THE EFFECTIVENESS OF A NATIONAL BODY CHECKING POLICY CHANGE ON REDUCING INJURY RISK IN YOUTH ICE HOCKEY
Bibliographic record
Abstract
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.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.006 | 0.026 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".