Oslo Sports Trauma Research Center

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Information about project titled 'Evaluation of an in-ear sensor system for quantifying head impacts in youth footballl'

Evaluation of an in-ear sensor system for quantifying head impacts in youth footballl

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Project status: Published
Project manager: Stian Bahr Sandmo
Supervisor(s): Roald Bahr, Inga Katharina Koerte, Thor Einar Andersen
Coworker(s): Andrew McIntosh


Background: The link between repetitive heading in football and potential neurological consequences remains controversial. Importantly, ongoing prospective studies exploring this link need accurate measures of head-impact exposure.  

Aim: To assess the validity of a novel in-ear sensor for quantifying head-impact exposure in youth football.

Methods: First, the sensor was mounted to a Hybrid III headform (HIII) and impacted with a linear impactor or football (range: 9-144g). Accelerative forces, including peak linear acceleration (PLA), were obtained from both systems; random and systematic error were calculated using HIII as reference. Then, six youth soccer players wore sensors during a structured training protocol including heading and non-heading exercises; they also completed two regular football sessions. For each recorded accelerative event, PLA outputs were compared to video. Mean values (±SD) were calculated for (1) all heading and (2) non heading events. Receiver operating characteristic curves were used to determine the sensor's discriminatory capacity in both on-field settings, and cut-off values for predicting outcomes were identified.  

Results: For the laboratory tests, both random and systematic error was 11% for PLA. For the structured training protocol, heading events resulted in higher absolute values (PLA=15.6±11.8g) than non-heading events (PLA=4.6±1.2g); area under the curve (AUC) was 0.98. In regular training sessions, AUC was >0.99. A 9g cut-off value yielded a positive predictive value of 100% in the structured training protocol vs. 65% in regular football sessions.

Conclusion: The in-ear sensor displayed considerable random error and overestimated head impact exposures substantially. It showed excellent on-field accuracy for discriminating headings from other accelerative events, but secondary means of verifying events are still necessary.