I LIST OF TABLES AND FIGURES
List of Tables
List of Figures
1.2 Literature Review
1.3 Aims and Objectives
2.1 Study Design
2.2 Data Collection
2.2.1 Injury Classification
2.3 Data Analysis and Presentation
2.5 Ethical Implications
3.1 Injury Summary Data
3.1.1 Injury Causation
3.1.2 Contact versus Non-contact Injuries
3.1.3 Injury Nature
3.1.3 Injury Location
3.1.4 Injury Severity
3.2 Injury Data Sub-analysis for different Session Types
3.2.1 Injury Causation
3.2.2 Contact versus Non-contact Injuries
3.2.3 Injury Nature
3.2.4 Injury Location
3.2.5 Injury Severity
3.2.6 Transient versus Time-loss Injuries
3.3 Injury Data for Main Playing Positions
3.3.2 Contact versus Non-contact Injuries
3.3.3 Injury Nature
3.3.4 Injury Location
3.3.5 Injury Severity
3.3.6 Transient versus Time-loss Injuries
4. DISCUSSION AND CONCLUSIONS
4.1 Summary of Main Findings
4.2 Study Limitations
4.2.1 Sample Size
4.2.2 Injury Reporting
4.2.3 Methodological Assumptions
4.2.4 Confounding Factors
4.3 Comparison to Previous Research
4.3.1 Injury Recording
4.3.2 Training Injuries
4.3.3 Match Injuries
4.3.4 Injury Severity Scoring
4.4 Conclusions and Recommendations
6.1 Participant Information Sheet
6.2 Participant Consent Form
6.3 Injury Report Form
Research into the incidence of injury in rugby league is very limited with a wide variation in injury rates for the same game even over comparable time periods. This may be explained by differences in the methodology of these studies and the fact that virtually all UK rugby league injury surveillance stud- ies have been conducted pre-2000, whereas studies from the southern hemi- sphere mostly tend to date from post-2000.
During the 2009 season, data was collected on all injuries incurred during competitive games and rugby training sessions, for a first team squad of a British Championship rugby league club. Data analysis was limited to injury incidence rates and relative sub-category frequencies for (1) injury causation and acuity, (2) contact versus non-contact, (3) nature, (4) location and (5) se- verity with (6) transient versus time-loss as well as the influence that rugby session type and main playing position may have on these.
The calculated incidence rate for match injuries was 170.7/1000 player expo- sure hours with a training injury incidence of 9.4/1000 player hours. Tackling action generated the most common match injuries (71.8%), whereas overuse was the single most common cause of training injuries (40.7%) (p< 0.0001). Lower limb injuries seemed to be the most common (60-70%), followed by injuries to the upper limb (~15%) and head & neck region (8-10%). Time-loss injuries were overall four times more common than transient injuries. Finally, the findings showed forwards were more susceptible to injury than backs, during matches (203.1 vs. 142.9 per 1000 hours) and rugby training (16.4 vs.
3.8 per 1000 hours) (p=0.0431).
This study was the first to trial rugby league injury data collection according to recently published IRB standards and revealed higher than usual overall and overuse training injury rates, a larger proportion of time-loss and contact injuries as well as different relative distribution of injury severities when com- pared to the existing literature. This may represent new injury trends in rugby league, which need to be further examined. Therefore a multi-team, multi season rugby league injury surveillance study should be performed, ideally at Super League and Championship level.
LIST OF TABLES AND FIGURES
List of Tables
TABLE 1: INJURY SEVERITY CLASSIFICATION ACCORDING TO THE IRB CONSENSUS STATEMENT ON STANDARDISATION OF INJURY SURVEILLANCE DATA RECORDING
TABLE 2: INJURY INCIDENCE BREAKDOWN FOR TRANSIENT, TIME-LOSS AND ALL-ENCOMPASSING INJURIES SUSTAINED DURING TRAINING, MATCH-PLAY AND OVERALL
TABLE 3: RELATIVE FREQUENCIES FOR DIFFERENT CAUSATIONS OF INJURIES SUSTAINED DURING MATCH PLAY AND RUGBY TRAINING
TABLE 4: RELATIVE FREQUENCIES FOR CONTACT VERSUS NON-CONTACT INJURIES SUSTAINED DURING MATCH PLAY AND RUGBY TRAINING
TABLE 5: RELATIVE FREQUENCIES FOR DIFFERENT TYPES OF INJURIES SUSTAINED DURING MATCH PLAY AND RUGBY TRAINING
TABLE 6: RELATIVE FREQUENCIES FOR DIFFERENT LOCATIONS OF INJURIES SUSTAINED DURING MATCH PLAY AND RUGBY TRAINING
TABLE 7: RELATIVE FREQUENCIES FOR DIFFERENT SEVERITIES OF INJURIES SUSTAINED DURING MATCH PLAY AND RUGBY TRAINING
TABLE 8: RELATIVE FREQUENCIES FOR TRANSIENT VERSUS TIME-LOSS INJURIES SUSTAINED DURING MATCH PLAY AND RUGBY TRAINING
TABLE 9: RELATIVE FREQUENCIES OF MATCH AND TRAINING INJURY RATES FOR FORWARDS AND BACKS
TABLE 10: RELATIVE FREQUENCIES FOR DIFFERENT INJURY CAUSATIONS IN FORWARDS AND BACKS
TABLE 11: RELATIVE FREQUENCIES FOR CONTACT VERSUS NON-CONTACT INJURIES IN FORWARDS AND BACKS
TABLE 12: RELATIVE FREQUENCIES FOR DIFFERENT INJURY TYPES IN FORWARDS AND BACKS
TABLE 13: RELATIVE FREQUENCIES FOR DIFFERENT INJURY LOCATIONS IN FORWARDS AND BACKS
TABLE 14: RELATIVE FREQUENCIES FOR DIFFERENT INJURY SEVERITIES IN FORWARDS AND BACKS
TABLE 15: RELATIVE FREQUENCIES FOR TRANSIENT VERSUS TIME-LOSS INJURIES IN FORWARDS AND BACKS
TABLE 16: LITERATURE REVIEW OF BASIC INJURY SURVEILLANCE DATA FOR RUGBY LEAGUE
TABLE 17: TIME-LOSS INJURY RATES FOR RUGBY LEAGUE AND UNION
List of Figures
FIGURE 1: DATA ANALYSIS FLOW CHART
FIGURE 2: RELATIVE FREQUENCIES FOR DIFFERENT INJURY CAUSATIONS
FIGURE 3: RELATIVE FREQUENCIES FOR DIFFERENT NATURES OF INJURY
FIGURE 4: RELATIVE FREQUENCIES FOR DIFFERENT INJURY LOCATIONS ACCORDING TO MAIN BODY REGION
FIGURE 5: RELATIVE FREQUENCIES FOR DIFFERENT INJURY SEVERITIES ACCORDING TO IRB CONSENSUS STANDARDS
I would like to thank the physiotherapy staff at Gateshead Thunder RLFC, Seamus McCallion and Stephen Barwick, for contributing to the injury data collection and recording as well as for their expertise in arriving at final con- sensus injury diagnoses.
The coaching and strength and conditioning staff, Steven McCormack, Chris Hood and Alan Dickinson, have been very helpful in providing weekly training and rehabilitation schedules and in reporting estimated player attendances during rugby training sessions.
The players of Gateshead Thunder RLFC have significantly contributed to this MSc research project by giving generously of their time and by reporting any injuries, no matter how minor, to the medical staff.
I am most grateful to my research project supervisor, Dr Colin Sanctuary, for his input into the study methodology and his intellectual coaching throughout the research project design.
My secretary, Emma Jameson, has been invaluable in proof-reading the manuscript and in helping to draft its final layout.
Finally, I would like to thank my wife for her loving support and understanding during the many long hours in evenings and on weekends that I have in- vested on the rugby pitch, at the rugby club or in my office in order to compile this MSc research project and dissertation.
1 .1 Background
Rugby league football is a full-contact form of football, played with a sphe- roid ball by two teams of thirteen players on a rectangular grass field (Gaul- ton 1974). Rugby league is one of the two codes of rugby football, the other being rugby union (Collins 1998). Over the decades following the 1895 incep- tion of rugby league, the rules of both forms of rugby were gradually changed, with rugby league's deliberately resulting in a faster, more open spectator sport (Crego 2003).
Subsequently, league and rugby union are distinctly different games. Rugby league is frequently cited as the toughest and most physically demanding of any team sport in the world (Larder 1989; Meares 2003). It requires a combi- nation of muscular strength, stamina, endurance, speed, acceleration, agility, flexibility, and aerobic endurance (Meir 1993a-b; Gibbs 1993). During an 80- minute game, the ball is in play for an average of 50 minutes (Larder 1989) with individual players covering 7,000m to 10,000m (Meir 2000) and being involved in 20 to 40 tackles per game (Larder 1989). Consequently, injuries are common (Gibbs 1993).
By nature, rugby league players do not use heavy protective guarding as do other body contact sports. It has been suggested that the wearing of protec- tive equipment and clothing may have an adverse effects on players’ heat exchange mechanisms (Meir 1994, Savdie 1991; Hodgson Phillips 2001) and may produce heat-induced injuries.
Rugby league is most prominent in Australia, England, New Zealand and Papua New Guinea, being the national sport in the latter. France and Wales also have professional clubs. The New Zealand “Kiwis” are the current World Cup champions as of 2008. Further, the game is played at a semi-Tonga, Fiji, Ireland, Scotland, Russia, Lebanon, Germany, Japan, the United States, Malta and Jamaica (RLIF 2009).
1 .2 Literature Review
Research into the incidence of injury in rugby league is very limited. Lower et al. (1995) reviewed injury data collection in the rugby codes using 49 refer- ences but only 3 specific to the sport of rugby league. A recent review exam- ining pooled data analysis of injury incidence in rugby league football identi- fied only 18 studies from the period 1985 to 2000. Of these articles, 10 spe- cifically mentioned incidence and exposure, and of these only 4 re-reported the same source data. Therefore, only 6 papers reported new injury inci- dence (Gissane 2002). One of the first published studies on rugby league in- juries was in Australia by Alexander et al. (1979) reporting an incidence of 277.8/1000 hours. This study continued into 1980 reporting the incidence over 2 seasons as 224.7/1000 hours (Alexander 1980). Gibbs (1993) re- ported a prospective incidence of 44.9/1000 hours in Australia and found this to be low compared with other rugby league studies. Gissane et al. (1993) conducted a study similar to that of Gibbs in England reporting an incidence of 173.9/1000 hours.
From the literature it can be seen that there is wide variation in injury rates for the same game even over comparable time periods. This may be explained by differences in the methodology of these studies. Alexander et al. (1979,
1980) recorded every injury, however minor. Gibbs (1993) recorded only inju- ries which resulted in at least one subsequent match being missed, whereas Gissane et al. (1993) recorded all injuries which resulted in a game or train- ing session to be missed.
Another reason for this heterogeneity in reported injury rates may be that vir- tually all UK rugby league injury surveillance studies have been conducted pre-2000 (Stephenson 1996; Gissane 1993, 1998; Hodgson Phillips 1998; Hodgson 2006), whereas studies from the southern hemisphere mostly tend to date from post-2000 (Gabbett 2000, 2003, 2005b; King 2008, 2009). This also holds true for any attempt at comparing rugby league and union injury data with major methodologically sound union studies having only been pub- lished very recently (Brooks 2005b-c, 2008a-b; Fuller 2007d, 2008; Take- mura 2007).
All of these rugby union studies have counted only time-loss injuries, i.e. when a player had missed a training session or match due to a previously sustained injury. These studies reported mean injury rates ranging from 52/1000 player hours to 91/1000 player hours which appear much higher than the results reported by Gibbs (1993) who also only reported time-loss injuries. This finding is corroborated by Bathgate et al. (2002) who found a rise in injury rates between 1994 and 2000 for rugby union which they have attributed to an increasing level of player professionalism. This has also been attributed to increasing player sizes and higher intensity of the game due to strategic player substitutions and directed double-tackles (Westerby 2009). The effect of professionalism on injury rates has also been extensively exam- ined for rugby league football by others (Gabbett 2004b; Baker 2001, 2002; Meir 2001), who all demonstrated rising injury rates for increasing levels of professionalism.
Finally, the transition of rugby league from a winter to a summer sport has seen increasing injury rates but with a relative reduction in severe injuries (Hodgson Phillips 1998). This study compared data from 4 consecutive sea- sons: two winter and two summer seasons. The incidence rate reported for the first winter season was nearly half that reported for the first summer sea- son which equated to a player in the winter receiving an injury every 2.1 ap- pearances to every 1.1 appearances in the summer.
The above study showed the highest incidence of injury ever reported in Eng- lish rugby league (462.7/1000 hrs) which remained true when considering game injuries alone (44.1/1000 hrs) and excluding all transient injuries. This was corroborated by Hodgson et al. (2006), who looked at three further summer seasons worth of rugby league football, in one Super League team from 1997 to 1999. They reported somewhat more stable time-loss injury rates ranging from 182/1000 hours to 239/1000 hours.
Due to the previously described heterogeneity of injury surveillance data, not just for rugby league and rugby union but also other football codes efforts were made to standardise injury reporting in order to allow comparability within codes across all contact sports. After Orchard et al. (2005) attempted the first ever standardisation of injury reporting for cricket, Fuller et al. (2006) published a landmark consensus paper on injury definitions and data collec- tion for future football (soccer) injury studies. This was soon followed by an- other consensus paper on recording of rugby union injuries commissioned by the International Rugby Board (IRB) (Fuller 2007a). Today, no such attempt has been made for the standardisation of injury reporting and data recording in rugby league football, although it does seem sensible to use the IRB re- cording standards.
However, as far as injury reporting is concerned the jury appears to be ‘still out’. Orchard et al. (2007) proposed that from a coach’s view only true “time- loss” injuries matter as they affect squad size and player availability for train- ing and match play. This contrasts with the view of Hodgson et al. (2007) who felt that any injuries leading to a subsequent contact with club medical staff should be reported, in order to allow for appropriate workforce planning for backroom staff. This “clash” of opinions becomes relevant when looking at data published by Gabbett et al. (2000, 2003, 2004b, 2005b) which suggest much higher injury rates amongst Australian Rugby League players due to the inclusion of transient injuries when compared to studies from UK authors, (Stephenson 1996; Gissane 1998; Phillips 1998; Hodgson 2006), who have traditionally incorporated time-loss injuries only.
1 .3 Aims and Objectives
The heterogeneity of the previously described injury surveillance data with regard to reported injury rates and the lack of recent UK rugby league data make it imperative that an up-to-date survey is conducted into the injury rates and severities for professional UK rugby league football. This is in particularly useful, as for UK rugby league, only Super League, i.e. elite professional in- jury surveillance data is available (Gibbs 1993; Gissane 1993; Hodgson- Phillips 1998, Phillips 2006). Whilst there is an abundance of amateur and sub-elite injury rates for the southern hemisphere (Gabbett 2000, 2003, 2005a), no UK-based studies have reported on Championship injury data. Likewise, it is desirable that the data gathered from this research is collected according to an internationally accepted standard. This leads on to the cen- tral research question posed by this MSc dissertation:
“Within sub-elite professional rugby league football in the UK what are the current rates, distributions, types and severities of injuries?”
In answering the previous question, this research project will provide an up- to-date benchmark for injury comparison within rugby league, as well as be- tween rugby league and union.
The aim of this research project was to conduct an up-to-date survey of inju- ries sustained during the 2009 competitive season of one Championship rugby league football club in the UK.
The objective was to trial the appropriate collection and statistical analysis of rugby league injury data according to recognised standards published by the International Rugby Board. This was to be followed by an appropriate pres- entation of the results in order to provide a valid benchmark for future injury comparison within rugby league and between differing football codes.
2 .1 Study Design
During the 2009 competitive season, data was collected on all injuries in- curred during competitive games and rugby training sessions, for a first team squad of a British Championship rugby league club. For the purposes of this study a “pragmatic” injury definition of any pain, discomfort, disability or ill- ness (new or recurrent) that a player acknowledged, after participating in a rugby-related activity (training session or game) and for which they had sought medical attention (team physiotherapist or club doctor) was employed (Hodgson 2006). Match injuries were either identified on a game day by the medical staff or were reported by players during the following recovery ses- sion. Injuries sustained during rugby training sessions were identified by the attending physiotherapist. The formal diagnosis was subsequently agreed between the team physiotherapist and team doctor, sometimes after consul- tation with an external orthopaedic specialist.
2 .2 Data Collection
Injuries were recorded on a standardised injury report form (appendix 3). In- formation collected included (1) injury date, timing, ground condition, ambient temperature, (2) date of return to full rugby-related activities, (3) playing posi- tion at time of injury, (4) injured body part/region, (5) side of injury, (6) nature of injury, (7) final diagnosis text, (8) whether the injury was a recurrence, (9) acuity of the injury, (10) session type during which the injury was sustained, and finally, (11) activity that caused the injury. All known injuries were re- corded in this way, irrespective of whether or not a player missed a subse- quent training session or competitive game. This allowed the subsequent analysis for time-loss versus transient (non-time-loss) injuries as previously suggested by Hodgson et al. (2006) and Fuller et al. (2007).
2 .2.1 Injury Classification
The causation of all recorded injuries were subdivided into contact activities, i.e. tackle, collision and scrum action versus non-contact activities such as sprinting or running and kicking, and they were either categorised as acute or due to overuse. The location of any sustained injury was mapped according to five major body regions including the head and neck, torso (trunk), upper limb, lower limb as well as the spine. The following main headings were used to describe the nature of an injury: (a) bone, (b) joint and ligament, (c) muscle and tendon, (d) skin and (e) brain as well as central and peripheral nervous system. Finally, the IRB-endorsed injury severity classification (Fuller 2007), was fully adopted, which included the following categories (Table 1):
illustration not visible in this excerpt
Table 1: Injury severity classification according to the IRB consensus statement on standardi- sation of injury surveillance data recording.
In addition to this, injuries were further classified as transient (<1 day) and time-loss injuries (≥1 day) in order to comply with the suggestions of Hodg- son et al. (2007) for recording all-encompassing injury rates. For the pur- poses of this study though, an injured player seeking medical attention and who therefore could not attend the full duration of a subsequent training ses- sion was considered to have sustained a time-loss injury of at least one day as they had by definition of the IRB not returned to full participation (Fuller 2007).
2 .3 Data Analysis and Presentation
In order to achieve the objectives of this research project and to avoid over- interpreting the limited data sample, data analysis was limited to injury inci- dence rates and relative sub-category frequencies for; (a) injury causation and acuity, (2) contact versus non-contact, (3) nature, (4) location and (5) se- verity with (6) transient versus time-loss (dependent variables) as well as the influence that rugby session type and main playing position (independent variables) may have on these (Figure 1).
illustration not visible in this excerpt
Figure 1: Data analysis flow chart.
Injury incidence rates were calculated through dividing the total number of injuries sustained by the total of recorded player exposure hours and subse- quent multiplication by the factor 1000. This yielded a standardised injury rate described as injuries per 1000 player exposure hours in accordance with recommendations by Orchard et al. (2005), Hodgson et al. (2006) and Fuller et al. (2006, 2007).
Match player exposure hours were calculated on the basis of each game be- ing played by 13 players and lasting 80 minutes. The seasonal number of hours was subsequently calculated using the formula:
M a tch exposure (hrs) = [total number of games] x [13 players x 80/60 hrs].
The calculation of training exposure, however, relied on the assumption, that on average 18 of the first team players attended each rugby training session, and that there were on average 5 rugby training sessions per week (Hodgson 2006) with a mean duration of 90 minutes (1.5 hours) each, arriving at the formula:
Training exposure (hrs) = [total number of sessions] x [18 players x 1.5 hrs].
This type of calculation allowed for the fact that about one-third of the first team squad were on semi-professional contracts.
In order to allow further subgroup analysis of injury classifications and inci- dence rates according to main playing positions, players were categorised as either forwards (prop forward, hooker, second row and loose forward) and backs (scrum half, stand-off, winger, centre and full-back). With regard to calculation of match exposure hours this meant that 6 forwards and 7 backs were playing each game, whilst for training exposure it was assumed that an average of 8 forwards and 10 backs attended each rugby session.
Injury incidence rates were presented as injuries per 1000 player exposure hours overall and sub-analysed for either main playing position or session type, but not for both. This would have been outwitting the power of the rela- tively small study sample. Median time-loss for the above groups was calcu- lated and expressed in days including ranges and interquartile ranges.
For each of the injury classification categories: (1) causation and acuity, (2) contact versus non-contact, (3) nature, (4) location and (5) severity with (6) transient versus time-loss, the number of injuries were expressed as totals and relative frequencies for each sub-type in absolute numbers and percent-ages or ratios. These were presented as (a) overall figures and, once again, sub-analysed for either (b) rugby session type or (c) main playing position.