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StatisticsSummary/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 defining its nature. Limitations identified include that current criteria for diagnosing SRC are clinically oriented, and 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. 3 Bullet statements What is already known?• Over the past 50 years, various definitions of sports-related concussion (SRC) and mild traumatic brain injury (mTBI) have been proposed by individual authors, different research groups and international bodies.• Currently, there is no gold or reference standard for SRC diagnosis, and the diagnostic properties of the various definitions have not been studied.• The different definitions of SRC do not concur with one another, and this variability has likely caused information or diagnostic misclassification bias in past studies on the management and prognosis of SRC. What are the new findings?• Amongst currently available consensus-based definitions of SRC, the consensus statement from the CISG can be considered the opinion leader based on citation statistics.• These consensus-based definitions, however, showed different levels of detail and weighted distinct domains differently. Limitations even in those definitions that provided additional clarifying statements were demonstrated, including the overlap / distinction between SRC and mTBI.• Angular and linear head accelerations linked to clinically confirmed SRC demonstrated considerable individual variation.