Twenty year analysis of professional men's rugby union knee injuries from the English premiership shows high rates and burden.

OBJECTIVES: To determine the rates, severity and burden of knee injuries in professional male rugby union from the English Premiership. METHODS: Injury and exposure data were captured over 20 seasons using a prospective cohort design. Knee injury incidence, days' absence and burden were recorded for each injury type and by pitch surface type for match and training. RESULTS: The rate of knee injury in matches was 9.8/1000 hours (95% CIs 9.3-10.3). Mean days lost were 50 (95% CI 46 to 53) in matches and 51 (95% CI 44 to 57) in training. In matches, medial collateral ligament injuries were the most common, while anterior cruciate ligament (ACL) injuries had the highest mean severity and burden. There was no significant change in the count of knee injuries over time; however, average severity increased significantly (annual change: 2.18 days (95% CI 1.60 to 2.77); p<0.001). The incidence of match knee injury was 44% higher on artificial pitches than grass pitches (incidence rate ratio: 1.44 (95% CI 1.21 to 1.69); p<0.01), with no significant difference in severity between surfaces. In matches, the tackle was the event most commonly associated with knee injuries for all diagnoses, except ACL injuries (running). In training, running was a more common injury event than the tackle. CONCLUSION: Knee injuries in matches are common and severe in English professional men's rugby union. Despite an increased focus on player conditioning and injury prevention throughout the study period, rates of knee injury remained stable, and resulting days' absence increased. New strategies for the prevention of knee injuries should be considered a priority.

Trends in match injury risk in professional male rugby union: a 16-season review of 10 851 match injuries in the English Premiership (2002-2019): the Professional Rugby Injury Surveillance Project.

OBJECTIVES: The Professional Rugby Injury Surveillance Project is the largest and longest running rugby union injury surveillance project globally and focuses on the highest level of rugby in England. METHODS: We examined match injuries in professional men's rugby over the period 2002/2003 to 2018/2019 and described trends in injuries over this time. RESULTS: Over the period 2002/2003-2018/2019, 10 851 injuries occurred in 1 24 952 hours of match play, equating to a mean of 57 injuries per club per season and one injury per team per match. The mean incidence, severity (days absence) and burden (days absence/1000 hours) of injury were 87/1000 hours (95% CI 82 to 92), 25 days (95% CI 22 to 28) and 2178 days/1000 hours (95% CI 1872 to 2484), respectively. The tackle accounted for 43% injuries with running the second most common activity during injury (12%). The most common injury location was the head/face with an incidence of 11.3/1000 hours, while the location with the highest overall burden was the knee (11.1 days/1000 hours). Long-term trends demonstrated stable injury incidence and proportion of injured players, but an increase in the mean and median severity of injuries. Concussion incidence, severity and burden increased from the 2009/2010 season onwards and from 2011 to 2019 concussion was the most common injury. CONCLUSION: The rise in overall injury severity and concussion incidence are the most significant findings from this work and demonstrate the need for continued efforts to reduce concussion risk as well as a greater understanding of changes in injury severity over time.

The epidemiology of kicking injuries in professional Rugby Union: A 15-season prospective study.

PURPOSE: While kicking in Rugby Union can be influential to match outcome, the epidemiology of kicking injuries remains unknown. This study therefore aimed to investigate the epidemiology of injuries attributed to kicking in professional rugby, including playing position-specific effects and differences in kicking volumes and kick types. METHODS: Fifteen seasons of injury surveillance data and two seasons of match kicking characteristics from professional rugby players were analyzed. Incidence, propensity, and severity of kicking-related injuries were calculated together with the locations and types of these injuries. Position-related differences in match kicking types and volumes were also established. RESULTS: Seventy-seven match and 55 training acute-onset kicking injuries were identified. The match kicking injury incidence for backs was 1.4/1000 player-match-hours. Across all playing positions, the propensity for match kicking injury was 0.57 injuries/1000 kicks. Fly-halves sustained the greatest proportion of match kicking injuries (47%) and performed the greatest proportion of match kicks (46%); an average propensity for match kicking injury (0.58/1000 kicks). Scrum-halves executed 27% of match-related kicks but had a very low propensity for match kicking injury (0.17/1000 kicks). All other positional groups executed a small proportion of match-related kicks but a high propensity for match kicking injury. Ninety-two percent of match kicking injuries occurred in the pelvis or lower limb, with the majority sustained by the kicking limb. 21% of all match kicking injuries were associated with the rectus femoris muscle. CONCLUSION: Match kicking profiles and kicking injuries sustained are position-dependent, which provides valuable insight for developing player-specific conditioning and rehabilitation protocols.

Patterns of training volume and injury risk in elite rugby union: An analysis of 1.5 million hours of training exposure over eleven seasons.

Rugby union is a popular team sport that demands high levels of physical fitness and skill. The study aim was to examine trends in training volume and its impact on injury incidence, severity and burden over an 11-season period in English professional rugby. Data were recorded from 2007/08 through 2017/18, capturing 1,501,606 h of training exposure and 3,782 training injuries. Players completed, on average, 6 h 48 minutes of weekly training (95% CI: 6 h 30 mins to 7 h 6 mins): this value remained stable over the 11 seasons. The mean incidence of training-related injuries was 2.6/1000 player-hours (95% CI: 2.4 to 2.8) with a mean severity rising from 17 days in 2007/08 to 37 days in 2017/18 (Change/season = 1.773, P <0.01). Rate of change in severity was dependent on training type, with conditioning (non-gym-based) responsible for the greatest increase (2.4 days/injury/season). As a result of increasing severity, injury burden rose from 51 days absence/1000 player-hours in 2007/08 to 106 days' absence/1000 player-hours in 2017/18. Despite the low incidence of injury in training compared to match-play, training accounted for 34% of all injuries. Future assessments of training intensity may lead to a greater understanding of the rise in injury severity.

Facts and values: on the acceptability of risks in children's sport using the example of rugby - a narrative review.

A clash of values has been identified between those who assert that:1. all childhood injuries, regardless of origin, are inherently undesirable and should be prevented and;2. those who believe that some measure of injury to children is an acceptable compromise for the physical benefits associated with physical activity and the development of abilities to appraise and deal with risks.A debate regarding whether the tackles and collisions permitted in schools' rugby represent acceptable risks, and what steps should be taken if they do not, exemplifies the issue.Questions regarding the magnitude of injury risks in sport are issues of fact and can be quantified via the results of injury surveillance studies. Risks are neither high nor low in isolation; they are relatively high or low with reference to other activities or across groups participating in an activity. Issues of the acceptability of a given degree of risk are value dependent. Research regarding perceptions of risk reveals wide variations in the degree of risk people view as acceptable. Factors impacting on risk perception include whether the risks are well known and understood, whether they are 'dread' risks and the degree to which people undertake the risks voluntarily and feel they have control over them.Based on the evidence currently available, the risks to children playing rugby do not appear to be inordinately high compared with those in a range of other childhood sports and activities, but better comparative information is urgently needed. Further evidence, however, should not necessarily be expected to result in the resolution of acceptable risk debates-pre-existing values shape our perspectives on whether new evidence is relevant, valid and reliable.

Subsequent Injuries and Early Recurrent Diagnoses in elite Rugby Union Players.

An eight-season (2005/06-2012/13) prospective cohort design was used to record time-loss injuries in 15 English Premiership teams. Data pertaining to a total of 1 556 players and 9 597 injuries (8 180 subsequent) were included in the analysis. Injuries subsequent to an index injury were classified as (1) New: different site; (2) Local: same site (and different type); or (3) Recurrent: same site and type. The severity of subsequent injuries (days missed) was compared with their related index injury. The proportions of early (<2 months), late (2-12 months) and delayed (>12 months) subsequent injuries were compared across injury classifications and diagnosis groupings. The majority of subsequent injuries (70%) were classified as new injuries, with 14% local and 16% recurrent. A large proportion of recurrent subsequent injuries (42%) occurred within two months of return-to-play. Subsequent injuries were not more severe than their corresponding index injury (effect sizes <0.20). Specific local and recurrent subsequent injury diagnoses with the highest risk of occurring within two months of return-to-play were: 'neck muscle strain', 'ankle joint capsule sprain', and 'cervical nerve root' injuries. These findings may be used to drive targeted secondary prevention efforts, such as reconsideration of return-to-play protocols for neck muscle strain injuries.

Time loss injuries compromise team success in Elite Rugby Union: a 7-year prospective study.

BACKGROUND: A negative association between injuries and team success has been demonstrated in professional football, but the nature of this association in elite Rugby Union teams is currently unclear. AIM: To assess the association between injury burden measures and team success outcomes within professional Rugby Union teams. METHODS: A seven-season prospective cohort design was used to record all time-loss injuries incurred by English Premiership players. Associations between team success measures (league points tally and Eurorugby Club Ranking (ECR)) and injury measures (injury burden and injury days per team-match) were modelled, both within (changes from season to season) and between (differences averaged over all seasons) teams. Thresholds for the smallest worthwhile change in league points tally and ECR were 3 points and 2.6%, respectively. RESULTS: Data from a total of 1462 players within 15 Premiership teams were included in the analysis. We found clear negative associations between injury measures and team success (70-100% likelihood), with the exception of between-team differences for injury days per team-match and ECR, which was unclear. A reduction in injury burden of 42 days (90% CI 30 to 70) per 1000 player hours (22% of mean injury burden) was associated with the smallest worthwhile change in league points tally. CONCLUSIONS: Clear negative associations were found between injury measures and team success, and moderate reductions in injury burden may have worthwhile effects on competition outcomes for professional Rugby Union teams. These findings may be useful when communicating the value of injury prevention initiatives within this elite sport setting.

Realising the potential for an Olympic legacy; teaching medical students about sport and exercise medicine and exercise prescribing.

BACKGROUND: Physicians are increasingly being called upon to promote physical activity (PA) among patients. However, a paucity of exercise medicine teaching in the UK undergraduate medical curricula prevents students from acquiring the necessary knowledge and skills to do so. To address this issue, King's College London School of Medicine introduced an exercise medicine strand of teaching. This study evaluated the acceptability of exercise promotion behaviour change lectures and explored the knowledge and attitudes of the students who received it. METHODS: Students were invited to complete a 6-item online questionnaire prior to and after exercise medicine lectures. The questionnaire assessed beliefs regarding the importance of PA in disease prevention and management, in addition to their confidence in advising patients on PA recommendations. A focus group (n=7) explored students' attitudes towards and knowledge of PA promotion and exercise prescribing. RESULTS: In total, 121 (15%) first-year and second-year MBBS students completed the questionnaire. Students' beliefs regarding the importance of PA in managing disease and their confidence in PA promotion among patients increased after the teaching (p<0.001). More students were able to correctly identify the Chief Medical Officer recommended adult PA guidelines (p<0.05). Students were enthusiastic about the exercise medicine teaching, strongly supportive of its continued inclusion in the curriculum and advocated its importance for patients and themselves as future doctors. CONCLUSIONS: Behaviour change teaching successfully improved students' knowledge of and confidence regarding PA promotion. These improvements are a step forward and may increase the rates and success of physician PA counselling in the future.

The effect of a comprehensive injury audit program on injury incidence in ballet: a 3-year prospective study.

OBJECTIVE: The aim of this study was to determine whether an intervention with individualized conditioning program based on injury history and functional movement screening would be effective in reducing ballet injury incidence. DESIGN: Prospective 3-year epidemiological study. SETTING: Professional ballet company and its in-house medical facility. PARTICIPANTS: Dancers from a professional ballet company over the 3-year study period. Participant numbers ranged from 52 to 58 (year 1: 52; year 2: 58; year 3: 53). INTERVENTIONS: The intervention consisted of individual conditioning programs developed using injury history and functional movement screening. Analysis was undertaken of the all dancers who were present in the company during the study period. The significance of change in injuries over a 3-year period was determined using a Poisson distribution model. MAIN OUTCOMES MEASURES: To determine whether individual conditioning programs resulted in a decrease in injury incidence over the study period. RESULTS: The injury count reduced significantly in years 2 and 3 (P < 0.001). Injury incidence for male dancers declined from year 1 (in year/1000 h) (4.76/1000 h) to year 2 (2.40/1000 h) and year 3 (2.22/1000 h). For women, a reduction in the injury incidence was observed from year 1 (4.14/1000 h) to year 2 (1.71/1000 h) and year 3 (1.81/1000 h). CONCLUSIONS: Through prospective injury surveillance, we were able to demonstrate the benefit of individualized conditioning programs based on injury history and functional movement screening in reducing injuries in ballet. CLINICAL RELEVANCE: The implementation of well-structured injury surveillance programs can impact on injury incidence through its influence on intervention programs.

Changes in the stature, body mass and age of English professional rugby players: a 10-year review.

The aim of the study was to evaluate changes in the stature, body mass, age and number of players by playing position in the first team squads of English Premiership rugby union teams from 2002 to 2011. Medical personnel at each club reported the individual data for every first team squad player. The average annual number of players included in the study was 485.2 players per season (standard deviation: 58.0). The mean stature of players in all positions increased in the period 2002 to 2011 but statistically significant trends (P < 0.01) were only observed at fly half and prop. While the mean body mass of players increased in most positions only fly half and back row players showed statistically significant (P < 0.01) upward trends. Apart from second row forwards, the average age of players in all positions decreased but this trend was only significant (P < 0.01) at prop. The numbers of registered players in every position increased but these trends were only significant (P < 0.01) at prop. English Premiership professional rugby players are generally getting taller, heavier and younger but statistically significant changes were limited to fly halves (taller and heavier), props (taller and younger) and back row forwards (heavier).

Shoulder instability in professional rugby players-the significance of shoulder laxity.

OBJECTIVE: Shoulder instability is a common cause of morbidity among professional rugby union players. This study explores whether the risk of shoulder dislocation is associated with innate shoulder laxity. DESIGN: Retrospective cohort study. SETTING: Clinical sports medicine research at professional rugby clubs. PARTICIPANTS: One hundred sixty-nine healthy rugby players (mean age 25.1 years) with no history of instability in either shoulder and 46 players (mean age 27.5 years) with shoulder instability in one shoulder (patient group). MAIN OUTCOME MEASURES: Anterior, inferior, and posterior laxity was measured in both shoulders for healthy players and in the uninjured shoulder only for injured players using dynamic ultrasound. RESULTS: There was no significant difference between the nondominant (anterior: mean 2.9 ± 1.2 mm; inferior: mean 3.1 ± 1.0 mm; posterior: mean 5.1 ± 1.7 mm) and dominant (anterior: mean 3.1 ± 1.1 mm; inferior: mean 2.9 ± 1.0 mm; posterior: mean 4.9 ± 1.7 mm) shoulders in healthy players (P > 0.05). The comparison between healthy shoulders (anterior: mean 3.0 ± 1.2 mm; inferior: mean 3.0 ± 1.0 mm; posterior: mean 5.0 ± 1.7 mm) and the uninjured shoulder (anterior: mean 4.2 ± 1.7 mm; inferior: mean 3.4 ± 1.2 mm; posterior: mean 6.2 ± 3.0 mm) from injured players identified that players with unstable shoulders have a significantly higher shoulder translation in their uninjured shoulder than healthy players (P < 0.05). CONCLUSIONS: Formal assessment of shoulder translation using dynamic ultrasound should enable sports medicine practitioners to identify players at greatest risk of subsequent shoulder instability for targeted prehabilitation programs.

The epidemiology of foot injuries in professional rugby union players.

BACKGROUND: Foot injuries represent a small but important proportion of injuries to professional rugby union players. There are no detailed epidemiological studies regarding these injuries. The aim of this study was to describe the epidemiology of foot injuries sustained by a cohort of professional rugby union players and identify areas that may be targeted for injury prevention in the future. METHODS: Medical personnel prospectively recorded injuries in professional Premiership rugby union players in England over four seasons. Injuries to the foot were identified and the time away from training and playing was reported. RESULTS: A total of 147 foot injuries were sustained resulting in 3542 days of absence in total. Acute events accounted for 73% of all foot injuries, with chronic, mostly overuse conditions, accounting for 25% (undiagnosed 2%). Chronic conditions led to proportionately more time away from training and playing (p=<0.001). Specifically, stress fractures in the foot accounted for 8% of the total foot injuries but 22% of the absence. Navicular stress fractures had the longest recovery time with the mean return to training and match play of 188 days. CONCLUSION: In collision sports such as rugby, some injuries may be inevitable but clinicians should always be seeking ways to minimise their occurrence and impact. This study revealed a high proportion of morbidity associated with chronic and overuse foot injuries in these professional athletes. With greater attention paid to risk factors, some of these injuries, and importantly, recurrent injuries may be avoided.

Injury risks associated with tackling in rugby union.

OBJECTIVE: To examine factors associated with tackles in rugby union and to assess their impact on the risk of injury. DESIGN: Two-season (2003/2004 and 2005/2006) prospective cohort design with video analysis. SETTING: 13 English Premiership clubs. PARTICIPANTS: 645 players. MAIN OUTCOME MEASURE: RR (95% CI) calculated by comparing the frequency of occurrence of risk factors in a cohort of players injured during tackles with their frequency of occurrence in tackles in general play. RISK FACTORS: Playing position; player's speed, impact force, head position, head/neck flexion and body region struck in the tackle; sequence, direction and type of tackle; and location and type of injury. RESULTS: High-speed going into the tackle, high impact force, collisions and contact with a player's head/neck were identified as significant (p<0.01) risk factors for ball carriers (BCs) and tacklers. Midfield backs were significantly (p<0.01) more prone to injury when tackling than other players. Relatively few tacklers were penalised by referees for collision tackles (general play: 2.0%; injured players: 3.3%) and tackles above the line of the shoulder (general play: 5.9%; injured players: 16.7%). CONCLUSIONS: Advice in national and international injury prevention programmes for reducing the risk of injury in tackles is strongly supported by the results obtained from this study. These programmes should be reviewed, however, to provide specific advice for each type of tackle. Stricter implementation of the Laws of Rugby relating to collisions and tackles above the line of the shoulder may reduce the number of head/neck injuries sustained by BCs.

The relationships between rugby union and health: a scoping review protocol.

INTRODUCTION: Rugby union is played by over eight million people across the world and is considered a form of moderate-to-vigorous physical activity. Consequently, playing rugby may confer health benefits; however, to date, the principal focus of research has been on associated injuries and potential detrimental long-term health sequelae. This protocol outlines the methods behind studying any potential associations between rugby union and both physical and mental health. METHODS AND ANALYSIS: Best practice methodological frameworks (Arksey and O'Malley, Levac et al and the Joanna Briggs Institute) and previously published scoping review protocols in sport informs the methodology of this protocol. This protocol enables us to map the key concepts and evidence available, summarise and share existing research findings, and identify research gaps in the current literature. A three-step search strategy will identify reviews, original research, and published and grey literature. An initial search will identify suitable search terms, followed by a search using keyword and index terms. Two reviewers will independently screen identified studies for final inclusion. DISSEMINATION: When publishing the scoping review, we will map key concepts and evidence both numerically and thematically, as well as identify key research priorities for further studies. The review will subsequently be disseminated to stakeholder groups, practitioners and policymakers through a variety of peer-reviewed and non-peer-reviewed publications, conferences and via multimedia platforms.

The epidemiology of knee injuries in English professional rugby union.

BACKGROUND: Detailed injury epidemiology is an invaluable tool for reducing risks associated with sporting injuries. Very little accurate injury surveillance data exist regarding knee injuries in professional rugby. HYPOTHESES: (1) Knee injuries have a greater impact on the game than injuries to other body locations. (2) Anterior cruciate ligament and medial collateral ligament injuries cause the greatest days absent from training and match play. STUDY DESIGN: Descriptive epidemiology study. METHODS: Medical personnel prospectively reported time-loss injuries sustained by 546 professional rugby union players from 12 clubs in England over 2 seasons, and the knee injuries were evaluated. RESULTS: Injuries to the knee accounted for the highest number of days absent due to injury (7776 days, 21%) and were characteristically severe, with a disproportionately high number of days missed per injury (37 days). Anterior cruciate ligament injuries accounted for the greatest proportion of days missed of all knee injuries (29%), followed by medial collateral ligament injuries (25%). Most severe injuries occurred during contact, mostly during a tackle, and most commonly in the final 20 minutes of a match. Injuries tended to be more common in backs. Injuries sustained during training accounted for 16% of all knee injuries. Each club studied had a mean of 10 knee injuries per season resulting in a total of 353 days absent. CONCLUSIONS: The incidence of knee injuries sustained during matches was higher than that reported in all other football codes, surpassed only by rugby union at the international level. Knee injuries accounted for the highest player absence due to injury; 5% of an average playing squad were absent at any one time due to knee injuries.

Contact events in rugby union and their propensity to cause injury.

OBJECTIVE: The objective of this study was to determine the incidence of contact events in professional rugby union matches and to assess their propensity to cause injury. DESIGN: The study was a two-season (2003/2004 and 2005/2006) prospective cohort design. It included 645 professional rugby union players from 13 English Premiership rugby union clubs. The main outcome measures were: incidence of match contact events (events per game); incidence (injuries per 1000 player-hours and per 1000 contact events), risk (days lost per 1000 player-hours and per 1000 contact events) and diagnosis of injury; referee's decision. Risk factors were player-player contact, position on pitch and period of play. RESULTS: Tackles (221.0 events/game) and rucks (142.5 events/game) were the most common events and mauls (13.6%) and scrums (12.6%) the most penalised. Tackles (701.6 days/1000 player-hours) were responsible for the greatest loss of time but scrums (213.2 days lost/1000 events) and collisions (199.8 days lost/1000 events) presented the highest risk per event. CONCLUSIONS: Tackles were the game event responsible for the highest number of injuries and the greatest loss of time in rugby union because they were by far the most common contact event. Collisions were 70% more likely to result in an injury than a tackle and scrums carried a 60% greater risk of injury than a tackle. The relative propensities for contact events to cause injury were rated as: lineout--very low; ruck--low; maul and tackle--average; collision and scrum--high.

Consensus statement on injury definitions and data collection procedures for studies of injuries in rugby union.

Wide variations in the definitions and methodologies used for studies of injuries in rugby union have created inconsistencies in reported data and made interstudy comparisons of results difficult. The International Rugby Board established a Rugby Injury Consensus Group (RICG) to reach an agreement on the appropriate definitions and methodologies to standardise the recording of injuries and reporting of studies in rugby union. The RICG reviewed the consensus definitions and methodologies previously published for football (soccer) at a meeting in Dublin in order to assess their suitability for and application to rugby union. Following this meeting, iterative draft statements were prepared and circulated to members of the RICG for comment; a follow-up meeting was arranged in Dublin, at which time all definitions and procedures were finalised. At this stage, all authors confirmed their agreement with the consensus statement. The agreed document was presented to and approved by the International Rugby Board Council. Agreement was reached on definitions for injury, recurrent injury, non-fatal catastrophic injury, and training and match exposures, together with criteria for classifying injuries in terms of severity, location, type, diagnosis and causation. The definitions and methodology presented in this consensus statement for rugby union are similar to those proposed for football. Adoption of the proposals presented in this consensus statement should ensure that more consistent and comparable results will be obtained from studies of injuries within rugby union.

How Much Rugby is Too Much? A Seven-Season Prospective Cohort Study of Match Exposure and Injury Risk in Professional Rugby Union Players.

INTRODUCTION: Numerous studies have documented the incidence and nature of injuries in professional rugby union, but few have identified specific risk factors for injury in this population using appropriate statistical methods. In particular, little is known about the role of previous short-term or longer-term match exposures in current injury risk in this setting. OBJECTIVES: Our objective was to investigate the influence that match exposure has upon injury risk in rugby union. METHOD: We conducted a seven-season (2006/7-2012/13) prospective cohort study of time-loss injuries in 1253 English premiership professional players. Players' 12-month match exposure (number of matches a player was involved in for ≥20 min in the preceding 12 months) and 1-month match exposure (number of full-game equivalent [FGE] matches in preceding 30 days) were assessed as risk factors for injury using a nested frailty model and magnitude-based inferences. RESULTS: The 12-month match exposure was associated with injury risk in a non-linear fashion; players who had been involved in fewer than ≈15 or more than ≈35 matches over the preceding 12-month period were more susceptible to injury. Monthly match exposure was linearly associated with injury risk (hazard ratio [HR]: 1.14 per 2 standard deviation [3.2 FGE] increase, 90% confidence interval [CI] 1.08-1.20; likely harmful), although this effect was substantially attenuated for players in the upper quartile for 12-month match exposures (>28 matches). CONCLUSION: A player's accumulated (12-month) and recent (1-month) match exposure substantially influences their current injury risk. Careful attention should be paid to planning the workloads and monitoring the responses of players involved in: (1) a high (>≈35) number of matches in the previous year, (2) a low (<≈15) number of matches in the previous year, and (3) a low-moderate number of matches in previous year but who have played intensively in the recent past. These findings make a major contribution to evidence-based policy decisions regarding match workload limits in professional rugby union.

The influence of methodological issues on the results and conclusions from epidemiological studies of sports injuries: illustrative examples.

Data obtained from epidemiological studies of sports injuries are an essential requirement for developing injury prevention, treatment and rehabilitation strategies. Although many authors have discussed the strengths and weaknesses of research methods employed in epidemiology, the potential effects that variations in research design and methods of analysis can have on study conclusions have not been clearly illustrated. This article addresses a number of methodological issues and illustrates their potential effects using examples based on injury data obtained from a single, large epidemiological study in professional rugby union. The examples demonstrate that conflicting conclusions can be reached depending on how the data are collected and analysed. The pivotal roles played by injury definition (loss-of-time, missed matches, diagnostic assessment and surgery), recurrent injury definition (clinical judgement and same injury/same location/same season), method of reporting injuries (number, proportions and incidence) and method of calculating incidence (injuries per 1000 player-hours, per 1000 athlete-exposures and per 1000 matches) are highlighted and illustrated. Other examples show that if training and match injuries are combined, the incidence of injury is more likely to reflect the incidence of training injuries but the distributions of injuries are more likely to reflect the distributions of match injuries. An example is presented that demonstrates that the identification of injuries causing the greatest concern within a sport depends on whether the assessment is based on injury incidence, severity or risk. Finally, examples are presented to show that the relationships identified between sports injuries and risk factors may be dependent on whether case-control or cohort study designs are used. Although there are no simple solutions available to resolve the issues raised, the discussion demonstrates the importance, at least within a sport, of reaching consensus agreements on acceptable study designs and methods of data analysis in sports epidemiology.