What are the Optimal Biomechanics of a Netball Shot?

Major Question:

What are the Optimal Biomechanics of the Netball Shot?

Biomechanics refers to the ‘application of the scientific principles of mechanics to understand movements and actions of human bodies and sport implements’ (Wuest & Fisette, 2012).  By having a sound understanding of biomechanical notions, the body can be programed to move with precision (Hede, Russel & Weatherby, 2011). Examining the biomechanics of sporting skills assists with the reduction and correction of technical errors, refining individual movement phases of particular skills, reducing injury and drawing attention to the importance of equipment design (Steele, 1990). This blog will address the movement phases involved in a netball shot and determine what the optimal biomechanical principles of a netball shot are.

The aim of netball is for the offensive side to move the ball down the court and into the goal circle, for the goal shooter or goal attack to score. Steele (1993) states that the overarching purpose of all offensive fundamentals in netball is to provide opportunities for the goal shooter or goal attack to score. Thus, highlighting its significance during a netball game. The accuracy of a goal shooter and goal attack is a crucial aspect of a netball match and can play a significant role in determining the outcome of the game. By identifying the optimal biomechanical principles of the netball shot, a goal shooter or goal attack is able to improve accuracy. In turn, these improvements will result in a higher shooting percentage.    

Three sub questions have been developed, explored and answered in order to address the major question. The three questions are as follows:

• What are the movement phases associated with performing a netball shot?
• What skill cues can be used when teaching each phase
• What optimal biomechanical principles are involved to achieve each movement phase/ optimal technique

The Answer:

Movement phases of netball shot

There are four movement phases associated with performing a netball shot. Each of the phases has specific skill cues and biomechanical principles. These need to be understood and applied in order to perform an accurate netball shot using the optimal technique.

The four phases are:

• The preparation phase
• The power production phase
•  The release phase, and
• The follow through phase

Having identified these movement phases, we are now able to understand which skill cues can be provided to learners and what biomechanical principles should be employed in order to achieve a successful netball shot.

Biomechanical principles of each movement phase associated with netball shot

The following table provides a brief overview of which biomechanical outcomes are present within each movement phase of the netball shot. These will be further explored in the section below.

Movement Phase	Biomechanical Principles
The preparation phase	Base of support  Balance and stability Centre of gravity
The power production phase	Summation of forces Kinetic chain
The release phase	Summation of forces Projection angle Projection motion (trajectory) Force Magnus effect Kinetic chain
The follow through phase	Summation of forces Kinetic chain Balance and stability

Table 1: Biomechanical principles of each movement phase

Movement phases, skill cues and biomechanical principles associated with the netball shot

In order to achieve a successful outcome of a chosen skill, it is important that the optimal technique of the skill is promoted. This section of the blog will address the individual movement phases, the optimal technique and skill cues that can be used when teaching the netball shot, and the biomechanical principles involved in performing each stage using the optimal technique.

The preparation phase:

Figure 1: The preparation phase of the netball

Figure 1a: The preparation phase of the netball shot

Skill cues and optimal technique:

As evident in Figures 1 and 1a the following skill cues are necessary when aiming for the optimal technique of a netball shot during the preparation phase:

• Feet placed in line with shoulders
• Feet spaced hip width apart, or slightly less
• Both feet are parallel, pointing directly to the goal ring
• Upright trunk position
• Upright head, centred in the midline of the body
• Ball high above the head, or slightly behind
• Ball resting on the finger pads of shooting hand
• Non-shooting hand placed lightly on side of the ball

The identified skill cues, as demonstrated in Figures and 1a, reflect the optimal technique of the netball shot during the preparation phase. According to Steele (1993), this foot placement provides stability and a base of support for the shooter and reduces trunk rotation. By minimising trunk rotation and head movement stability is more easily achieved, which in turn improves the overall accuracy of the shot. By lightly placing the non-shooting hand on the side of the ball, the shooter is able to remove it quickly without allowing it to interfere with the motion of the shooting hand.

Biomechanical principles:

Steele (1993) states that skilled shooters spend 58% of the time, from receiving the ball to the release of the shot, preparing to shoot. The preparation phase of the netball shot requires the establishment of balance, stability and a steady base of support. Centre of gravity is also a fundamental aspect of this primary phase. Blazevich (2010) defines centre of gravity to be ‘the point around which all of the particles in the body are evenly distributed, and therefore the point at which we could draw a single weight vector’. As shown in Figure 2, the bodies centre of gravity can transfer depending on the position or movement of the body. By limiting trunk movement, thus altering the body’s centre of gravity, the shooter can maintain a balanced position and increase the accuracy of the shot. Gaining balance through even distribution of weight is a crucial foundation of the preparation phase of a netball shot.

Figure 2: The shift of centre of gravity in relation to the position or movement of the body.

The power production phase:

Figure 3: The power production phase

Figure 3a: The power production phase

Skill cues and optimal technique:

As evident in Figures 3 and 3a, the following skill cues are necessary when aiming for the optimal technique of a netball shot during the power production phase:

• Balanced, stable position
• Knee’s flexed
• Flexed forearm- at the elbow
• Lever the ball backwards
• Minimal trunk and movement
• Even weight distribution
• Push through the ground using ankles and knees
• Eyes focused on the goal ring

During the power production phase, a balanced and stable position must be maintained. Adequate flexing at the knees is necessary to ensure sufficient force can be generated during subsequent release phase of the shooting action to propel the ball to the goal ring (Steele, 1993). The forearm is flexed at the elbow, with an approximate optimal relative angle of 90 degrees. The flexion of the forearm and the knees tend to occur almost simultaneously. The ball is levered backwards without allowing the elbow to drop below head height. There is minimal movement in the trunk as the shooter evenly applies a vertical downward force, thus a ground reaction force is created- a part of Newtons Third Law.

Biomechanical principles:

Newtons three laws of motion can help us to understand the biomechanics involved in the second movement phase of the netball shot- the power production phase. Newton’s first law draws attention to the concept of inertia. It states that ‘an object will remain at rest or continue to move with constant velocity as long as the net force equals zero’ (Blazevich, 2010). Therefore, by applying force to the netball, it will change the motion of the ball.

Newton’s second law focuses on the acceleration of an object. The law states that ‘the acceleration of an object is proportional to the net force acting on it and inversely proportional to the mass of an object. Figure 4 demonstrates the formula used to calculate the sum of the force that moves an object. Therefore, during the power production phase, in order to accelerate the ball faster, more force need to be applied.

Figure 4: The sum of the force that moves an object is equal to the objects mass, multiplied by the acceleration: Force= mass x acceleration. Source: http://www.physics4kids.com/files/motion_force.html 

Newton’s third law states that ‘for every action, there is an equal and opposite reaction' (Blazevich, 2010). As the shooter sinks into the flexion of the knees and forearms, an evenly applied vertical downward force takes place as the shooter pushes through the ground, producing force. This creates a ground reaction force, stopping the foot from sinking into the ground (Figure 5 and 5a).

Figure 5: An example of a downwards force being applied to the ground

Figure 5a: Ground reaction force

The release phase:

Figure 6: The release phase

Figure 6a: The release phase

Skill cues and optimal technique:

As evident in Figures 6 and 6a, the following skill cues are necessary when aiming for the optimal technique of a netball shot during the release phase:

• Eyes focused on the goal ring
• Straight trunk
• Upright head position
• Arm extended, not locked
• Knee’s extended
• Ball positioned directly above head at point of release
• Point of release of the ball kept high
• Non-shooting hand removed from the ball
• Shooting wrist is ‘flicked’
• Backspin is achieved

During the release phase, the shooter should be maintaining an upright trunk and head position to achieve a balanced state, improving accuracy. The arms and knees are extended during the release phase. However, it is important to recognise that hyperextension of the hand is likely to cause strain and tension, resulting in an uncontrolled and inaccurate shot. The shooting hand should be extended only as far as necessary to stabilise the ball (Steele, 1993). A push-like movement pattern is used when projecting the ball towards the goal ring and during this point of release; the ball should be kept high. Releasing the ball from a higher height will shorten the path the ball has to travel and therefore, reduce the chance of the ball being intercepted mid-flight (Blazevich, 2010). As the ball is leaving the fingertips, the wrist engages in a ‘flicking’ action, creating backspin on the ball due to the Magnus Effect taking place.

Biomechanical principles:

During the release phase, the shooter uses a push-like movement pattern when projecting the ball towards the ring. All of the joints in the kinetic chain are extended simultaneously in one movement. The cumulative forces that are generated during this extension result in a high overall force. Steele (1993) highlights that successful goal shooters will be able to determine the correct amount of force required for their shot based on their height and preferred level of flexion they apply to the knees and forearms. Forces have four major properties and these are presented in relation to a netball shot in Figure 7.

Figure 7: Location of the four common properties of forces during a netball shot. Magnitude: the amount of force applied, Direction: the angle at which force is applied, Point of Application: the specific point at which the force is applied, A Line of Action: the straight line through the point of application in the direction the force is acting. 

The projectile motion of the ball is concerned with ‘the motion of an object projected at an angle in to the air (Blazevich, 2010). The angle of projection influences the projectile range, which means that if a shooter was to project the ball vertically into the air, it would land back in the shooters hands due to gravity. The trajectory of the ball is impacted by projection speed, projection angle and the projection height. A high projection height has already been determined as an optimal release point and in addition to that, Steele (1993) suggests 60 degrees as an optimal angle of release. However, this can change due to weather conditions, the defensive players height and physical dynamics of the individual shooting. Figure 8 demonstrates the angle and height of release that is optimal for the netball shot.

Figure 8: The angle and height of release during the release phase of the netball shot.

By applying a ‘flicking’ action with the shooting wrist as the ball is released from the fingertips, backspin occurs due to the Magnus effect. The Magnus Effect takes place when a spinning object is moving through air. By applying backspin to the ball during a netball shot, the flight direction is maintained and the speed of the ball is reduced when the ball makes contact with the ring. Figure 9 depicts the way The Magnus Effect occurs. 

Figure 9: The Magnus Effect: The Magnus Effect occurs through the collision of oncoming air, with the air the ball has produced on one side, decreasing velocity. On the other side of the ball, the air moves through untouched causing less air on one side (Blazevich, 2010).

Source: The Magnus Effect. Reprinted from Fundamentals of biomechanics. (Knudsen, 2007). By Knudson, D. Copyright 2007. Springer Verlag GMBH

The follow through phase:

Figure 10: The follow through phase

Figure 10 a: The follow through phase

Skill cues and optimal technique:

As evident in Figures 10 and 10a, the following skill cues are necessary when aiming for the optimal technique of a netball shot during the follow through phase:

• Shooting hand is arched
• Eyes focused on goal ring
• Upright trunk and head position
• Feet hip-width apart
• Maintained balance 

The follow through phase is the final movement phase of the netball shot. The eyes are kept focused on the goal ring, and the shooting hand finishes in an arching position after the wrist has flicked the ball. By keeping feet hip-width apart, and upholding an upright trunk and head position, the goal shooter is able to maintain the balance needed for the next move they take.

Biomechanical principles:

The biomechanical principles associated with the follow through phase are similar to those of the preparation phase in regards to the balance and stability needed through maintaining an even centre of gravity. Regaining balance and stability during the follow through phase increases the shooters chances of collecting a rebound or assuming a defensive position.  

How else can we use this information?

By analysing the biomechanics of any given sport can be precisely examined. The information presented in this blog can provide coaches with the necessary theoretical background to teach the basics of a netball shot to junior players, as well as to refine the existing techniques of experienced players (Steele, 1993). In turn, it aims to achieve optimal technical performance and minimise prospective injury. This information can also be used within an educational setting like a physical education lesson. By allowing students to develop a sound understanding of the biomechanics associated with particular skills of sports, they are able to improve their current skill level and refine the motor skills needed to achieve the optimal techniques within different sports. The concepts and biomechanical principles identified within this blog are relatively transferable to other sports the require shooting a projectile, such as basketball.  

References

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

Hede, C., Russell, K., & Weatherby, R. ( 2011) Applying biomechanics to sport (3rd ed). New York: University of Oxford.

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

Wuest, D & Fisette, J 2012, Foundations of Physical Education, Exercise Science, and Sport, 17^th edition, Mcgraw Hill, New York, p149