and stop, deep lunge, explosive jumping but limited straight sprint. To benefit optimally from the training, badminton player must train specifically on the sudden sprint and stop in various directions but not only the straight sprint.
Leg muscles quality is exclusively responsible for change of directional movements. The available research provides little support that leg muscle strength, power, and reactive strength are major contributors to agility performance. However, a rationale was made to suggest that plyometric training program involving jumping exercises that contain single leg lateral takeoffs, such as bounding in a zigzag pattern could potentially be beneficial to change of directional speed development. A better quality of leg muscle in badminton can help to reduce time taken from ready position to move to receive a shot.
Agility Contribution in Badminton
Motion analysis of a typical badminton match reveals that there are many changes in direction and it requires the athlete to be very agile in all directions . Notational analysis of European players during international tournaments indicated that badminton can be characterized by repetitive, short-duration, high-intensity efforts with high-frequency movement.
Badminton is the fastest sport among the racket games with the speed of the shuttlecocks capable of travelling up to 421kph. This means in the court area of approximately 34m2 for badminton singles, the shuttlecock will take not more than 0.15 second to pass through the entire badminton court which is 13.4m in length (Olympics ABC, 2007). As a sport with such a high speed, agility plays a very important role to contribute to the performance.
In an elite badminton match, the competition can be played up to more than 60 minutes, and the total running distance can be covered up to 6km. But it does not mean the energy spent for both players are the same. When a player is more agile and faster than opponent, he can play the shot to move opponent around in the badminton court which will lead to greater radius of movement for the opponent. In another word, throughout the match, the player who have better agility are having advantage and spending less effort and energy compare to the less agile opponent.
Olympic ABC (2007) also proposed that a player need approximately 0.32 to 0.36 second to move from a ready position towards the shuttle and approximately 0.486 seconds to react to the coming shot. This lead to an idea that a badminton player needs about 0.8 second to react to a shot and move to receive the shot.
In this condition, agility is a critical factor affecting the performance. Time taken to react to the coming shot is affecting by the perceptual and decision making factor, while the time taken to move from a ready position towards the shuttle is affecting by the agility, which have the direct relationship with the change of direction speed. Good agility and fast action to move from ready position enable a badminton player to return the shot in a favourable position and have advantage over opponent.
Plyometric Training in Improving Agility
Plyometrics are training techniques used by athletes in all types of sports to increase strength and explosiveness (Chu, 1998). Plyometric training program involving jumping exercises that could potentially be beneficial to agility development.
Plyometric drills usually involve stopping, starting, and changing directions of movement in an explosive manner. These movements are components that can contribute to developing agility . Previous studies found that plyometric training, when used in a periodized manner, can contribute to agility gains .
Agility is an explosive movement which can be referred to running speed and changes of direction ability. Fast running speed and quick change of direction contribute to good agility. Explosiveness is affecting the running speed and change of direction ability. Thus, improvement in explosiveness leads to agility development. Plyometrics have been proven to be an effective method to improve on explosiveness.
By enhancing balance and control of body positions during movement, agility theoretically should improve . Plyometric activities have been used in sports such as football, tennis, soccer or other sports event. These sports are intermediate sports which require rapid whole body movement with changes of direction or velocity in response to a stimulus, which is similar to badminton.
Conclusion
Badminton is an intermediate sport which is the fastest among the racket games, it is a very high speed sport which the shuttlecocks capable of travelling up to 421kph (Guinness World Record, 2009), as such, agility is a critical physical attribute affecting the performance.
In badminton, a player performed on a court requires high-speed total body movements. Many of these movements are in response to the motion of the shuttlecock, opponents, or partner. Agility permits badminton player to start quickly and efficiently, move in the correct direction, and to change direction or stop quickly to make a play in fast, smooth, efficient, and repeatable manner, in response to a stimulus.
A competitive badminton match can be played up to more than 60 minutes, agility allow a player to play the shot to move opponent around in the badminton court which will lead to greater radius of movement for the opponent. In another word, agility lead to the advantage of lesser effort and energy spent than the less agile player.
Young and Farrow (2006) noted that agility is affected by change of direction speed. Quality of leg muscles is exclusively responsible for change of directional speed. Better quality of leg muscle and good agility in badminton help to reduce time taken from ready position to move to receive a shot. This enables a badminton player to return the shot in a favourable position and have advantage over opponent.
Agility refers to running speed and changes of direction in explosive manner. Fast running speed and quick change of direction is the key of good agility, which is affected by explosiveness. Thus, improvement in explosiveness should leads to agility development. Plyometrics has been proven to be effective and efficient in developing explosiveness.
A rationale was made to suggest that plyometric training program involving jumping exercises could potentially be beneficial to agility gain
Plyometric drills involve starting, stopping, and change of movement directions in an explosive manner. These movements contribute to agility development. Previous studies showed that plyometric training, when used in a periodized manner, can contribute to agility gains .
Miller (2006) and Young and Farrow (2006) proposed that agility should improve by enhancing balance and control of body positions during movement. Plyometric activities have been used in sports which are similar to badminton, such as football, tennis, soccer or other sports event. These sports are intermediate sports which require rapid whole body movement with changes of direction or velocity in response to a stimulus.