What are the most effective Biomechanics for a netball shot?
Biomechanics is the field of science concerned with
the mechanical laws, and internal and external forces acting on the human body
and the resultant effects of these forces (Blazevich, 2010). Analysing sports
and specific skills within these sports from a biomechanical perspective,
allows us to manipulate these factors and forces for an effective technique.
In Australia, netball proves to be a very popular
sport with one million people reported to participate nationwide (Netball
Australia, 2015). Goal shooting is one of the most important components of netball
as it is critical to the success of a team. Therefore, goal shooters must
understand the most effective biomechanics of a netball shot to ensure accuracy
from a range of shooting positions.
At the end of this blog you should:
·
Know the
most effective technique for a successful netball shot
·
Know how
this technique ensures accuracy in relation to biomechanical factors
·
Understand
how this information can be applied elsewhere
Major Question
What are the most effective
biomechanics for a successful netball shot?
The Answer
The most effective biomechanics for a successful
netball shot can be conveyed in three phases: preparation, force production and
release.
Preparation Phase
Balance/ Centre of
Gravity
Static and dynamic balance are both
important skills within a game of netball. Static balance however is the vital
first step in developing an effective shooting technique. As Blazevich (2010)
explains, “The point around which all the
particles of the body are evenly distributed, and therefore the point at which
we could place a single weight vector is the body’s centre of gravity.”
In
a netball shot, this is found through a stance where knees are slightly bent
and shoulder width apart, an engaged and upright trunk, slightly leaning
backwards and head upright. This stance achieves balance and a stable position
to take a shot from. Additionally, it creates a base of support. |
| Figure 1: Knees bent in order to create a balanced base of support and lower the centre of gravity. |
Base of Support
A solid base of support is crucial for the
following process of shooting a goal. If a person’s centre of gravity is
outside of their base of support (legs not shoulder width apart or trunk
leaning to one side etc.), the base of support is minimised and steady balance
will not be achieved (Steele, 1993). Therefore, the effective technique discussed
previously, increases one’s core stability and allows the centre of mass to
remain directly above the base of support.
Positioning the Netball
Once a solid base of support has been established, the player will put the netball into their ‘ready position’. This involves placing the netball on the fingertips of the dominant hand and placing the other hand lightly on the side of the ball to steady it and during the release, guide the netball shot (BBC Sport, 2005).
 |
Figure 2: Natalie
Medhurst of Australia, placing the ball into her ‘ready position’ (Walshe,
2014).
|
Potential/Kinetic Energy
Two forms of mechanical energy that also form part
of the biomechanical process are potential energy (PE) and kinetic energy (KE).
Potential energy refers to energy referring to the position of an object before
motion (Blazevich, 2010). Following this, kinetic energy is then related to an
object in motion. While taking a netball shot, there are two instances where
both PE and KE play a role. When the arms and legs flex just prior to release
of the ball, the potential for energy is created before it is turned into
kinetic energy when limbs are extended and pushed upward. Additionally, the
ball holds its own PE when it is sitting in the player’s hand, prior to being
released. The ball is not yet in motion but has the possibility to become KE.
When the player takes the shot at goal, the energy then becomes KE. The ball is
now in motion as the player applies force to the ball allowing it to accelerate
towards the goal.
Figure 3: Stages of Potential and Kinetic Energy of both the ball and the arm/wrist flexion and extension
Distance from Goal Post
Another factor affecting the accuracy of a shot is
the distance a player is positioned from the goal post. Having a shot from a
further distance requires changes in the biomechanics of the shooting action.
These can include but are not limited to the flexion of both arms and knees
which affects release height, trajectory and amount of force produced (Steele,
1993). These factors will be discussed in more depth throughout the remainder of
the blog. Ultimately the accuracy of the shot is suggested to decrease the
further away the shot is taken and the netball shooter should constantly be
aiming to shoot close to the goal post (Knudson, 2007).
Force Production Phase
Newton’s 3rd Law
Newton’s third law states “for every action, there is an equal and opposite reaction” (Blazevich, 2010, p. 45). Force production through the body results in a vertical (downward) force into the ground, the ground then exerts an equal and opposite force back into the body causing it to lift off the ground depending on the amount of force produced, known as ground reaction force (Blazevich, 2010). If the player is far away from the goal ring, more force and ground reaction force must be produced for the ball to reach the ring.
Kinetic Chain
All human motion involves the complex coordination
of individual movements about several joints at the same time (Blazevich,
2010). This chain of motion is most commonly referred to as the kinetic chain.
Within a netball shot, this occurs through the simultaneous flexion of knees,
elbows and wrists (see figure 3), resulting in a great total force production.
This provides an effective performance outcome because each part of the
movement has its own individual force and when combined produce a great
cumulative force.
 |
Figure 4: Kinetic Chain – simultaneous flexion of
movements to complete the netball shot.
|
Push-like movement
The two main categories within the kinetic chain
are ‘push-like’ and ‘throw-like’ movements. The netball shot falls under the
category of ‘push-like’ as it involves the simultaneous extension of joints in
a single movement (Blazevich, 2010). The push-like movement is commonly used
not just within netball, but in a range of everyday exercises and activities.
One reason it is so common is due to the simultaneous joint rotations, which
often result in a straight line motion. Within this straight line, highly
accurate movements can be produced (Blazevich, 2010). Contrasting to a
throw-like movement, the push-like movement does not allow for great speeds to
be reached. However, the netball shot does not require great speed, but an
accurate and fluent action. Thus, the push-like motion proves highly suitable
for this particular skill.
Additionally, it is important to note that the
netball shot is an open kinetic chain movement. The open kinetic chain has an ‘open’
end which is able to move freely (Blazevich, 2010). For example, the beginning
of the chain (shoulder) is fixed in position and the other end is free to move
(hand). This movement pattern is very effective for completing a successful netball
shot as it allows for accuracy as well as higher generation of force.
Lever
A netball shot is classified as a first-class lever.
The first-class lever consists of the load at one end, effort at the other end
and the fulcrum in the middle (Williams, 2017). Levers are used to enhance
force, adding to force produced by the lower body muscles and making it easier
to shoot the netball.
 |
Figure 5: Diagram of a first-class lever, showing the
relative positions of the load, fulcrum and effort (Williams, 2017).
|
 |
| Figure 6: Diagram showing the positions of the load, fulcrum and effort in a netball shot lever |
Release Phase
Newton’s
First and Second Laws
Newton’s first law of motion states “an object will
remain at rest or continue to move with constant velocity as long as the net
force equals zero” (Blazevich, 2010, p. 44). The force production phase
consists of creating force through the body to shoot the netball. The amount of
force produced will impact on the inertia of the ball and how far it will
travel before being pulled down by gravity and slowed by air resistance. As
discussed in the preparation phase, if the player is further from the goal
post, they will need to produce more force for the ball to reach the ring. This
point is also in conjunction with Newton’s second law of motion, acceleration,
in that:
Force (F) = mass (m) x acceleration (a) (Blazevich,
2010, p.45).
The mass of the netball will remain constant.
Depending on the player’s distance from the goal post, acceleration will either
be faster or slower and therefore the force will be larger or smaller.
Projectile
Motion
The action of shooting a netball shot causes the
netball to be a projectile. Gravity and air resistance are the two forces that
act on a projectile (McGinnis, 2013). Shooting a successful netball shot
however, requires not just movement of the ball but accuracy. There are three
important release parameters that impact the release stage of a netball shot:
release speed, angle and height (Zatsiorsky, 2008). Release height varies
between individuals, due to one’s height and arm length and is held constant.
If the release angle is also held constant, the release speed determines the
apex (highest point) and the range (distance travelled) of the netball
(Zatsiorsky, 2008). The size of the release angle depends on the distance from
the goal ring. For a shot just under the ring, the release angle will be very
high with lesser speed and for a shot four metres from the ring, the release
angle will be slightly lower with greater speed to cover the longer distance to
the ring. A netball shooter needs to be able to correctly alter their release
speed and angle in order to score a goal.
 |
Figure 7: Images showing release height and release
angle of a shot very close to the goal post.
 |
Figure 8: Images showing release height and release
angle of a shot far from the goal post.
|
Magnus
Effect
During the release of the ball, an effective player
will ‘flick’ their wrist and fingers in the follow though, causing backspin on
the ball along with what is known as the Magnus effect. The Magnus effect is
caused by a pressure differential on either side of the object. Due to the
friction between the air and the ball, when the ball spins backwards, it
‘grabs’ the air flowing past it at the bottom and these air particles spin with
the ball (Blazevich, 2010). The air spinning with the ball comes into contact
with the oncoming air, while the air on the top flows freely, resulting in the
ball spinning backwards (Blazevich, 2010). The advantage of spinning the
netball backwards and creating the Magnus effect is that if the ball hits the
edge of the ring it will slow down and increase the chances of it falling into
the net, rather than bouncing over it (Steele, 1993).
 |
Figure 9: Diagram showing the Magnus effect pressure
differential on the netball spinning backwards.
Potential/Kinetic
Energy
As the netball is released, it changes from having
potential energy to kinetic energy. As the mass of the netball is held
constant, the velocity of the netball is the greatest factor in the amount of
kinetic energy the netball possesses (Blazevich, 2010).
How else can we
use this information?
The information discussed in this blog can be used in
a number of different applications. A netball shot is similar to a basketball
and korfball shot. The biomechanical principles of balance, base of support,
distance from goal post, kinetic chain, push like movement, Newton’s laws,
levers, projectile motion, and Magnus effect can all be transferred from a
successful netball shot to a successful basketball or korfball shot. The Magnus
effect can also transfer to sports such as tennis, soccer, golf, cricket and
volleyball as spin is placed on the ball for an advantage in each of these
sports.
The information discussed in force production can be
useful to netball shooters in that they understand the major muscle and joint
groups used in a netball shot and can strengthen these to make shooting more
successful for them.
The successful netball shot technique discussed in
this blog using biomechanical principles can be used in teaching and coaching
netball. This information can equip teachers and coaches with the means of
teaching a successful shooting technique to young children, which will
significantly aid them if they continue playing netball or other sports
throughout their lives.
Conclusion
In conclusion, whilst an effective skill pattern varies
slightly between individuals for a successful netball shot, the discussed
biomechanical principles can be used by coaches, teachers or the player
themselves to improve shooting technique and increase success. Ensuring a solid
base of support, using a simultaneous push-like movement, adjusting to the
distance from the goal post and creating the Magnus effect are all important
biomechanical principles that should be used by a player to construct their
most effective netball shooting technique.
Reference List
BBC Sport. (2005, October). Netball: shooting. Retrieved from http://news.bbc.co.uk/sport2/hi/other_sports/netball/4187548.stm
Blazevich, A. (2010). Sports
biomechanics the basics: Optimising human performance. (2nd ed). London:
Bloomsbury Publishing.
Knudson, D. (2007). Fundamentals of
biomechanics: Department of Kinesiology. California Springer Publishing. 2,
4-334.
McGinnis, P. (2013). Biomechanics of
sport and exercise. USA: Human Kinetics.
Netball
Australia,. (2015). What is Netball? - Netball Australia. Retrieved 15 June
2017, from http://netball.com.au/our-game/what-is-netball/.
Steele, J. ( 1993). Biomechanical
factors affecting performance in netball. Department of Biomedical Science.
3, pp. 1-18.
Walshe, C. (2014). Australia extends netball winning run over
New Zealand to six tests with 59-42 thrashing. Retrieved from http://www.adelaidenow.com.au/sport/netball/australia-extends-netball-winning-run-over-new-zealand-to-six-tests-with-5942-thrashing/news-story/49d14762a19fe525d972b0c339478b63
Williams, K. (2017). Angular Motion & Levers. Lecture
presented at Flinders University, 10-05-17.
Zatsiorsky, V. (2008). Biomechanics in Sport. Great Britain: John
Wiley & Sons, Incorporated.