THEMATIC ISSUE For Debate: Consensus Injury Definitions in Team Sports Should Focus on Encompassing all Injuries Lisa Hodgson, PhD, MSc,* Conor Gissane, PhD,† Tim J. Gabbett, PhD,‡ and Doug A. King, BN§ Objective: The purpose of this paper is to highlight the most effective method of collecting injury data by using a definition that encompasses all injuries into the data collection system. The definition provides an accurate picture of injury incidence and also allows filtering of records so that data can be reported in a variety of comparable ways. Data Sources/Synthesis: A qualitative review of literature in team sports, plus expert opinion, served as the basis for data collection strategies. Articles were retrieved from SportsDiscus and PubMed using the terms ‘‘sports injury definition’’ and ‘‘injury definition.’’ These terms were searched for the period 1966 to November 2006. Results: One of the major results (from this paper) that supports the use of an all-encompassing injury definition is that 70% to 92% of all injuries sustained fall into the transient category—that is, by only recording injuries that result in missed matches, the majority of injuries are missed and therefore injury rates are underreported. Conclusion: An injury definition should be the most encompassing definition that enables a true, global picture of injury incidence to be seen in participation in any team sport. Key Words: data collection, injury definition, incidence, team sports (Clin J Sport Med 2007;17:188–191) INTRODUCTION Published studies on the incidence of sporting injuries vary in 2 main areas: the definitions used and the meth- odologies undertaken. 1–8 As a consequence of these variations between studies, the results and conclusions obtained often have some important differences. 1,3–5,8–11 Therefore data that are similar in collection, analysis, and methodology are required to enable an appropriate analysis to be conducted. A fundamental process, and typically the first step behind the injury prevention process, is ongoing injury surveillance. 1,5,12 However, this may prove to be elusive as a result of the inconsistencies in the injury definitions used. Variations reported in injury incidence are often the result of data obtained from studies with differing injury definitions. Some focus on purely match injuries or injuries that require only a match to be missed before the injury is included, 9,13–15 whereas others focus on all-encompassing injuries that occur in either match or training participation and do not require time loss to be included. 8,10,16–24 Recording all injuries [including those not requiring lost game/training time (ie, transient injuries)] may place an additional burden on researchers, but it is also likely that recording injuries that only result in missed matches/sessions will underreport the actual incidence of injury. Recording all injuries will also provide answers to questions such as ‘‘What is the injury risk?’’ and ‘‘What is the injury risk for a given unit of exposure?’’ It also will allow planning from a resource–utilization perspective. 25 The formation of standardized injury definitions enables meaningful comparisons for all future injury surveillance data from different sports, countries, and playing levels. The pur- pose of this article is to review the existing literature and pro- pose the argument for an all-encompassing, comprehensive injury data collection for team sports and to demonstrate that it has advantages over definitions that exclude a proportion of all injuries. BACKGROUND The primary aim of any injury surveillance study is to gain an accurate estimation of injury incidence. There are 3 different measures of incidence and 3 target audiences to this question. First, the athlete playing his or her desired sport may wish to know the true risk of obtaining an injury (ie, number of athletes at risk to injured athlete ratio). Second, a scientist may wish to know the epidemiologic incidence versus exposure (match or training), thus expressing incidence as rates rather than risk. Finally, the clinician may wish to determine how many injuries to expect to treat throughout a season. 25 Thus, incidence refers to the number of new injury occurrences in a given time period. Risks and rates can be used in injury surveillance but are not mutually exclusive terms. To be able to answer all 3 questions, all injuries, including those that do not result in any time loss from training or competition (ie, transient injuries) must be recorded. 16,17 Some studies exclude transient injuries, 13 whereas other studies have shown 18,26,27 that the inclusion of injuries that do Submitted for publication November 24, 2006; accepted February 19, 2007. From the *Head of Sports Medicine, The Rugby Football League, Red Hall, Leeds, UK; †Sports Rehabilitation Directorate, Department of Human Sciences, St Mary’s University College, Twickenham, Middlesex, UK; ‡Athlete and Coach Support Services, Queensland Academy of Sport, Queensland, Australia; and §Emergency Department, Otago District Health Board, Dunedin, New Zealand. Reprints: Lisa Hodgson, PhD, MSc, RFL, Red Hall, Red Hall Lane, Leeds, LS17 8NB, UK (e-mail: lisa.hodgson@rfl.uk.com). Copyright Ó 2007 by Lippincott Williams & Wilkins 188 Clin J Sport Med  Volume 17, Number 3, May 2007