Breakdown of the Biomechanical principles of the drop punt for accuracy and power

http://biomechanicalpunt.blogspot.com.au/


The Biomechanical breakdown of the AFL drop punt from a stationary kick is something which really intrigues me and will help me in assessing not only professional performance but amateur performance and be able to assess my own kicking technique and improve to a sound level.

To assess the drop punt it needs to broken down into seperate stages, the stages which will be looked at in detail are as follows;

•  Lead Up (Sequential Movement Pattern)

• Ball drop (Balance/ Stability)
• Leg swing (Kinetic Chain/Summation of Forces)
• Follow through (Projectile Motion, Magnus Effect)

The drop punt is not the only kick in AFL but it is the most accurate and it achieves the most distance other than the torpedo.

From a biomechanical perspective the drop punt is an example of successful application of the Magnus effect. According to Blazevich (2007) Soccer players and in particular goalkeepers hoping to kick the ball a long way kick the ball with backspin, so that they can apply a large horizontal force (and therefore velocity) while the lift created increases the ball’s flight time. This is the same for the drop punt in AFL.

Blazevich (2007) highlights that Newton’s Third Law works on the ball when you place spin on the ball, where the bottom of the ball spins over the top of the ball (i.e. backspin), the air on top would move quicker than the air underneath. Therefore, the pressure on top of the ball would be lower; a Magnus Force would be directed up and the ball will then rise, therefore increasing distance.

An example of this can be seen in Diagram 1.

Diagram 1

There are forces which work against the Magnus effect and is a reason why the drop punt is not always 100% accurate. These are environmental effects which work against the Magnus effect; Ball Speed, Wind Speed. 

How To Kick a Drop Punt?

According to the Auskick manual (2015) there are four main teaching points of the drop punt. These are as follows;

1. Line up the ball with your target. Have your head bent slightly over the ball. Hold the ball over the thigh of the kicking leg

2. Guide the ball down with one hand.

3. Point your toes at your target – see the ball hit the foot.

4. Follow through straight towards the target.

These key components can be seen performed by Nathan Buckley in the video below.

Nathan places a big emphasis on a nice balanced approach in the lead up, guide the ball down with one hand and aim to kick the ball on its bottom point, pointing your toes towards your target and focusing on your follow through.

One thing which will be discussed further on is the difference in technique when kicking a further or shorter distance kick.

LEAD UP 

 

Video 1

The run up/approach of the drop punt is important. The ball is held during the run-up by both hands and released by the non-kicking hand, the kicking hand is released before the point of contact at the foot. The right arm was then abducted during the remainder of the motion to balance the body. The progression of the ball after release was downward (due to gravity) and forward due to the momentum of the hand. This can be seen in detail in Video 1. (Orchard, Walt, McIntosh & Garlick, 1999)

The drop punt begins with a sequential movement pattern where the proximal joints increase velocity first and the more distal segments increase velocity later. This is shown in Diagram 2.

Diagram 2

BALL DROP

The ball drop is an essential factor in successfully performing a drop punt. The key factor in the ball drop is the roll the guiding hands plays in guiding it to your foot. Releasing of the guiding hand to early can decrease the accuracy of the kick. 

According to Brisbane Lions Academy (2014) the ball drops main focus points are as follows;

• Ball  release  should  be  at  approximate height of hips

• Preferred  hand  should  guide ball down and forward away from the body

• Non-­‐preferred  hand  raised  to approximate shoulder height and extended away from torso to help balance body (centre of mass) 

• Non-­‐preferred  leg  should  be  slighlty bent at knee with good foot contact on ground

Below we can see Lindsay Gilbee who was an extremely accurate and penetrating kick. From his ball drop we can see he is very balanced and is following the correct technique.

Balance is extremely important in the ball drop and looking at the two middle pictures we can see during the kicking movements analyzed here (Lindsay's kicking approach picture 3) Lindsay has almost parallel knee flexion of the kicking foot and his supporting leg is straight with a bend in the upper thigh. His centre of mass stays in the centre while his body works as stabilisers as he leans back when kicking.

 Not only does this produce a better balance, it also helps in producing the greater range of motion in the leg as it creates a lower inertia on the kicking leg enabling it to swing back further (Dichiera et al., 2006).

Lindsay Gilbee's Kicking Approach

Amateur Technique

If you compare this technique with an amateur we can begin to critique certain parts of his action. The amateur technique is almost sound but his ball drop is from a higher level above the recommended hip height. The guiding hand is not present long enough to the point of contact and can lead to a less accurate kick, wind can move ball before foot contact and remove the ball from its correct point of contact.

 Kinetic Chain / Summation of Forces/ Leg Swing in Kicking Phase

Diagram 3

Kicking for distance is very important skill for football. The ability to kick long distances with accuracy provides a clear advantage to the player. Kicking is a a ‘throwlike’ movement pattern where the speed at the most distal segment, the foot, is important for kick distance. (Young, Clothier, Otago, Bruce & Liddell, 2004)

According to Blazevich (2007) The kinetic chain involves the complex co-ordination of individual movements about several joints at the same time. This is an example of a moving chain of body parts: the kinetic chain.

For example in Diagram 3 we can see an example of a Rugby drop kick which is similar to the drop punt.

This is the wind up phase and comes just after the release of the ball drop. During kicking, the thigh is accelerated followed by the lower leg. This results in a high end velocity.

The muscles around the hip accelerate the thigh segment, before the leg and foot swing through later in the kick cycle, this highlights that the kick is an example of a  throw-like pattern.

 Blazevich (2007) also highlights during this phase the lower leg and foot have inertia and tend to continue to move backwards. The flexion occurring at the knee is a result of the elastic knee (patellar) tendon stretching under the load. When the force in the tendon is high enough, (this is during the backswing of the kick) the tendon will begin to recoil at very high speed. The muscles that extend the knee, the quadriceps extend fully to provide extra force; the combination of these results in a very fast extension of the knee and a very high foot speed.

This is very important in developing power and distance in the drop punt. In comparison if we analyse the video below we can see that the subjects kicking leg does not have a very high flexion of the knee and will not allow the quadriceps to help develop that extra force for a fast extension of the knee. This will not lead to a very high foot speed and the force acting upon it will be minimal. This will lead to a shorter kick. This can be seen evident in the comparison between Diagram 4 (longer Kick) and Diagram 5 (shorter kick)

Diagram 5

Diagram 4

Point of Contact/Follow Through (Projectile Motion)

According to Orchard, Walt, McIntosh and Garlick (1999) the follow through is important for injury prevention as well as the successful execution of a kick.

Swinging the kicking leg through after contact with the ball helps to slowly dispel the momentum that was built up through the kinetic chain (Blazevich, 2007). 

Also the follow through has an impact on the accuracy of the kick, following through towards the target provides the ball with the direction in which to travel which is essential for kicking set shots. (Auskick Manual, 2015)

When looking at the projectile motion of the drop punt you first need to look at the point of contact. According to Blazevich (2007) projectile motion refers to the motion of an object projected angle into air. A projected object can move at any angle between 0 and 90 degrees. 

Diagram 6 explains that the maximum range of projectile is determined by its angle of projection. Diagram 6 shows that at a projection angle of 45 degrees, the object will have an equal magnitude of vertical and horizontal velocity therefore its range is maximised.In saying this though is it important for the drop punt to be kicked at a 45 degree angle?

Projectile Motion- Diagram 6
(The maximum range of a projectile is determined partly by its angle of projection.)

The answer is no and for an AFL drop punt optimum trajectory is based on the the athlete who is actually going to kick it. This can also be linked backed to the magnus effect and Newtons third law 'for every action, there is an equal and opposite reaction.'.

Brancazio's (1985) study of American football punt kick believed that the preferred launching angle lied somewhere between 40 to 60 degrees. This was supported by Linthorne and Patel's (2011) study on the soccer punt kick which calculated optimum projection angles were in agreement with the player’s preferred projection angles (40° and 44°).

How else can we use this information?

As a amateur football player there has been several downfalls to my technique and it has taken creating this blog to be able to see some of them.

I had broken down the drop punt into four simple steps;

•  Lead Up (Sequential Movement Pattern)

• Ball drop (Balance/ Stability)
• Leg swing (Kinetic Chain/Summation of Forces)
• Follow through (Projectile Motion, Magnus Effect)

I found that my ball drop was relatively high and was dropped from above hip height and did not guide the ball down with my hand as low as I should be. This had resulted in on windy days my drop punts to often come off the side of the boot or not have the right trajectory through the air. 

From the amateur video of my technique I noticed my leg swing and in particular my knee angle was not flexed enough and this showed in my kick not going a far distance.

This information is transferable to other sports which involve punt kicking as the same steps are involved. It is interesting to note that due to the success and accuracy of the drop punt kick it was introduced in the NFL as a safe option to use as well as the torpedo punt.

Reference List

AUSKICK, N. A. (2015). Kicking: Drop Punt. Retrieved June 18, 2015, from NAB AFL AUSKICK: http://www.aflcommunityclub.com.au/fileadmin/user_upload/Coach_AFL/Drills__Skills_and_Tactics/Skills___Drills/General/Auskick_Lesson_Plans/Auskick_Lesson_Plans_-_Age_7_to_8.pdf

Blazevich, A. (2007). Sports Biomechanics: The Basics: optimising human performance. London: A&C Black .

Brancazio, P. (1985). The physics of kicking a football. The Physics Teacher, 23(7), 403.

Brisbane Lions Academy: Kicking program for junior players and coaches. (2014). Retrieved June 19, 2015, from http://s.afl.com.au/staticfile/AFL%20Tenant/BrisbaneLions/Lions%20Academy/2014%20Website/Academy%20Kicking%20Program%20-%20Junior%20Coaches%20and%20Playersv2.pdf

Dichiera, A., Webster, K., Kuilboer, L., Morris, M., Bach, T., & Feller, J. (2006). Kinematic patterns associated with accuracy of the drop punt kick in Australian Football. Journal Of Science And Medicine In Sport, 9(4), 292-298. doi:10.1016/j.jsams.2006.06.007

 Linthorne, N. P., & Patel, D. S. (2011). Optimum Projection Angle for Attaining Maximum Distance in a Soccer Punt Kick. Journal of Sports Science & Medicine, 10(1), 203–214.

Orchard, J., Walt, S., McIntosh, A., & Garlick, D. (1999). MUSCLE ACTIVITY DURING THE DROP PUNT KICK . Journal of Sport Science , 17 (10), 837-838.

Young, W., Clothier, P., Otago, L., Bruce, L., & Liddell, D. (2004). Acute effects of static stretching on hip flexor and quadriceps flexibility, range of motion and foot speed in kicking a football. Journal of Science and Medicine in Sport, 7(1), 23-31.