{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,6]],"date-time":"2026-06-06T00:42:07Z","timestamp":1780706527197,"version":"3.54.1"},"reference-count":31,"publisher":"SAGE Publications","issue":"3","license":[{"start":{"date-parts":[[2021,3,1]],"date-time":"2021-03-01T00:00:00Z","timestamp":1614556800000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100000024","name":"canadian institutes of health research","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100000024","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100000145","name":"alberta innovates - health solutions","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100000145","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100013053","name":"hotchkiss brain institute","doi-asserted-by":"publisher","id":[{"id":"10.13039\/100013053","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100003206","name":"Alberta Children\u2019s Hospital Foundation","doi-asserted-by":"crossref","id":[{"id":"10.13039\/501100003206","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["journals.sagepub.com"],"crossmark-restriction":true},"short-container-title":["Orthopaedic Journal of Sports Medicine"],"published-print":{"date-parts":[[2021,3,1]]},"abstract":"<jats:sec>\n                    <jats:title>Background:<\/jats:title>\n                    <jats:p>To reduce the risk of concussion in youth ice hockey, Hockey Canada implemented a national \u201czero tolerance for head contact\u201d (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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Purpose:<\/jats:title>\n                    <jats:p>To compare the rates of primary and secondary HCs and HC policy enforcement in elite U15 ice hockey leagues (players &lt;15 years) before (2008-2009) and after (2013-2014) the zero-tolerance policy change.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Study Design:<\/jats:title>\n                    <jats:p>Cohort study; Level of evidence, 3.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods:<\/jats:title>\n                    <jats:p>\n                      A total of 32 elite U15 games before (n\n                      <jats:sub>2008-2009<\/jats:sub>\n                      = 16; 510 players) and after (n\n                      <jats:sub>2013-2014<\/jats:sub>\n                      = 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.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results:<\/jats:title>\n                    <jats:p>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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion:<\/jats:title>\n                    <jats:p>Despite implementation of the \u201czero tolerance for HC\u201d 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\u2019s future referee training and rule enforcement modifications.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1177\/2325967121992375","type":"journal-article","created":{"date-parts":[[2021,3,5]],"date-time":"2021-03-05T04:02:47Z","timestamp":1614916967000},"update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":15,"title":["Incidence of Head Contacts, Penalties, and Player Contact Behaviors in Youth Ice Hockey: Evaluating the \u201cZero Tolerance for Head Contact\u201d Policy Change"],"prefix":"10.1177","volume":"9","author":[{"given":"Rylen A.","family":"Williamson","sequence":"first","affiliation":[{"name":"Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ash T.","family":"Kolstad","sequence":"additional","affiliation":[{"name":"Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maciej","family":"Krolikowski","sequence":"additional","affiliation":[{"name":"Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luc","family":"Nadeau","sequence":"additional","affiliation":[{"name":"Department of Physical Education, Faculty of Education, Universit\u00e9 Laval, Qu\u00e9bec City, Qu\u00e9bec, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Claude","family":"Goulet","sequence":"additional","affiliation":[{"name":"Department of Physical Education, Faculty of Education, Universit\u00e9 Laval, Qu\u00e9bec City, Qu\u00e9bec, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Brent E.","family":"Hagel","sequence":"additional","affiliation":[{"name":"Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada."},{"name":"Alberta Children\u2019s Hospital Research Institute, Calgary, Alberta, Canada."},{"name":"Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada."},{"name":"Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada."},{"name":"O\u2019Brien Institute for Public Health, University of Calgary, Calgary, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carolyn A.","family":"Emery","sequence":"additional","affiliation":[{"name":"Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada."},{"name":"Alberta Children\u2019s Hospital Research Institute, Calgary, Alberta, Canada."},{"name":"Department of Paediatrics, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada."},{"name":"Department of Community Health Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada."},{"name":"O\u2019Brien Institute for Public Health, University of Calgary, Calgary, Canada."}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"179","published-online":{"date-parts":[[2021,3,5]]},"reference":[{"key":"bibr1-2325967121992375","doi-asserted-by":"publisher","DOI":"10.1136\/bjsports-2016-097392"},{"key":"bibr2-2325967121992375","doi-asserted-by":"publisher","DOI":"10.1249\/JSR.0b013e318205e063"},{"key":"bibr3-2325967121992375","doi-asserted-by":"publisher","DOI":"10.1136\/bjsm.2009.063693"},{"key":"bibr4-2325967121992375","unstructured":"Dartfish Video Analysis Software. 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