Correction: Currie et al. Reality Check 2: The Cost-Effectiveness of Policy Disallowing Body Checking in Non-Elite 13- to 14-Year-Old Ice Hockey Players. Int. J. Environ. Res. Public Health 2021, 18, 6322.

There was an error in our original publication [...].

Bodychecking experience and rates of injury among ice hockey players aged 15-17 years.

BACKGROUND: Although high rates of injury occur in youth ice hockey, disagreements exist about the risks and benefits of permitting bodychecking. We sought to evaluate associations between experience with bodychecking and rates of injury and concussion among ice hockey players aged 15-17 years. METHODS: We obtained data from a prospective cohort study of ice hockey players aged 15-17 years in Alberta who played in leagues that permitted bodychecking. We collected data over 3 seasons of play (2015/16-2017/18). We compared players based on experience with bodychecking (≤ 2 v. ≥ 3 yr), estimated using local and national bodychecking policy and region of play. We used validated methodology of ice hockey injury surveillance to identify all injuries related to ice hockey games and defined concussions according to the Consensus Statement on Concussion in Sport. RESULTS: We included 941 players who contributed to 1168 player-seasons, with 205 players participating in more than 1 season. Compared with players with 2 years or less of bodychecking experience, those with 3 or more years of experience had higher rates of all injury (adjusted incidence rate ratio [IRR] 2.55, 95% confidence interval [CI] 1.57-4.14), injury with more than 7 days of time loss (adjusted IRR 2.65, 95% CI 1.50-4.68) and concussion (adjusted IRR 2.69, 95% CI 1.34-5.42). INTERPRETATION: Among ice hockey players aged 15-17 years who participated in leagues permitting bodychecking, more experience with bodychecking did not protect against injury. This provides further support for removing bodychecking from youth ice hockey.

No association found between body checking experience and injury or concussion rates in adolescent ice hockey players.

OBJECTIVES: To compare rates of injury and concussion among U-15 (ages 13-14 years) ice hockey players playing in leagues allowing body checking, but who have a varying number of years of body checking experience. METHODS: This 5-year longitudinal cohort included U-15 ice hockey players playing in leagues where policy allowed body checking. Years of body checking experience were classified based on national/local body checking policy. All ice hockey game-related injuries were identified using a validated injury surveillance methodology. Players with a suspected concussion were referred to a study sport medicine physician. Multiple multilevel Poisson regression analysis was performed, adjusting for important covariates and a random effect at a team level (offset by game exposure hours), to estimate injury and concussion incidence rate ratios (IRRs). RESULTS: In total, 1647 players participated, contributing 1842 player-seasons (195 players participating in two seasons). Relative to no body checking experience, no significant differences were found in the adjusted IRRs for game-related injury for players with 1 year (IRR=1.06; 95% CI: 0.77 to 1.45) or 2+ years (IRR=1.16; 95% CI: 0.74 to 1.84) body checking experience. Similarly, no differences were found in the rates of concussion for players with 1 year (IRR=0.92; 95% CI: 0.59 to 1.42) or 2+ years (IRR=0.69; 95% CI: 0.38 to 1.25) body checking experience. CONCLUSIONS: Among ice hockey players aged 13-14 years participating in leagues permitting body checking, the adjusted rates of all injury and concussion were not significantly different between those that had body checking experience and those that did not. Based on these findings, no association was found between body checking experience and rates of injury or concussion specifically in adolescent ice hockey.

The "SHRed Injuries Basketball" Neuromuscular Training Warm-up Program Reduces Ankle and Knee Injury Rates by 36% in Youth Basketball.

OBJECTIVE: To evaluate the effectiveness of a neuromuscular training warm-up prevention program, Surveillance in High school and community sport to Reduce (SHRed) Injuries Basketball, for reducing all-complaint ankle and knee injuries in youth basketball players. DESIGN: Quasi-experimental study. METHODS: High school/club basketball teams (male and female players aged 11-18 years) in Calgary, Canada participated in 2016-2017 (control; season 1) and 2017-2018 (intervention; season 2). The control season included a standard-of-practice warm-up. In season 2, a SHRed Injuries Basketball coach workshop was completed by participating team coaches. Teams were randomized by school/club to an unsupervised or a supervised (weekly supervision by study personnel) implementation of the coach-delivered SHRed Injuries Basketball program. The 10-minute SHRed Injuries Basketball program included 13 exercises (ie, aerobic, agility, strength, balance). All-complaint ankle and knee injuries were collected weekly using validated injury surveillance. Multilevel, multivariable Poisson regression analyses (considering important covariates, clustering by team and individual, and offset by exposure hours) estimated incidence rate ratios (IRRs) by intervention group (season 1 versus season 2) and secondarily considered the control versus completion of the SHRed Injuries Basketball program, unsupervised and supervised. RESULTS: Sixty-three teams (n = 502 players) participated in season 1 and 31 teams (n = 307 players: 143 unsupervised, 164 supervised) participated in season 2. The SHRed Injuries Basketball program was protective against all-complaint knee and ankle injuries (IRR = 0.64; 95% confidence interval [CI]: 0.51, 0.79). Unsupervised (IRR = 0.62; 95% CI: 0.47, 0.83) and supervised (IRR = 0.64; 95% CI: 0.49, 0.85) implementations of the SHRed Injuries Basketball program had similar protective effects. CONCLUSION: The SHRed Injuries Basketball program was associated with a 36% lower rate of ankle and knee injuries. Neuromuscular training warm-ups are recommended as the minimal standard of practice for injury prevention in youth basketball. J Orthop Sports Phys Ther 2022;52(1):40-48. doi:10.2519/jospt.2022.10959.

An Economic Evaluation of Disallowing Body Checking in 11- to 12-Year-Old Ice Hockey Leagues.

BACKGROUND: After a national policy change in 2013 disallowing body checking in Pee Wee ice hockey games, the rate of injury was reduced by 50% in Alberta. However, the effect on associated health care costs has not been examined previously. HYPOTHESIS: A national policy removing body checking in Pee Wee (ages 11-12 years) ice hockey games will reduce injury rates, as well as costs. STUDY DESIGN: Cost-effectiveness analysis alongside cohort study. LEVEL OF EVIDENCE: Level 3. METHODS: A cost-effectiveness analysis was conducted alongside a cohort study comparing rates of game injuries in Pee Wee hockey games in Alberta in a season when body checking was allowed (2011-2012) with a season when it was disallowed after a national policy change (2013-2014). The effectiveness measure was the rate of game injuries per 1000 player-hours. Costs were estimated based on associated health care use from both the publicly funded health care system and privately paid health care cost perspectives. Probabilistic sensitivity analysis was conducted using bootstrapping. RESULTS: Disallowing body checking significantly reduced the rate of game injuries (-2.21; 95% CI [-3.12, -1.31] injuries per 1000 player-hours). We found no statistically significant difference in public health care system (-$83; 95% CI [-$386, $220]) or private health care costs (-$70; 95% CI [-$198, $57]) per 1000 player-hours. The probability that the policy of disallowing body checking was dominant (with both fewer injuries and lower costs) from the perspective of the public health care system and privately paid health care was 78% and 92%, respectively. CONCLUSION: Given the significant reduction in injuries, combined with lower public health care system and private costs in the large majority of iterations in the probabilistic sensitivity analysis, our findings support the policy change disallowing body checking in ice hockey in 11- and 12-year-old ice hockey leagues.

Body checking in non-elite adolescent ice hockey leagues: it is never too late for policy change aiming to protect the health of adolescents.

OBJECTIVES: The objective of this study is to evaluate the effect of policy change disallowing body checking in adolescent ice hockey leagues (ages 15-17) on reducing rates of injury and concussion. METHODS: This is a prospective cohort study. Players 15-17 years-old were recruited from teams in non-elite divisions of play (lower 40%-70% by division of play depending on year and city of play in leagues where policy permits or prohibit body checking in Alberta and British Columbia, Canada (2015-18). A validated injury surveillance methodology supported baseline, exposure-hours and injury data collection. Any player with a suspected concussion was referred to a study physician. Primary outcomes include game-related injuries, game-related injuries (>7 days time loss), game-related concussions and game-related concussions (>10 days time loss). RESULTS: 44 teams (453 player-seasons) from non-body checking and 52 teams (674 player-seasons) from body checking leagues participated. In body checking leagues there were 213 injuries (69 concussions) and in non-body checking leagues 40 injuries (18 concussions) during games. Based on multiple multilevel mixed-effects Poisson regression analyses, policy prohibiting body checking was associated with a lower rate of injury (incidence rate ratio (IRR): 0.38 (95% CI 0.24 to 0.6)) and concussion (IRR: 0.49; 95% CI 0.26 to 0.89). This translates to an absolute rate reduction of 7.82 injuries/1000 game-hours (95% CI 2.74 to 12.9) and the prevention of 7326 injuries (95% CI 2570 to 12083) in Canada annually. CONCLUSIONS: The rate of injury was 62% lower (concussion 51% lower) in leagues not permitting body checking in non-elite 15-17 years old leagues highlighting the potential public health impact of policy prohibiting body checking in older adolescent ice hockey players.

Secondary consequences of juvenile idiopathic arthritis in children and adolescents with knee involvement: physical activity, adiposity, fitness, and functional performance.

OBJECTIVE: Secondary consequences of juvenile idiopathic arthritis (JIA) may impact long-term health outcomes. This study examined differences in physical activity, cardiorespiratory fitness, adiposity, and functional performance in children and adolescents with JIA compared to their typically developing (TD) peers. METHODS: Participants with JIA (n = 32; 10-20 years old) and their TD peers (n = 35) volunteered for assessments of: daily moderate-to-vigorous physical activity (MVPA, body-worn accelerometer); peak oxygen consumption (VO2 Peak, incremental bike test); fat mass index (FMI, dual-energy X-ray absorptiometry); and triple-single-leg-hop (TSLH) distance. Statistical analyses were performed in R using four linear mixed-effect models with Bonferroni adjustment (⍺ = 0.0125). Fixed effects were group, sex, and age. Participant clusters based on sex and age (within 1.5 years) were considered as random effects. RESULTS: Participants with JIA displayed lower mean daily MVPA than their TD peers [p = 0.006; ß (98.75% CI); -21.2 (-40.4 to -2.9) min]. VO2 Peak [p = 0.019; -1.4 (-2.5 to -0.2) ml/kg/min] decreased with age. Females tended to have lower VO2 Peak [p = 0.045; -6.4 (-13.0 to 0.4) ml/kg/min] and greater adiposity [p = 0.071; 1.4 (-0.1 to 3.0) kg/m2] than males. CONCLUSION: The findings support the need for strategies to promote MVPA participation in children and adolescents with JIA. Sex and age should be considered in research on the consequences of JIA.

Sport Specialization, Physical Performance and Injury History in Canadian Junior High School Students.

BACKGROUND: Youth sports participation is encouraged for proposed physical and psychological benefits. However early sport specialization and the potentially negative consequences may be a cause for concern. PURPOSE: To describe sport specialization in Canadian youth and investigate associations with previous injury and physical performance. STUDY DESIGN: Cross-sectional study. METHODS: Junior high school students (grades 7-9, ages 11-16) were invited to participate. All participants completed a questionnaire capturing specialization level (low, moderate, high; based on year-round training, exclusion of other sports, and single-sport training) and injury history in the previous 12-months. Additionally, all participants completed physical performance measures including vertical jump (cm), predicted VO2max (mL/kg/min), single-leg balance (secs) and Y-Balance composite score (%). Logistic regression examined the association between school grade, school size, sex and sport specialization (Objective 1) and the association between sport specialization and injury history (Objective 2). Multivariable linear regression analyses (4) assessed associations between sport specialization category and physical performance measures (Objective 3). RESULTS: Two hundred and thirty-eight students participated in the study. Eighteen percent of participants reported high specialization, with no significant associations between sex, grade or school size and specialization category. There was no significant difference in the odds of sustaining previous injury between participants reporting moderate (odds ratio [OR]=1.94, 95% CI 0.86-4.35) or high (OR=2.21, 95% CI 0.43-11.37) compared to low specialization. There were no significant differences in vertical jump height (mean diff [MD] = -0.4 to 2.1cm), predicted VO2max (MD = 2.2 to 3.1mL/kg/min), single leg balance (MD = 0.5 to 1.9sec) or Y-balance (MD = 0.6 to 7.0%) between sport specialization categories. CONCLUSIONS: Sport specialization exists in Canadian junior high schools but may be less common than previously reported and it was not associated with sex, grade, or school size. Level of specialization was not associated with history of injury nor a range of physical performance measures. LEVEL OF EVIDENCE: Level 3.

The Burden and Risk Factors of Patellar and Achilles Tendinopathy in Youth Basketball: A Cohort Study.

This study aimed at evaluating the burden and risk factors of patellar and Achilles tendinopathy among youth basketball players. Patellar and Achilles tendinopathy were prospectively monitored in 515 eligible male and female youth basketball players (11-18 years) through a competitive season. Overall, the season prevalence of patellar tendinopathy was 19.0% (95% CI: 15.7-22.7%), 23.2% (95% CI: 18.6-28.2%) in males and 12.5% (95% CI: 8.3-17.9%) in females. The season prevalence of Achilles tendinopathy was 4.3% (95% CI: 2.7-6.4%), 4.1% (95% CI: 2.2-7.0%) in males and 4.5% (95% CI: 2.1-8.4%) in females. Median proportion of symptoms duration was 83% of average total weeks of basketball exposure for patellar tendinopathy and 75% for Achilles tendinopathy. Median time to patellar tendinopathy onset was 8 weeks for male players and 6 weeks for female players. Higher odds of patellar tendinopathy risk were seen in males (OR: 2.23, 95% CI: 1.10-4.69) and players with previous anterior knee pain had significantly elevated odds (OR: 8.5, 95% CI: 4.58-16.89). The burden and risk of patellar tendinopathy is high among competitive youth basketball players. Risk factors include sex and previous anterior knee pain. These findings provide directions for practice and future research.

Reality Check 2: The Cost-Effectiveness of Policy Disallowing Body Checking in Non-Elite 13- to 14-Year-Old Ice Hockey Players.

Sport-related injuries are the leading cause of injury in youth and are costly to the healthcare system. When body checking is disallowed in non-elite levels of Bantam (ages 13-14 years) ice hockey, the injury rate is reduced, but the impact on costs is unknown. This study compared rates of game injuries and costs among non-elite Bantam ice hockey leagues that disallow body checking to those that did not. Methods: An economic evaluation was conducted alongside a prospective cohort study comparing 608 players from leagues where body checking was allowed in games (Calgary/Edmonton 2014-2015, Edmonton 2015-2016) with 396 players from leagues where it was not allowed in games (Vancouver, Kelowna 2014-2015, Calgary in 2015-2016). The effectiveness measure was rate of game injuries per 1000 player-hours. Costs were estimated based on associated healthcare use within the publicly funded healthcare system as well as privately paid healthcare costs. Probabilistic sensitivity analysis was conducted using bootstrapping. Results: Disallowing body checking reduced the rate of injuries by 4.32 per 1000 player-hours (95% CI -6.92, -1.56) and reduced public and total healthcare system costs by $1556 (95% CI -$2478, -$559) and $1577 (95% CI -$2629, -$500) per 1000 player-hours, respectively. These finding were robust in over 99% of iterations in sensitivity analyses in the public healthcare and the total healthcare system perspectives. There was no statistically significant difference in privately paid healthcare costs (-$65 per 1000 player-hours (95% CI -$220, $99)). Interpretation: Disallowing body checking in non-elite 13-14-year-old ice hockey nationally would prevent injuries and reduce public healthcare costs.

Factors Associated With Clinical Recovery After Concussion in Youth Ice Hockey Players.

BACKGROUND: The identification of factors associated with clinical recovery in youth after sports-related concussion could improve prognostication regarding return to play (RTP). PURPOSE: To assess factors associated with clinical recovery after concussion in youth ice hockey players. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Participants were part of a larger longitudinal cohort study (the Safe to Play study; N = 3353). Included were 376 ice hockey players (age range, 11-17 years) from teams in Calgary and Edmonton, Canada, with 425 physician-diagnosed ice hockey-related concussions over 5 seasons (2013-2018). Any player with a suspected concussion was referred to a sports medicine physician for diagnosis, and a Sport Concussion Assessment Tool (SCAT) form was completed. Time to clinical recovery was based on time between concussion and physician clearance to RTP. Two accelerated failure time models were used to estimate days to RTP clearance: model 1 considered symptom severity according to the SCAT3/SCAT5 symptom evaluation score (range, 0-132 points), and model 2 considered responses to individual symptom evaluation items (eg, headache, neck pain, dizziness) of none/mild (0-2 points) versus moderate/severe (3-6 points). Other covariates were time to physician first visit (≤7 and >7 days), age group (11-12, 13-14, and 15-17 years), sex, league type (body checking and no body checking), tandem stance (modified Balance Error Scoring System result ≥4 errors out of 10), and number of previous concussions (0, 1, 2, and ≥3). RESULTS: The complete case analysis (including players without missing covariates) included 329 players (366 diagnosed concussions). The median time to clinical recovery was 18 days. In model 1, longer time to first physician visit (>7 days) (time ratio [TR], 1.637 [95% confidence interval (CI), 1.331-1.996]) and greater symptom severity (TR, 1.016 [95% CI, 1.012-1.020]) were significant predictors of longer clinical recovery. In model 2, longer time to first physician visit (TR, 1.698 [95% CI, 1.399-2.062]), headache (moderate/severe) (TR, 1.319 [95% CI, 1.110-1.568]), and poorer tandem stance (TR, 1.249 [95% CI, 1.052-1.484]) were significant predictors of longer clinical recovery. CONCLUSION: Medical clearance to RTP was longer for players with >7 days to physician assessment, poorer tandem stance, greater symptom severity, and moderate/severe headache at first visit.

Knee Injury and Osteoarthritis Outcome Score (KOOS) Responder Criteria and Minimal Detectable Change 3-12 Years Following a Youth Sport-Related Knee Injury.

The applicability of thresholds that constitute an acceptable score or meaningful change on the Knee injury and Osteoarthritis Outcome Score (KOOS) in cohorts ≥ 5 years following knee injury is not well understood. The primary objective of this study was to evaluate the association between intra-articular knee injury type and two different KOOS pain thresholds (patient acceptable symptom state (PASS) and Englund symptomatic knee criteria) in the Alberta Youth Prevention of Osteoarthritis (PrE-OA) cohort, which includes participants 3-12 years following a youth sport-related knee injury and uninjured controls with similar age, sex and sport characteristics. Analyses accounted for sex, time since injury and the interaction between time since injury and injury type. Secondary objectives were to report proportions meeting thresholds for KOOS outcomes and minimal detectable change (MDC) from published test-retest reliability data, over a 1-4-year follow-up. Two hundred and fifty-three (253) participants (124 injured, 129 controls) were included in analyses, of which 153 (77 injured, 76 controls) had follow-up data. Similar odds were observed for presence of pain (below PASS threshold) in participants with anterior cruciate ligament (ACL)/meniscus injury (odds ratio (OR) 4.2 (97.5% confidence interval (CI): 1.8, 9.9)) and other knee injuries (OR 4.9 (97.5% CI: 1.2, 21.0)), while there were higher odds for presence of Englund "symptomatic knee" criteria in participants with ACL/meniscus injury (OR 13.6 (97.5% CI: 2.9, 63.4)) than other knee injuries (OR 7.3 (97.5% CI: 0.8, 63.7)) compared to controls. After a median 23.4 (8 to 42) month follow-up, 35% of previously injured participants had at least one KOOS sub-scale score that worsened by more than the MDC published threshold. Despite limited research, this study shows that individuals with youth sport knee injuries other than ACL or meniscus injury may also experience significant pain and symptoms 3-12 years following injury. Replication and further follow-up are needed to identify a possible clinical trajectory towards osteoarthritis.

Concussion Burden, Recovery, and Risk Factors in Elite Youth Ice Hockey Players.

OBJECTIVE: To examine rates of concussion and more severe concussion (time loss of greater than 10 days) in elite 13- to 17-year-old ice hockey players. METHODS: This is a prospective cohort study (Alberta, Canada). Bantam (13-14 years) and Midget (15-17 years) male and female elite (top 20% by division of play) youth ice hockey players participated in this study. Players completed a demographic and medical history questionnaire and clinical test battery at the beginning of the season. A previously validated injury surveillance system was used to document exposure hours and injury during one season of play (8 months). Players with a suspected ice hockey-related concussion were referred to the study sport medicine physicians for assessment. Time loss from hockey participation was documented on an injury report form. RESULTS: Overall, 778 elite youth ice hockey players (659 males and 119 females; aged 13-17 years) participated in this study. In total, 143 concussions were reported. The concussion incidence rate (IR) was 17.60 concussions/100 players (95% CI, 15.09-20.44). The concussion IR was 1.31 concussions/1000 player-hours (95% CI, 1.09-1.57). Time loss of greater than 10 days was reported in 74% of cases (106/143), and 20% (n = 28) had time loss of greater than 30 days. CONCLUSIONS: Concussion is a common injury in elite youth ice hockey players. In this study population, a large proportion of concussions (74%) resulted in a time loss of greater than 10 days, possibly reflecting more conservative management or longer recovery in youth athletes.

Epidemiology of all-complaint injuries in youth basketball.

This study evaluated the incidence and characteristics of all-complaint injuries, including acute and overuse injuries, in female and male youth basketball players. A total of 518 players (16 ± 1.4 years; 38.6% females), from 63 teams, participated in this prospective cohort study. Players were observed through one competitive high school or club basketball season to record exposure and all-complaint injuries, defined as any complaint resulting from participating in basketball-related activities, including but irrespective of the need for medical attention or time loss. Injury incidence rates and rate ratios were derived from Poisson's regression with 99.4% CI (Bonferroni's correction for multiple comparisons). The overall injury incidence rate was 14.4 (99.4% CI: 12.2-17.0) injuries/1000 h; 13.8 (99.4% CI: 11.2-16.8) in females and 14.8 (99.4% CI: 11.7-18.8) in males. While the incidence of injury was similar across injury classifications for female and male players, a potential lower overuse knee injury rate was noted for females vs males [IRR = 0.61 (99.4% CI: 0.34-1.07)]. The most commonly injured body location was the ankle (45%) in females and the knee (51%) in males. Overuse (vs acute) injuries were about 2x more common in the knee while acute (vs overuse) injuries were about 3x more common in the ankle, overall, and for female and male players. Based on an all-complaint injury definition, injury rates in competitive female and male youth basketball players are much higher than previously reported. This study provides an evidence base to inform more tailored interventions to reduce injuries in youth basketball.

How much, how often, how well? Adherence to a neuromuscular training warm-up injury prevention program in youth basketball.

Adherence is a key implementation outcome that determines the effectiveness of an intervention. This study, an observational design involving coaches and players from 33 high school basketball teams, evaluated the dimensions of adherence to a basketball-specific neuromuscular training (NMT) warm-up program in youth basketball. Coach adherence (daily report of team adherence) was collected prospectively. Adherence measures: cumulative utilization (proportion of total sessions possible), utilization fidelity (average # of exercises completed per NMT session), utilization frequency (average # of NMT sessions completed per week) were calculated and further evaluated for optimal adherence (≥80%, ≥10.4 exercises/session and ≥2 sessions/week, respectively) per coach. Additionally, exercise fidelity (proportion of players performing individual exercises correctly) was assessed. Coach (n = 31; 27-59 years) median cumulative utilization was 80%, utilization fidelity was 12 (of a possible 13 exercises per session) and utilization frequency was 2.3 sessions per week. Optimal adherence ranged from 52% to 71% across measures of adherence. Player exercise fidelity was 48%. Time constraint (47%) was the most frequently reported adherence barrier. While coach adherence to the NMT warm-up program was reasonably high across measures of adherence, a considerable proportion of coaches did not attain optimal adherence levels and player exercise fidelity was low.

Statement on Methods in Sport Injury Research From the First METHODS MATTER Meeting, Copenhagen, 2019.

SYNOPSIS: High-quality sports injury research can facilitate sports injury prevention and treatment. There is scope to improve how our field applies best-practice methods-methods matter (greatly!). The first METHODS MATTER meeting, held in January 2019 in Copenhagen, Denmark, was the forum for an international group of researchers with expertise in research methods to discuss sports injury methods. We discussed important epidemiological and statistical topics within the field of sports injury research. With this opinion document, we provide the main take-home messages that emerged from the meeting. Meeting participants agreed that the definition of sport injury depends on the research question and context. It was considered essential to be explicit about the goal of the research effort and to use frameworks to illustrate the assumptions that underpin measurement and the analytical strategy. Complex systems were discussed to illustrate how potential risk factors can interact in a nonlinear way. This approach is often a useful alternative to identifying single risk factors. Investigating changes in exposure status over time is important when analyzing sport injury etiology, and analyzing recurrent injury, subsequent injury, or injury exacerbation remains challenging. The choice of statistical model should consider the research question, injury measure (eg, prevalence, incidence), type and granularity of injury data (categorical or continuous), and study design. Multidisciplinary collaboration will be a cornerstone for future high-quality sport injury research. Working outside professional silos in a diverse, multidisciplinary team benefits the research process, from the formulation of research questions and designs to the statistical analyses and dissemination of study results in implementation contexts. This article has been copublished in the British Journal of Sports Medicine and the Journal of Orthopaedic & Sports Physical Therapy. J Orthop Sports Phys Ther 2020;50(5):226-233. doi:10.2519/jospt.2020.9876.

Statement on methods in sport injury research from the 1st METHODS MATTER Meeting, Copenhagen, 2019.

High quality sports injury research can facilitate sports injury prevention and treatment. There is scope to improve how our field applies best practice methods-methods matter (greatly!). The 1st METHODS MATTER Meeting, held in January 2019 in Copenhagen, Denmark, was the forum for an international group of researchers with expertise in research methods to discuss sports injury methods. We discussed important epidemiological and statistical topics within the field of sports injury research. With this opinion document, we provide the main take-home messages that emerged from the meeting.

Mouthguard use in youth ice hockey and the risk of concussion: nested case-control study of 315 cases.

BACKGROUND: Concussion is the most common injury in youth ice hockey. Whether mouthguard use lowers the odds of concussion remains an unanswered question. OBJECTIVE: To determine the association between concussion and mouthguard use in youth ice hockey. METHODS: Nested case-control design. Cases and controls were identified from two prospective cohort studies using valid injury surveillance methods. Cases were players concussed during a game or practice; controls were players who sustained a non-concussion injury during a game or practice. The primary exposure was mouthguard use at time of injury; mouthguard type (dental custom fit or off the shelf) was a secondary exposure. Physician-diagnosed or therapist-suspected concussion was the primary outcome. Dental injury was a secondary outcome. Multilevel logistic regression with random effect at a team level was used to obtain ORs for the mouthguard effect, adjusted for level of play, age group, position, concussion history, mechanism of injury, cohort, session type and body checking policy. RESULTS: Among cases, 236/315 (75%) were wearing a mouthguard at time of injury, while 224/270 (83%) controls were wearing a mouthguard at time of injury. Any mouthguard use was associated with an adjusted OR for concussion of 0.36 (95% CI 0.17 to 0.73). Off-the-shelf mouthguards were associated with a 69% lower odds of concussion (adjusted OR: 0.31; 95% CI 0.14 to 0.65). Dental custom-fit mouthguards were associated with a non-significant 49% lower odds of concussion (adjusted OR: 0.51; 95% CI 0.22 to 1.10). No dental injuries were identified in either cohort. CONCLUSION: Mouthguard use was associated with lower odds of concussion. Players should be required to wear mouthguards in youth ice hockey.

Psychosocial Factors and the Effects of a Structured Injury Prevention Workshop on Coaches' Self-Efficacy to Implement the 11+ Exercise Program.

Psychosocial factors have both direct and indirect influence on behavior change. Self-efficacy is a key psychosocial factor driving behavior change. It is an individual's perceived capability of performing a desired action. Structured injury prevention workshops targeting improvements in psychosocial factors in coaches may enhance the dissemination and implementation of the 11+ program in community settings. This study describes baseline psychosocial factors in youth soccer coaches and the effects of a structured 11+ injury prevention workshop on coaches' self-efficacy to implement the 11+. An adapted questionnaire based on the Health Action Process Approach Model was administered to a sample of coaches, before and after an 11+ workshop. Measures of self-efficacy included: their understanding of the 11+; their ability to use the 11+; using the 11+ with limited space, and using the 11+ when players lacked interest. Data from 73 of 81 coaches were retained for analyses. The majority (74%) of coaches knew about the 11+ program before the workshop, mostly through internet resources and colleagues. 40% to 55% of coaches had at least one unit increase (range, 1 to 6); 29% to 48% did not have a change in measures of self-efficacy. Ten percent to 24% had at least one unit decrease (range, -1 to -3). Wilcoxon matched-pairs signed-ranks test (with Bonferroni correction) indicated significant increases in coaches' post-workshop (compared to baseline) mean ranks for three of the four self-efficacy measures (p≤0.013). A structured workshop significantly improved self-efficacy towards the implementation of the 11+ program in youth soccer coaches.

Does disallowing body checking in non-elite 13- to 14-year-old ice hockey leagues reduce rates of injury and concussion? A cohort study in two Canadian provinces.

OBJECTIVE: To compare rates of injury and concussion among non-elite (lowest 60% by division of play) Bantam (ages 13-14 years) ice hockey leagues that disallow body checking to non-elite Bantam leagues that allow body checking. METHODS: In this 2-year cohort study, Bantam non-elite ice hockey players were recruited from leagues where policy allowed body checking in games (Calgary/Edmonton 2014-2015, Edmonton 2015-2016) and where policy disallowed body checking (Kelowna/Vancouver 2014-2015, Calgary 2015-2016). All ice hockey game-related injuries resulting in medical attention, inability to complete a session and/or time loss from hockey were identified using valid injury surveillance methodology. Any player suspected of having concussion was referred to a study physician for diagnosis and management. RESULTS: 49 body checking (608 players) and 33 non-body checking teams (396 players) participated. There were 129 injuries (incidence rate (IR)=7.98/1000 hours) and 54 concussions (IR=3.34/1000 hours) in the body checking teams in games. After policy change, there were 31 injuries (IR=3.66/1000 hours) and 17 concussions (IR=2.01/1000 hours) in games. Policy disallowing body checking was associated with a lower rate of all injury (adjusted incidence rate ratio (IRR)=0.44; 95% CI: 0.27 to 0.74). The point estimate showed a lower rate of concussion (adjusted IRR=0.6; 95% CI: 0.31 to 1.18), but this was not statistically significant. CONCLUSION: Policy change disallowing body checking in non-elite Bantam ice hockey resulted in a 56% lower rate of injury. There is growing evidence that disallowing body checking in youth ice hockey is associated with fewer injuries.