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ObjectiveTo evaluate the effectiveness of a junior high school-based sports injury prevention programme to reduce injuries through neuromuscular training (NMT).MethodsThis was a cluster randomised controlled trial. Students were recruited from 12 Calgary junior high schools (2014–2017). iSPRINT is a 15 min NMT warm-up including aerobic, agility, strength and balance exercises. Following a workshop, teachers delivered a 12-week iSPRINT NMT (six schools) or a standard-of-practice warm-up (six schools) in physical education classes. The definition of all recorded injuries included injuries that resulted in participants being unable to complete a sport and recreation (S&R) session, lost time from sport and/or seek medical attention. Incidence rate ratios (IRRs) were estimated based on multiple multilevel Poisson regression analyses (adjusting for sex (considering effect modification) and previous injury, offset by S&R participation hours, and school-level and class-level random effects were examined) for intent-to-treat analyses.Results1067 students (aged 11–16) were recruited across 12 schools (6 intervention schools (22 classes), 6 control schools (27 classes); 53.7% female, 46.3% male). The iSPRINT programme was protective of all recorded S&R injuries for girls (IRR=0.543, 95% CI 0.295 to 0.998), but not for boys (IRR=0.866, 95% CI 0.425 to 1.766). The iSPRINT programme was also protective of each of lower extremity injuries (IRR=0.357, 95% CI 0.159 to 0.799) and medical attention injuries (IRR=0.289, 95% CI 0.135 to 0.619) for girls, but not for boys (IRR=1.055, 95% CI 0.404 to 2.753 and IRR=0.639, 95% CI 0.266 to 1.532, respectively).ConclusionThe iSPRINT NMT warm-up was effective in preventing each of all recorded injuries, lower extremity injuries and medically treated S&R injuries in female junior high school students.Trial registration numberNCT03312504

Objective To evaluate acute changes in measures of cervical spine, vestibulo-ocular reflex (VOR) function, dynamic balance and tasks of divided attention in elite youth ice hockey players following a sport-related concussion. Study Design Prospective Case series Setting Sport Medicine Centre, Calgary, Alberta, Canada Participants Five hundred and fifty-nine (474 males) elite (AA and AAA) Bantam (13-14 years) and Midget (15-17 years) youth ice hockey players. Outcome measures Clinical measurements including cervical flexor endurance test (CFE), head perturbation test, head thrust test, dynamic visual acuity (DVA) (clinical and computerised), Functional Gait Assessment (FGA) and Walking While Talking (WWTT) test at baseline and acutely following concussion. Main results Sixty-nine of 97 (71%) players completed both baseline and acute post concussion measures for their first concussion and were included in these analyses. Following concussion, neck pain, headache and dizziness increased in 42%, 58% and 40% of participants respectively. After Bonferroni corrections (α=0.00625), using Wilcoxon Signed-Rank Test, cervical spine measures were significantly worse following concussion compared to baseline [cervical flexor endurance test (z=−5.195, p Conclusions Measures of cervical spine function and tasks of divided attention were worse following concussion. However, tests of VOR and dynamic balance were not significantly different than at baseline. Future research to evaluate the mechanism underlying these changes is warranted. Competing interests None.

Objective To determine preseason values on cervical, vestibular and divided attention measures in youth ice hockey players aged 10-14 years Design Cross-Sectional study Setting Sport Injury Prevention Research Centre, Alberta, Canada Participants Youth Ice Hockey players (n=934, age 10-14 years). Outcome measures Numeric pain rating scores for neck pain, headache, dizziness; Cervical flexor endurance test (CFE), cervical flexion rotation test (CFRT), cervical spine strength, head perturbation test, functional gait assessment (FGA), walking while talking test (WWTT), head thrust test and dynamic visual acuity (DVA). Main results Symptoms of neck pain, headaches and dizziness were reported by 17%, 18% and 10% of participants respectively. The median time of CFE was 27.0 seconds (IQR: 19.9, 40.7). CFRT was positive in 52 (6.2%) participants. Median anterolateral cervical spine strength was 8.0 lbs (IQR: 6.1, 10.3) right and 7.8 lbs (IQR: 6.0, 10.1) left. 13% of participants were unable to maintain a stationary head position when an external force was applied. 48% of participants performed less than perfect on the FGA. Time to complete a complex task while walking increased 40 foot walking time by a median of 6.4 seconds (IQR: 4.0, 10.3). Head thrust test was positive in 33 (3.7%) participants. Clinical DVA score was a median of 0.2 logMar (IQR: 0.1, 0.3). Conclusions Symptoms are common at baseline and outcomes on many commonly used clinical tests may be different for healthy 10-14 year olds compared to the adult literature. These findings form an important reference point for the interpretation of post-injury testing. Competing interests None.

Objective To determine the value of the Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) tool in measuring neurocognitive recovery following concussion. Design Nested case-control. Setting Sport Medicine Centre, Alberta, Canada. Participants Ice hockey players (n=96; 88.5% male, 11-17 years old) following concussion who completed ImPACT at baseline and medical clearance to return to play (RTP) were compared to controls (n=31) matched for age, sex, and testing time interval. Assessment of risk factors Players who sustained a concussion were referred to a study physician for assessment and RTP clearance based on clinical assessment and SCAT2/3. Physicians were blinded to ImPACT scores. Outcome measures ImPACT composite scores were measured (i.?e., verbal memory, visual memory, reaction time, visual motor) at each time interval [i.e., baseline and RTP (cases)/second measurement (controls)]. Between-interval ImPACT reliable change scores (80%CI) were compared. Main results At RTP (Median days since injury: 22, range: 2–84), 43/96 (44.8%) concussed players and 11/31 (35.5%) controls had ≥1 composite scores reliably worse than at baseline. Conditional logistic regression analysis (n=31 matched pairs) did not demonstrate a difference in the odds of having ≥1 reliably worse composite score between concussed and controls [OR=2.00 (95% CI: 0.5–8.0)] or ≥1 reliably better composite score [OR=1.2 (95% CI: 0.37–3.93)]. Conclusions The utility of baseline ImPACT scores in medical decisions to RTP may be limited by the reliability of composite scores in youth populations. Caution is warranted when interpreting ImPACT scores post-concussion on an individual level using baseline performance. Future research including multivariable analyses is warranted in a larger sample. Competing interests Brian Brooks is a co-author of a paediatric memory test for which he receives royalties. No financial interests in ImPACT are declared. None for all other authors.

Objective To determine if preseason measures of cervical, vestibulo-ocular function, balance and divided attention change over one year in 10-12 year old ice hockey players. Design Prospective cohort study Setting Sport Injury Prevention Research Centre, Alberta, Canada Participants Youth Ice Hockey players (10-12 years old) who completed cervical, vestibular and divided attention tasks at a preseason assessment during two seasons of play. Outcome measures Numeric pain rating scores (neck pain, headache, dizziness), cervical flexor endurance test (CFE), cervical flexion rotation test (CFRT), anterolateral cervical spine strength, head perturbation test, functional gait assessment (FGA), walking while talking test, head thrust test and dynamic visual acuity (DVA). Main results A total of 193 uninjured youth ice hockey players [95% males; median age 11 (range 10-12) in the first season] completed preseason testing measures in two consecutive seasons (2013-2015). After Bonferroni corrections (α=0.0042), using Wilcoxon Signed-Rank Test, anterolateral neck strength increased (right: z=−5.96, p Conclusions Symptom reports did not differ between two years of play. However, tests of clinical function were different between two seasons of play in youth ice hockey players. These data suggest that developmental and/or maturational changes should be taking into consideration when interpreting these tests in youth. Competing interests None.

Objective To evaluate the association between self-reported physical activity (PA) and concussion incidence in male youth ice hockey players. Design pooled data from three prospective cohort studies. Setting Community ice hockey rinks and sport medicine clinics. Participants PeeWee (ages 11–12), Bantam (ages 13–14), and Midget (ages 15–17) male youth ice hockey players (n=1208). Assesment of risk factors Participants reported six-week physical education and extra-curricular sport participation history upon study entry. Concussion incidence rate ratios [IRRs (95% CI)] associated with 1). total six-week PA volume, and 2). meeting the Canadian PA recommendations of one hour of daily PA (≥42 hours/six weeks) were calculated using multivariable Poisson regression (covariates: age, competition level, concussion history). Models were adjusted for hockey exposure, and cluster by team, study year and city (α Outcome measure Medically-diagnosed concussions during the study period. Main results Total PA volume did not affect concussion incidence in male youth ice hockey players [IRR: 0.996 (95% CI: 0.990–1.003]. Concussion incidence was higher in male ice hockey players who did not meet the PA recommendations versus those who met the PA recommendations amongst PeeWee [IRR: 2.94 (95% CI: 1.29–6.66)] and Bantam [IRR: 2.18 (95% CI: 1.12–3.94)] participants, but not amongst Midget participants [IRR: 1.37 (95% CI: 0.72–2.59)]. There was no evidence of confounding or modification by competition level or concussion history. Conclusions While total PA volume was not associated with concussion risk, PeeWee and Bantam male youth ice hockey players whose six-week PA history was below the PA recommendations were at greater risk of concussion. This research will inform future studies examining the mechanism of this association. Competing interests None.

Objective To examine rates of concussion and severe concussion (time loss greater than 10 days) in elite youth ice hockey players. Design Prospective cohort study Setting Alberta, Canada Participants Bantam (13–14 years) and Midget (15–17 years) male and female elite (top 30% by division of play) youth ice hockey players. Assessment of risk factors Participants 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). Outcome measures 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. Main results Overall, 778 elite youth ice hockey players (659 males, 119 females; aged 13–17 years) participated in this study. In total, 143 concussions occurred. The concussion incidence proportion (IP) was 18 concussions/100 players. The concussion incidence rate (IR) was 1.31 concussions/1000 player-hours (95% CI; 1.09, 1.57). Time loss 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. Competing interests None.

Background Policy allowing body checking (BC) increases injury and concussion risk in youth ice hockey players. Hockey Calgary introduced BC policy change in 2015 that disallows BC at the Bantam (ages 13–14) non-elite level (lowest 60% by division of play). Objective To compare game offensive performance (OP) between non-elite Bantam players playing in a league allowing BC and players in a league not allowing BC. Design Prospective cohort. Setting Arenas in Calgary, Alberta. Participants Non-elite Bantam games were videotaped in Calgary, Alberta during the 2014–15 (n=348 players) and 2015–16 (n=309 players) playing seasons. Assessment of Risk Factors Players from the 2014–15 season played in a league allowing BC, while players from 2015–16 season played in a league where BC was not allowed. Main Outcome Measurements Using Dartfish video analysis software, games were analyzed for OP metrics for the puck carrier using the ice hockey adapted Team Sport Assessment Procedure. These metrics included puck possession (conquered puck from an opponent and received pass from a teammate) and puck outcome (successful shot on goal, lost puck to an opponent, and offensive pass to a teammate). Unadjusted incidence rate-ratios (IRRs), clustered by game, were calculated for each puck action per team game between players in Calgary, Alberta 2014–15 (BC allowed) and 2015–16 (BC not allowed). Results No differences were found in puck possession metrics [conquered puck IRR=1.07 (95% CI: 1.00,1.16), received pass IRR=1.05 (95% CI: 0.93,1.18)] or puck outcome [successful shot IRR=0.97 (95% CI: 0.86,1.10), lost puck IRR=1.07 (95% CI: 0.98,1.18), offensive pass IRR=0.98 (95% CI: 0.86,1.12)]. Conclusions There were no differences found across all OP metrics between a non-elite Bantam league allowing BC and a league not allowing BC. There is no evidence to conclude that offensive performance was negatively nor positively affected by Hockey Calgary9s decision to disallow BC at Bantam non-elite levels.

Background There is a growing body of evidence illustrating the contribution of training load to musculoskeletal injury risk. There is a gap in the literature, however, regarding the impact of training on concussion risk. Objective To evaluate the association between sport-specific participation volume and concussion risk in male youth ice hockey players. Design Cohort study. Setting Community ice rinks and sport medicine clinics (2011–15 hockey seasons). Patients (or Participants) Male Pee Wee (11–12 years old), Bantam (13–14 years old) and Midget (15–17 years old) ice hockey players were eligible. Players were excluded if they reported unhealed injuries at study entry, had missing/systematically incomplete hockey participation exposure data, or if they sustained a concussion but participation volume could not be estimated from the day of injury. Interventions (or Assessment of Risk Factors) Cumulative hockey participation volume (CPHV) was estimated based on participation exposure data reported by team designate. The association between concussion risk and total 7-day and 28-day CHPV was evaluated using multivariable logistic regression [OR (95%CI)]. Models were adjusted for concussion history and cluster by player (α Main Outcome Measurements Medically diagnosed concussion. Results Participants who met the inclusion criteria (n=1235/1990) sustained 34 medically diagnosed concussions. Increased concussion risk was associated with hourly increases in 7-day CHPV [OR=1.16 (95%CI: 1.08–1.25), p Conclusions Increased hockey participation volume was associated with increased concussion risk in male youth ice hockey players. This is the first study to explore the association between training volume and concussion risk. Future research utilizing objective volume measurements and training response tools will be critical to the development of primary concussion prevention strategies that optimize the role of training load.

Background In 2013, Hockey Canada announced a national policy change delaying the introduction of body checking in ice hockey until Bantam (ages 13–14). Following this change, several local organizations in Canada changed policy to also disallow body checking in Bantam non-elite levels (lower 60–70% by division of play). Objective To determine if the risk of concussion and severe concussion differs for non-elite Bantam ice hockey players in leagues where body checking is permitted compared with leagues where local policy change removed body checking. Design Cohort study. Setting Ice hockey rinks (2014/15, 2015/16 seasons). Participants Youth ice hockey players in non-elite Bantam body checking leagues (52 teams, 653 players) in Calgary and Edmonton (2014/15) and non-body checking leagues (33 teams, 396 players) in Kelowna and Vancouver (2014/15) and Calgary (2015/16), Canada. Assessment of Risk Factors Exposure to a Bantam league where body checking was not allowed. Main Outcome Measurements Suspected concussions were identified by a team designate and referred to a sport medicine physician. Severe concussions were defined by greater than 10 days of time-loss from ice hockey. Results There were 47 game-related concussions (Incidence Proportion per 100 players [IP] =7.2; 95% CI; 5.33-9.46) and 27 severe concussions (IP=4.1; 95% CI; 2.74-5.96) in body checking leagues. In non-body checking leagues there were 12 concussions (IP=3.03; 95% CI; 1.58-5.23) and 8 severe concussions (IP=2.02; 95% CI; 0.87-3.94). There was no evidence of a difference between the non-body checking leagues in Kelowna and Vancouver (2014/15) and Calgary (2015/16). Preliminary univariate analysis indicates a protective effect of policy disallowing body checking [risk ratio (RR)=0.42 (95% CI; 0.2-0.88) for concussion and RR=0.49 (95% CI; 0.23-1.04) for severe concussion. Conclusions This preliminary analysis suggests a 58% lower risk of game-related concussion in non-elite Bantam leagues where local policy disallows body checking.

Background Concussion is the most common injury in youth ice hockey. Mouthguards can play a role in reducing the risk dental injuries; however there is limited evidence evaluating their association with concussion in youth ice hockey. Objective To assess the association between mouthguard use and risk of concussion and dental trauma in youth ice hockey. Design Nested case-control. Setting Youth ice hockey leagues (elite and non-elite) in Calgary, Canada, where mouthguard use is not mandatory. Participants Baseline and injury data were collected for 11–17 year old players from 2013–2016. Assessment of Risk Factors Mouthguard use at time of injury as reported on Injury Report Forms. Main Outcome Measurements Case groups were defined as concussed players (therapist suspected or study physician diagnosed) and those with dental injuries; controls were players who sustained a non-concussion/non-dental injury during a game or practice. Only the first injury sustained within or between seasons was included. Frequency of mouthguard usage between cases and controls was compared. Information on baseline self-reported mouthguard use and type was also collected. Results At baseline, the majority of players self reported always wearing a mouthguard during games 2,156/2,606 (82.7%) and practices 1,853/2,539 (73.0%). No dental injuries were reported during the study period. Amongst concussion cases 147/185 players (79.5%) reported mouthguard use at time of injury, compared with 134/147 controls (91.2%) (unadjusted OR=0.38 95% CI 0.18–0.76). Future analyses will include multivariable logistic regression adjusting for relevant covariates and considering effect modification. The effect of mouthguard type at time of injury, and concordance between mouthguard use at baseline and time of injury will also be examined. Conclusions The majority of players self reported always wearing a mouthguard at baseline when there was not mandatory enforcement. Based on preliminary univariate analyses, mouthguard use was associated with reduced odds of concussion.

Background The FIFA 11+ program is efficacious in preventing lower extremity injuries in youth soccer players; however, its implementation remains a challenge. Coaches9 beliefs and actions regarding injury prevention may influence program implementation. Objective To describe baseline psychosocial factors and evaluate their relationship with intended FIFA 11+ implementation amongst youth soccer coaches, using the Health Action Process Approach (HAPA) behaviour change model. Design Cross-sectional study. Setting Community youth soccer. Participants Seventy-nine youth soccer coaches from across Canada who attended a FIFA 11+ workshop (Spring 2016) during a nationwide program implementation initiative. Assessment of Risk Factors A HAPA-based questionnaire was used to measure risk perceptions (RP), outcome expectancies (OE) and task self-efficacy (TSE) on a 7-point Likert scale. Scale levels were combined (positive, negative and neutral) to describe baseline values. Spearman correlation was used to assess relationship between factors and intention (INT) (with Bonferroni correction). Main Outcome Measurements INT to implement the FIFA 11+ in the successive soccer season as measured by the questionnaire. Results In total, 92.4% of coaches completed the survey. Most coaches (84.6%) believed the overall risk of injury in youth soccer was high (RP). 80.6% of coaches believed soccer injuries were preventable (OE1) and 94.4% believed that the FIFA 11+ would decrease injury risk (OE2). 69.1% were confident in their understanding of the FIFA 11+ (TSE1) and 76.8% were confident in their ability to use it (TSE2). Most coaches (82.5%) intended to use the program (INT). Only TSE2 was found to be significantly associated with INT (r s =0.42, p=0.001). Conclusions This preliminary analysis demonstrates that task self-efficacy relating to youth soccer coaches9 confidence in being able to use the FIFA 11+ correlates positively with their intention to implement the program. No other significant relations were found between the other psychosocial factors and coaches9 intention.

Background Coach-led delivery of the FIFA 11+ warm-up program is an effective strategy for program implementation. There is emerging evidence that coaches9 task self-efficacy (TSE) predicts FIFA 11+ implementation in youth soccer. Objective To determine the impact of a comprehensive FIFA 11+ workshop on youth soccer coaches9 TSE. Design Quasi-experimental pilot study. Setting Community youth soccer. Participants This study involved 73 Canadian coaches (66.7% male, aged 18–66 years) participating in a pilot pre-implementation FIFA 11+ workshop (Spring 2016). Interventions Experts with experience in program implementation delivered a coach workshop, comprising an extensive theory-based classroom session and a field-based practical demonstration of the FIFA 11+ program. Main Outcome Measurements A questionnaire was used to assess coaches9 TSE for implementing the FIFA 11+ on a 7-point Likert scale. Difference in the pre-post workshop ratings of TSE as measured by coaches9 confidence in both their understanding the FIFA 11+ program (TSE1) and their ability to use the program with their teams (TSE2). Wilcoxon matched-pairs signed-ranks test analysis was used to assess any statistical differences between baseline and post-workshop ratings of TSE. Results Coaches had a median (1st, 3rd quartiles) baseline TSE1 rating of 6 (4, 6) and TSE2 rating of 6 (5, 6). There were statistical significant differences in coaches9 TSE1 (z=−3.99; p Conclusions A comprehensive FIFA 11+ workshop generated positive increases in coach TSE, which may help optimize program uptake and implementation. Further evaluation of this coach workshop strategy on behavioural and implementation outcomes will be performed in a large population of coaches across different cities in Canada in an ongoing nationwide implementation of the FIFA 11+ program in youth soccer.

Background In 2013, Hockey Canada introduced an evidence-informed policy change delaying the earliest age of introduction to body checking in hockey until Bantam (ages 13–14) nationwide. Objective To determine if the risk of injury, including concussions, differs for Pee Wee (11–12 years) ice hockey players in the hockey season following a national policy change disallowing body checking (2013–2014) compared with a season (2011–2012) when body checking was allowed. Design Historical cohort study. Setting Ice hockey rinks (Alberta, Canada). Participants Pee Wee players (all divisions of play) in 2011/12 Alberta prior to the rule change (59 teams, n=883) and 2013/14 following the rule change (73 teams, n=617). Assessment of Risk Factors Exposure to a Pee Wee league where policy change disallowed body checking. Main Outcome Measurements Injuries were identified by a safety designate or team therapist if players: 1) required medical attention, 2) were unable to complete the session and/or 3) were unable to participate in sporting activity for one day. Any player with a suspected concussion was referred to a study sport medicine physician. Results There were 163 game-related injuries [incidence rate (IR)=4.37/1000 game-hours], and 104 concussions (IR=2.79/1000 game-hours) prior to the rule change and 48 injuries (IR=2.16/1000 game-hours) and 24 concussions (IR=1.08/1000 game-hours) after the rule change. Based on a multivariable Poisson regression model adjusting for player size, age, body checking attitudes, previous injury, level of play, and position, accounting for clustering by team, the rate of injury and concussions significantly declined following policy change [IRR=0.50 (95% CI; 0.33 to 0.75)] and [IRR=0.34 (95% CI; 0.21 to 0.56), respectively]. Conclusions Introduction of the 2013 national body checking policy change disallowing body checking in Pee Wee had a significant public health impact resulting in a 50% reduction in injury risk and a 66% reduction in concussion risk in Alberta, Canada.

Background The influence of injury definition on the interpretation of epidemiological outcomes of injury risk has not been previously evaluated in a dance population. Objective To determine the influence of injury definition (i.e., time loss, medical attention, all complaints) on the prevalence and rate of musculoskeletal injuries in pre-professional ballet and contemporary dancers. Design Prospective cohort. Setting Pre-professional ballet school; university dance program. Participants Dancers registered in full-time pre-professional ballet [n=85, 77 females, median (range) age 15 yrs (11–19 yrs)] and contemporary [n=60, 58 females, 19 yrs (17–30 yrs)] training. Main Outcome Measurements Dancers completed a weekly online questionnaire (modified Oslo Sports Trauma Research Centre9s Questionnaire on Health Problems) using three definitions for dance-related injuries: (1) time loss (an inability to complete one or more classes, rehearsals or performances one or more days beyond onset); (2) medical attention; and (3) any complaint. Physiotherapists completed injury report forms, capturing dance-related medical attention and time loss injuries. Percent agreement was estimated between injury registration methods. Descriptive statistics [proportions, 95% confidence intervals (95% CI)] summarized injury prevalence (IP; seasonal proportion of dancers injured). Injury incidence rates (IIR; number of new injuries/1000 dance exposure hours) were examined for each definition, registration method, and dance style. Results Dancer questionnaire response rate was 98.99%. Agreement between injury registration methods ranged between 58.82% (time loss) and 72.94% (medical attention). Depending on definition, registration, and dance style, IP varied from 9.41% (95% CI: 4.15, 17.71; time loss) to 82.35% (95% CI: 72.56, 89.77; all complaint), and IIRs spanned 0.09 (95% CI: 0.01, 0.17; time loss) to 4.89 (95% CI: 4.04, 5.74; all complaint) injuries/1000 dance hours. Conclusions Injuries resulting in time loss and medical attention underestimate the burden of injury in a pre-professional dance population. To understand the full impact of injury on a dance population, it is imperative that registration methodologies consider definitions that capture all injuries.

Background A 2015, Hockey Calgary body checking (BC) policy change disallowed BC from non-elite Bantam (ages 13–14, lower 60% of divisions). This was informed by evidence that disallowing BC in Pee Wee (ages 11–12) reduced the risk of injury, specifically concussion, by >3-fold. Objective To compare the frequency of type and intensity of player-to-player contacts (PC) and head contact in non-elite Bantam ice hockey games in leagues allowing BC (2014–15) compared with leagues disallowing BC (2015–16). Design Cohort study. Setting Ice-hockey arenas in Calgary, Canada. Participants Non-elite Bantam players in 2014–15 (n=348 players) and 2015–16 (n=309 players) seasons. Interventions In the 2014–15 season, non-elite Bantam leagues allowed BC. In 2015–2016, BC was disallowed. Main Outcome Measurements Thirteen games pre-policy change (2014–2015) and 13 post-policy change were video recorded. Analysis using validated methodology was used to compare the frequency, type (i.e., trunk, head and other types of PC with limb/head/stick), and intensity (trunk contacts level 1–5 with increasing intensity) of PCs. Incidence rate ratios (IRR) were estimated using Poisson regression (controlling for cluster by team, offset by player minutes). Results There were a total of 3485 trunk contacts and 1395 other contacts in 26 games. The overall risk of trunk PCs was lower post-policy change (IRR=0.50, 95% CI; 0.45–0.56). Post-policy change, high intensity (body checking - level 4,5) contacts decreased (IRR 4 =0.19, 95% CI; 0.13–0.26 IRR 5 =0.11, 95% CI; 0.03–0.51), lower intensity (level 2,3) PCs were less frequent (IRR 2 =0.45, 95% CI; 0.40–0.50 and IRR 3 =0.47, 95% CI; 0.35–0.63), and other contacts made with the limb/stick also decreased (IRR=0.60, 95% CI; 0.48–0.73). Head contact decreased (IRR=0.40, 95% CI; 0.25–0.61). Conclusions Post-policy change disallowing BC in non-elite Bantam, incidence of high intensity (level 4,5) PCs decreased 82%. Head contact decreased 60% and stick/limbs contact decreased 40%. These findings inform the mechanisms of injury explaining concussion risk reduction post-BC policy change.

Background A multitude of risk factors have been reported to increase an athlete9s risk of developing jumper9s knee. An overuse injury definition has been cited as more sensitive in capturing knee injuries when compared to a time-loss injury definition. To date, risk factors for jumper9s knee have not been assessed for the development of knee problems captured by an overuse injury definition. Objective To assess a multitude of potential intrinsic risk factors for jumper9s knee in volleyball players. Design Prospective Cohort. Setting Collegiate and national team training facilities. Patients (or Participants) Sixty elite adult male volleyball players were recruited from collegiate and national team programs in Canada. Interventions (or Assessment of Risk Factors) Participants completed risk factor assessments at the commencement of the season including: vertical jump ability (cm), weight bearing ankle dorsiflexion range (degrees), dynamic balance (cm), dynamic knee alignment (degrees) and landing mechanics (degrees). Main Outcome Measurements Self-reporting knee problems utilizing an overuse injury questionnaire collected via short message service (SMS) was completed prospectively over one season. Substantial knee problems were identified and logistic regression was used to estimate odds ratios for each risk factor independently. Results The season prevalence of knee problems was 75.0% (95% CI: 62.2 to 84.6) and the incidence proportion of those rated as substantial was 30.0% (95% CI: 19.5 to 43.1). The SMS system of tracking overuse injuries demonstrated 98.2% completeness. No single risk factor was found to predict substantial knee problems. All odds ratios were close to unity with narrow confidence intervals (0.91–1.07) and p>0.05. Conclusions A more sensitive capture of overuse knee injuries did not result in the identification of distinct risk factors for the development of jumper9s knee. These findings bring question to the utility of field based pre-season risk factor assessment for the identification of at risk athletes.

Background Policy disallowing body checking in youth ice hockey significantly reduces the risk of injury and concussion. Based on video analysis, frequency and intensity of player to player physical contacts (PCs) are higher in Pee Wee players (ages 11–12) in leagues allowing body checking, however this has not been examined in Bantam leagues (ages 13–14). Objective To determine the association between body checking policy and the frequency and intensity of physical contacts in Bantam ice hockey players (ages 13–14). Design Cohort study. Setting Ice hockey arenas. Participants Thirteen non-elite (lowest 60% by division of play) Bantam ice hockey games in Calgary, Alberta, Canada (2014–15 season) and 13 non-elite games in Vancouver, British Columbia, Canada (2014–15 season) were videotaped. Intervention Policy allowed body checking in Calgary and not Vancouver in the non-elite levels (2014–15). Main Outcome Measurements Incidence rate ratios [IRRs] (adjusted for player position) were estimated using multiple Poisson regression to examine the effect of body checking policy on player-to-player PCs [levels 1–5 with increasing intensity (levels correspond to 4–5 body checking)] and hooking/slashing behaviours. Results Lower rates of higher intensity contacts (levels 4–5 body checking) were observed in Bantam ice hockey players in a league where body checking was disallowed [IRR=0.09; 95% CI: 0.05–0.15]. Players in a league where body checking was disallowed, however, had significantly higher rates of hooking and slashing behaviours [IRR=1.81; 95% CI: 1.33–2.47]. Conclusions Bantam ice hockey players in a league where policy disallowed body checking are at a lower risk of high intensity physical contacts, but commit higher rates of hooking and slashing behaviours. This research informs the mechanisms explaining injury risk reduction related to body checking policy change and have important national public health implications for policy decisions related to rule enforcement in youth sport.

Background Hockey Canada’s evidence-based body checking (BC) policy change (2013) was informed by evidence that policy allowing BC in Pee Wee (11–12 year old) ice hockey players resulted in a >3-fold increased risk of injury and concussion compared with leagues where BC was not allowed. Objective To compare the frequency of type and intensity of physical contacts (PC) and head contact in elite (upper 30%) Pee Wee ice hockey games in leagues not allowing BC (2013–2014) compared with leagues allowing BC (2007–2008) using video analysis. Methods Ten elite games pre-policy change (2007–2008) and 11 elite games post-policy change (2013–2014) were video recorded and analysed using a validated methodology to compare the frequency of type (trunk and other types of PC with limb/head/stick) and intensity (trunk contacts – level 1–5 intensity) of PC and head contact. Incidence rate ratios (IRR) were estimated using Poisson regression controlling for clustering by game) to compare PC before and after the BC policy change. Results A total of 4409 trunk PCs and 2623 other PCs were observed. The total number of trunk PCs (IRR = 0.97, 95% CI: 0.83–1.14) and other contacts (IRR = 0.87, 95% CI: 0.59–1.29) did not change post-policy change. High intensity contacts (levels 4 and 5) were less frequent post-policy change (IRR 4 = 0.13, 95% CI: 0.09–0.19 and IRR 5 = 0.13, 95% CI: 0.07–0.26) and low intensity contacts (level 2) increased (IRR 2 = 1.47, 95% CI: 1.21–1.79). Limb PCs decreased in 2013–14 (IRR = 0.48, 95% CI; 0.33–0.71) and there was no difference for head contacts (IRR = 0.81, 95% CI; 0.51–1.30). Conclusions There were no significant differences in total number of PC by study year. However, the incidence of high intensity (level 4–5) PCs decreased post -policy change. There was no significant difference in direct head contact or total number of other contacts. This will inform the development and evaluation of injury prevention and skill training strategies in youth ice hockey.

Background Hockey Canada’s 2013 body checking (BC) policy change was informed by evidence that BC leads to a >3-fold increased risk of injury compared with non-BC leagues. Video analyses found a reduction in high intensity physical contacts (PC) following this policy change. The association between BC experience and incidence of PCs has not been examined. As such, the incidence of intensity and types of PC were examined following the policy change in Pee Wee (PW) leagues (ages 11–12) with (Calgary) and without (Quebec) BC experience. Methods PW games were videotaped in Calgary (N = 21, with BC experience) and Quebec City (N = 20, without BC experience), both non-BC leagues. Games were analysed using Dartfish with a validated observation system to quantify incidence of PC. Five levels of intensity (trunk contacts coded Level 1–5 intensity) and other types of PC (limb/head/stick). PC incidence rates per team-game and incidence rate ratios (IRR) (95% CI) were estimated to compare games between two cohorts. Results In total 4433 trunk contacts in Calgary and 2667 in Quebec were recorded. Of the trunk contacts, 97.5% (Calgary) and 95.7% (Quebec) were classified as low level PC. The incidence of total trunk contacts (number of contacts per team-game) was higher in Calgary than Quebec (IRR = 1.58, 95% CI: 1.40–1.79). There was no difference in high intensity contacts (Level 4 [IRR = 0.72 95% CI: 0.48–1.07], Level 5 [IRR = 1.21, 95% CI: 0.57–2.56]). The incidence of other PCs was lower in Calgary than Quebec (IRR = 0.71, 95% CI: 0.53–0.96). Conclusion Following a policy change disallowing BC, PW players with experience BC had a greater incidence of total trunk contacts but not greater high intensity contacts than players without BC experience. Players with no experience had a higher incidence of other PCs. These results inform a greater understanding of mechanisms of contact in youth ice hockey that will in turn inform injury prevention and player development.

Background Sport participation is the leading cause of injury in youth and ankle sprain is the most common sport injury. This study evaluates the effectiveness of neuromuscular training (NMT) in reducing the risk of ankle sprains in youth soccer and basketball players. The secondary objective includes evaluation of sex, age, sport and previous lower extremity (LE) injury as independent risk factors for ankle sprain. Methods A secondary data analysis of three cohort studies and two randomised controlled trials conducted in one season of play in youth soccer and basketball players (ages 11–18) in Alberta, Canada (2005–2011) was completed. The definition of ankle sprain and injury surveillance methodology was consistent in all studies. Multivariable Poisson regression analysis (controlling for clustering by team) was used to estimate incidence rate ratios (IRR) with 95% confidence intervals (CI), considering confounding and effect modification (e.g., sex, age, sport, previous injury). Results There were 188 ankle sprains in 171 players in 2,265 study participants. Multivariable analysis suggests that NMT was protective for ankle sprain injury [IRR = 0.69 (95% CI: 0.45–1.05)] based on the point estimate. Sex, age, sport and previous injury did not modify this effect. Independent risk factors for ankle sprain injury included previous LE injury history [(IRR = 1.77 (95% CI: 1.34–2.35)] and participation in basketball vs. soccer [(IRR = 1.98 (95% CI: 1.30–3.01)]. The risk of ankle sprain injury did not differ by sex [IRR = 1.01 (95% CI: 0.53–1.92)]. Conclusions Exposure to a NMT program is protective for ankle sprain injury in youth soccer and basketball players. Independent risk factors for ankle sprain in youth sport include basketball participation (vs. soccer) and previous LE injury. Future research should focus on optimising NMT programs for the prevention of ankle sprain injuries and maximising player-adherence to NMT programs in youth soccer and basketball.