Head Impact Monitoring In Youth Football: Comparing Measurements From Helmet-Mounted Sensors And Instrumented Mouthguards

Head impact monitoring in American football is used to describe concussion biomechanics and to quantify head impact exposure (HIE). The Head Impact Telemetry (HIT) System has been the most widely used impact sensor system in football and the basis for the majority of reported HIE data. Recently, advancements in instrumented mouthguards (iMGs) have led to greater adoption of this technology. It is unknown how HIT System measures compare to those from iMGs. PURPOSE: To compare head impact measurements in youth football players captured by the HIT System and Prevent Biometrics iMGs. METHODS: During the 2020-21 football seasons, 30 youth players (13.2 ± 0.7 yr) wore helmets outfitted with HIT System impact sensors, and during the 2022-23 seasons, 14 youth players (13.1 ± 0.6 yr) wore Prevent iMGs. The HIT System calculated resultant linear acceleration (LA) and resultant rotational acceleration (RA) for every impact above 10 g from its helmet-mounted array of six single-axis accelerometers. Prevent iMG software computed LA and RA for impacts above 5 g from a triaxial accelerometer and gyroscope, respectively. LA and RA distributions of all impacts from the HIT System (2020-21) and Prevent iMGs (2022-23) above 10 g were compared using Mann-Whitney U tests. Frequency distributions by impact location were compared with a chi-square test. Level of significance for all tests was α = 0.05. RESULTS: There were 1375 head impacts registered by the HIT System and 985 head impacts registered by Prevent iMGs. Head impacts measured by the HIT System had significantly greater LA (20.8 [15.6-30.5] g) (U = 313134, P < .001) and RA (1442 [947-2155] rad · sec-1) (U = 478100, P < .001) than those measured by Prevent iMGs (13.7 [11.5-17.6] g; 1095 [673-1448] rad · sec-1, respectively). The frequency distribution of head impacts by location was also significantly different between the HIT System and Prevent iMGs, χ2 (4, n = 2356) = 160.2, P < .001. CONCLUSION: Head impact measurements in youth football are qualitatively similar using the HIT System and Prevent iMGs; however, quantitative values differ considerably, with the HIT System providing greater measures of LA and RA. Furthermore, frequency distributions of head impact location do not match. Therefore, head impact metrics obtained from the HIT System and Prevent Biometrics iMGs are not equivalent.