Major Question

What are the biomechanics of the netball shot for achieving optimal accuracy?

Biomechanics is the sport science field that applies the laws of mechanics and physics to human performance (Topend sport, 2015). It is used to gain an understanding of how athletes perform in sport through modeling, simulation and measurement. Furthermore, it is also necessary to have a good understanding of the application of physics to sport, as physical principles such as motion, resistance, momentum and friction play a part in most sporting events (Topend sport, 2015).  The study of biomechanics ensures that the correct technique is performed, to assist in injury prevention and provides the player with the best opportunity at performing movement patterns and execution. The question “what are the biomechanics of the netball shot for achieving optimal accuracy”, will be addressed and explored throughout this blog as in order to win a game of netball, the team must score. Therefore, the accuracy of a shooter is vital and it is crucial that the optimal technique is performed via the correct skill queues and biomechanical principles.

Throughout this blog the following phases of the netball shot will be explored and analysed to inform players of how to achieve optimal accuracy when taking a shot:

·         The preparation phase:

o   Balance and stability

o   Landing

·         The release phase:

o   Shooting action

o   The Magnus Effect and Backspin

o   Distance from the post

·         The follow through phase

o   Ball release

o   Ball Trajectory

The Answer

Preparation Phase

According to Blazevich (2013), prior to execution, a player must ensure that they are in a balanced and stable state to assist in shooting accuracy. When performing the netball shot, a major focus of the athlete is to ensure appropriate stance is adhered to before executing the movement. Balance, position, concentration and aim play a crucial role in accurately performing this skill and have the potential to influence the success of the netball shot. Management of static balance is a fundamental component to netball shooting as it controls and manipulates the body while stationary. Balancing is linked to an individual’s base of support, which in the case of netball is achieved by planting both feet on the ground prior to taking a shot. In order to gain balance, the player’s Centre of Mass (COM) must be established. COM is understood as the point at which the body is evenly distributed in all directions (Blazevich, 2013). When conducting the netball shot, COM is achieved through positioning the feet shoulder width apart (figure 1), which is the body’s base of support and acts as a stabiliser, therefore, the larger the base of support, the greater the stability. Conversely, it is important to position the head, shoulders and trunk over the feet, therefore they must be an appropriate distance apart to ensure stability in relation to the shooting accuracy and execution (Steele, 1993). Steele (1993, p. 14) explains how ‘...skilled shooters placed the foot corresponding to the shooting side of the body either slightly forward or aligned with both feet parallel to pointing directly at the goal ring, spaced approximately shoulder width apart...’. Effectively, the player increases likelihood of accuracy by exhibiting a stable base of support in collaboration with minimal trunk rotation throughout the shot. Additionally, to help balance the shooting stance, the player is advised to maintain an upright trunk position, leaning backwards (15 degrees from vertical) with their head upright and centred in the midline of the body, while maintaining minimal head movement (Steele, 1993). However, there may be occasions within a match where a shooter is required to change the optimal base of support in order to achieve the outcome of accurately shooting a goal. Typically, the player will step closer to the ring requiring balance on chosen foot to decrease distance between the player and the ring.

Figure 1 - In this example, the shooter is ensuring that their feet are a shoulder width apart to support their stance and maintain balance

Another movement that impacts the preparation phase, is the landing after the shooter receives the ball. To ensure stability of the COM, the player is required to land in an upright trunk and flexed knees position. This landing process is also the beginning of the summation of forces and kinetic chain which falls in line with Newton’s third law stating: ‘For every action, there is an equal or opposite reaction’ (Blazevich, 2013, p.45). Therefore, when a player lands, force is applied at point of contact with the ground then exerts an equal and opposite reaction force. This occurrence is a result of force infiltrating the legs and consequently, allowing the summation of forces to initiate, which is when the different parts of the body act together to maximise force simultaneously (Figure 2) (Jeffery, 2014).

Figure 2 - Summation of forces ensures that force is applied simultaneously when shooting for goal

Release Phase

Predominantly, the desired netball shooting technique is comprised of a one handed shot, with the opposite hand placed on the other side of the ball to support and direct the attempt. According to Steele (1993), the optimal angle for the elbow during flexion when shooting in netball is situated between 90-104 degrees (Figure 3).

Figure 3 - Elbow flexion throughout release stage

This is based on the notion that excessive strain and tension within flexor muscles of the hand generally produce inaccurate and uncontrolled attempts for goal. To rectify the shooting action, the optimal biomechanical technique suggests that players extend the shooting hand, only as far as necessary to stabilise the ball when preparing to shoot thus avoiding excessive hypertension of the hand at the wrist (Steele, 1993). Consequently, less hypertension of the hand and optimal elbow angle increases the likelihood of accurately shooting a goal in netball with consideration of other biomechanical principles. The most common action sequence when performing a goal shot in netball is applying the push-like movement. For an optimal goal shot to occur, a push-like action is often adapted as it allows for the kinetic chain of the body to form a straight-line movement (Figure 4)(Watson, 2013; Naulty, 2014). The kinetic chain increases accuracy by allowing the entire body to join forces from the base of support through to the ball release (push-like movement) which in turn maximises force production and accuracy of the shot (Blazevich, 2013). This occurs when power is exerted from the base of support, through a slight bend in the knees to build momentum. The knees project forward while pushing up on the toes and the shooting arm extends straight and close to the ear to push the ball off the finger tips in an upwards movement. Essentially, the ball is lifted towards the goal ring as a result of this sequence.

Figure 4 – As a result of the kinetic chain, the body will be in a straight line prior to release

There is a substantial disadvantage to the push-like pattern in a game of netball which decreases movement speed of the ball, providing the opposition with an opportunity to intercept the shot mid-air. Furthermore, the throw-like pattern could be applied as a movement concept which provides increased force and speed, however, generates a curved pattern when released, therefore can reduce accuracy of the shot. Due to the outcome of an invasion game being scoring, it is in the athletes best interest to perform push-like movements when attempting shots for goal to enhance accuracy, however, throw-like movements would be more appropriate for different aspects of the game such as passing.

As a player releases the netball, they are required to push through the ball using both arms and legs to apply the optimal force. This sequence allows the energy to build up throughout all the joints being used to ensure maximum force and accuracy is obtained (Naulty, 2014). As the objective of a shooter relies on accuracy, it is vital that angle and height of release is optimised by decreasing the release speed, also known as the magnus effect (Figure 3), occurring when a spinning object is moving through air or water (Naulty, 2014).

At the point of release, the netball begins moving in a straight line but the spin impacts this to create a curve shape. As the netball travels between the player and the goal ring, airflow is captured forming a spin on the ball, positively impacting and maintaining flight direction (Steele, 1993). Rebound off the ring and towards the net is more likely to occur due to backspin as it decreases ball speed on impact with the goal ring while also increasing entry angle. The player shooting for goal would ensure that the angle of release is approximately 60 degrees with a backwards spin of 1-1.5 revolutions (Steele, 1993).

Figure 5 - The magnus effect (Knusdon, 2007). 

A player also needs to consider the suitable amount of force to apply to the netball when shooting for a goal, dependent on their position within the goal ring. Shooters who are standing closer to the goal circle will be more inclined to apply greater force horizontally as opposed to player who is positioned directly beneath the ring, who would be required to shoot at a more vertical angle. Furthermore, Elliott & Smith (1983) emphasise how shooting accuracy can be improved through encouraging players to position themselves as close to the goal ring as possible prior to shooting, preferably between the vicinity of 0.9metres and 1.5metres to the post.

The following video is an example of how to execute correct goal shooting technique explained above according to the biomechanical principles.

Follow-through Phase

According to Steele (1993), the optimal biomechanical technique throughout the release stage involves extending the knees and shooting elbow while flexing the wrist simultaneously. There should be minimal trunk, arm and forearm movement while emphasising action of the shooting hand to propel the ball towards the goal. This action sequence is adapted to avoid excessive trunk movement during the shooting action which has the potential to interfere with body balance and concentration of the player (Steele, 1993).

Blazevich (2013) states Newton’s Second Law as: ‘The acceleration of an object is proportional to the net force acting on it and inversely proportional to the mass of the object’, therefore, ideal force, angle and spin is needed in netball shooting to increase accuracy. Consequently, it is fundamental that the player considers the influence of gravity, in order to project the ball at an angle which permits it to travel both vertically and horizontally towards the ring. This optimal angle of projection ensures the ball is accurately pulled down through the goal ring by gravity. In addition, a high arm release action is the ideal movement to ensure that the distance between the release point and the goal ring is minimal, creating a more succinct attempt and increased chance of attaining the optimal relative height of projection. This explanation highlights how a higher release point lowers the flight time after the release and consequently, the probability of the opposition intercepting the ball throughout this period. Furthermore, Elliott & Smith (1983, p. 173) accentuate how ‘…increasing extension at the knees and elbow of the shooting arm and increasing the height the shooter pushes off the ground at ball release can further improve accuracy.’. It is fundamental to consider unique characteristics in match situations such as opponent height and ability in relation to how this may affect shooting accuracy, therefore the shooter must be versatile and able to adapt their angle of projection according to the specific context, allowing for maximum opportunity of accuracy.

After the execution of the shot, a player will typically balance on their toes which is the optimal stance for preparing to catch the rebound of a missed shot. This stance allows the player to accelerate off the ground efficiently and react to the phase of play accordingly. This movement phase is an example of propulsion occurring particularly when the toes push against the ground to drive the body forward.

Summary of the shooting sequence:

Preparation phase

·         Land with two feet shoulder width apart

·         Body is positioned to support centre of mass via having the legs shoulder-width apart

Release phase

·         One handed shot with elbow angled between 90-104 degrees

·         Extension of the hand and push movement

·         Slight bend in knees prior to release point and straight trunk at release point

Follow through phase

·         Release the ball at the highest point

·         Position body for the rebound balancing on the toes

How else can we use this information?

Understanding the biomechanical elements required for the optimal netball shooting technique can be applied to various sports. For example, the base of support is applied to all sports although different rules, positions and phases of play would determine the required positioning to support stability of the body. The game of golf involves similar biomechanical principles to netball shooting, which requires the golfer to stand shoulder width apart when teeing off to create a comfortable and stable base of support.

  

Figure 6 - As a golfer tees off, the body is stabilized and balanced through positioning the feet approximately shoulder-width apart with toes facing forward (Pilates Power, 2010)

Furthermore, a basketball player would adopt similar biomechanical principles when required to shoot. For example, the player would need to establish their COM to ensure ideal stability and balance is achieved throughout the preparation phase of shooting for a goal. In addition, they would generally incorporate a push-like movement allowing the kinetic chain to form a straight-line and enhance force. Similar bodily actions occur throughout this phase in basketball also allowing for the summation of forces to occur and in turn for the ball to reach the goal ring. Overall, knowledge of how to apply the biomechanics is a central component to teaching as it allows the educator to manipulate certain biomechanical principles to suit a student’s needs and improve technique.

References

Basham, N. (2013) Netball Australia shooting. Retrieved from https://www.youtube.com/watch?v=N20vo_pXNnU

Blazevich, A. (2010). Sports biomechanics the basics: Optimising human performance. Bloomsbury: Black Publishing.

Elliott, B., & Smith, J. U. L. I. E. (1983). The relationship of selected biomechanic and anthropometric measures to accuracy in netball shooting. Journal of Human Movement Studies, 9(4), 171-187.

Jeffery, S. (2014) How can a goal shooter improve their shooting accuracy through biomechanical principles. Retrieved from http://sjefferynetballshotbiomechanics.blogspot.com.au/

Knusdon, D. (2007). Fundamentals of biomechanics: Department of Kinesiology. California Springer Publishing. 2, 4-334.

Naulty, G. (2014) How can a netball shooter improve the accuracy of their shot. Retrieved from http://biomechanicsnetaball.blogspot.com.au/2013/04/how-can-goalie-immprove-accuracy-of-her.html

Pilates Power. (2010). Anatomy of the golf swing and its applicable pilates. Retrieved from http://www.pilatespower.tv/PilatesPLUS/Fitness/PilatesandyourGolfSwing.aspx

Steele, J. (1993). Biomechanical factors affecting performance in netball. Department of Biomedical Science. 3, 1-18.

Top End Sports (2015) Biomechanics & Physics of Sport. Retrieved from http://www.topendsports.com/biomechanics/

Watson, M. (2013) What biomechanical principles must be applied to best perform a goal shot in netball. Retried from http://madeleinewatson-biomechanics.blogspot.com.au/

By Emily Willsmore & Danielle Sharp