Head impact analysis in elite football (soccer)

Abstract

Introduction Trauma related neuropathologies including recent reports involving chronic traumatic encephalopathy (CTE) in 8 soccer players have been concerning. Purposeful sub-concussive head impacts, known as headers, are an integral part of the game. The purpose of this study was to describe dynamic head response and brain tissue strains for front ball-tohead impacts in elite soccer. Methods Video analysis thirteen (13) Champion's League soccer footage was completed to establish reconstruction parameters of head impact events. Analysis of 5 (5) front ball-to-head events were reconstructed using a Hybrid III 50th percentile headform and a pneumatic linear impactor. The University College Dublin Brain Trauma Model was used to calculate maximum principal strain (MPS). Results and discussion Recorded head impact velocities during elite soccer game play were 3.5-23.0 m/s. Most purposeful head-to-ball impacts occurred on the front-temporal region of the head (66.4%) at 0-15 degrees of cervical flexion. There was an average of 1.5 unintentional head impacts and 62.2 headers per game 49.6% of headers occurred at an inbound velocity below 10 m/s. The lowest velocity reconstructed was 4.7 m/s, yielding 12.8 g and 604 rad/s2 for peak resultant linear and rotational accelerations, respectively the MPS for this impact was 0.09. Neurophysiologic changes and functional impairment have been reported in past research on sub-concussive impacts with 5%-15% strain. The mean 0.11 MPS yielded in this study reflects a potential for these changes in elite soccer athletes. Conclusion The main objective of this analysis was to identify impact characteristics and quantify dynamic cerebral response and brain tissue deformation in elite soccer game play. Further research must include cervical muscle activation, the level of play and player position, inbound ball-to-head velocities during different game play events and appropriate impact characteristics to appropriately characterize risk of injury in the attempts of mitigating risk of head injury during soccer game play.