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Objective: To investigate the underlying causes and regional patterns of sudden death in football (soccer) players worldwide to inform and improve existing screening and prevention measures., Methods: From 2014 to 2018 cases of sudden cardiac death (SCD), survived sudden cardiac arrest (SCA) and traumatic sudden death were recorded by media monitoring (Meltwater), a confidential web-based data platform and data synchronisation with existing national Sudden Death Registries (n=16). Inclusion criteria were met when sudden death occurred during football-specific activity or up to 1 hour afterwards. Death during other activities was excluded., Results: A total of 617 players (mean age 34±16 years, 96% men) with sudden death were reported from 67 countries; 142 players (23%) survived. A diagnosis by autopsy or definite medical reports was established in 211 cases (34%). The leading cause in players >35 years was coronary artery disease (76%) and in players ≤35 years was sudden unexplained death (SUD, 22%). In players ≤35 years the leading cause of SCD varied by region: cardiomyopathy in South America (42%), coronary artery anomaly in North America (33%) and SUD in Europe (26%). Traumatic sudden death including commotio cordis occurred infrequently (6%). Cardiopulmonary resuscitation (CPR) resulted in a survival rate of 85% with the use of an automated external defibrillator (AED) compared with 35% without., Conclusions: Regional variation in SCD aetiology should be verified by expansion of national registries and uniform autopsy protocols. Immediate access to an AED at training and competition sites, as well as CPR training for players, coaches and staff members, is needed to improve survival from SCA., Competing Interests: Competing interests: TM is chairman of the Medical Committee of the German FA and UEFA. JD is former chairman of F-MARC. All authors declare that they have no competing interests regarding the aims of the study., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Pain is a common problem among elite athletes and is frequently associated with sport injury. Both pain and injury interfere with the performance of elite athletes. There are currently no evidence-based or consensus-based guidelines for the management of pain in elite athletes. Typically, pain management consists of the provision of analgesics, rest and physical therapy. More appropriately, a treatment strategy should address all contributors to pain including underlying pathophysiology, biomechanical abnormalities and psychosocial issues, and should employ therapies providing optimal benefit and minimal harm. To advance the development of a more standardised, evidence-informed approach to pain management in elite athletes, an IOC Consensus Group critically evaluated the current state of the science and practice of pain management in sport and prepared recommendations for a more unified approach to this important topic., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Background: Sport-related concussion (SRC) is a clinical diagnosis made after a sport-related head trauma. Inconsistency exists regarding appropriate methods for assessing SRC, which focus largely on symptom-scores, neurocognitive functioning and postural stability., Design: Systematic literature review., Data Sources: MEDLINE, EMBASE, PsycINFO, Cochrane-DSR, Cochrane CRCT, CINAHL, SPORTDiscus (accessed July 9, 2016)., Eligibility Criteria for Selecting Studies: Original (prospective) studies reporting on postinjury assessment in a clinical setting and evaluation of diagnostic tools within 2 weeks after an SRC., Results: Forty-six studies covering 3284 athletes were included out of 2170 articles. Only the prospective studies were considered for final analysis (n=33; 2416 athletes). Concussion diagnosis was typically made on the sideline by an (certified) athletic trainer (55.0%), mainly on the basis of results from a symptom-based questionnaire. Clinical domains affected included cognitive, vestibular and headache/migraine. Headache, fatigue, difficulty concentrating and dizziness were the symptoms most frequently reported. Neurocognitive testing was used in 30/33 studies (90.9%), whereas balance was assessed in 9/33 studies (27.3%)., Summary/conclusions: The overall quality of the studies was considered low. The absence of an objective, gold standard criterion makes the accurate diagnosis of SRC challenging. Current approaches tend to emphasise cognition, symptom assessment and postural stability with less of a focus on other domains of functioning. We propose that the clinical assessment of SRC should be symptom based and interdisciplinary. Whenever possible, the SRC assessment should incorporate neurological, vestibular, ocular motor, visual, neurocognitive, psychological and cervical aspects., Competing Interests: Competing interests: KJS has received speaking honoraria for presentations at scientific meetings. She is a physiotherapy consultant at Evidence Sport and Spinal Therapy and for many athletic teams. RJE is co-chair of the NHL/NHLPA Concussion Subcommittee, Chair of the MLS Concussion Committee, and a neuropsychological consultant to Princeton University and the US Soccer Federation. He receives financial compensation for each of these activities. He is engaged in the practice of clinical neuropsychology and occasionally serves as an expert in medico-legal cases involving TBI and SRC. He has received speaking honoraria for presentations at scientific meetings. GSS is a full-time employee of the Vanderbilt University Medical Center. He is a consulting neuropsychologist for the NHL Nashville Predators, NFL Tennessee Titans and several collegiate athletic teams, with all fees paid to institution. He is also a member of the ImPACT Scientific Advisory Board, and receives expense reimbursements for attendance at board meetings. He has received speaking honoraria for presentations at scientific meetings., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Objective: Systematic review of possible long-term effects of sports-related concussion in retired athletes., Data Sources: Ten electronic databases., Study Selection: Original research; incidence, risk factors or causation related to long-term mental health or neurological problems; individuals who have suffered a concussion; retired athletes as the subjects and possible long-term sequelae defined as > 10 years after the injury., Data Extraction: Study population, exposure/outcome measures, clinical data, neurological examination findings, cognitive assessment, neuroimaging findings and neuropathology results. Risk of bias and level of evidence were evaluated by two authors., Results: Following review of 3819 studies, 47 met inclusion criteria. Some former athletes have depression and cognitive deficits later in life, and there is an association between these deficits and multiple prior concussions. Former athletes are not at increased risk for death by suicide (two studies). Former high school American football players do not appear to be at increased risk for later life neurodegenerative diseases (two studies). Some retired professional American football players may be at increased risk for diminishment in cognitive functioning or mild cognitive impairment (several studies), and neurodegenerative diseases (one study). Neuroimaging studies show modest evidence of macrostructural, microstructural, functional and neurochemical changes in some athletes., Conclusion: Multiple concussions appear to be a risk factor for cognitive impairment and mental health problems in some individuals. More research is needed to better understand the prevalence of chronic traumatic encephalopathy and other neurological conditions and diseases, and the extent to which they are related to concussions and/or repetitive neurotrauma sustained in sports., Competing Interests: Competing interests: GTM has been reimbursed by the government,professional scientific bodies and commercial organisations for discussing orpresenting research relating to mild TBI at meetings, scientific conferencesand symposiums. He serves as an Unaffiliated Neurotrauma Consultant for theNational Football League. He has received funding from General ElectricCompany, acting through its GE Healthymagination unit. He is also a subcontractPI on The NCAA-DOD Grand Alliance-Concussion Assessment, Research and Education(CARE Consortium). AG has a clinical practice in neuropsychology involvingindividuals who have sustained sport-related concussion (including current andformer athletes). He has operated as a contracted concussion consultant to theAustralian Rugby Union(ARU) from July 2016. He has received travel funding fromthe Australian Football League (AFL) to present at the Concussion in FootballConference in 2013. Previous grant funding includes the NSW Sporting InjuriesCommittee, the Brain Foundation (Australia), and the Hunter Medical ResearchInstitute (HMRI), supported by Jennie Thomas. He is currently funded throughthe HMRI, supported by Anne Greaves, and the University of Newcastle’s PriorityResearch Centre for Stroke and Brain Injury. KS is a physiotherapy consultantat Evidence Sport and Spinal Therapy in Calgary, Alberta, Canada. She hasreceived research grant support through the University of Calgary from theAlberta Children’s Hospital Research Institute, Hotchkiss Brain Institute andthe Canada Foundation for Innovation (including matching funds through theProvince of Alberta). She is a faculty member at the Sport Injury PreventionResearch Centre, which is one of the International Research Centres forPrevention of Injury and Protection of Athlete Health supported by theInternational Olympic Committee (IOC). KMG serves on the NCAA ConcussionProtocol Subcommittee as the Atlantic Coast Conference representative. He isalso a member of the USA Soccer Concussion Committee. JB supervises a TBIresearch laboratory which has received grant funding from pharmaceutical andindustry sponsors and the National Institutes of Health. He has receivedconsulting fees from industry and royalties from intracranial surgeryinstrumentation and has been a consultant for AIBA, NCAA, as well as providingexpert witness testimony for legal cases and the NCAA, and received speaker’shonoraria. He is the chairman of the Medical Advisory Board of Pop WarnerFootball, which is a non-compensated position. RCC serves as aconsultant/advisor to the National Football League Head, Neck and SpineCommittee and National Operating Committee on Standards for Athletic Equipment.He is Medical Director of Concussion Legacy Foundation and receives royaltiesfrom Houghton Mifflin. RC has a clinical and consulting practice in forensicneuropathology, including postmortem neuropathological interpretation ofindividuals who have sustained various types of traumatic brain injury. Hereceives salary support from the Lieber Institute for Brain Development, andsubcontracts with the NIH Neurobiobank at the University of Maryland forneuropathology interpretation. MT has been reimbursed for his travel andaccommodation expenses by conference and seminar organisers internationallywhen invited to speak on concussion and concussion-related topics. In situationswhere the organisers have been unable to provide financial support, theInternational Concussion and Head Injury Research Foundation (ICHIRF) hasreimbursed the cost of his travel and accommodation for attendance at theseevents. He is Medical Director of ICHIRF which receives research funding fromGodolphin Racing, the Injured Jockeys Fund, the NFL and private sponsors. Hedoes not receive any salary from ICHIRF, apart from the expenses mentionedabove. BDJ acts as an Unaffiliated Neurotrauma Consultant for theNational Football League, serves on the NFL Players Association Health andSafety Committee and is a Medical Advisory Physician for NFL Player Benefits. CRhas been reimbursed by professional scientific organisations and commercialentities for presenting research findings on sport-related concussion and mildtraumatic brain injury. He has had a clinical and consulting practice inneuropsychology including forensic neuropsychology, closed to new cases in July2016. He has received no salary support, or any other type of support, for hisresearch on sport-related concussion or brain injury in general. GI has beenreimbursed by the government, professional scientific bodies and commercialorganisations for discussing or presenting research relating to mild TBI andsport-related concussion at meetings, scientific conferences and symposiums. Hehas a clinical and consulting practice in forensic neuropsychology involvingindividuals who have sustained mild TBIs (including professional athletes). Hehas been a principal investigator and co-investigator on federal and industrygrants on topics relating to mild traumatic brain injury, neuropsychologicalassessment and depression. He has received consulting fees from pharmaceuticalcompanies. He receives royalties for books and one neuropsychological test. Hehas received research funding from several test publishing companies, includingImPACT Applications, CNS Vital Signs and Psychological Assessment Resources (PAR).He acknowledges unrestricted philanthropic support from the Mooney-ReedCharitable Foundation and ImPACT Applications. He previously served as acontractor in the area of TBI research through General Dynamics for the Defenseand Veterans Brain Injury Center within the US Department of Defense. Hereceives salary support for chairing the Brain and Behavior committee for theHarvard Integrated Program to Protect and Improve the Health of NFLPA Members., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

The Concussion Recognition Tool 5 (CRT5) is the most recent revision of the Pocket Sport Concussion Assessment Tool 2 that was initially introduced by the Concussion in Sport Group in 2005. The CRT5 is designed to assist non-medically trained individuals to recognise the signs and symptoms of possible sport-related concussion and provides guidance for removing an athlete from play/sport and to seek medical attention. This paper presents the development of the CRT5 and highlights the differences between the CRT5 and prior versions of the instrument., Competing Interests: Competing interests: For full author disclosures and competing interests see the online supplementary folder ICMJE forms on the BJSM website (http://dx.doi.org/10.1136/bjsports-2017-097508)., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

This article presents the Child Sport Concussion Assessment Tool 5th Edition (Child SCAT5). The Sport Concussion Assessment Tool was introduced in 2004, following the 2nd International Conference on Concussion in Sport in Prague, Czech Republic. Following the 4th International Consensus Conference, held in Zurich, Switzerland, in 2012, the SCAT 3rd edition (Child SCAT3) was developed for children aged between 5 and12 years. Research to date was reviewed and synthesised for the 5th International Consensus Conference on Concussion in Sport in Berlin, Germany, leading to the current revision of the test, the Child SCAT5. This article describes the development of the Child SCAT5., Competing Interests: Competing interests: GAD is an honorary member of the Australian Football League Concussion Working Group and has attended meetings organised by sporting organisations including the NFL (USA), National Rugby League (Australia) and FIFA (Switzerland); however, he has not received any payment, research funding or other monies from these groups other than for travel costs. LP is an expert consultant to mdBriefcase in the development of an online concussion education module and has received speaking honoraria/travel expenses for presentations at scientific meetings. KJS has received speaking honoraria for presentations at scientific meetings. She is a physiotherapy consultant at Evidence Sport and Spinal Therapy in Calgary, Alberta, Canada, and for athletic teams. KOY has received grant funding from NIH and Canadian Institutes of Health Research and book royalties from Guilford Press and Cambridge University Press and has occasionally served as an expert witness in forensic cases; he is President-Elect of the International Neuropsychological Society and a member of the Expert Panel on Acute Diagnosis and Management of Mild Traumatic Brain Injury among Children and Adolescents convened by the Centers for Disease Control and Prevention. RGE is a volunteer co-chairman of the NFL Head Neck and Spine Medical Committee. RJE is a consultant to the NHL, Major League Soccer, US Soccer Federation and Princeton University. He has received financial remuneration for these consulting relationships. He has a clinical practice in sport neuropsychology and serves as an expert (neuropsychology, sport neuropsychology) in medico-legal cases involving traumatic brain injury. He at times has received honoraria and reimbursement of expenses to attend professional meetings. MM is Consultant Sport and Exercise Medicine Physician at Olympic Park Sports Medicine Centre, Team Doctor—Hawthorn football club (Australian Football League(AFL)). AFL research grant—funding for research program on concussion in AFL (collaboration between the AFL and the Florey Institute of Neuroscience & Mental Health). Shareholder—Olympic Park Sports Medicine Centre. IOC—travel and accommodation paid as part of Ad Hoc Committee to evaluate rule changes in boxing. FIFA—Travel and accommodation paid as part of International Concussion in Sport Group. AFL—support for travel to NFL concussion ‘think tank’ August 2014. CogState Pty Ltd—free access to computerised neuropsychological testing program for research purposes. AFL Doctors Association—paid role as executive officer. Honorary member of the Australian Rugby Union Concussion Advisory Group; World Rugby Concussion working group; Concussion in AFL working group; AFL Concussion Scientific Committee and Member and the International Olympic Committee ad hoc group to evaluate rule change in boxing. AS is an unaffiliated neurotrauma consultant, the NFL . GLI acknowledges philanthropic research support from the Mooney-Reed Charitable Foundation and ImPACT Applications, Inc. He has a medical-legal consulting practice, including expert testimony, in the area of neuropsychology and mild traumatic brain injury. PMcC is a co-investigator, collaborator, or consultant on grants relating to mild TBI funded by several governmental organizations. He is directly employed by the National Health & Medical Research Council of Australia and is based at the Florey Institute of Neuroscience and Mental Health. He is Co-Chair of the Australian Centre for Research into Sports Injury and its Prevention (ACRISP), which is one of the International University Research Centres for Prevention of Injury and Protection of Athlete Health supported by the International Olympic Committee (IOC). He is co-chair of the International Concussion in Sport Group and is a member of the scientific advisory boards of the International Concussion & Head Injury Research Foundation (London, UK) and the Sports Surgery Clinic (Dublin, Ireland). He has a clinical and consulting practice in general and sports neurology. He receives book royalties from McGraw-Hill and was employed in an editorial capacity by the British Medical Journal Publishing Group from 2001 to 2008. He has been reimbursed by the government, professional scientific bodies, and sporting bodies for travel costs related to presenting research on mild TBI and sport-related concussion at meetings, scientific conferences, and symposiums. He received consultancy fees in 2010 from Axon Sports (US) for the development of educational material (which was not renewed) and has received research funding since 2001 from CogState Inc. The Australian Football League funds research at the Florey Institute under a legal memorandum and Dr. McCrory does not receive any money from this industry funded research. Dr. McCrory is a cofounder and shareholder in two biomedical companies (involved in eHealth and Compression garment technologies) but does not hold any individual shares in any company related to concussion or brain injury assessment or technology. He did not receive any form of financial support directly related to this manuscript. WM is Medical Director for the National Hockey League. JP is concussion consultant to South African Rugby’s BokSmart injury prevention programme and a member of World Rugby’s Concussion Advisory Group; both organisations have contributed honoraria towards conference expenses. GAG receives royalties as a test author from Psychological Assessment Resources, receives research funding from the CDC and NIH, receives speaking Honoria for professional lectures, and is on the pediatric mild TBI guidelines panel of the CDC. CCG receives grants/research support from NIH, NCAA, DoD, Today’s and Tomorrow’s Children Fund, UCLA Brain Injury Research Center, UCLA Faculty Grants Program, UCLA Steve Tisch BrainSPORT program, Avanir (research grant 2016-2017), NINDS Neural Analytics SBIR grant (2016-2018)Consultant: NFL-Neurological Care Program, NHLPA, Neural Analytics Inc (2015-16), is on the advisory panel of LoveYourBrain, MLS, NBA, NCAA, USSF, performs medicolegal work 1-2 cases annually, and speaks on the Medical Education Speakers Network.JSK provides consulting to National Basketball Association, National Football League Players' Association, National Hockey League Players' Association, ElMindA, Ltd. VA and JD have nothing to declare., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Aim or Objective: To examine the effectiveness of concussion prevention strategies in reducing concussion risk in sport., Design: Systematic review according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) guidelines., Data Sources: Eleven electronic databases searched and hand-search of references from selected studies., Eligibility Criteria for Selecting Studies: The following were the study inclusion criteria: (1) contained original human research data; (2) investigated an outcome of concussion or head impact; (3) evaluated a concussion prevention intervention; (4) included sport participants; (5) analytical study designand (6) peer-reviewed. The following were the exclusion criteria: (1) review articles, case series or case studies and (2) not in English., Results: The studies selected (n=48) provided evidence related to protective gear (helmets, headgear, mouthguards) (n=25), policy and rule changes (n=13) and other interventions (training, education, facilities) (n=10). Meta-analyses demonstrate a combined effect of a 70% reduction (incidence rate ratio (IRR)=0.3 (95% CI: 0.22 to 0.41)) in concussion risk in youth ice hockey leagues where policy disallows body checking, and the point estimate (IRR=0.8 (95% CI: 0.6 to 1.1)) suggests a protective effect of mouthguards in contact and collision sport (basketball, ice hockey, rugby)., Summary/conclusions: Highlights include a protective effect of helmets in skiing/snowboarding and the effectiveness of policy eliminating body checking in youth ice hockey. Future research should examine mouthguards in contact sport, football helmet padding, helmet fit in collision sport, policy limiting contact practice in youth football, rule enforcement to reduce head contact in ice hockey and soccer, ice surface size and board/glass flexibility in ice hockey and training strategies targeting intrinsic risk factors (eg, visual training)., Systematic Review Registration: PROSPERO 2016:CRD42016039162., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Competing Interests: Competing interests: For full author disclosures and competing interests see the online supplementary folder ICMJE forms on the BJSM website (http://dx.doi.org/10.1136/bjsports-2017-097699).

This paper presents the Sport Concussion Assessment Tool 5th Edition (SCAT5), which is the most recent revision of a sport concussion evaluation tool for use by healthcare professionals in the acute evaluation of suspected concussion. The revision of the SCAT3 (first published in 2013) culminated in the SCAT5. The revision was based on a systematic review and synthesis of current research, public input and expert panel review as part of the 5th International Consensus Conference on Concussion in Sport held in Berlin in 2016. The SCAT5 is intended for use in those who are 13 years of age or older. The Child SCAT5 is a tool for those aged 5-12 years, which is discussed elsewhere., Competing Interests: Competing interests: For full author disclosures and competing interests see the online supplementary folder ICMJE forms on the BJSM website (http://dx.doi.org/10.1136/bjsports-2017-097506)., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

The purpose of this paper is to summarise the methodology for the 5th International Consensus Conference on Concussion in Sport. The 18 months of preparation included engagement of a scientific committee, an expert panel of 33 individuals in the field of concussion and a modified Delphi technique to determine the primary questions to be answered. The methodology also involved the writing of 12 systematic reviews to inform the consensus conference and submission and review of scientific abstracts. The meeting itself followed a 2-day open format, a 1-day closed expert panel meeting and two additional half day meetings to develop the Concussion Recognition Tool 5 (Pocket CRT5), Sport Concussion Assessment Tool 5 (SCAT5) and Child SCAT5., Competing Interests: Competing interests: WHM is the medical director of the National Hockey League. He has received research grant support through the University of Calgary from the Canadian Institutes of Health Research, Alberta Innovates Health Solutions, the FIFA, Alberta Children’s Hospital Research Institute and the Hotchkiss Brain Institute. He is the founding chair of the Sport Injury Prevention Research Centre, which is one of the International Research Centres for Prevention of Injury and Protection of Athlete Health supported by the IOC. He has a clinical consulting practice in sport medicine at the University of Calgary Sport Medicine Centre. He is an expert group member of the IOC Medical Commission and has received travel funding in that capacity. KJS is a physiotherapy consultant at Evidence Sport and Spinal Therapy in Calgary, Alberta, Canada. She has received honoraria for speaking at various conferences. She has received research grant support through the University of Calgary from the Alberta Children’s Hospital Research Institute, Hotchkiss Brain Institute and the Canada Foundation for Innovation (including matching funds through the Province of Alberta). She is a faculty member at the Sport Injury Prevention Research Centre, within is one of the International Research Centres for Prevention of Injury and Protection of Athlete Health supported by the IOC. CFF is a member of World Rugby’s Independent Expert Panel on Concussion. She was not involved in any other aspects of the International Consensus Conference on Concussion in Sport except for the planning for the Delphi study and review and editing of the manuscript. PM is a coinvestigator, collaborator, or consultant on grants relating to mild TBI funded by several governmental organisations. He is directly employed by the National Health and Medical Research Council of Australia and is based at the Florey Institute of Neuroscience and Mental Health. He is co-chair of the Australian Centre for Research into Sports Injury and its Prevention (ACRISP), which is one of the International University Research Centres for Prevention of Injury and Protection of Athlete Health supported by the IOC. He is co-chair of the International Concussion in Sport Group. He has a clinical and consulting practise in general and sports neurology. He receives book royalties from McGraw-Hill and was employed in an editorial capacity by the British Medical Journal Publishing Group from 2001 to 2008. He has been reimbursed by the government, professional scientific bodies and sporting bodies for travel costs related to presenting research on mild TBI and sport-related concussion at meetings, scientific conferences and symposiums. He received consultancy fees in 2010 from Axon Sports (US) for the development of educational material (which was not renewed) and has received research funding since 2001 from Cogstate Inc. He has not received any research funding, salary or other monies from the Australian Football League, FIFA or the NFL. The Australian Football League funds research at the Florey Institute under a legal memorandum and PM does not receive any money from this industry-funded research. PM is a cofounder and shareholder in two biomedical companies (involved in eHealth and Compression garment technologies) but does not hold any individual shares in any company related to concussion or brain injury assessment or technology., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Objectives: Various definitions for concussion have been proposed, each having its strengths and weaknesses. We reviewed and compared current definitions and identified criteria necessary for an operational definition of sports-related concussion (SRC) in preparation of the 5th Concussion Consensus Conference (Berlin, Germany). We also assessed the role of biomechanical studies in informing an operational definition of SRC., Design: This is a systematic literature review., Data Sources: Data sources include MEDLINE, Embase, Cumulative Index to Nursing and Allied Health Literature, Cochrane Central Register of Clinical Trials and SPORT Discus (accessed 14 September 2016)., Eligibility Criteria for Selecting Studies: Eligibility criteria were studies reporting (clinical) criteria for diagnosing SRC and studies containing SRC impact data., Results: Out of 1601 articles screened, 36 studies were included (2.2%), 14 reported on criteria for SRC definitions and 22 on biomechanical aspects of concussions. Six different operational definitions focusing on clinical findings and their dynamics were identified. Biomechanical studies were obtained almost exclusively on American football players. Angular and linear head accelerations linked to clinically confirmed concussions demonstrated considerable individual variation., Summary/conclusions: SRC is a traumatic brain injury that is defined as a complex pathophysiological process affecting the brain, induced by biomechanical forces with several common features that help define its nature. Limitations identified include that the current criteria for diagnosing SRC are clinically oriented and that there is no gold/standard to assess their diagnostic properties. A future, more valid definition of SRC would better identify concussed players by demonstrating high predictive positive/negative values. Currently, the use of helmet-based systems to study the biomechanics of SRC is limited to few collision sports. New approaches need to be developed to provide objective markers for SRC., Competing Interests: Competing interests: PM is a co-investigator, collaborator or consultant on grants relating to mild TBI funded by several governmental organisations. He is directly employed by the National Health and Medical Research Council of Australia and is based at the Florey Institute of Neuroscience and Mental Health. He is co-chair of the Australian Centre for Research into Sports Injury and its Prevention (ACRISP), which is one of the International University Research Centres for Prevention of Injury and Protection of Athlete Health supported by the International Olympic Committee (IOC). He is co-chair of the International Concussion in Sport Group. He has a clinical and consulting practice in general and sports neurology. He receives book royalties from McGraw-Hill and was employed in an editorial capacity by the British Medical Journal Publishing Group from 2001 to 2008. He has been reimbursed by the government, professional scientific bodies and sporting bodies for travel costs related to presenting research on mild TBI and sports-related concussion at meetings, scientific conferences and symposiums. He received consultancy fees in 2010 from Axon Sports (USA) for the development of educational material (which was not renewed) and has received research funding since 2001 from CogState Inc. He has not received any research funding, salary or other monies from the Australian Football League, FIFA or the National Football League. The Australian Football League funds research at the Florey Institute under a legal memorandum and PM does not receive any money from this industry-funded research. PM is a cofounder and shareholder in two biomedical companies (involved in eHealth and compression garment technologies) but does not hold any individual shares in any company related to concussion or brain injury assessment or technology. He did not receive any form of financial support directly related to this manuscript. NF-D and JD report no conflicts of interest. AM is a self-employed consultant and holds honorary academic appointments. He has been funded as a consultant to undertake research and policy related work for government, sports federations and industry on the topic of safety and injury risk management, including concussion, head injury and helmets. He did not receive any form of financial support directly related to this manuscript. He reports no conflicts of interest. PEV is a neurologist and Chairman of the Steering Commitee of a trial in traumatic brain injury sponsored by EVER Neuro Pharma GmbH. He has been funded as a consultant for EVER Neuro Pharma. He did not receive any form of financial support directly related to this manuscript. He reports no conflicts of interest. JDC is an injury epidemiologist employed by the University Health Network, University of Toronto. He is a professor in the Division of Epidemiology and the Institute of Health Policy, Management and Evaluation at the Dalla Lana School of Public Health, University of Toronto. He has received funding from the Ontario Neurotrauma Foundation to undertake systematic reviews on mild traumatic brain injury and served on the WHO Collaborating Centre Task Force on Mild Traumatic Brain Injury, which received funding from various sources, including traffic insurance companies in North America and Europe. He was retained as an expert witness for the National Hockey League on November 30, 2016. He did not receive any form of financial support related to this manuscript, and has no other conflicts of interest to report. RJE is a consultant to the National Hockey League, Major League Soccer, US Soccer Federation and Princeton University. He receives financial remuneration for these consulting relationships. He has a clinical practice in sport neuropsychology and serves as an expert (neuropsychology and sport neuropsychology) in medico-legal cases involving traumatic brain injury. WM is the Medical Director of the National Hockey League. He has received research grant support through the University of Calgary from the Canadian Institutes of Health Research, Alberta Innovates Health Solutions, the International Football Association (FIFA), Alberta Children’s Hospital Research Institute and the Hotchkiss Brain Institute. He is the founding Chair of the Sport Injury Prevention Research Centre, which is one of the International Research Centres for Prevention of Injury and Protection of Athlete Health supported by the International Olympic Committee (IOC). He has a clinical consulting practice in sport medicine at the University of Calgary Sport Medicine Centre. He is an Expert Group member of the IOC Medical Commission and has received travel funding in that capacity., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Background: FIFA has surveyed match injuries in its tournaments since 1998., Aim: To analyse the incidence and characteristics of match injuries incurred during the 2014 FIFA World Cup in comparison to previous FIFA World Cups., Methods: The chief physicians of the participating teams reported all newly incurred injuries of their players after the match on a standardised report form. 124 (97%) forms were returned., Results: A total of 104 injuries were reported, equivalent to an incidence of 1.68 injuries per match (95% CI 1.36 to 2.00). 64 (63.4%) injuries were caused by contact with another player. Thigh (26; 25%) and head (19; 18%) were the most frequently injured body parts. The most frequent diagnosis was thigh strain (n=18). Five concussions and three fractures to the head were reported. While most thigh strains (15/17; 88.2%) occurred without contact, almost all head injuries (18/19; 94.7%) were caused by contact. 0.97 injuries per match (95% CI 0.72 to 1.22) were expected to result in absence from training or match. Eight injuries were classified as severe. The incidence of match injuries in the 2014 FIFA World Cup was significantly lower than the average of the four preceding FIFA World Cups, both for all injuries (2.34; 95% CI 2.15 to 2.53) and time-loss injuries (1.51; 95% CI 1.37 to 1.65)., Conclusions: The overall incidence of injury during the FIFA World Cups decreased from 2002 to 2014 by 37%. A detailed analysis of the injury mechanism is recommended to further improve prevention strategies., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.)