{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,2]],"date-time":"2026-10-02T13:59:10Z","timestamp":1790949550858,"version":"4.1.0"},"reference-count":33,"publisher":"PeerJ","license":[{"start":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T00:00:00Z","timestamp":1785888000000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"A Rackham Pre-Candidate Research Grant from the University of Michigan"},{"name":"philanthropic donation"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"abstract":"<jats:sec>\n                    <jats:title>Introduction<\/jats:title>\n                    <jats:p>Concussion is a traumatic brain injury (TBI) with potential short- and long-term neurological consequences. Recognition of objective concussion signs remains limited. In slap fighting, a combat event involving the exchange of defenseless head contact, concussion signs are visible. The study objective was to examine the frequency of observable signs of concussion among professional slap fighters based on established video review protocols and determine whether participant characteristics predict concussion signs.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Three independent reviewers evaluated publicly available video of professional slap fighting events (Power Slap\u2122; 2023\u20132024) against the National Football League Concussion Protocol, the World Rugby Head Injury Assessment, and International Consensus Guidelines for observable signs of concussion. Signs were recorded for each strike and aggregated across rounds, matches, events, and combatants. Mixed effects logistic regression evaluated associations among pre-slap characteristics and the likelihood of observing a sign of concussion following a strike.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Combatants (60 male, three female) competed across 62 matches in six Power Slap\u2122 events. Of the 61 combatants who received a strike, 46 exhibited at least one sign of concussion. Overall, 29% (82\/280) of strikes resulted in at least one observable sign of concussion, with lower, identical results across protocol guidelines (24%; 66\/280). Signs of concussion were observed in 90% (56\/62) of matches.\n                      <jats:italic>Motor incoordination<\/jats:italic>\n                      (23%; 64\/280),\n                      <jats:italic>blank\/vacant look<\/jats:italic>\n                      (15%; 41\/280), and\n                      <jats:italic>slow to get up<\/jats:italic>\n                      (14%; 40\/280) were the most frequently observed signs.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Observable signs of concussion from professional slap fighting occurred in one-third of strikes and the majority of matches.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.7717\/peerj.21623","type":"journal-article","created":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T08:53:42Z","timestamp":1785920022000},"page":"e21623","source":"Crossref","is-referenced-by-count":1,"title":["Observable signs of concussion in professional slap fighting using established video review protocols for professional sports: frequency, predictors, and implications for public concussion recognition awareness"],"prefix":"10.7717","volume":"14","author":[{"given":"Corey J.","family":"Stewart","sequence":"first","affiliation":[{"name":"Michigan Concussion Center, University of Michigan\u2014Ann Arbor, Ann Arbor, MI, United States of America"},{"name":"Physical Medicine and Rehabilitation, Michigan Medicine, University of Michigan\u2014Ann Arbor, Ann Arbor, MI, United States of America"},{"name":"Michigan Neuroscience Institute, University of Michigan\u2014Ann Arbor, Ann Arbor, MI,  United States of America"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Erik B.","family":"Philipson","sequence":"additional","affiliation":[{"name":"Elson S. College of Medicine, Washington State University, Spokane, WA, United States of America"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jeremy R.","family":"Caspell","sequence":"additional","affiliation":[{"name":"Health Sciences, Thompson Rivers University, Kamloops, British Columbia, Canada"},{"name":"Emergency Medical Services, Alberta Health Services, Calgary, Alberta, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Keilin","family":"Gorman","sequence":"additional","affiliation":[{"name":"Southern Medical Program, University of British Columbia Okanagan, Kelowna, British Columbia, Canada"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Rory A.","family":"Marshall","sequence":"additional","affiliation":[{"name":"Michigan Concussion Center, University of Michigan\u2014Ann Arbor, Ann Arbor, MI, United States of America"},{"name":"Physical Medicine and Rehabilitation, Michigan Medicine, University of Michigan\u2014Ann Arbor, Ann Arbor, MI, United States of America"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jonathan","family":"Lifshitz","sequence":"additional","affiliation":[{"name":"Michigan Concussion Center, University of Michigan\u2014Ann Arbor, Ann Arbor, MI, United States of America"},{"name":"Physical Medicine and Rehabilitation, Michigan Medicine, University of Michigan\u2014Ann Arbor, Ann Arbor, MI, United States of America"},{"name":"Michigan Neuroscience Institute, University of Michigan\u2014Ann Arbor, Ann Arbor, MI,  United States of America"},{"name":"Veteran Administration Ann Arbor Health Care System, Ann Arbor, MI, United States of America"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"4443","published-online":{"date-parts":[[2026,8,5]]},"reference":[{"issue":"1","key":"10.7717\/peerj.21623\/ref-1","doi-asserted-by":"publisher","first-page":"39","DOI":"10.1186\/s13102-022-00430-4","article-title":"The pentagram of concussion: an observational analysis that describes five overt indicators of head trauma","volume":"14","author":"Beitchman","year":"2022","journal-title":"BMC Sports Science, Medicine and Rehabilitation"},{"key":"10.7717\/peerj.21623\/ref-2","article-title":"Brain Injury Association of America","author":"Brain Injury Awareness\u00a0Survey","year":"2025"},{"issue":"1","key":"10.7717\/peerj.21623\/ref-3","doi-asserted-by":"publisher","first-page":"e20154635","DOI":"10.1542\/peds.2015-4635","article-title":"Sports- and recreation-related concussions in US Youth","volume":"138","author":"Bryan","year":"2016","journal-title":"Pediatrics"},{"key":"10.7717\/peerj.21623\/ref-4","article-title":"Report to Congress on Traumatic Brain Injury in the United States: Epidemiology and Rehabilitation","author":"Center for Disease Control and Prevention","year":"2025"},{"key":"10.7717\/peerj.21623\/ref-5","author":"Dana White announces the launch\u00a0of Power Slap \u2014UFC","year":"2022"},{"issue":"20","key":"10.7717\/peerj.21623\/ref-6","doi-asserted-by":"publisher","first-page":"1264","DOI":"10.1136\/bjsports-2019-100628","article-title":"International consensus definitions of video signs of concussion in professional sports","volume":"53","author":"Davis","year":"2019","journal-title":"British Journal of Sports Medicine"},{"issue":"2","key":"10.7717\/peerj.21623\/ref-7","doi-asserted-by":"publisher","first-page":"475","DOI":"10.1007\/s11682-020-00417-0","article-title":"A global collaboration to study intimate partner violence-related head trauma: the ENIGMA consortium IPV working group","volume":"15","author":"Esopenko","year":"2021","journal-title":"Brain Imaging and Behavior"},{"key":"10.7717\/peerj.21623\/ref-8","article-title":"Concussion","volume-title":"StatPearls","author":"Ferry","year":"2025"},{"issue":"1","key":"10.7717\/peerj.21623\/ref-9","doi-asserted-by":"publisher","first-page":"29","DOI":"10.1186\/s40798-017-0097-9","article-title":"Evidence of concussion signs in national rugby league match play: a video review and validation study","volume":"3","author":"Gardner","year":"2017","journal-title":"Sports Medicine - Open"},{"issue":"4","key":"10.7717\/peerj.21623\/ref-10","doi-asserted-by":"publisher","first-page":"1270","DOI":"10.1177\/1524838019850623","article-title":"Battered and brain injured: traumatic brain injury among women survivors of intimate partner violence-a scoping review","volume":"23","author":"Haag","year":"2022","journal-title":"Trauma, Violence, & Abuse"},{"issue":"7","key":"10.7717\/peerj.21623\/ref-11","doi-asserted-by":"publisher","first-page":"990","DOI":"10.1089\/jwh.2018.7299","article-title":"Battered and brain injured: assessing knowledge of traumatic brain injury among intimate partner violence service providers","volume":"28","author":"Haag","year":"2019","journal-title":"Journal of Women\u2019s Health"},{"issue":"1","key":"10.7717\/peerj.21623\/ref-12","doi-asserted-by":"publisher","first-page":"15","DOI":"10.1136\/bjsports-2012-091941","article-title":"American Medical Society for Sports Medicine position statement: concussion in sport","volume":"47","author":"Harmon","year":"2013","journal-title":"British Journal of Sports Medicine"},{"key":"10.7717\/peerj.21623\/ref-13","article-title":"Neck and spine committee\u2019s concussion diagnosis and management protocol","author":"Head","year":"2025"},{"issue":"3","key":"10.7717\/peerj.21623\/ref-14","doi-asserted-by":"publisher","first-page":"194","DOI":"10.1249\/JSR.0000000000000157","article-title":"Effect of neurocognition and concussion on musculoskeletal injury risk","volume":"14","author":"Herman","year":"2015","journal-title":"Current Sports Medicine Reports"},{"issue":"9","key":"10.7717\/peerj.21623\/ref-15","doi-asserted-by":"publisher","first-page":"1687","DOI":"10.1249\/MSS.0b013e31819fcd1b","article-title":"Brain injury forces of moderate magnitude elicit the fencing response","volume":"41","author":"Hosseini","year":"2009","journal-title":"Medicine and Science in Sports and Exercise"},{"issue":"11","key":"10.7717\/peerj.21623\/ref-16","doi-asserted-by":"publisher","first-page":"981","DOI":"10.1016\/j.jsams.2017.04.019","article-title":"Misunderstandings of concussion within a youth rugby population","volume":"20","author":"Kearney","year":"2017","journal-title":"Journal of Science and Medicine in Sport"},{"issue":"9339","key":"10.7717\/peerj.21623\/ref-17","doi-asserted-by":"publisher","first-page":"1083","DOI":"10.1016\/S0140-6736(02)11133-0","article-title":"The world report on violence and health","volume":"360","author":"Krug","year":"2002","journal-title":"The Lancet"},{"issue":"12","key":"10.7717\/peerj.21623\/ref-18","doi-asserted-by":"publisher","first-page":"1435","DOI":"10.1001\/jamasurg.2024.2605","article-title":"Video analysis of concussion among slap fighting athletes","volume":"159","author":"Lavadi","year":"2024","journal-title":"JAMA Surgery"},{"issue":"6","key":"10.7717\/peerj.21623\/ref-19","doi-asserted-by":"publisher","first-page":"531","DOI":"10.1080\/02699052.2026.2629943","article-title":"Observed but overlooked (possible) concussions in slap fighting\u2014a video analysis study","volume":"40","author":"Lima","year":"2026","journal-title":"Brain Injury"},{"key":"10.7717\/peerj.21623\/ref-20","doi-asserted-by":"publisher","DOI":"10.1097\/HTR.0000000000001071","article-title":"Video-based analysis of suspected concussions in slap fighting: incidence and characteristics","author":"Lima","year":"2025","journal-title":"The Journal of Head Trauma Rehabilitation"},{"key":"10.7717\/peerj.21623\/ref-21","doi-asserted-by":"publisher","first-page":"1","DOI":"10.3389\/fspor.2021.655890","article-title":"Education, political party, and football viewership predict americans\u2019 attention to news about concussions in sports","volume":"3","author":"Lindner","year":"2021","journal-title":"Frontiers in Sports and Active Living"},{"issue":"5","key":"10.7717\/peerj.21623\/ref-22","doi-asserted-by":"publisher","first-page":"423","DOI":"10.1177\/19417381211011446","article-title":"Epidemiology of concussion in the national football league, 2015\u20132019","volume":"13","author":"Mack","year":"2021","journal-title":"Sports Health"},{"key":"10.7717\/peerj.21623\/ref-23","article-title":"Second impact syndrome","volume-title":"StatPearls","author":"May","year":"2025"},{"key":"10.7717\/peerj.21623\/ref-24","article-title":"Power Slap Official TikTok Page. TikTok","author":"Power\u00a0Slap","year":"2026"},{"key":"10.7717\/peerj.21623\/ref-25","article-title":"Power Slap Official Instagram Page. Instagram","author":"Power Slap","year":"2026"},{"key":"10.7717\/peerj.21623\/ref-26","article-title":"R: The R Project for Statistical Computing","author":"R Core Team","year":"2025"},{"issue":"3","key":"10.7717\/peerj.21623\/ref-27","doi-asserted-by":"publisher","first-page":"e2268","DOI":"10.7759\/cureus.2268","article-title":"Parent knowledge and perceptions of concussion related to youth football","volume":"10","author":"Rieger","year":"2018","journal-title":"Cureus"},{"key":"10.7717\/peerj.21623\/ref-28","doi-asserted-by":"publisher","first-page":"e39061","DOI":"10.2196\/39061","article-title":"Public awareness of the fencing response as an indicator of traumatic brain injury: quantitative study of twitter and wikipedia data","volume":"7","author":"Roe","year":"2023","journal-title":"JMIR Formative Research"},{"key":"10.7717\/peerj.21623\/ref-29","article-title":"Power Slap","author":"Rules","year":"2025"},{"issue":"2","key":"10.7717\/peerj.21623\/ref-30","doi-asserted-by":"publisher","first-page":"194","DOI":"10.1001\/jamaneurol.2023.4618","article-title":"Trends in traumatic brain injury mortality in the US","volume":"81","author":"Shaik","year":"2024","journal-title":"JAMA Neurology"},{"issue":"1","key":"10.7717\/peerj.21623\/ref-31","doi-asserted-by":"publisher","first-page":"570","DOI":"10.32614\/RJ-2021-053","article-title":"Reproducible summary tables with the gtsummary package","volume":"13","author":"Sjoberg","year":"2021","journal-title":"The R Journal"},{"issue":"23","key":"10.7717\/peerj.21623\/ref-32","doi-asserted-by":"publisher","first-page":"e109603","DOI":"10.1136\/bjsports-2024-109603","article-title":"Role of video review for sport-related concussion identification: a systematic review","volume":"59","author":"Townsend","year":"2025","journal-title":"British Journal of Sports Medicine"},{"key":"10.7717\/peerj.21623\/ref-33","author":"World Rugby Head Injury Assessment (HIA)\u00a0Protocol","year":"2025"}],"container-title":["PeerJ"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/peerj.com\/articles\/21623.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/peerj.com\/articles\/21623.xml","content-type":"application\/xml","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/peerj.com\/articles\/21623.html","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/peerj.com\/articles\/21623.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,5]],"date-time":"2026-08-05T08:53:45Z","timestamp":1785920025000},"score":1,"resource":{"primary":{"URL":"https:\/\/peerj.com\/articles\/21623"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,5]]},"references-count":33,"alternative-id":["10.7717\/peerj.21623"],"URL":"https:\/\/doi.org\/10.7717\/peerj.21623","archive":["CLOCKSS","LOCKSS","Portico"],"relation":{},"ISSN":["2167-8359"],"issn-type":[{"value":"2167-8359","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,5]]},"article-number":"e21623"}}