Original research
The incidence, prevalence, severity, mechanism and body region of injury in elite junior Australian football players: A prospective cohort study over one season

https://doi.org/10.1016/j.jsams.2018.03.002Get rights and content

Abstract

Objectives

To describe the incidence, prevalence, severity, mechanism and body region of injuries in elite junior Australian football (AF) players over one competitive season in order to help inform injury prevention interventions.

Design

Prospective cohort, data collected during the 2014 playing season.

Methods

Player and staff-reported injuries sustained by 562 players from an under-18 state league were entered into an online sports injury surveillance system. An injury was recorded if it led to a missed training session or match. Injury incidence was calculated as the number of injuries per 1000 h of training and competition. Injury severity was defined by the number of days players missed training or competition. Injury mechanism was identified as either contact, non-contact or overuse.

Results

There were 1192 football-related injuries sustained during the season; the majority (n = 1041, 87.3%) were new, occurred during competition (n = 954, 86%) and led to 4–7 missed days in severity (n = 429, 46%). Injury incidence was 37.2 injuries per 1000 h of exposure. Over half of injuries were contact in mechanism (n = 355, 51%). Most injuries were to the lower limb (n = 720, 60%), with the thigh representing the highest proportion of these.

Conclusions

This study provides key information as to the aetiology of injury in this level of competition and provides a stronger foundation from which injury prevention studies could be carried out. Future research is well-placed to develop an understanding of the injury risk factors in the elite junior cohort, whilst also reducing injury risk once players transition to the AFL.

Introduction

In order to transition successfully to the Australian Football League (AFL), elite junior Australian football (AF) players need to develop certain physiological characteristics including high jumping ability, running endurance, acceleration and speed1 and desirable anthropometric characteristics, including optimal power to body weight ratios.2 Further, players need to be able to win contested possessions and frequently and accurately deliver the ball inside the attacking 50 m zone.3 Optimal training loads in the absence of injury are required to develop these characteristics and help bridge the gap between elite junior and elite senior (AFL) competitions.4 Appropriate loading strategies are needed to both develop suitable physical characteristics for performance and to protect against the risk of injury.5, 6, 7 For example, aerobic-running fitness and overall greater body mass are factors that are likely to have a protective effect against injury incidence and severity in AFL players6 as well as elite junior AF players.8

Talent-identified junior AF players are selected into an elite under-16 development program (state academy), from which they then progress to the elite under-18 level.9 These talent academies were initially established to focus on skill progression and the development of key physical traits,10 in order to facilitate a pathway to becoming an elite senior (AFL) player. Despite these formalised development structures, young aspiring athletes often play across multiple levels of competition, are involved in other sports and carry out their own self-administered strength and conditioning activities.11 These extra commitments can add substantially to the overall load placed on elite junior AF players12; consequently, increasing their risk of negative events such as impaired wellness and injury.13 Further, players sustaining injuries at the junior level have been identified as being six times more likely to sustain subsequent injuries throughout their career, than players who do not sustain injuries at this level.14

The AFL has a standardised injury data collection protocol that has been in place since 1992 in its elite senior players.15 At the elite junior level of AF, there is no comparable standardised injury data collection protocol and only a small number of studies have reported injury epidemiology.2, 14, 16 Across these studies, injury incidence has ranged from 17.1 new injuries per club17 (14.3 per 1000 h) to 24.3 new injuries per club8 (20.2 per 1000 h) and 26.2 injuries per 1000 player hours.18 Appendix A.1 in Supplementary material details the injury incidence across previous elite junior AF studies. In this latter study, match injury incidence (76.6 injuries per 1000 h) was reported as much higher than training injury incidence (3.8 injuries per 1000 h).18 Injury severity was reported as 3.3 matches missed per injury (95% CI 3.1–3.6).17 Body contact (67.3% of all injuries)18 and ‘collision with another player’ (29.3% of all injuries)17 were the predominant mechanisms of injury mechanism, with between 67.7%8 and 72.2%.17 A previous review highlighted inconsistencies with data reporting across these studies, which partly explains the range in incidence, severity, and mechanism information.19

According to the Translating Research into Injury Prevention Practice (TRIPP) framework,20 there are six stage stages that have been outlined as leading to real-world injury prevention gains. At present, injury prevention efforts have focused on stages 1 (injury surveillance) to 4 (scientific of injury prevention methods/‘real world’ evidence). In a 2013 review, Chalmers et al.19 identified five prospective cohort studies on injury surveillance and 12 studies of varying methodological quality that investigate the aetiology and mechanisms of injury and five implementing injury prevention strategies in this level of play. This study highlighted inconsistences with data across the 17 included studies.19 A number of the key recommendations, specifically related to methodological discrepancies and inconsistencies in data in TRIPP stage 1 studies, still apply five years later.

Establishing standardised injury collection protocols at the elite junior AF level can help to identify the characteristics of players at risk of injuries, and help identify injury risk factors such as previous injury, low cardiovascular fitness and hence increased levels of fatigue later in the game as well as poor jumping technique,8, 14, 16 that predispose players to injury. Injury surveillance systems have previously been implemented in some places, e.g. in the South Australian elite junior AF competition,17 and across different junior age groups in Victoria and New South Wales.18 Surveillance systems have also been implemented in community AF21 and, recently, an effort has been made to summarise current data collection, injury definition and reporting practices across professional football codes, including the AFL.22

At present, there remain key discrepancies and inconsistencies in establishing the epidemiology of injuries in elite junior AF players.19 Previous injury surveillance studies in elite junior AF have either used injury definitions that are described as “too broad”18, 23 or “too narrow”.17 The “too broad” definition includes any injury resulting in medical attention, whereas the “too narrow” definition (used by the AFL) only incudes missed matches. Studies using a ‘too-broad’ definition may involve players reporting their injuries. This may lead to a large amount of data, however, may not have the precision or detail of specific staff-reported injury information.18 As injury surveillance is a fundamental component of injury prevention research,20 it is important that these methodological issues are overcome.

Currently there is a major gap in the literature because “too-broad” approach used in most elite junior AF studies does not include minor injuries and so underestimates the number of injuries affecting players at this level, in turn, not providing an accurate picture of the overall injury problem. This may then affect the ability of elite junior aspiring AFL players to develop the physical characteristics identified by other studies3, 9 as required at the more senior level. Previous studies have also not collected clear training exposure data that includes the volumes and intensities – and hence, loads – of training. For these reasons, additional injury surveillance and aetiology (defined as TRIPP stage 1 and 220) research of high power (i.e. large sample size), that captures injury incidence, prevalence, severity, body region and mechanism, is warranted.

The aim of this study was to describe the incidence, prevalence, severity, mechanism and body region of injuries in elite junior Australian football (AF) players over one competitive season in order to help inform injury prevention interventions.

Section snippets

Methods

All 12 clubs participating in the 2014 Transport Accident Commission (TAC) Cup, the elite junior AF competition in Victoria, season were invited to participate in the study and nine did so (75% club response). Before participation, informed written consent was obtained from AFL Victoria, team managers from each club, and the players from each participating club. The study was approved by Monash University’s Human Research Ethics committee and carried out according to the Declaration of Helsinki

Results

Overall, training injury incidence was 7.0 injuries per 1000 h of training exposure. Match injury incidence was 147.2 injuries per 1000 h of match exposure (total match participation time the player reported). The overall injury incidence (both match and training) was 37.2 injuries per 1000 h of exposure. Over the whole season observed, there were 1192 football-related injuries across 449 players (80% of all participating players), at an average of 2.7 injuries per player. Appendix A.2 in

Discussion

This study described the incidence, prevalence, severity, mechanism and body region of injuries in elite junior AF players over one competitive season. It highlighted the high number of injuries that occur in competition compared with training and provided insight into where players sustain their injuries (mostly lower limb), the mechanisms of these injuries (majority due to impact with another player) and the nature of these injuries (inflammation and swelling). This study provides key

Conclusion

The aim of this study was to describe the injury epidemiology across an elite junior AF season. This study provided insight into where players sustain their injuries (mostly lower limb), the mechanisms of these injuries (majority due to impact with another player) and the nature of these injuries (inflammation and swelling). This study also provides a reference point for future injury reporting in this level of competition and provides a foundation from which the aetiology of injuries can be

Practical implications

  • This study has strengthened injury epidemiology research across a large cohort of elite junior AF players providing useful information on injury incidence, prevalence, severity, mechanism and body region.

  • This study further highlights the high incidence of contact injuries, mostly in competition, as a persistent issue in elite junior AF.

  • Lower limb non-contact injuries are also a problem for players and elite junior AF clubs due to their severity.

  • The ‘missed training’ injury definition used in

Acknowledgements

This research did not receive any specific grant from funding agencies in the public, commercial or not-for-profit sectors. The authors acknowledge and thank AFL Victoria and the participating TAC Cup club staff for their contributions in helping to facilitate this research. Tim Lathlean led this work as part of his PhD studies, under the supervision of the co-authors.

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