Thursday, 18 June 2015


Introduction to AFL & the drop punt


Australian Rules Football is the most popular and recognised sport in Australia. The Australian Football League (AFL) is the highest-level of professional competition in the sport, with strong support bases for all 18 teams in the league. The most significant skill undertaken in the AFL is kicking, as it is the only option players have to score a goal and the fastest way to push the ball forward of play. While kicking is essential in the sport, the drop punt is the most effective and proffered way of kicking the ball to successfully play the game. 

A direct focus on the biomechanical principles involved in a successful AFL drop punt has given me the chance to reflect on the skill learning poster and expand on the skill in more depth. Throughout this blog I endeavour to discuss the biomechanical rewards of executing an AFL drop punt and the physical factors that contribute to kicking a successful drop punt. I will be defining a successful drop punt as displaying accuracy, having power and ably replicating the skill with consistency. It is important to address the reasoning behind why the drop punt is widely accepted as the preferred kicking style, and the skills critical parts that are made up of 5 key phases: 
  • Run up
  • Ball drop
  • Leg swing
  • Impact
  • Follow through

Why is the drop punt the most effective and proffered kick in the AFL?


It is important to acknowledge the key factors of the Australian Rules style drop punt. The football needs to be dropped from the players leading hand onto their kicking foot, preferably at the beginning of the boots laces. A crucial factor of a successful drop punt involves how the ball spins off the kicking foot and through the air to create equal air flow around both sides of the football. Having the ball positioned in an upright manner and spinning backwards straight along its vertical axis is considered a proficient drop punt (AFL, 2014). The drop punt is commonly used because of its reliability for accuracy and its ability to get to the intended target with power. 

This video best acknowledges the drop punt as having the most accuracy and power for distance in reaching the intended target as quickly as possible, optimising how effective the skill is in AFL. 



It is important to consider Newtons Three Laws of Motion when addressing a skill like the drop punt. Newton’s first law expresses that all things at rest want to remain at rest (Blazevich, 2012), leaving a few questions unanswered. The football is the main object that is at rest, but how does the player apply force to bring that object from rest to motion? Force is applied by moving the ball from a rest position towards a target through running with the object and then dropping it onto the foot. 

Newton’s second Law as stated by Blazevich (2012) explains that Force = Mass multiplied by acceleration. Accurately kicking to targets over shorter distances means that force applied to the football that allows it to move is equal to the max of the ball multiplied by the acceleration of the foot that is kicking the football. Therefore, the greater acceleration of the kicking foot generates more power to the footballs motion. 
The third and final law that Newton states is that for every action there is has equal and opposite reaction (Blazevich, 2012). The equal and opposite reacting forces occur when the football is kicked causing friction between the foot and the ball as the it travels towards its intended target. 

The third law further applies to why the back spin of the ball is valuable to a successful drop punt, the Magnus Effect helps explain how varied types of spin effect the trajectory of a ball in flight through different ways. If a ball is spinning and moving forward through the air, from the front to the back of the ball the air is flowing around it. The football is spinning in the same direction at the top but in the opposite direction at the bottom. This causes friction between the ball and the air, forcing air to be dragged around the top of the ball towards the back. With the air above the ball being pushed down as it passes the football and the air below remaining fairly impartial, the net force can be observed as acting upon the air surrounding the ball is in a downwards direction. Referring to Newton’s third law ‘for every action there is has equal and opposite reaction’, the downwards force on the air is creating an equal upward force acting upon the ball. 

This video best demonstrates the Magnus Effect to gain further understanding of what it is and its relationship with Newton’s Third Law of Motion.



The outcomes suggesting why the drop punt is the most effective and proffered kick in the AFL:
  • Players find the football easier to read when back spin increases the time the ball is in flight, caused by the Magnus Effect.
  • It is easier for players to mark the ball with the end-over-end kicking style. Making it uncomplicated for players to know where to position their hands to trap the ball on either side for best control, due to the minimal change in horizontal perimeters of the ball.
  • The bounce is easier to judge for players once it hits the ground, an uncontrolled ball spin would make it less predictable and harder to read.

The Run Up


The biomechanical purposes that form the bases of the run up are to increase stability and to increase the force transfer into the ball. Stability looks to further improve accuracy and ability to consistently replicate the skill, allowing more control in the ball drop and leg swing. 

The picture below of St Kilda player Arryn Siposs highlights the importance of the final step of the run up on the non kicking foot, allowing the kicking leg to be left at a stronger angle behind the body and for the hips to rotate on a horizontal plane away from the kicking leg. In motion of Siposs's kicking his shoulders remain mostly perpendicular to the target, creating for draw back of the trunk, although the hips are rotated away from kicking leg. Generating greater time of force and force to be applied to the kicking leg before impact with the ball. 



The Ball Drop
The crucial aspect of a successful drop punt occurs when the ball drops from the hand to the foot. According to Coach AFL (2015) any deviation in the position or angle of the ball during the drop therefore affects the foot’s contact with the ball, its direction and swing of the resulting kick. 

In the video below you should take notice of the extended guiding time of the ball in the hand prior to release. More kicking control is shown when the players contact time is longer in the ball drop. Trunk position plays a significant part in the ball drop, leaning forward and dropping the ball closer to the foot may allow for more control. Producing less power and more accuracy to the kick, while a backward leaning trunk causes the ball drop to be higher decreasing its overall control. Environmental factors and variables can impact the variability of the ball drop, making it critical for all players to consider when kicking. 


Releasing the ball closely to your hip height is most beneficial for successful ball drop, despite the guiding of the ball begins around the torso. Generating perfect trunk position and creating enough distance and time for the ball to be guided while in the hand.

Leg Swing
The leg swing predominately aims to increase speed, generating force to the foot during impact with the ball to produce more kinetic energy into the ball. The final step of the run up importunely leaves the kicking leg behind the body, increasing the duration that force can be applied to the leg swing to help generate foot speed. While the shoulders remain square, the pelvis rotes to leave the hip of the kicking leg behind. This allows the kicking leg to begin swinging, bringing the pelvis back to square and extending out, propelling the the hip and kicking leg forward. 
The slow motion video above of my leg swing acknowledges that as my thigh begins to swing through, the knee bends back, leaving the lower leg bent and ready to swing. In the final phase the knee extends, releasing all the built up energy to swing the foot through with speed to connect with the ball. You will notice that my body moves noticeably forward, this increases the foot speed of the kick.

Impact
The impact refers to the point in which the player’s foot makes contact with the ball, ensuring toes are pointed and muscles in the leg are contracted. Keeping the toes pointed ensures the foot has a flatter point of area for contact with the ball (Coach AFL, 2015). Making it important to keep the kicking foot tightly extended and ball contact on the laced area of the boot rather than near the toes, reducing the absorption of energy in the foot. According to Ball (2007) stiffening of the joints at point of contact possibly increases the effective mass of the foot through incorporating some of the weight of the leg into the transfer of force.


Follow Through 


Despite the follow through not critically impacting the contact of the ball, it is important for players follow through action to remain the same, encouraging them to reduce the power in the leg swing during the kick to wipe off distance (AFL, 2015). This can help highlight possible flaws in players kicking action and what specifically needs improvement. When players attempt to kick over long distances the follow through can skew across the body, showing the arc of the leg not being parallel to the intended direction of the ball delivery. The picture below demonstrates how the follow through should be straight along the sagittal plane of the hip joint.


The Answer


This question has allowed me to detail the important small factors that contribute to a successful AFL drop punt and how they each impact the intended outcome. In saying that the action of kicking a drop punt is a whole body, complex skill that requires years of practice to perfect. It is fundamental to address the key extended phases of a drop punt already mentioned within the blog, consisting of: 
The run up, longer final step, hip rotation, one handed ball guide, guiding to hip before release, dropping over kicking leg, impact on boot laces, toes pointed on impact, backwards ball spin, and straight leg swing after contact. 



How else can we use this information?


The information is directly useful for players who consider their drop punt kicking action as unsuccessful and needs guided improvement. This greatly contributes to coaches to further develop understanding and appreciation to the key phases that contribute to a successful drop punt. All coaches  should have some experience and be experienced in teaching the complex skill, the videos and photos highlight resources that can help guide kickers understanding of where they can improve. Ably acknowledging an incorrect kicking action in order to establish what specific phases need further development and training. 


References




AFL (2015). Basic Mechanics of Kicking. AFL Community/Development, accessed online 17/6/15


AFL Skills- Kicking- Ball Drop. YouTube Video, Published 27/3/12, accessed 16/6/15,           


AFL Skills Video- Drop Punt. YouTube Video, Published 2/1/08, accessed 15/6/15,


Ball, K. (2007). Use of weighted balls for improving kicking for distance. Journal of Sports Science and Medicine, 6 (Suppl.10), 44.


Blazevich, A. (2012) Sports Biomechanics: Newtons Laws, A&C Black Publishers, Bloomsbury, London, pp. 43-50.


Coach AFL (2015). ‘Secrets of kicking an AFL drop punt’, accessed online 17/6/15 http://www.coachafl.com/index.php?pr=Feature_-_Jason_Akermanis_Kicking 


What is Magnus Force? 2011, YouTube Video, accessed 16/6/15,






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