Sport-related concussion and video analysis of wearable impact sensor data in rugby league

Background: Rugby league is a full-contact collision sport that carries a high risk of sport-related concussion. There are few studies in rugby league that utilise video analysis and wearable head impact sensor data together to investigate head impact exposures across a full season. Purpose: To verify wearable head impact sensor data using video analysis and describe game-play characteristics and head biomechanics that contribute to concussion in rugby league. Methods: The x-PatchTM was used for a season of men’s semi-professional and junior boys representative level rugby league. A total of twenty-nine players were monitored and game-day footage by a trained videographer was recorded and analysed to verify head impacts and describe impact rates, playing and gameplay characteristics of video-verified head impacts. Results: The x-PatchTM recorded a total of 1,403 impacts 20g between game start and finish across the two studies in this thesis, of which 1,296 (92%) were verified on video. In study ,1 the number of video-verified impacts 20g, per playing hour, was 7.8 for forwards and 4.8 for backs. Impacts resulting in concussion had a much greater peak linear acceleration (M = 76.1g, SD = 17.0) than impacts that did not result in concussion (M = 34.2g, SD = 18.0; Cohen’s d = 2.4). Study 2 found 73.2% of all verified impacts 20g where determined to be direct head impacts and occurred at a rate of 5.2 impacts per game hour. Conclusion: There were high rates of agreement between video-verified and sensor recorded game play impacts 20g and also a number of triggered events that occurred during gameplay that did not correlate with an impact on video review. The use of a secondary source, such as video review, to verify x-PatchTM recorded impacts is extremely important when analysing total head impact exposure as failure to remove ‘false-positive’ impacts may inflate player’s cumulative and average head impact exposures.