What biomechanical factors are most effective to improve accuracy and power in an AFL Handball?

Jobe Watson handballing

 

 

The handball skill in Australian Football is one of two main methods of disposing the ball.  Handball is an important skill in today’s game, allowing individuals to pass the ball accurately, quickly and effectively down the ground to team mates to score, whilst catching the opposition off guard (Australian Football League, 2009).  It is vital handball is performed effectively and efficiently with optimal force, placing the ball in a position for team mates to receive easily without changing momentum (Marano, 2013).  This can be determined by considering a range of biomechanical factors such as summation of forces, the kinetic chain and projectile motion.

 

 

 

 

The Answer

How can force summation be used to teach maximum velocity?
When handball is performed with summation of forces in conjunction with the kinetic chain it allows the football to travel at greater distances than if a force came from a single movement (Morano, 2013).  Summation of forces is a series of forces added together creating larger forces.  Summation of forces changes from a single force because it is created from one large force.  It is formed with larger muscle movements that flow into smaller muscles to the point of its release (Blazevich, 2010).  Therefore, performing a handball like the below image (figure 1) will allow for summation of forces and the kinetic chain (Parrington, Ball, MacMahon & Taylor, 2009).

The first image in figure 1 shows the ball being cradled in the left hand. This is known as the platform hand. A step forward is taken (larger muscles) with the left leg. The right arm is then pulled back away from the ball in a back-swing phase, continuing to rock backwards onto the right leg (Parrington, Ball, MacMahon, & Taylor, 2009). Position is maintained throughout the movement phase and continuing to move the momentum forward with right arm starting to swing forward (aussierulesuk, 2008). 

This summation of force is a large group of forces that continues through to the smaller muscles.  This force allows the ball to travel at greater distances as opposed to a handball being performed by a flatfooted stance because there is no forward movement from the legs (figure 2) (aussierulesuk, 2008).  Therefore the summation of forces allows individuals to increase the power into their movement and handball allowing the ball to travel at greater speeds (United States Australian Football League).   Summation of forces and kinetic chain may also have a negative effect on accuracy because as the body increases momentum the toes and knees may not be aiming directly to the target (Blazevich, 2010).

 

Figure 1: Summation of forces for the handball

 

 

 

Figure 2:  Standing still handball

 

 

 

 

 

Where is the best part of the ball to make contact with and why?

For an accurate and powerful handball, it is best to strike the ball at the cross made by the seams at both ends of the ball, with stitching on top (Figure 3) (aussierulesuk, 2008).  Striking the ball at the cross is perfect because it’s the smallest surface area, allowing an individual to have more control over the handball technique  (United States Australian Football League). 

 

 

The shape of an AFL football is oval.  Therefore, the accuracy within a handball is largely affected by its centre of mass.  The centre of mass is located through the seams of the ball. Centre of mass allows the football to travel with accuracy aiming and reaching its correct target.  This can be explained by the ball having larger coefficient restitution at the side of the ball and a smaller coefficient restitution that meets at the four seams at each end (Blazevich, 2010).  As a result, the ball has more power when striking it on its side but will usually have less accuracy as the surface area of the ball is much larger than the side of the hand striking it. 

 

This is the opposite effect when contact is made at the point of the ball where the seams meet.  Why? Because the ball has a smaller coefficient of restitution that will decrease the power of the handpass due to the point of impact having a smaller surface area.  The striking hand contacting the point of the ball is closer in size; which allows the ball to travel on a trajectory with more suitable accuracy (Blazevich, 2010).  Therefore, the centre of mass is highly desirable for an accurate handball because of the seams located through the ball.  As a result, striking the ball at the seams allows the ball to spin backwards in the path of the handballer but moves forward.  This technique is most effective when delivering the ball through the air because of less air resistance.  Less air resistance causes the football to drop or rise but allows for spinning, which is most effective and simplest way for a team mate to catch (Blazevich, 2010).
 

Figure 3:  Seems of the ball

 

 

What is the optimal release for ball trajectory and why?

In Australian Rules football a handball can be executed in a number of ways.  While the standing position is the most ideal way to complete the skill, handball can also be executed whilst players are prone on their front or back as well from a kneeing stance (figure 4) (Australian Football League, 2009).  The optimal angle of release for a projectile to cover the greatest distance is 45 degrees from ground level (Blazevich, 2010).  Why? Because a projectile released at a higher or lower angle will decrease the distance travelled.  A higher trajectory will travel higher and shorter and a lower trajectory will travel lower and fall to the ground due to gravity.  Therefore, it is important to perform a handball with an optimal angle of release at approximately 43-44 degrees with the ball held 1 metre above ground level (Blazevich, 2010).  However, the technique and physical characteristics of an athlete will determine the height of the delivery point.   

 

Projectiles are affected by several external influences that include gravity, drag force and air resistance.  These external influences are the reason projectiles, which in this case the AFL football either rise or fall and potentially move from side to side.  Drag force affects a football when fluid air molecules are present and causes the projectile to lose kinetic energy with reducing the amount of velocity on the projectile (Blazevich, 2010).  The laminar flow is the flow of air that is constant and travels in the opposite direction to the projectile.  Laminar flow passes over and around the object as seen in figure 5.  After the air is passed over the projectile, the flow becomes non-laminar which changes the direction of air flow.  Non-laminar flow is also called turbulent flow.  The change of air flow causes the projectile to lose energy but turbulent air flow allows the projectile to gain energy.  Gravity is a natural force that constantly affects a projectile.  An example of this is gravity pulls the projectile down to the earth’s surface (Blazevich, 2010).



 

Figure 4:  Sitting handball

 

 

 

Figure 5:  Laminar Air Flow

 

 

 

How else can we use this information?

Force of summation and kinetic chain

Force summation and kinetic chain is useful information that can be used when teaching an individual skill and technique.  Each individual is diverse and has different levels of strength and physiological appearance.  For example when some individuals perform the shot put action, they may find using a push like technique will be easier to perform whilst others may find a chest-pass technique is simpler (Blazevich, 2010).

 

 

Coefficient of restitution

Another way the coefficient of restitution can be explained is reducing the impact of collisions to improve and reduce injuries.   An example is gridiron is using padding as this will reduce energy imparted whilst helping improve the dissipation of energy to reduce the impact of collisions.  Another implication of the coefficient of restitution is to improve tactical thinking of coaches and managers.  Why? Because in wet conditions on field sports a greater energy must be imparted into the ground to get the same rebound and output as if in playing in dry conditions.  If this tactical thinking is implemented an attacking team will play a style of sport that will reduce their need to run.  Therefore, this tactical thinking will see the oppositions legs become fatigued (Blazevich, 2010).

 

Angle of release

The angle of release at 45° is not always possible as an individual’s technique and physical attributes will cause the optimal angle to change as the position of the projectile is released.  If the athlete can get a higher velocity at a lower angle, then there has to be a trade-off between the optimum release angle and maximum release velocity.  In soccer it is believed that the optimal angle of release for a throw in after the ball has been kicked out is approximately 30° (Blazevich, 2010).

 

Centre of mass

The centre of mass can be manipulated in other sports to evade opponents when the player is carrying the ball down the field.  It can also be manipulated when having a jump shot in basketball when the player raises their body of the ground in what’s known as the ‘hang’ phase.  The ‘hang’ causes the centre of mass to rise and become centred.  The balanced body allows for the shot to be performed with an already upward force as the upper body momentarily remains stationary in the air (Blazevich, 2010). 

 

 

 

Drag

The information relating to drag can be useful in most sports that require a projectile to be either thrown or kicked.  This is also useful in creating clothing and trying to gain an advantage in making individuals performance better through the use of aerodynamics.  Drag has been tested by many sporting experts and it is now known that oval shaped balls can reduce the amount of drag in flight by imparting the ball with a spiral spin so that the ball remains stable and can create what’s known as a ‘torque vector’ (Blazevich, 2010)

 

 

 

References

aussierulesuk. (2008, January 2). AFL Skills Video - Handball Pass [video file]. Retrieved March 29, 2014, from http://www.youtube.com/watch?v=Do2plgdfYYw&NR=1&feature=endscreen

Australian Football League. (2009). NAB AFL Auskick. Skills Guide, 61. Retrieved April 8, 2014, from <http://www.afl.com.au/portals/0/afl_docs/development/coaching/junior_manual/AFL_Junior_Coaching_Manual_5.pdf>

Blazevich, A. J. (2010). Sports Biomechanics, The Basics: Optimising human performance (2nd ed.). London: Bloomsbury.

Marano, J. (2013). Biomechanically what is the most effective way to improve the accuracy and power in an AFL Handball. Retrieved March 29, 2014, from Blogger: www.biomechanics-handball.blogspot.com.au/

Parrington, L., Ball, K., MacMahon, C., & Taylor, S. (2009). Biomechanical analysis of the handball in Australian Football. School of Sport and Exercise Science.

United States Australian Football League. (n.d.). Handball and Types of Handball. Retrieved from Us Footy: http://www.usfooty.com