The Biomechanics of the AFL Set Shot: Factors Influencing Goal-Kicking Accuracy

HLPE3531 Biomechanics blog report:

HLPE3531

Skill Acquisition and Biomechanics

Biomechanics Blog Report 

 Student Name, I.D Number

 

Student Name 1:_Thomas Crettenden / Student ID Number: ______________ 

Student Name 2:  Jayden Virgo      / Student ID Number: 23346641

Student Name 3: Lachlan Charman / Student ID Number: 2339964      

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1. Major Question

Movement background/rationale:

The AFL set shot is one of the most vital aspects of the game. If a free kick is secured within an appropriate distance of the attacking team’s goal, players will often decide to utilise a sixty second window with the intention of scoring from this free kick, these shots account for more than half of all goals scored in the AFL (Anderson et al., 2018). Capitalising on set shot opportunities are a major part of winning an AFL game. Refer to the graph below for more details:

 

 

Figure 1: Depiction of set shot accuracy in contrast with premiership points. The figure of positive correlation on this graph is 0.2189

Figure 1 displays a positive linear correlation between percentage of scores from set shots and premiership points, the measurement of how many games a team has won in a season (Smith, 2025). The numerical value of correlation attached to this graph is 0.2189, implying a moderate positive correlation. Therefore, using the graphed data, we can infer that set shot accuracy is a moderate determinant of whether or not an AFL team wins a game.

Players may employ a curvilinear run up when faced on the absolute brink of their kicking distance. This curvilinear run up is not without reason, and biomechanical evidence suggests it may produce a longer kick. Evidence displays that a curvilinear run up allows for a greater summation of sequential forces between the trunk, hips, legs and foot (Mallo, Dellal, 2020). Given the relationship between force and acceleration, a player who is able to produce a greater summation of forces during their run up will accelerate faster. This phenomenon is displayed in the equation below:                                                              

A greater summation of forces increasing acceleration will ultimately have an impact on an athlete’s velocity, implying that the athlete will reach a higher velocity at the end of a curvilinear run up than a straight run up. See this displayed in the equation below:                                                                 

Finally, the impact on the kick’s velocity, and therefore displacement, can be observed by solving for momentum, and the transfer of momentum from the player to the ball. At the ball contact, the mass of the player and the ball are constant, and therefore the amount of momentum the ball carries when kicked is determined by the velocity of the player when kicking the ball. This is observable in a momentum equation:                                                                  

Using the momentum transfer to the ball, as well as the relationship between velocity and displacement, a hypothesis can be formed regarding the relationship between these variables.

Hypothesis: 

If an AFL player utilises a curvilinear run up approach to a set shot, the horizontal and vertical displacement will increase. This is because the player will display a greater summation of forces, causing increased acceleration and therefore a greater value of momentum transferred to the ball.

Variables:

Independent variable:

- Type of approach (Straight, curvilinear)

- Radius of curvature

Dependent Variable:

Horizontal displacement – total horizontal vector of displacement from initial point of contact to first point of ground contact

Vertical displacement – Peak vector of vertical displacement following initial contact

Controlled variables:

- Football used

- Dominant kicking leg

- Controlled surface

- Controlled approach distance

- Controlled kicking target (goals)

- Individual participant

Equipment

- Match standard Australian rules Football

- Cones to define approach path

- Ipads with Kinovea tracking system

- High speed video camera

- Trundle wheel

2. Biomechanical Analysis/Answer

Method: 

1. Mark a fixed kicking point roughly 40-50m from the goal

2. Set three different approach paths:

- One with zero deviation from the mark

- One with a 2m radius of curvature from the mark

- One with a 4m radius of curvature from the mark

3. Players are to complete ten kicks from each point, randomised in order as to avoid fatigue or skill repetition interacting with data

4. For each kick, utilise a trundle wheel to measure horizontal displacement at first point of ground contact. 

5. Use Kinovea tracking system to determine the peak vertical displacement of the ball

For the sake of consistency, it is worth noting there will be no manned mark, as a curvilinear approach would allow for a point of first contact closer to the goal than a straight approach should there be a manned mark. 

According to the hypothesis, a curvilinear run up will increase angular velocity and momentum of the hip and trunk rotation. This will improve the efficiency of the kinetic chain, thus increasing ball velocity and finally, greater displacement. Altered body positioning at contact will influence the launch angle, the angle of parabolic motion, and consequently the vertical displacement. 

Limitations:

Individual skill level will provide an uncontrolled variable that questions the validity of comparing data. Furthermore, environmental variability may also impact the results, as wind and rain will be uncontrollable variables during the enactment of the method. While the learning effect will be negated by randomization, it cannot be entirely controlled, and thus individuals may see a positive trend of displacement between their first kick and their final kick. Finally, Individuals may find difficulty in controlling the consistency of their radius of curvature and may see variations in this regard. 

Potential improvements:

An increased sample size of elite level footballers would minimise the impact of skill deficiency on the testing and make data more comparable on a larger scale than just within the individual. Run ups could be standardised with marked painted lanes instead of cones, to ensure no deviations between approaches. Finally, speed gates or wearable motion sensors could determine individual variances in velocity or acceleration, opening the discussion of this variable’s implications on results

3. Practical findings

Results

Results recorded were horizontal displacement, initial velocity and angle of the kicker considering the ground as perpendicular. The angle of the kicker was only recorded on one kick per sample due to lack of resources. The mean data points of each participant are observable below:

Figure 2: Results table displaying the mean data points of three participants

Observing the data in figure two, the independent variable changed each test is the radius of curvature. Following this, typical behaviour displayed by the kicker is to decrease the angle of their leg in relation to the ground, rotating their body to lean on a sharper kicking angle to retain kicking accuracy. Resultantly, increases in horizontal displacement and initial velocity are typically observed on each kick. Outliers within this trend may have been influenced by a multitude of factors to be discussed further. 

Utilising the horizontal displacement and radius of curvature, a visual representation of the relationship between this data has been constructed in the figure below:

Figure 3: A column graph representing the relationship between the mean horizontal displacement of each participant in relative to the radius of curvature

As is observable in figure 3, each participant demonstrated a positive correlation between increase in radius of curvature and mean horizontal displacement of their kick. Relating these results back to the initial hypothesis, the positive linear relationship between horizontal displacement and radius of curvature suggests the hypothesis is correct.

To calculate vertical displacement from these values, we must first find the launch angle of the ball. It is worth noting that these calculations have been done without factoring air resistance, something to observe in the following discussion. This process begins by utilising the range equation, rearranged to find the launch angle, where R refers to range, and u refers to initial velocity.

This equation will produce two different angles, each the opposing integer resulting in a sum of 90. The more plausible angle for the kick has been chosen for each point of data. From here, each kick’s vertical velocity can be found using this formula

Finally, to find the peak horizontal displacement, all relevant data can be run through this formula, where s refers to vertical displacement.

Following the initial summary, the following means can be produced for each player. These values are in degrees in reference to the ground.

Figure 4: Table of data displaying the mean launch angle of each participant’s kicks between each radius of curvature

Two external variables that have not been accounted for is the air resistance on the ball, and the vertical height difference between the first point of contact with the foot, and the point of contact with the ground. Finally, the below tables have been constructed using the mean values of each participant to examine horizontal displacement, and all relating factors

Figure 5: Table demonstrating the data obtained from the operations above

Following this, a graph was constructed showing the correlation between the radius of curvature and vertical displacement.

Figure 6: A chart examining the relationship between vertical displacement and the radius of curvature

Examining the data sets above in relation to the hypothesis, no conclusion can be made regarding the relationship between the radius of curvature and horizontal displacement. Examining the dataset from participant 1, with an increase in the radius of curvature, the angle to the ground is decreased, as well as the launch angle of the kick. Subsequently, the initial velocity of the kick increases drastically with a curved approach. The parabolic profile of a kick with a 5m radius-curved approach is much flatter, and faster than its counterpart. This relationship is not present within the other two profiles, with participant two showing the inverse profile of this and participant 3 showing no trend. 

To summarise, three participants were made to take three kicks with varying degrees of curvature dependent on the radius. The results suggest that there is a direct correlation between an individual’s curved approach and horizontal displacement of their kick. The initial velocity of the ball also consequently increased as a result of implementing a curved run up. No relationship can be observed between curvature of an approach and the vertical displacement of a kick however, and discovering a relationship would require further testing, greater resources, and idealistic conditions. 

4. How else can we use this information? 

Impacts - Environmental

Environmental constraints which can include wind, rain, crowd noise and the location where the data was collected (Anderson et al., 2018), were not the primary focus of this exercise, however it is important to include the conditions as they provide some context for interpreting the results. On the day of data collection, the weather was still with minimal wind assistance, this meant the ball flight was not noticeably altered by external forces. This allows the observed changes in horizontal displacement and ball velocity to be attributed more confidently to the curvilinear run up technique rather than environmental interference. 

It was not raining on the day of the data collection, but the ground was damp and soft underfoot, which introduces a subtle biomechanical consideration. A softer and slightly wet surface can influence plant‑leg stability, traction during the approach, and the athlete’s ability to generate force efficiently. In wet conditions, a heavier and more difficult to grip ball typically requires greater force to achieve the same distance as in dry conditions (Orchard, 2001), reinforcing the importance of stable footing and effective force transfer during the run up. From a practical standpoint, these conditions reflect authentic AFL environments, where players will frequently perform set shots on a damp playing surface. 

The fact that the curved approach still produced performance advantages under these conditions, strengthens the real-world relevance of the findings and highlights the technique's potential usefulness in match play.

Impacts - Performance

The performance impacts of this investigation demonstrate how a curvilinear run up can directly influence the outcome of an AFL set shot. The finding that stood out the most was the consistent increase in horizontal displacement as the radius of the curvature increased. From a performance perspective, this means players are able to generate more distance on the kick therefore extending their effective scoring range. This occurs because the curved run up enhances the combination of forces through the players trunk, hips and kicking leg, increasing in the approach velocity, therefore the momentum transfers to the ball on impact. When the player is near the limit of their kicking range, the extra force can mean the difference between the ball falling short or, going the distance required to score.

A secondary impact was the increase in the initial ball velocity observed in the participants. The faster ball flight is of more benefit in actual match play because it reduces the influence of defensive pressure, wind and air resistance (Ball, 2008).  A ball that travels faster and more direct is harder to smother, less affected by the environment and more likely to maintain its intended trajectory. This suggests that a curved run up may not only increase the distance but also improve the consistency and reliability of long-range set shots.

The data did not show a consistent relationship between curvature and vertical displacement, highlighting that players can adopt a curved approach without compromising the height or the trajectory of the ball. This is important for performance as it means players can strive for greater distance and velocity without having to sacrifice the ball's parabolic flight profile.

The variation between the participants shows the performance benefits of a curved run up is specific to the individual. Some athletes may experience noticeable gains in distance and velocity, whilst others may see a lesser improvement which is dependent on their co-ordination, strength and natural kicking mechanics. This reinforces the importance of tailoring the run up strategy to the athlete and not applying a one size fits all approach.

Impacts - Coaching, Training and Performance

Practical coaching strategies that can be implemented based on the data and analysis include; 

1. Set shot - 10 shot challenge

• Each player takes 2-4 shots at each spot, changing the angle and distance at each spot
• Complete the drill in pairs to challenge your teammate
• Practice for 15-30 minutes each time
• If possible, video to analyse trunk rotation, approach velocity and leg to ground angle

(GN Sports, 2026)

The set shot challenge uses the data showing how a curvilinear run up improves force integration, approach velocity and momentum transfer. By taking repeated shots from varying angles and distances, players practice stabilising their run up, curvature, refining trunk rotation and maintaining their leg to ground angle. These are the exact variables that increased the horizontal displacement and ball velocity in the analysis. By completing the drill in pairs adds game like pressure, whilst the optional video feedback can help identify inefficient or risky movement patterns by reinforcing the mechanics that produced longer, faster kicks in the data and reduces injury by promoting controlled trunk rotation, stable plant-leg loading and safer movement patterns.

    2.    Maintaining a consistent radius of curvature - keeping the ball in the channel

• Making sure you know your number of steps and routine, be aware of your starting foot
• Correct ball position in your hand
• Aim at the far goal post

(Ryan, 2011)

Maintaining a consistent radius of curvature is supported by the data showing players produced greater horizontal displacement and ball velocity when their curved approach remained stable. Keeping the ball in the channel, knowing the number of steps in the routine and starting on the correct foot all reduce unnecessary variability in the approach. Correct ball positioning and aiming at the far goal post also supports cleaner contact and more efficient alignment through impact. Combined, these adjustments lift the performance by establishing a repeatable, well-timed approach, whilst reducing injury risk through minimising sudden changes in trunk rotation or plant-leg loading than can occur with an inconsistent run up.

Other Applications

The findings from this analysis justify the use of these drills and cross‑sport comparisons further demonstrating their relevance through shared movement strategies across accuracy‑based sports. Similar techniques apply in basketball free throw, penalty kicks in soccer, place kicking in rugby and American NFL field goal kicking. Athletes rely on stable, repeatable approach patterns, controlled trunk rotation and consistency in the application, reducing variability and enhancing accuracy. Similar to AFL, these sports use repeated practice drills from varied angles and distances during competitive or paired drills to recreate game like scenarios.

Technique evaluation is fundamentally based on mechanical principals, multi-segmented interactions and musculoskeletal characteristics (Lees, 2002).  Applying these principals, the importance of maintaining a consistent run up, regulated step count, stabilising the curvature and ensuring the correct ball positioning aligns with the performance principals observed across these sports, where structured routines and controlled variability contribute to more efficient mechanics, improved accuracy and better decision making under pressure.

References 

Anderson, D., Breed, R., Spittle, M., & Larkin, P. (2018). Factors Affecting Set Shot Goal-kicking Performance in the Australian Football League. Perceptual and Motor Skills, 125(4), 817–833. https://doi.org/10.1177/0031512518781265

Ball, K. (2008). Biomechanical considerations of distance kicking in Australian Rules football. Sports Biomechanics, 7(1), 10–23. https://doi.org/10.1080/14763140701683015 

GN Sports. (2026). Precision drills for coaches. Sherrin.com.au; GN Sports. https://www.sherrin.com.au/precision/drills-for-coaches?srsltid=AfmBOoowD0A7tCjSG89MvIntLdS6xXa5KYtXRYnG9BYoEP-zxxAeh6Ti 

Lees, A. (2002). Technique analysis in sports: a critical review. Journal of Sports Sciences, 20(10), 813–828.

Mallo, J., & Dellal, A. (2020). Influence of contextual variables in changes of direction and centripetal force generated during elite soccer. International Journal of Environmental Research and Public Health, 17(3), 967. https://doi.org/10.3390/ijerph17030967

Orchard, J. W. (2001). Intrinsic and Extrinsic Risk Factors for Muscle Strains in Australian Football. The American Journal of Sports Medicine, 29(3), 300–303. https://doi.org/10.1177/03635465010290030801

Ryan, P. (2011, May 2). The kicking revolution. www.afl.com.au; Australian Football League. https://www.afl.com.au/news/88600/the-kicking-revolution 

Smith, M. (2025, June). Wayward Dees, precise Cats: Every club’s goalkicking accuracy in the AFL in 2025. Australian Football League. https://www.afl.com.au/news/1345689/wayward-dees-precise-cats-every-clubs-goalkicking-accuracy-in-the-afl-in-2025