Author Identifier

Christopher Wing

https://orcid.org/0000-0002-3105-4410

Date of Award

2022

Document Type

Thesis - ECU Access Only

Publisher

Edith Cowan University

Degree Name

Doctor of Philosophy

School

School of Medical and Health Sciences

First Supervisor

Ken Nosaka

Second Supervisor

Nicolas Hart

Third Supervisor

Fadi Ma'ayah

Abstract

Australian Football (AF) matches consist of high and low intensity activities and specific periods of play. Previous research has identified maximum periods of high intensity using a rolling time frame approach. However, the development of a non-uniform analysis method may be more desirable in intermittent type sports. Additionally, there is a paucity of information within the published literature that describes how to use such data to improve training design and subsequent monitoring. Furthermore, the physical and technical characteristics of specific phases of play have been identified in recent research. However, these findings can be developed further by ascertaining the effect of playing position, field location and successful/ unsuccessful play. The impact of factors such as venue and a player’s physical capacity and the constraints these may have upon performance should also be systematically analysed.

The purpose of the present PhD research project, therefore, was to gain a greater understanding of the physical and technical demands of AF in specific phases of play, and how this data can be used to evaluate performance and inform training program design. To achieve this, six studies were included in the project to identify maximum periods of play using the ball in play (BiP) method, whilst additionally contextualising these time periods with key technical actions (e.g., kicks) (Study 1), the physical and technical demands of offence, defence, and contested phases of play, and how these outputs may be affected by playing position, successful and unsuccessful play, field location, environment and players’ physical capacity (Studies 3 and 5). Additionally, the intensity distribution was compared between competitive matches and small-sided games during training (Study 4). Based on this, position specific drills were established and running intensities in the drills were investigated (Study 6).

Study one ascertained the maximum running intensities of ball in play (BiP) periods, and contextualised these with technical (e.g., kicks) actions. The findings demonstrated that maximum BiP period intensity was significantly (p < 0.0001) higher than that derived using whole match data methods for all measured metrics (relative distance high-speed running, very high-speed running, PlayerLoadTM, high-intensity efforts, and acceleration efforts). However, no significant differences were found between playing positions. A technical action (e.g., a kick) was recorded in 21-48% of the maximum BiP periods, depending upon the primary microsensor technology metric assessed, with kicks and handballs constituting > 50% of all actions performed.

Study two uniquely assessed the impact of sudden rule changes due to the COVID-19 pandemic (2020 season) upon match running performance and injuries within AF. The total distance (ES=1.28), high-speed ( > 18 km/h) (ES=0.44) and very high-speed ( > 24 km/h) (ES=0.27) distances, PlayerLoadTM (ES=0.96), high-intensity efforts (ES=0.48), and accelerations (ES=0.33) were smaller (p ≤ 0.01) for the 2020 than the 2019 season. Expressed relative to playing time, distance (ES=-0.38), PlayerLoadTM (ES=-0.27), and acceleration efforts (ES=-0.50) were greater (p < 0.05) for the 2020 than the 2019 season. No significant differences in maximum ball-in-play periods nor the difference between the 1st and 4th quarters were evident. Injury rates remained similar between 2019 (3.36 per game) and 2020 (3.55 per game). However, the proportion of injuries that led to lost time (missed games) was greater for the 2020 (38%) than 2019 season (24%). The changes in the rules had a profound impact on player performance and increased the likelihood of time loss injuries.

Study three compared the physical and technical demands between offence, defence, and contested phases of play within playing positions (backs, forwards, and midfielders). Furthermore, study two ascertained the effect of field location upon offence, defence, and contested play, as well as making comparisons between successful and unsuccessful offence and defence. The results indicated that relative measures of distance, high-speed running, accelerations and decelerations were significantly (p < 0.001) higher in defence versus offence and contested play for backs, and in offence versus defensive and contested play for forwards. Amongst midfielders, only relative measures of distance and high-speed running were significantly (p < 0.001) greater in offence versus defence and contested play, with no significant differences between phases for accelerations and decelerations. Successful offence was underpinned by greater physical and technical demands for midfielders and forwards, whereas the opposite was found for backs. Unsuccessful defence was largely categorised by increases in physical output, whereas tackles and marks were increased in successful defence. Larger field locations (e.g., full ground) recorded the highest distance and high-speed running per minute, however, no pattern was evident for acceleration or deceleration efforts relative to playing time. These findings demonstrate that phase of play (offence, defence, contested), as well as successful and unsuccessful phases have different physical and technical demands, which vary between playing positions and field location.

Study four compared the intensity distribution of BiP periods from competitive matches to the intensity distribution of SSGs in 10% intensity buckets, using maximum BiP periods as a reference point. Although few significant differences were noted between BiP periods from matches and SSGs, several players were unable to record the same percentage of efforts in the higher intensity buckets. Specifically, 25 of 67 players (37%) did not record any SSGs efforts within intensity buckets classified as ≥ 90% for relative distance. Additionally, 33 of 67 (49%) and 28 of 67 (42%) of players recorded no SSGs efforts in buckets classified as ≥ 80% for relative measures of high-speed running and acceleration efforts respectively. Therefore, SSGs are a sub-optimal training stimulus for the purpose of exposing all players in a team to the running intensities recorded in the most intense periods of play.

Study five examined the effect of both match (e.g., venue) and player (e.g., physical capacity, and playing experience) factors on the physical and technical performance of players in successful offence and defence, as well as maximum BiP periods. The main findings regarding match factors were highlighted during successful defence, where playing at home significantly reduced both distance and high-speed running relative to playing time (moderate effect size), as well as significantly increasing the rate of tackles (small effect size). During successful offence, 1-repetition maximum trap bar deadlift relative to body mass significantly increased relative distance (large effect size), and high-speed running (moderate effect size). During successful defence, increased performance (i.e., shorter time to completion) upon the two-kilometre time trial significantly increased relative distance (large effect size), high-speed running (large effect size), and acceleration efforts (moderate effect size). Additionally, increased two-kilometre time trial performance significantly increased relative distance and high-speed running within maximum BiP periods (both large effect size). Playing experience had a significant effect upon the rate of kicks and marks in successful offence, where those with moderate experience performed a greater amount (both moderate effect size). Furthermore, those with lower playing experience performed greater relative distance and high-speed running in maximum BiP periods (both moderate effect size).

Study six established position specific drills and assessed their utility to match or supersede the running intensities recorded during maximum BiP periods from competitive matches, whilst concurrently training the technical (e.g., kicks) actions commonly recorded in AF. Three drills were designed for this purpose, which included offence, defence, and a combination drill (where two players performed the drill at the same time, one as the forward and one as the back). All three training drills recorded significantly greater (p < 0.001) measures of distance, high and very high-speed running, and high-intensity efforts relative to playing time when compared to maximum BiP periods. Only the defence drill recorded significantly (p < 0.001) greater measures of PlayerLoadTM and accelerations relative to playing time than BiP periods. Conversely, accelerations per minute were significantly (p < 0.001) greater in BiP periods than those recorded during both the offence and combination drill. When comparing the drills to each other, all measured metrics were significantly (p < 0.001) greater for the defence drill when compared to the offence drill, whilst distance, high-speed running, PlayerLoadTM, and accelerations were significantly (p < 0.001) greater when compared to the combination drill. These findings demonstrate that a position specific drill may be an attractive addition to AF players training regimes where the aim is match, or supersede, the highest intensity periods derived from competitive matches whilst concurrently training technical aspects of performance.

The findings demonstrate that utilising discrete analysis methods (BiP, offence, defence, contested) can provide greater detail for practitioners concerning the physical and technical characteristics of AF matches. Additionally, these characteristics may be influenced by factors such as playing venue and a player’s levels of physical capacity. The data presented within the studies may be used to optimise representative training (e.g., SSGs) or a position specific drill may be integrated into training in order to expose players to the relevant physical and technical demands. Future research should explore additional features (e.g., change of direction, collisions, time to execute skill) that may enhance the application of position specific drills, as well as exploring if the uptake of such drills improves aspects of both physical (e.g., time trial performance) and match performance (e.g., running intensity, skill execution).

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