Please cite this article in press as: McIntosh AS, et al. An assessment of the utility and functionality of wearable head impact sensors in Australian Football. J Sci Med Sport (2019), https://doi.org/10.1016/j.jsams.2019.02.004 ARTICLE IN PRESS G Model JSAMS-2034; No. of Pages 6 Journal of Science and Medicine in Sport xxx (2019) xxx–xxx Contents lists available at ScienceDirect Journal of Science and Medicine in Sport j our na l ho me page: www.elsevier.com/locate/jsams Original research An assessment of the utility and functionality of wearable head impact sensors in Australian Football Andrew S McIntosh a,b,∗ , Catherine Willmott c,d , Declan A. Patton b , Biswadev Mitra e,f , James H. Brennan e , Bleydy Dimech-Betancourt c,d , Teresa S. Howard e,h , Jeffrey V. Rosenfeld g,h a MUARC, Monash University, Melbourne, Australia b Federation University Australia, Ballarat, Australia c Monash Institute of Cognitive & Clinical Neurosciences, School of Psychological Sciences, Monash University, Melbourne, Australia d Monash-Epworth Rehabilitation Research Centre, Epworth Hospital, Melbourne, Australia e National Trauma Research Institute, The Alfred Hospital, Melbourne, Australia f Department of Epidemiology & Preventive Medicine, Monash University, Melbourne, Australia g Department of Neurosurgery, The Alfred Hospital, Melbourne, Australia h Department of Surgery, Monash University, Melbourne, Australia a r t i c l e i n f o Article history: Received 20 August 2018 Received in revised form 5 January 2019 Accepted 21 February 2019 Available online xxx Keywords: Head impact biomechanics Wearable sensors Australian Football Concussion Sports injury a b s t r a c t Objectives: To assess the utility and functionality of the X-Patch ® as a measurement tool to study head impact exposure in Australian Football. Accuracy, precision, reliability and validity were examined. Designs: Laboratory tests and prospective observational study. Methods: Laboratory tests on X-Patch ® were undertaken using an instrumented Hybrid III head and neck and linear impactor. Differences between X-Patch ® and reference data were analysed. Australian Football players wore the X-Patch ® devices and games were video-recorded. Video recordings were analysed qualitatively for head impact events and these were correlated with X-Patch ® head acceleration events. Wearability of the X-Patch ® was assessed using the Comfort Rating Scale for Wearable Computers. Results: Laboratory head impacts, performed at multiple impact sites and velocities, identified significant correlations between headform-measured and device-measured kinematic parameters (p < 0.05 for all). On average, the X-Patch ® -recorded peak linear acceleration (PLA) was 17% greater than the reference PLA, 28% less for peak rotational acceleration (PRA) and 101% greater for the Head Injury Criterion (HIC). For video analysis, 118 head acceleration events (HAE) were included with PLA ≥30 g across 53 players. Video recordings of X-Patch ® -measured HAEs (PLA ≥30 g) determined that 31.4% were direct head impacts, 9.3% were indirect impacts, 44.1% were unknown or unclear and 15.3% were neither direct nor indirect head impacts. The X-Patch ® system was deemed wearable by 95–100% of respondents. Conclusions: This study reinforces evidence that use of the current X-Patch ® devices should be limited to research only and in conjunction with video analysis. © 2019 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. Practical implications • Comprehensive evaluation of wearable sensors is required prior to their implementation as a research, sports science or clinical tool. ∗ Corresponding author at: Monash University Accident Research Centre, Monash University, Level 1, Building 70, Clayton Campus, 21 Alliance Lane, Clayton VIC 3800, Australia E-mail address: as.mcintosh@bigpond.com (A.S. McIntosh). • The X-Patch ® has many limitations. At present the optimal use of this device would be in combination with video analysis. • Small head worn sensors are considered to be wearable by adult athletes in a contact sport 1. Introduction Technology developments in the last decade have resulted in the availability and application of wearable sensor systems, includ- ing helmet mounted systems, to measure head impact events in sport. 1–3 There are multiple objectives of measuring head impact https://doi.org/10.1016/j.jsams.2019.02.004 1440-2440/© 2019 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.