The incidence of behaviours associated with body checking among youth ice hockey players

Who Is Keeping Score: The Effect of a Mercy Rule on Head Impact Rates in Canadian High School Tackle Football Games

OBJECTIVE

To examine the association between the Mercy Rule (MR) and head impact incidence rates (IRs) in Canadian high school football games.

DESIGN

Cross-sectional.

SETTING

Calgary, Canada.

PARTICIPANTS

Two high school football teams (ages 15-16 years) had a total of 16 team-games videorecorded and analyzed.

INTERVENTIONS

The MR mandates continuous running time in the second half of games when the score differential is 35 points or greater.

MAIN OUTCOME MEASURES

Head impact IRs and incidence rate ratios (IRRs) were used to compare head impact rates in MR and non-MR games.

RESULTS

Mercy Rule games had 28% fewer plays, and the head impact IR per team-game was 27% lower [IRR, 0.73; 95% confidence interval (CI), 0.61-0.89] in MR games (IR, 241.67; 95% CI, 199.24, 293.13) than in non-MR games (IR, 328.91; 95% CI, 313.04, 345.57). Across all games (MR and non-MR), running plays accounted for more than half of all head impacts, and the head impact rates for running plays exceeded all other play types except for a sack of the quarterback. Players engaged in blocks (blocking or being blocked) accounted for 68.90% of all recorded head impacts. The highest proportion of impacts involved the front of the helmet (54.85%). There was no difference in head impact rates by player-play comparing MR and non-MR games (IRR, 1.01; 95% CI, 0.85, 1.19).

CONCLUSIONS

Given the concerns for potential long-term consequences of repetitive head impacts, the MR is a prevention strategy by which head impact rates can be significantly lowered when a significant score differential exists.

Time to Ring in the Body Checking, Head Contact, and Suspected Injury Rates in Youth Ringette: A Video-Analysis Study in Youth Ringette and Female Ice Hockey

OBJECTIVE

To compare physical contacts (PCs), including head contacts (HCs), suspected concussion, and nonconcussion injury incidence rates between youth ringette and female ice hockey.

DESIGN

Cross-sectional.

SETTING

Alberta ice arenas.

PARTICIPANTS

Players participating in 8 U16AA (ages 14-15 years) ringette and 8 U15AA (ages 13-14 years) female ice hockey games during the 2021 to 2022 season.

ASSESSMENT OF RISK FACTORS

Dartfish video-analysis software was used to analyze video recordings.

MAIN OUTCOME MEASURES

Univariate Poisson regression analyses (adjusted for cluster by team-game, offset by game minutes) were used to estimate PCs (including HCs) and suspected injury (concussion and nonconcussion) and concussion-specific IRs and incidence rate ratios (IRRs) to compare sports. Proportions of all PCs that were body checks (level 4-5 trunk PC) and direct HCs (HC 1 ) penalized were reported.

RESULTS

Ringette had a 2.6-fold higher rate of body checking compared with hockey (IRR = 2.63, 95% CI: 1.59-4.37). Ringette also had a 2-fold higher rate of HC 1 compared with hockey (IRR = 2.08, 95% CI: 1.37-3.16). A 3.4-fold higher rate of suspected injury was found in ringette (IRR = 3.37, 95% CI: 1.40-8.15). There was no significant difference in suspected concussion IRs in ringette compared with hockey (IRR = 1.93, 95% CI: 0.43-8.74). Despite being prohibited in both sports, only a small proportion of body checks (Ringette = 18%; Hockey = 17%) and HC 1 (Ringette = 6%; Hockey = 6%) were penalized.

CONCLUSIONS

Higher rates of body checking, HC 1 , and suspected injuries were found in ringette compared with female ice hockey. Body checking and HC 1 were rarely penalized, despite rules disallowing them in both sports. Future research should consider other youth age groups.

Physical Contact and Suspected Injury Rates in Female versus Male Youth Ice Hockey: A Video-Analysis Study

OBJECTIVE

Canada's national winter sport of ice hockey has high youth participation; however, research surrounding female ice hockey is limited and the injury burden remains high. This study compared rates of head contact (HC), body checking (BC; high-intensity player-to-player contact), and suspected concussion between female and male youth ice hockey.

DESIGN

Cross-sectional.

SETTING

Game video-recordings captured in Calgary, Canada.

PARTICIPANTS

Ten female (BC prohibited) and 10 male (BC permitted) U15 elite AA (13-14-year-old) game video-recordings collected in the 2021 to 22 seasons and 2020 to 21, respectively.

ASSESSMENT OF RISK FACTORS

An analysis of player-to-player physical contact and injury mechanisms using video-analysis.

MAIN OUTCOME MEASURES

Videos were analyzed in Dartfish video-analysis software and all physical contacts were coded based on validated criteria, including HCs (direct [HC1], indirect [HC2]), BC (levels 4-5 on a 5-point intensity scale), and video-identified suspected concussions. Univariate Poisson regression clustering by team-game offset by game-length (minutes) were used to estimate incidence rates and incidence rate ratios (IRR, 95% confidence intervals).

RESULTS

The female game had a 13% lower rate of total physical contacts (IRR = 0.87, 0.79-0.96) and 70% lower rate of BC (IRR = 0.30, 0.23-0.39). There were however no differences in the rates of direct HC (IRR = 1.04, 0.77-1.42) or suspected concussion (IRR = 0.42, 0.12-1.42) between the cohorts. Although prohibited in the female game, only 5.4% of HC1s and 18.6% of BC resulted in a penalty.

CONCLUSIONS

The rates of HC1s and suspected concussions were similar across youth ice hockey. BC rates were lower in the female game, yet still prevalent despite being prohibited.

Associations between the circumstances and severity of head impacts in men's university ice hockey

Improved evidence on the most common and severe types of head impacts in ice hockey can guide efforts to preserve brain health through improvements in protective gear, rink design, player training, and rules of play. In this observational cohort study of men's university hockey, we compared video evidence on the circumstances of 234 head impacts to measures of head impact severity (peak linear accelerations and rotational velocities) from helmet-mounted sensors (GForceTracker). Videos were analyzed with a validated questionnaire, and paired with helmet sensor data. Shoulder-to-head impacts were more common than hand- or elbow-, but there were no differences in head impact severity between upper limb contact sites (p ≥ 0.2). Head-to-glass impacts were nearly four times more common, and just as severe as head-to-board impacts (p ≥ 0.4). Head impacts resulting in major penalties (versus no penalty), or visible signs of concussion (versus no signs), involved greater head rotational velocities (p = 0.038 and 0.049, respectively). Head impacts occurred most often to the side of the head, along the boards to players in their offensive zone without puck possession. Head impact severity did not differ between cases where the head was (versus was not) the primary site of contact (p ≥ 0.6). Furthermore, penalties were called in only 4% of cases where the head was the initial point of contact. Accordingly, rules that focus on primary targeting of the head, while important and in need of improved enforcement, offer a limited solution.

How to harness and improve on video analysis for youth rugby player safety: a narrative review

Video analysis is a useful tool for injury surveillance in rugby union. There are few video analysis studies in the professional female game, with most studies published in the male elite/professional settings. Moreover, there is a sparsity of literature in youth rugby settings. The following narrative review outlines the strengths and limitations of the current video analysis literature for injury surveillance in youth rugby union, highlights the importance of video analysis for youth rugby player safety and welfare, and discusses recommendations for using video analysis to inform player safety in youth rugby.

Higher Rates of Head Contacts, Body Checking, and Suspected Injuries in Ringette Than Female Ice Hockey: Time to Ring in Opportunities for Prevention

OBJECTIVE

Ringette and female ice hockey are high participation sports in Canada. Despite policies disallowing body checking, both sports have high injury and concussion rates. This study aimed to compare physical contact (PC), head contact (HC), and suspected injury and concussion incidence rates (IRs) in female varsity ringette and ice hockey.

DESIGN

Cross-sectional.

SETTING

Canadian ice arenas.

PARTICIPANTS

Eighteen Canadian female university ringette and ice hockey tournament/playoff games in the 2018-2019/2019-2020 seasons.

ASSESSMENT OF RISK FACTORS

Game video-recordings were analyzed using Dartfish video-analysis software to compare both sports.

MAIN OUTCOME MEASURES

Univariate Poisson regression analyses (adjusted for cluster by team, offset by game-minutes) were used to estimate PC, HC, and suspected injury IRs and incidence rate ratios (IRRs) to compare rates across sports. Proportions of body checks (level 4-5 trunk PC) and direct HC (HC 1 ) penalized were reported.

RESULTS

Analyses of 36 team-games (n = 18 ringette, n = 18 hockey) revealed a 19% lower rate of PCs in ringette than ice hockey {IRR = 0.81 [95% confidence interval (CI), 0.73-0.90]}, but a 98% higher rate of body checking [IRR = 1.98 (95% CI, 1.27-3.09)] compared to ice hockey. Ringette had a 40% higher rate of all HC 1 s [IRR = 1.40 (95% CI, 1.00-1.96)] and a 3-fold higher rate of suspected injury [IRR = 3.11 (95% CI, 1.13-8.60)] than ice hockey. The proportion of penalized body checks and HC 1 s were low across sports.

CONCLUSIONS

Body checking and HC 1 rates were significantly higher in ringette compared to ice hockey, despite rules disallowing both, and very few were penalized. These findings will inform future injury prevention research in ringette and female ice hockey.

Does Increasing the Severity of Penalties Assessed in Association With the "Zero Tolerance for Head Contact" Policy Translate to a Reduction in Head Impact Rates in Youth Ice Hockey?

OBJECTIVE

The risk of concussion is high in Canadian youth ice hockey. Aiming to reduce this burden, in 2011, Hockey Canada implemented a national "zero tolerance for head contact (HC)" policy mandating the penalization of any player HC. In 2018 to 2020, Hockey Canada further amended this HC policy including stricter enforcement of severe HCs. This study aimed to compare HC rates, head impact location, and HC enforcement prepolicy, postpolicy, and after policy amendments in elite U15 Canadian youth ice hockey.

DESIGN

This is a prospective cohort study.

SETTING

A collection of events with the video camera located at the highest point near center ice in public ice hockey arenas in Calgary, Alberta.

PARTICIPANTS

A convenience sample of 10 AA U15 games prepolicy (2008-2009), 8 games postpolicy (2013-2014), and 10 games after policy amendments (2020-2021).

INDEPENDENT VARIABLES

An analysis of 3 cohort years regarding the HC-policy implementation and amendments.

MAIN OUTCOME MEASURES

Using Dartfish video-analysis software, all player contacts and HCs [direct (HC1), indirect (eg, boards, ice) (HC2)] were tagged using validated criteria. Univariate Poisson regression clustering by team-game offset by game length (minutes) was used to estimate incidence rates (IR) and incidence rate ratios (IRR) between cohorts.

RESULTS

With additional rule modifications, a 30% reduction in HC1s emerged (IRR 2013-2020 = 0.70, 95% CI, 0.51-0.95). Since the HC-policy implementation, HC1s decreased by 24% (IRR 2008-2020 = 0.76, 95% CI, 0.58-0.99). The proportion of HC1s penalized was similar across cohorts (P 2008-2009 = 14.4%; P 2013-2014 = 15.5%; P 2020-2021 = 16.2%).

CONCLUSIONS

The HC-policy amendments have led to decreased HC1 rates. However, referee enforcement can further boost the HC-policy effectiveness. These findings can help future referee training and potential rule modifications to increase player safety nationally.

Evaluating the Effect of Policy Prohibiting Body Checking on Physical Contacts in U15 and U18 Youth Ice Hockey Leagues

OBJECTIVE

To compare physical contacts (PCs) and head contacts (HCs) in nonelite U15 (ages 13-14) and U18 (ages 15-17) ice hockey players in body checking (BC) and non-BC leagues.

DESIGN

Cohort video analysis study.

SETTING

Ice hockey arenas in Calgary, Canada.

PARTICIPANTS

Players from 13 BC and 13 non-BC games at the nonelite U15 and U18 levels (n = 52 total games).

ASSESSMENT OF RISK FACTORS

Games were videotaped and analyzed to compare PC variables between leagues allowing and prohibiting BC.

MAIN OUTCOME MEASURES

Validated methodology for PC type (trunk PC and other types of PC with limb/stick/head), intensity (low and high intensity), and HC. Incidence rate ratios (IRRs) were estimated using Poisson regression (controlling for cluster by team game and offset by player minutes) to compare the incidence of PCs in BC and non-BC games.

RESULTS

The rate of trunk PCs was lower in the non-BC leagues for both U15 (IRR = 0.50, 99% confidence interval [CI]: 0.43-0.58) and U18 (IRR = 0.56, 99% CI: 0.46-0.67) players. This was most significant for BC contacts (U15: IRR = 0.18, 99% CI: 0.11-0.29; U18: IRR = 0.16, 99% CI: 0.08-0.34), although also significant for body contacts (U15: IRR = 0.54, 99% CI: 0.46-0.64; U18: IRR = 0.58, 99% CI: 0.48-0.70), other PCs, (U15: IRR = 0.60, 99% CI: 0.45-0.78; U18: IRR = 0.71, 99% CI: 0.58-0.88), and HCs (U15: IRR = 0.40, 99% CI: 0.22-0.71; U18: IRR = 0.37, 99% CI: 0.25-0.57).

CONCLUSIONS

The incidence of BC was 82% lower in the U15 and 84% lower in U18 levels not allowing BC, with lower HC and other PC rates also in non-BC leagues. These findings demonstrate high adherence with BC policy change in youth ice hockey.

Incidence of Head Contacts, Penalties, and Player Contact Behaviors in Youth Ice Hockey: Evaluating the “Zero Tolerance for Head Contact” Policy Change

Background:

To reduce the risk of concussion in youth ice hockey, Hockey Canada implemented a national “zero tolerance for head contact” (HC) policy in 2011. A previous cohort study revealed higher concussion rates after this implementation in players aged 11 to 14 years. However, it is unknown whether the elevated risk was due to higher HC rates or factors such as increased concussion awareness and reporting.

Purpose:

To compare the rates of primary and secondary HCs and HC policy enforcement in elite U15 ice hockey leagues (players <15 years) before (2008-2009) and after (2013-2014) the zero-tolerance policy change.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

A total of 32 elite U15 games before (n_2008-2009 = 16; 510 players) and after (n_2013-2014 = 16; 486 players) HC policy implementation were video recorded. Videos were analyzed with validated criteria for identifying HC types (primary/direct contact by players [HC1], secondary/indirect contact via boards, glass, or ice surface [HC2]) and other player-to-player contact behavior. Referee-assessed penalties were cross-referenced with the official Hockey Canada casebook, and penalty types were displayed using proportions. Univariate Poisson regression (adjusted for cluster by team game, offset by game length [minutes]) was used to estimate HC incidence rates (IRs) and incidence rate ratios (IRRs) between cohorts.

Results:

A total of 506 HCs were analyzed, 261 before HC policy implementation (IR, 16.6/100 team minutes) and 245 after implementation (IR, 15.5/100 team minutes). The HC1 rate (IRR, 1.05; 95% CI, 0.86-1.28) and HC2 rate (IRR, 0.74; 95% CI, 0.50-1.11) did not significantly differ before versus after implementation. Only 12.0% and 13.6% of HC1s were penalized pre- and postimplementation, respectively. Before implementation, HC1s were commonly penalized as roughing or elbowing penalties (59%), while after implementation, HC1s were penalized with the HC penalty (76%), and only 8% as roughing or elbowing.

Conclusion:

Despite implementation of the “zero tolerance for HC” policy, there was no difference in the rate of HC1s and HC2s or the proportion of HC1 penalized from before to after implementation. This research is instrumental in informing Hockey Canada’s future referee training and rule enforcement modifications.

Effects of Caffeine on Exertion, Skill Performance, and Physicality in Ice Hockey

PURPOSE

To determine the effects of low-dose caffeine supplementation (3 mg/kg body mass) consumed 1 h before the experiment on rating of perceived exertion (RPE), skills performance (SP), and physicality in male college ice hockey players.

METHODS

Using a double-blind, placebo-controlled, randomized crossover experimental design, 15 college ice hockey players participated in SP trials and 14 participated in scrimmage (SC) trials on a total of 4 d, with prescribed ice hockey tasks occurring after a 1-h high-intensity practice. In the SP trials, time to complete and error rate for each drill of the validated Western Hockey League Combines Testing Standard were recorded. Peak head accelerations, trunk contacts, and offensive performance were quantified during the SC trials using accelerometery and video analysis. RPE was assessed in both the SP and SC trials.

RESULTS

RPE was significantly greater in the caffeine (11.3 [2.0]) than placebo (9.9 [1.9]) condition postpractice (P = .002), with a trend toward greater RPE in caffeine (16.9 [1.8]) than placebo (15.7 [2.8]) post-SC (P = .05). There was a greater number of peak head accelerations in the caffeine (4.35 [0.24]) than placebo (4.14 [0.24]) condition (P = .028). Performance times, error rate, and RPE were not different between intervention conditions during the SP trials (P > .05).

CONCLUSIONS

A low dose of caffeine has limited impact on sport-specific skill performance and RPE but may enhance physicality during ice hockey SCs.

The Effect of the "Zero Tolerance for Head Contact" Rule Change on the Risk of Concussions in Youth Ice Hockey Players

BACKGROUND

Ice hockey is a popular winter sport in Canada. Concussions account for the greatest proportion of all injuries in youth ice hockey. In 2011, a policy change enforcing "zero tolerance for head contact" was implemented in all leagues in Canada.

PURPOSE

To determine if the risk of game-related concussions and more severe concussions (ie, resulting in >10 days of time loss) and the mechanisms of a concussion differed for Pee Wee class (ages 11-12 years) and Bantam class (ages 13-14 years) players after the 2011 "zero tolerance for head contact" policy change compared with players in similar divisions before the policy change.

STUDY DESIGN

Cohort study; Level of evidence, 3.

METHODS

The retrospective cohort included Pee Wee (most elite 70%, 2007-2008; n = 891) and Bantam (most elite 30%, 2008-2009; n = 378) players before the rule change and Pee Wee (2011-2012; n = 588) and Bantam (2011-2012; n = 242) players in the same levels of play after the policy change. Suspected concussions were identified by a team designate and referred to a sport medicine physician for diagnosis. Incidence rate ratios (IRRs) were estimated based on multiple Poisson regression analysis, controlling for clustering by team and other important covariates and offset by game-exposure hours. Incidence rates based on the mechanisms of a concussion were estimated based on univariate Poisson regression analysis.

RESULTS

The risk of game-related concussions increased after the head contact rule in Pee Wee (IRR, 1.85; 95% CI, 1.20-2.86) and Bantam (IRR, 2.48; 95% CI, 1.17-5.24) players. The risk of more severe concussions increased after the head contact rule in Pee Wee (IRR, 4.12; 95% CI, 2.00-8.50) and Bantam (IRR, 7.91; 95% CI, 3.13-19.94) players. The rates of concussions due to body checking and direct head contact increased after the rule change.

CONCLUSION

The "zero tolerance for head contact" policy change did not reduce the risk of game-related concussions in Pee Wee or Bantam class ice hockey players. Increased concussion awareness and education after the policy change may have contributed to the increased risk of concussions found after the policy change.

Effect of the look-up line on the gaze and head orientation of elite ice hockey players

A "look-up line" (LUL) has been proposed for ice hockey, which is an orange 1 m (40') warning line (WL) painted on the ice at the base of the boards. The LUL purports to provide an early warning to players to keep their head up prior to and as they are being checked. We determined if players looked up more on a rink with the LUL compared to a traditional Control rink. Elite offensive (O) and defensive (D) players competed 1 vs. 1, while wearing an eye tracker that recorded their quiet eye (QE) and fixation and tracking (F-T) and an electrogoniometer that measured head angle. External cameras recorded skate duration during four skate phases: P1 preparation, P2 decision-making, P3 cut to boards, P4 contact. The QE was the final fixation prior to contact between O and D as they skated towards and across the WL during P3 and P4. Skate phase durations (%) did not differ by rink or rink by position. More QE and F-T occurred on the WL on the LUL rink than on the Control. The expected increase in head angle on the LUL rink did not occur during P3 or P4. Post-hoc results also showed O and D skated further from the boards on the LUL rink, suggesting the players preferred to control the puck on white ice, rather than the orange colour of the LUL rink. More research is needed to determine if these results apply to the competitive setting.

The Incidence and Types of Physical Contact Associated with Body Checking Regulation Experience in 13-14 Year Old Ice Hockey Players

BACKGROUND

Ice hockey has one of the highest sport participation and injury rates in youth in Canada. Body checking (BC) is the predominant mechanism of injury in leagues in which it is permitted. The objectives of this study were to determine whether the incidence and types of physical contact differ for Bantam players (aged 13-14 years) who were exposed to BC at Pee Wee level (aged 11-12 years) in Calgary, Alberta versus Bantam players who were not exposed to BC at Pee Wee level in Québec City, Québec. All teams were exposed to BC at bantam level;

METHODS

A cohort study was conducted in Québec City and Calgary. Sixteen games for Calgary and 15 for Québec City were randomly selected and analysed with a validated observation system to quantify five intensities of physical contact and to observe different types of physical contact such as slashing and holding;

RESULTS

A total of 5610 incidences of physical contact with the trunk and 3429 other types of physical contact were observed. Very light intensity trunk contact was more frequent in Calgary (adjusted incidence RR (ARR): 1.71; 95% CI: 1.28-2.29). Holding (ARR: 1.04; 95% CI: 1.02-1.07) and slashing (ARR: 1.38; 95% CI: 1.07-1.77) were more frequent in Calgary;

CONCLUSION

RESULTS suggest that players' physical contacts differ between Bantam leagues in which BC was permitted at Pee Wee level and leagues in which it was not permitted until Bantam level.

Safe-Play Knowledge, Aggression, and Head-Impact Biomechanics in Adolescent Ice Hockey Players

CONTEXT

Addressing safe-play knowledge and player aggression could potentially improve ice hockey sport safety.

OBJECTIVES

To compare (1) safe-play knowledge and aggression between male and female adolescent ice hockey players and (2) head-impact frequency and severity between players with high and low levels of safe-play knowledge and aggression during practices and games.

DESIGN

Cohort study.

SETTING

On field.

PATIENTS OR OTHER PARTICIPANTS

Forty-one male (n = 29) and female (n = 12) adolescent ice hockey players.

INTERVENTION(S)

Players completed the Safe Play Questionnaire (0 = less knowledge, 7 = most knowledge) and Competitive Aggressiveness and Anger Scale (12 = less aggressive, 60 = most aggressive) at midseason. Aggressive penalty minutes were recorded throughout the season. The Head Impact Telemetry System was used to capture head-impact frequency and severity (linear acceleration [g], rotational acceleration [rad/s(2)], Head Impact Technology severity profile) at practices and games.

MAIN OUTCOME MEASURE(S)

One-way analyses of variance were used to compare safe play knowledge and aggression between sexes. Players were categorized as having high or low safe-play knowledge and aggression using a median split. A 2 × 2 mixed-model analysis of variance was used to compare head-impact frequency, and random-intercept general linear models were used to compare head-impact severity between groups (high, low) and event types (practice, game).

RESULTS

Boys (5.8 of 7 total; 95% confidence interval [CI] = 5.3, 6.3) had a trend toward better safe-play knowledge compared with girls (4.9 of 7 total; 95% CI = 3.9, 5.9; F1,36 = 3.40, P = .073). Less aggressive male players sustained significantly lower head rotational accelerations during practices (1512.8 rad/s (2) , 95% CI = 1397.3, 1637.6 rad/s(2)) versus games (1754.8 rad/s (2) , 95% CI = 1623.9, 1896.2 rad/s(2)) and versus high-aggression players during practices (1773.5 rad/s (2) , 95% CI = 1607.9, 1956.3 rad/s (2) ; F1,26 = 6.04, P = .021).

CONCLUSIONS

Coaches and sports medicine professionals should ensure that athletes of all levels, ages, and sexes have full knowledge of safe play and should consider aggression interventions for reducing head-impact severity among aggressive players during practice.