Epidemiological Principles in Claims of Causality: An Enquiry into Repetitive Head Impacts (RHI) and Chronic Traumatic Encephalopathy (CTE).

Determining whether repetitive head impacts (RHI) cause the development of chronic traumatic encephalopathy (CTE)-neuropathological change (NC) and whether pathological changes cause clinical syndromes are topics of considerable interest to the global sports medicine community. In 2022, an article was published that used the Bradford Hill criteria to evaluate the claim that RHI cause CTE. The publication garnered international media attention and has since been promoted as definitive proof that causality has been established. Our counterpoint presents an appraisal of the published article in terms of the claims made and the scientific literature used in developing those claims. We conclude that the evidence provided does not justify the causal claims. We discuss how causes are conceptualised in modern epidemiology and highlight shortcomings in the current definitions and measurement of exposures (RHI) and outcomes (CTE). We address the Bradford Hill arguments that are used as evidence in the original review and conclude that assertions of causality having been established are premature. Members of the scientific community must be cautious of making causal claims until the proposed exposures and outcomes are well defined and consistently measured, and findings from appropriately designed studies have been published. Evaluating and reflecting on the quality of research is a crucial step in providing accurate evidence-based information to the public.

NZ-RugbyHealth Study: Self-reported Injury Experience and Current Health of Former Rugby Union and Non-contact Sport Players.

BACKGROUND: There is limited research on associations between playing rugby union and player health post-retirement. OBJECTIVE: This study investigated differences in self-reported sport injury history and current self-reported health characteristics between former New Zealand rugby and non-contact sport players with a view to identifying issues to be further investigated with stronger epidemiological research designs. METHODS: Using a cross-sectional design, the NZ-RugbyHealth study surveyed 470 former rugby and non-contact sport players (43.8 ± 8.1 years; 127 elite rugby, 271 community rugby, 72 non-contact sport) recruited from October 2012 to April 2014. Demographic information, engagement in sport, sport injuries, medical conditions, mood, alcohol and substance use and ratings of current health status were obtained from a self-report 58-item general health e-questionnaire. We highlighted standardised differences in means of > 0.6 and differences in relative percentages of > 1.43 for variables between groups as representing at least moderate effect sizes, and of being worthy of follow-up studies. RESULTS: Higher percentages of the elite rugby player group had sustained injuries of a given body-site type (e.g. neck sprain/strain, thigh bruising, hamstring strain) combination than the non-contact sports players. Higher percentages of the rugby groups reported having sustained concussion (94% for elite, 82% for community, 26% for non-contact), injuries requiring hospitalisation (73%, 46%, 25%), injuries that stopped participation in sport permanently (28%, 28%, 11%) and sport-related surgery (72%, 46%, 32%) during their playing career. Both rugby groups had a higher prevalence of osteoarthritis (37%, 18%, 6%) than non-contact athletes and community rugby players had higher levels of hazardous alcohol consumption (38%, 40%, 25%) in retirement than non-contact athletes. There was little difference between rugby players and non-contact sports athletes in self-reported mood, substance use and current physical or psychological health ratings. CONCLUSIONS: Former rugby player groups were at higher risk than the non-contact player group for most injuries during their playing careers, and in retirement had greater prevalence of osteoarthritis and hazardous alcohol consumption. The relative youth of the groups (43.8 years on average) means that health issues that typically do not emerge until later life may not have yet manifested.

Employing Standardised Methods to Compare Injury Risk Across Seven Youth Team Sports.

Injury surveillance systems seek to describe injury risk for a given sport, in order to inform preventative strategies. This often leads to comparisons between studies, although these inferences may be inappropriate, considering the range of methods adopted. This study aimed to describe the injury epidemiology of seven youth sports, enabling valid comparisons of injury risk. Consistent methods were employed across seven sports [male American football, basketball, soccer, rugby league, rugby union; female soccer and rugby union] at a high school in England. A 24-hour time-loss injury definition was adopted. Descriptive statistics and injury incidence (/1000 match-hours) are reported. In total, 322 injuries were sustained by 240 athletes (mean age=17.7±1.0) in 10 273 player-match hours. American football had a significantly greater injury incidence (86/1000 h; 95% CI 61-120) than all sports except female rugby union (54/1000 h; 95% CI 37-76). Concussion was the most common injury (incidence range 0.0-26.7/1000 h), while 59% of injuries occurred via player contact. This study employed standardized data collection methods, allowing valid and reliable comparisons of injury risk between youth sports. This is the first known study to provide epidemiological data for female rugby union, male basketball and American football in an English youth population, enabling the development of preventative strategies.

Nutritional interventions to improve neurophysiological impairments following traumatic brain injury: A systematic review.

Traumatic brain injury (TBI) accounts for significant global health burden. Effects of TBI can become chronic even following mild injury. There is a need to develop effective therapies to attenuate the damaging effects of TBI and improve recovery outcomes. This literature review using a priori criteria (PROSPERO; CRD42018100623) summarized 43 studies between January 1998 and July 2019 that investigated nutritional interventions (NUT) delivered with the objective of altering neurophysiological (NP) outcomes following TBI. Risk of bias was assessed for included studies, and NP outcomes recorded. The systematic search resulted in 43 of 3,748 identified studies met inclusion criteria. No studies evaluated the effect of a NUT on NP outcomes of TBI in humans. Biomarkers of morphological changes and apoptosis, oxidative stress, and plasticity, neurogenesis, and neurotransmission were the most evaluated NP outcomes across the 43 studies that used 2,897 animals. The risk of bias was unclear in all reviewed studies due to poorly detailed methodology sections. Taking these limitations into account, anti-oxidants, branched chain amino acids, and ω-3 polyunsaturated fatty acids have shown the most promising pre-clinical results for altering NP outcomes following TBI. Refinement of pre-clinical methodologies used to evaluate effects of interventions on secondary damage of TBI would improve the likelihood of translation to clinical populations.

International Olympic Committee Consensus Statement: Methods for Recording and Reporting of Epidemiological Data on Injury and Illness in Sports 2020 (Including the STROBE Extension for Sports Injury and Illness Surveillance (STROBE-SIIS)).

BACKGROUND: Injury and illness surveillance, and epidemiological studies, are fundamental elements of concerted efforts to protect the health of the athlete. To encourage consistency in the definitions and methodology used, and to enable data across studies to be compared, research groups have published 11 sport- or setting-specific consensus statements on sports injury (and, eventually, illnesses) epidemiology to date. OBJECTIVE: To further strengthen consistency in data collection, injury definitions, and research reporting through an updated set of recommendations for sports injury and illness studies, including a new Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist extension. STUDY DESIGN: Consensus statement of the International Olympic Committee (IOC). METHODS: The IOC invited a working group of international experts to review relevant literature and provide recommendations. The procedure included an open online survey, several stages of text drafting and consultation by working groups, and a 3-day consensus meeting in October 2019. RESULTS: This statement includes recommendations for data collection and research reporting covering key components: defining and classifying health problems, severity of health problems, capturing and reporting athlete exposure, expressing risk, burden of health problems, study population characteristics, and data collection methods. Based on these, we also developed a new reporting guideline as a STROBE extension-the STROBE Sports Injury and Illness Surveillance (STROBE-SIIS). CONCLUSION: The IOC encourages ongoing in- and out-of-competition surveillance programs and studies to describe injury and illness trends and patterns, understand their causes, and develop measures to protect the health of the athlete. The implementation of the methods outlined in this statement will advance consistency in data collection and research reporting.

Consensus on a video analysis framework of descriptors and definitions by the Rugby Union Video Analysis Consensus group.

Using an expert consensus-based approach, a rugby union Video Analysis Consensus (RUVAC) group was formed to develop a framework for video analysis research in rugby union. The aim of the framework is to improve the consistency of video analysis work in rugby union and help enhance the overall quality of future research in the sport. To reach consensus, a systematic review and Delphi method study design was used. After a systematic search of the literature, 17 articles were used to develop the final framework that described and defined key actions and events in rugby union (rugby). Thereafter, a group of researchers and practitioners with experience and expertise in rugby video analysis formed the RUVAC group. Each member of the group examined the framework of descriptors and definitions and rated their level of agreement on a 5-point agreement Likert scale (1: strongly disagree; 2: disagree; 3: neither agree or disagree; 4: agree; 5: strongly agree). The mean rating of agreement on the five-point scale (1: strongly disagree; 5: strongly agree) was 4.6 (4.3-4.9), 4.6 (4.4-4.9), 4.7 (4.5-4.9), 4.8 (4.6-5.0) and 4.8 (4.6-5.0) for the tackle, ruck, scrum, line-out and maul, respectively. The RUVAC group recommends using this consensus as the starting framework when conducting rugby video analysis research. Which variables to use (if not all) depends on the objectives of the study. Furthermore, the intention of this consensus is to help integrate video data with other data (eg, injury surveillance).

International Olympic Committee consensus statement: methods for recording and reporting of epidemiological data on injury and illness in sport 2020 (including STROBE Extension for Sport Injury and Illness Surveillance (STROBE-SIIS)).

Injury and illness surveillance, and epidemiological studies, are fundamental elements of concerted efforts to protect the health of the athlete. To encourage consistency in the definitions and methodology used, and to enable data across studies to be compared, research groups have published 11 sport-specific or setting-specific consensus statements on sports injury (and, eventually, illness) epidemiology to date. Our objective was to further strengthen consistency in data collection, injury definitions and research reporting through an updated set of recommendations for sports injury and illness studies, including a new Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist extension. The IOC invited a working group of international experts to review relevant literature and provide recommendations. The procedure included an open online survey, several stages of text drafting and consultation by working groups and a 3-day consensus meeting in October 2019. This statement includes recommendations for data collection and research reporting covering key components: defining and classifying health problems; severity of health problems; capturing and reporting athlete exposure; expressing risk; burden of health problems; study population characteristics and data collection methods. Based on these, we also developed a new reporting guideline as a STROBE Extension-the STROBE Sports Injury and Illness Surveillance (STROBE-SIIS). The IOC encourages ongoing in- and out-of-competition surveillance programmes and studies to describe injury and illness trends and patterns, understand their causes and develop measures to protect the health of the athlete. Implementation of the methods outlined in this statement will advance consistency in data collection and research reporting.

Predicting Sport-related mTBI Symptom Resolution Trajectory Using Initial Clinical Assessment Findings: A Retrospective Cohort Study.

OBJECTIVES: To identify which aspects of initial clinical assessment for sport-related mild traumatic brain injury (SR-mTBI) predict whether an athlete achieves symptom resolution within 14 days of the injury. RESEARCH DESIGN: Retrospective cohort study using prospectively collected data. METHODS: Clinical assessment data were collected from 568 patients diagnosed with SR-mTBI at a single medical clinic between February 2017 and December 2018. Demographic data, medical history, SCAT-5 testing, and physician notes were included in the data set. Data were processed and analysed to identify a shortlist of predictor variables to develop a logistic regression model to discriminate between SR-mTBI symptom resolution that occurred in ≤ 14-days or > 14-days. The data were randomly divided into model development and validation subsamples. The top 15 models were analysed to determine the predictor variables to be included in the final logistic regression model. The final model was then applied to the validation subsample. RESULTS: Half of the athlete participants in this study experienced > 14-day symptom resolution. The final logistic regression model included sex, symptom reporting at initial assessment and presentation with a physiological predominant symptom cluster. The model accounted for 0.90 and 0.85 of the area under the curve and predicted recovery trajectory with 81% and 76% accuracy for the training and validation subsamples, respectively. CONCLUSIONS: Being female, reporting a higher Positive Symptom Total at initial assessment, and being less likely to have a physiological predominant symptom cluster at initial assessment predicted > 14 versus ≤ 14-day SR-mTBI symptom resolution with a high level of accuracy.

The Epidemiology of Sport-Related Concussion: What the Rehabilitation Clinician Needs to Know.

SYNOPSIS: Sport-related concussion is common in full-contact and collision sports. Epidemiology studies use different types of surveillance systems and concussion definitions. Concussion incidence rates vary across age, sex, sport, and level of competition. Incidence rates are increasing, likely due to higher rates of reporting following improved knowledge and increased regulations. In this review, we summarize 7 key concepts related to concussion epidemiology: concussion definition, changes in concussion knowledge, reliability and accuracy of injury surveillance systems, conservative management and return to play, reliability of self-report, incidence of concussion across levels of play, and understanding the behaviors of players, coaches, and medical personnel from a multidisciplinary management perspective. J Orthop Sports Phys Ther 2019;49(11):768-778. doi:10.2519/jospt.2019.9105.

Managing player load in professional rugby union: a review of current knowledge and practices.

BACKGROUND: The loads to which professional rugby players are subjected has been identified as a concern by coaches, players and administrators. In November 2014, World Rugby commissioned an expert group to identify the physical demands and non-physical load issues associated with participation in professional rugby. OBJECTIVE: To describe the current state of knowledge about the loads encountered by professional rugby players and the implications for their physical and mental health. FINDINGS: The group defined 'load' as it relates to professional rugby players as the total stressors and demands applied to the players. In the 2013-2014 seasons, 40% of professional players appeared in 20 matches or more, and 5% of players appeared in 30 matches or more. Matches account for ∼5-11% of exposure to rugby-related activities (matches, team and individual training sessions) during professional competitions. The match injury rate is about 27 times higher than that in training. The working group surmised that players entering a new level of play, players with unresolved previous injuries, players who are relatively older and players who are subjected to rapid increases in load are probably at increased risk of injury. A mix of 'objective' and 'subjective' measures in conjunction with effective communication among team staff and between staff and players was held to be the best approach to monitoring and managing player loads. While comprehensive monitoring holds promise for individually addressing player loads, it brings with it ethical and legal responsibilities that rugby organisations need to address to ensure that players' personal information is adequately protected. CONCLUSIONS: Administrators, broadcasters, team owners, team staff and the players themselves have important roles in balancing the desire to have the 'best players' on the field with the ongoing health of players. In contrast, the coaching, fitness and medical staff exert significant control over the activities, duration and intensity of training sessions. If load is a major risk factor for injury, then managing training loads should be an important element in enabling players to perform in a fit state as often as possible.

A Comparison of Cognitive Function in Former Rugby Union Players Compared with Former Non-Contact-Sport Players and the Impact of Concussion History.

AIM: This study investigated differences in cognitive function between former rugby and non-contact-sport players, and assessed the association between concussion history and cognitive function. METHODS: Overall, 366 former players (mean ± standard deviation [SD] age 43.3 ± 8.2 years) were recruited from October 2012 to April 2014. Engagement in sport, general health, sports injuries and concussion history, and demographic information were obtained from an online self-report questionnaire. Cognitive functioning was assessed using the online CNS Vital Signs neuropsychological test battery. Cohen's d effect size statistics were calculated for comparisons across player groups, concussion groups (one or more self-reported concussions versus no concussions) and between those groups with CNS Vital Signs age-matched norms (US norms). Individual differences within groups were represented as SDs. RESULTS: The elite-rugby group (n = 103) performed worse on tests of complex attention, processing speed, executive functioning, and cognitive flexibility than the non-contact-sport group (n = 65), and worse than the community-rugby group (n = 193) on complex attention. The community-rugby group performed worse than the non-contact group on executive functioning and cognitive flexibility. Compared with US norms, all three former player groups performed worse on verbal memory and reaction time; rugby groups performed worse on processing speed, cognitive flexibility and executive functioning; and the community-rugby group performed worse on composite memory. The community-rugby group and non-contact-sport group performed slightly better than US norms on complex attention, as did the elite-rugby group for motor speed. All three player groups had greater individual differences than US norms on composite memory, verbal memory and reaction time. The elite-rugby group had greater individual differences on processing speed and complex attention, and the community-rugby group had greater individual differences on psychomotor speed and motor speed. The average number of concussions recalled per player was greater for elite rugby and community rugby than non-contact sport. Former players who recalled one or more concussions (elite rugby, 85 %; community rugby, 77 %; non-contact sport, 23 %) had worse scores on cognitive flexibility, executive functioning, and complex attention than players who did not recall experiencing a concussion. CONCLUSIONS: Past participation in rugby or a history of concussion were associated with small to moderate neurocognitive deficits (as indicated by worse CNS Vital Signs scores) in athletes post retirement from competitive sport.

Evaluation of goal kicking performance in international rugby union matches.

OBJECTIVES: Goal kicking is an important element in rugby but has been the subject of minimal research. To develop and apply a method to describe the on-field pattern of goal-kicking and rank the goal kicking performance of players in international rugby union matches. DESIGN: Longitudinal observational study. METHODS: A generalized linear mixed model was used to analyze goal-kicking performance in a sample of 582 international rugby matches played from 2002 to 2011. The model adjusted for kick distance, kick angle, a rating of the importance of each kick, and venue-related conditions. RESULTS: Overall, 72% of the 6769 kick attempts were successful. Forty-five percent of points scored during the matches resulted from goal kicks, and in 5.7% of the matches the result of the match hinged on the outcome of a kick attempt. There was an extremely large decrease in success with increasing distance (odds ratio for two SD distance 0.06, 90% confidence interval 0.05-0.07) and a small decrease with increasingly acute angle away from the mid-line of the goal posts (odds ratio for 2 SD angle, 0.44, 0.39-0.49). Differences between players were typically small (odds ratio for 2 between-player SD 0.53, 0.45-0.65). CONCLUSIONS: The generalized linear mixed model with its random-effect solutions provides a tool for ranking the performance of goal kickers in rugby. This modelling approach could be applied to other performance indicators in rugby and in other sports in which discrete outcomes are measured repeatedly on players or teams.

The relationship between physical fitness and game behaviours in rugby union players.

The physical preparation of team sport athletes should reflect the degree to which each component of fitness is relied upon in competition. The aim of the study was therefore to establish the relationship between fitness-test data and game behaviours known or thought to be important for successful play in rugby union matches. Fitness-test measures from 510 players were analysed with game statistics, from 296 games within the 2007 and 2008 calendar years. Sprint times over 10, 20 and 30 m had moderate to small negative correlations (r) with line breaks (~0.26), metres advanced (~0.22), tackle breaks (~0.16) and tries scored (~0.15). The average time of 12 repeated sprints and percentage body fat in the forwards, and repeated sprint fatigue in the backs had moderate to small correlations with a measure of activity rate on and around the ball (-0.38, -0.17 and -0.17, respectively). These low correlations are partly due to uniformly high physical fitness as a result of selection pressures at the elite level and leave room for the identification of other key predictors. Nonetheless, physical conditioning programmes should be adapted to reflect the importance of speed, repeated sprint ability and body composition in the performance of key game behaviours during competition.

Positional demands of international rugby union: evaluation of player actions and movements.

UNLABELLED: In rugby union, published analyses of actions and movements of players during matches have been limited to small samples of games at regional or national level. OBJECTIVES: To analyse movements and activities of players in international rugby union matches with a sample size sufficient to clearly delineate positional roles. DESIGN: Observational study. METHODS: Actions of 763 players were coded from video recordings of 90 international matches played by the New Zealand national team (the All Blacks) from 2004 to 2010. Movements of players were coded for 27 of these matches via a semi-automated player-tracking system. Movements and activities of all players from both teams were coded. RESULTS: Cluster analysis of activities and time-motion variables produced five subgroups of forwards (props, hookers, locks, flankers, Number 8 forwards) and five subgroups of backs (scrum-half, fly-half, midfield backs, wings and fullbacks). Forwards sustained much higher contact loads per match than backs, via scrums, rucks, tackles and mauls. Mean distance covered per match ranged from 5400 to 6300m, with backs generally running further than forwards. There were marked differences between positional groups in the amount of distance covered at various speeds. The amount of play per match varies by position due to differences in rates at which players are substituted. CONCLUSIONS: The distance covered by players at relatively fast running speeds (in excess of 5ms(-1)) appears to be higher during international matches than when competing at lower levels of the professional game. The specific match demands for positional groups need to be considered when managing player workloads.

Tackle injuries in professional Rugby Union.

BACKGROUND: The tackle is the most dangerous facet of play in rugby union, but little is known about risk factors for tackle injuries. PURPOSE: To estimate the injury risk associated with various characteristics of tackles in professional rugby union matches. STUDY DESIGN: Descriptive epidemiology study. METHOD: All 140 249 tackles in 434 professional matches were coded from video recordings for height and direction of tackle on the ball carrier, speed of tackler, and speed of ball carrier; injuries were coded for various characteristics, including whether the tackler or ball carrier required replacement or only on-field assessment. RESULTS: There were 1348 injury assessments requiring only on-field treatment and 211 requiring player replacement. The inciting event and medical outcomes were matched to video records for 281 injuries. Injuries were most frequently the result of high or middle tackles from the front or side, but rate of injury per tackle was higher for tackles from behind than from the front or side. Ball carriers were at highest risk from tackles to the head-neck region, whereas tacklers were most at risk when making low tackles. The impact of the tackle was the most common cause of injury, and the head was the most common site, but an important mechanism of lower limb injuries was loading with the weight of another player. Rates of replacement increased with increasing player speed. CONCLUSION: Strategies for reducing tackle injuries without radically changing the contact nature of the sport include further education of players about safe tackling and minor changes to laws for the height of the tackle.

Effect of nationwide injury prevention programme on serious spinal injuries in New Zealand rugby union: ecological study.

OBJECTIVE: To investigate the effect of RugbySmart, a nationwide educational injury prevention programme, on the frequency of spinal cord injuries. DESIGN: Ecological study. SETTING: New Zealand rugby union. PARTICIPANTS: Population at risk of injury comprised all New Zealand rugby union players. INTERVENTION: From 2001, all New Zealand rugby coaches and referees have been required to complete RugbySmart, which focuses on educating rugby participants about physical conditioning, injury management, and safe techniques in the contact phases of rugby. MAIN OUTCOME MEASURES: Numbers of all spinal injuries due to participation in rugby union resulting in permanent disablement in 1976-2005, grouped into five year periods; observed compared with predicted number of spinal injuries in 2001-5. RESULTS: Eight spinal injuries occurred in 2001-5, whereas the predicted number was 18.9 (relative rate=0.46, 95% confidence interval 0.19 to 1.14). Only one spinal injury resulted from scrums over the period; the predicted number was 9.0 (relative rate=0.11, 0.02 to 0.74). Corresponding observed and predicted rates for spinal injuries resulting from other phases of play (tackle, ruck, and maul) were 7 and 9.0 (relative rate=0.83, 0.29 to 2.36). CONCLUSIONS: The introduction of the RugbySmart programme coincided with a reduction in the rate of disabling spinal injuries arising from scrums in rugby union. This study exemplifies the benefit of educational initiatives in injury prevention and the need for comprehensive injury surveillance systems for evaluating injury prevention initiatives in sport.

Risk factors and risk statistics for sports injuries.

BACKGROUND: Risk factors for sports injuries include characteristics and behaviors of athletes and characteristics of sports and the environment that are associated with some measure of risk of injury. OBJECTIVE: To introduce risk statistics to clinicians evaluating studies of sports injuries. METHODS: Plain-language review of risk statistics and their practical application to sports injuries. RESULTS: The various measures of injury incidence are injury risk (proportion of athletes injured in a given period of training, playing, or other exposure time), injury rate (number of injuries per unit of exposure time), odds of injury (probability injury will happen divided by probability injury will not happen), injury hazard (instantaneous proportion injured per unit of time or mean injury count per unit of time), and mean time or mean number of playing exposures to injury. Effects of risk factors are estimated as values of effect statistics representing differences or ratios of one or more of these measures between groups defined by the risk factor. Values of some ratios and their sampling uncertainty (confidence limits) are estimated with specialized procedures: odds ratios with logistic regression, rate ratios with Poisson regression, and hazard ratios with proportional hazards (Cox) regression. Injury risks and mean time to injury in each group can also be estimated and can give a better sense of the effect of a risk factor. Risk factors identified in nonexperimental cohort and case-control studies are not always causes of injury; data from randomized controlled trials provide stronger evidence of causality. CONCLUSION: Expressing risk statistics as meaningful numbers should help clinicians make better use of sports injury studies.

Changes in player characteristics and match activities in Bledisloe Cup rugby union from 1972 to 2004.

To illustrate changes in elite rugby union match activities, we analysed coded videotape recordings of the first match in each Bledisloe Cup series played between Australia and New Zealand from 1972 to 2004. We also analysed the stature and body mass of players. Effects associated with professionalism, weather conditions, and time (expressed as change per decade) were estimated with a simple generalized linear model and standardized for interpretation of magnitude. The sample size permitted confident conclusions about effects that were of at least moderate magnitude (standardized mean difference >0.6). Increases in passes, tackles, rucks, tries, and ball-in-play time were associated with the advent of professionalism, whereas there were reductions in the numbers of lineouts, mauls, kicks in play, and in mean participation time per player. Noteworthy time trends were an increase in the number of rucks and a decrease in the number of scrums. Good weather conditions were associated with increases in tries and points scored and with reductions in the number of kicks in play and participation time per player. With the advent of professionalism, players have become heavier and backs have become taller. Overall, there have been major changes in international rugby match activities and player size over the past three decades. We believe law changes and developments in match analysis, equipment technology, and player training have contributed to the changes associated with the introduction of professionalism.

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.

Evaluation of protective equipment for prevention of injuries in rugby union.

BACKGROUND: Rugby union has a high rate of injury. The increased use of protective equipment may help mitigate these injuries. This study investigated the injury prevention effectiveness of the protective equipment used in rugby union. METHODS: A cohort of 304 rugby players in Dunedin, New Zealand was followed weekly during the 1993 club season to assess protective equipment use, participation in rugby, and injury outcomes. Generalized Poisson regression was used to model the rate of injury while adjusting for covariates such as level of competition, playing position, and injury history. RESULTS: The use of mouthguards appeared to lower the risk of orofacial injury [rate ratio (RR) = 0.56, 95% confidence interval (CI): 0.07-4.63], and padded headgear tended to prevent damage to the scalp and ears (RR = 0.59, 95% CI: 0.19-1.86). Support sleeves tended to reduce the risk of sprains and strains (RR = 0.58, 95% CI: 0.26-1.27). The risk of concussion was not lessened by the use of padded headgear (RR = 1.13, 95% CI: 0.40-3.16) or mouthguards (RR = 1.62, 95% CI: 0.51-5.11). There was no evidence of protective effects for any other equipment item (taping, shinguards, and grease). CONCLUSIONS: The protective equipment used in rugby union has limited effectiveness in preventing injuries. The results are supportive, however, of a role for mouthguards and padded headgear in preventing orofacial and scalp injuries, respectively, and for support sleeves in preventing sprains and strains.