Skill Phases
Though the badminton smash may appear simple at first glance, from a biomechanical perspective this is not the case. There are 5 main skill phases that can be identified within the forehand badminton smash (Harrison, 2011) and they are as follows:
1. Preparation Phase
2. Backswing Phase
3. Forward Swing Phase
4. Point of Contact Phase
5. Follow Through Phase
Each of these phases of movement can be broken down further to into skill cues which assist in summarising techniques needed to achieve optimal performance.
Zarif0602. (Nov 27, 2011). CHINA Badminton Training [Smash] Slow Motion [Video File]. Retrieved on June 18, 2015, from https://www.youtube.com/watch?v=Tz8dolkwoMs
Figure 2- Slow Motion Smash, Lin Dan
In 2015, Lin Dan is ranked the number one badminton player around the world. Having joined China's national badminton team at the age of 18, Lin has been virtually unstoppable; winning gold in 10 out of 11 elite competitions across the globe (Olympics30, 2015). As figure 2 provides a front-on and side-on view encompassing the optimal technique and body movement throughout the smash, it is evident Lin has a near perfect technique throughout the smash shot, which comes as no surprise being his signature attack move. It is also important to note that during the jumping motion, Lin Dan appears to almost 'hang' in the air. This is done through conserving vertical momentum; beginning with bent knees before straightening them out mid air. This can also be described through Newton's Third Law which states; for every action, there is an equal and opposite reaction (Blazevich, 2013). As the video demonstrates, the five phases previously mentioned are crucial to achieving optimal techniques. 1. Preparation Phase
*Position of the hitting arm prior to the swinging motion
Figure 3- Smash Process, Preparation Phase
Skill Cue: Hitting arm with elbow pointing outwards with
racket perpendicular to floor.
Biomechanics: During the player’s positioning prior to the swinging motion it is essential to have the hitting arm pointing outwards from the body in order to create a steady centre of gravity. Having a steady centre of gravity is caused when all of the bodies particles are distributed (Blazevich, 2013). This helps the player balance themselves and creates an alignment between the centre of mass and the centre of gravity. Though the centre of gravity and the centre of mass are often used in relation to one another they have there differences, with centre of mass referring to the point at which a persons body weight is distributed equally in all directions (Blazevich, 2013). This again, will assist the player’s body to remain stable whilst going into the proceeding motion, as seen in figure 3 above; maintaining optimal speed and force.
Whilst performing the preparation phase it is important to take into account how the racket is being held. The basic grip in badminton is most commonly used for the smash shot as it can allow for optimum performance (Hopley, n.d). By having a high, relaxed grip the athlete will be better prepared for the effects of inertia. Newton's first law of Inertia states:
Whilst performing the preparation phase it is important to take into account how the racket is being held. The basic grip in badminton is most commonly used for the smash shot as it can allow for optimum performance (Hopley, n.d). By having a high, relaxed grip the athlete will be better prepared for the effects of inertia. Newton's first law of Inertia states:
"An object will remain at rest or continue to move with constant velocity as long as the net force equal zero," (Blazevich, 2013, pg 44)
Inertia refers to the tendency for an object to remain in its current state of being (Blazevich, 2013). Through using a high grip on the racket, there is an increase in mass and therefore increase in inertia. As there is a high correlation between inertia and force (the product of mass and acceleration) having increased inertia will then result in greater force required throughout the backswing and forward swing phases (Blazevich, 2013).
2. Backswing Phase
*Position of the hitting arm during the swinging motion
Figure 4- Smash Process, Backswing Phase
Biomechanics: In the backswing phase it is crucial for the player to raise their hitting arm in an upward motion prior to the backswing as displayed in figure 4; this way when the arm reaches full extension the other arm will propel in a forwards motion. This part of the movement demonstrates an opposite/equal reaction force where one movement causes another movement. This is Newton’s third law which states “For every action, there is an equal and opposite reaction,” (Henderson, 2015; Blazevich, 2013). This refers to the pair of forces that act on two objects when they interact with each other. The amount of force is equal amongst both objects, with the direction of force on the first object being opposite to the direction of the force on the second object. Hence why when the hitting arm is propelled backwards at full extension, the other arm is propelled in front of the body, both arms acting as the two objects involved in the interaction, again demonstrated in figure 3 above. Post the backward swing the positioning of the player’s hitting arm needs to be at remain at full extension in order to successfully prepare for the next phase; the forward swing and height of release.
3. Forward Swing Phase
*Height of racket prior to making contact
Figure 5- Smash Process, Forward Swing Phase
Skill Cue: Hitting arm is required to be at maximal
extension prior to height of contact.
Biomechanics: In order to successfully play out the forward swing during the badminton smash the player needs to ensure their hitting arm is at maximal extension for height of the racket prior to contact. The racket being at optimal height is crucial prior to making contact with the shuttlecock. For this to happen the player needs to first ensure the direction, force and balance between their centre of mass and centre of gravity are adjusted accordingly. During the hitting arm swinging forward a powerful inward rotation of the arm is made. Following this an inward rotation of the forearm is made before the hand flexes in preparation for the impact phase which is demonstrated in figure 5 above (Yap, 2012). The player needs to ensure their hitting arm is still at full extension before swinging forward and then bending their arm slightly to increase force accumulation. This slight bending motion is used as a build-up movement to when the player will then extend their arm at maximal extension to create a faster projection speed. When extending the arm at maximal extension this forward pushing motion creates the optimal height of the racket prior to contact. This also accounts for a stronger amount of force being projected into the forward swing prior to the impact phase and point of contact. The direction in which the player’s hitting arm is moving helps to determine the amount of force being projected into the swinging motion, e.g. the player needs to push their arm and racket forward in a diagonal motion, coming across their body. By doing this the player’s entire technique is influencing where and how the point of contact is made in the next phase and how the follow through is pursued later in the final phase.
Biomechanics: In order to successfully play out the forward swing during the badminton smash the player needs to ensure their hitting arm is at maximal extension for height of the racket prior to contact. The racket being at optimal height is crucial prior to making contact with the shuttlecock. For this to happen the player needs to first ensure the direction, force and balance between their centre of mass and centre of gravity are adjusted accordingly. During the hitting arm swinging forward a powerful inward rotation of the arm is made. Following this an inward rotation of the forearm is made before the hand flexes in preparation for the impact phase which is demonstrated in figure 5 above (Yap, 2012). The player needs to ensure their hitting arm is still at full extension before swinging forward and then bending their arm slightly to increase force accumulation. This slight bending motion is used as a build-up movement to when the player will then extend their arm at maximal extension to create a faster projection speed. When extending the arm at maximal extension this forward pushing motion creates the optimal height of the racket prior to contact. This also accounts for a stronger amount of force being projected into the forward swing prior to the impact phase and point of contact. The direction in which the player’s hitting arm is moving helps to determine the amount of force being projected into the swinging motion, e.g. the player needs to push their arm and racket forward in a diagonal motion, coming across their body. By doing this the player’s entire technique is influencing where and how the point of contact is made in the next phase and how the follow through is pursued later in the final phase.
Tee, D. (2013). How to play basic forehand badminton smash. How to Play Badminton. Retrieved on June 19, 2015, from http://www.how-to-play-badminton.com/badminton-smash.html
Figure 6- Forward Swing Motion
The player’s centre of gravity remains in the centre of their body during the weight transfer when moving forward, the player’s arm extension and grounded feet keeping them balanced. The player’s centre of mass is increased in this situation due to the player’s arms being extended and brought out from the body as demonstrated in figure 6. This will become more prominent as the hitting arm completes the swinging motion and the non-racket arm is brought down to conserve angular momentum (the product of angular velocity and moment of inertia)(blazevich 2013). The movement of the player’s hitting arm when extending and pushing forwards will adjust where the player’s centre of mass is. In this phase of the skill the centre of mass and centre of gravity are not perfectly aligned at all times but are adjusted accordingly during the weight transfer when moving forward.
The forward swing phase uses a kinetic chain movement, more specifically a throw-like movement. This is a pattern where the joints of the kinetic chain extend consecutively one after the other (Blazevich, 2013). When completing the forward swinging motion during the badminton smash the player’s shoulders are the first part of the body to extend, the elbow and wrist following afterwards. At the time of the shoulder extending and coming forward the elbow is still flexing from the back swing phase, ready to propel forwards after the shoulder. The throw-like movement pattern then continues into the impact phase when the wrist is flexed and point of contact is made.
Kwan, M., De Zee, M., & Rasmussen, J. (2008). Dynamic Effects of Badminton Racket Compliance. Journal of Biomechanics, 41, S88.
Figure 7- Racket Velocity With Time, Rigid (blue) and Flexible (red) Grip
A study on racket compliance by Kwan, Zee and Rasmussen suggests that elastic energy stored within the racket can have significant impact on racket speed and overall force accumulation. This is visible in figure 7 above, which supports the idea that having a flexible, lose grip can create greater force needed for the impact phase.
Kwan, M., De Zee, M., & Rasmussen, J. (2008). Dynamic Effects of Badminton Racket Compliance. Journal of Biomechanics, 41, S88.
Figure 8- Motion of Racket, Forward Swing Phase
The racket moves in a forward, curved movement, projecting forwards with the player’s maximal arm extension. To achieve optimal performance within the forward swing phase racket motion is required to complete the direction in the figure 8 above. This is shown through black lines indicating racket handles and red lines indicated racket head.
4. Point of Contact Phase
*Flicking action of the wrist at contact with shuttle
Badminton Doubles. (2014). How to hit a great smash in badminton. HubPages. Retrieved on June 19, 2015, from http://badmintondoubles.hubpages.com/hub/Badminton-Smash-How-to-Play-the-Shot
Figure 9- Smash Process, Contact Phase
Skill Cue: Wrist is flexed and snaps in a forward extension for greater impact.
Biomechanics: Within the making contact phase the player needs to ensure that at height of racket, prior to contact, the wrist is flexed and snapped in a forward extension as seen in figure 9. This enables the wrist to store elastic energy acting as a “sling-shot.” The tendon is stretched in order to create a more forceful and higher speed movement facilitating a more powerful impact. This is a throw-like kinetic chain movement which creates wrist and racket acceleration while in the projectile motion phase (Blazevich, 2013). Like phase 3 this uses a throw-like pattern as the joints of the kinetic chain prolong consecutively. When this throw-like pattern is put in play the extension velocity of the hand and racket considerably increases, resulting in the racket having a higher impact velocity (Blazevich, 2013).
The rotation of the body just prior to the point of contact (see figure 10) precedes arm swing and wrist flexion, once again influencing the player’s entire technique (Blazevich, 2013). The correct technique of the projection speed, height and direction of the player’s hitting arm and racket influences the trajectory of the shuttlecock. The trajectory of shuttlecock is the racket’s path following the shuttlecock in the air as it is moving under the action of the player’s hitting arm. Hence, if the player wants a more effect and more powerful smash they need to ensure the correct technique is followed. When the racket reaches point of contact with the shuttlecock the hitting arm is high and just in front of the body (Yap, 2012). In order to successfully make direct contact with the shuttlecock and to finish the shot effectively the player needs to ensure they are still swinging down and across the body in a diagonal motion. By doing this not only is the player finishing the shot effectively by using optimal technique but they are in the ideal body positioning for the follow through phase. This swinging across the body motion also creates greater impulse momentum as the force of the hitting arm swinging down enables faster racket acceleration.
Badminton Doubles. (2014). How to hit a great smash in badminton. HubPages. Retrieved on June 19, 2015, from http://badmintondoubles.hubpages.com/hub/Badminton-Smash-How-to-Play-the-Shot
Figure 10- Smash Process, Body rotation
When analysing figure 10 above, it can be seen that there is a rotation of the upper body during the forward swing phase and point of contact phase. This is caused by and increase in angular displacement which describes to the change in orientation of an axis. Due to this change torque is then influenced and has an increasing affect (Blazevich, 2013).
5. Follow Through Phase
*Position of hitting arm post shuttle contact
Figure 11- Smash Process, Follow Through Phase
Skill Cue: Hitting arm swings through in a forward diagonal
motion, completing the shot and returning to ready position.
Biomechanics: The fifth and final follow through phase is one of the most essential phases throughout the skill as it completes the shot. Not only this, but in case of the opponent being able to receive the smash the follow through phase allows a smooth transition from completing the smash to regaining the ready positioning. Through examining figure 11, it can be seen that in order for the follow through phase to work the player needs to ensure their hitting arm is swinging through in a diagonal motion, across the body. By achieving this element with competency the player is able to focus solely on the smash, not lacking any determination or power at this time. For example, if the player was to not worry about following through the whole shot would lack energy, power and optimal technique, the shuttlecock not travelling as far or as forcefully as possible. Whereas if the player uses the correct follow through technique the shot will be finished in a strong, purposeful motion, the shuttlecock travelling the desired distance, speed and force. This way the whole skill is played out in one swift motion rather than two to three awkward motions; the player hitting the shuttlecock, having to regain balance and then repositioning themselves. Hence why the follow through motion is so effective, as the whole shot is played as one and the player is already prepared for the opponent’s delivery.
As the player approaches the follow through motion the centre of mass decreases as the hitting arm and overall body position lowers. This is where the racket and hitting arm are the objects that are distributing mass in varying directions. The centre of mass will then increase when the player regains steadiness and returns to ready position. There would be a weight transfer between the player’s lower body, transferring from the back leg to the front leg to accommodate for the centre of gravity accordingly. This is where the player’s body positioning effect where the body’s particles are distributed, the player adjusting their movement accordingly. The player’s hitting arm also influences the centre of gravity, as the hitting arm follows through it swings down and out from the body causing the centre of gravity to move forwards. As the hitting arm comes across the body, the non-hitting arm swings in the opposite direction, as an equal/opposite reaction is caused. As previously mentioned this is when Newton’s third law states that, “For every action, there is an equal and opposite reaction,” (Henderson, 2015; Blazevich, 2013). This again influences the player’s centre of gravity, before both arms return to their original positioning ready for the next move. It is here that the player’s centre of gravity and centre of mass will realign, in the ready position.
As the player approaches the follow through motion the centre of mass decreases as the hitting arm and overall body position lowers. This is where the racket and hitting arm are the objects that are distributing mass in varying directions. The centre of mass will then increase when the player regains steadiness and returns to ready position. There would be a weight transfer between the player’s lower body, transferring from the back leg to the front leg to accommodate for the centre of gravity accordingly. This is where the player’s body positioning effect where the body’s particles are distributed, the player adjusting their movement accordingly. The player’s hitting arm also influences the centre of gravity, as the hitting arm follows through it swings down and out from the body causing the centre of gravity to move forwards. As the hitting arm comes across the body, the non-hitting arm swings in the opposite direction, as an equal/opposite reaction is caused. As previously mentioned this is when Newton’s third law states that, “For every action, there is an equal and opposite reaction,” (Henderson, 2015; Blazevich, 2013). This again influences the player’s centre of gravity, before both arms return to their original positioning ready for the next move. It is here that the player’s centre of gravity and centre of mass will realign, in the ready position.