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Background The consequences of exposure to head acceleration events (HAEs) in collision sports, including Australian Rules football, are a growing concern. Instrumented mouthguards (iMGs) now enable accurate quantification of HAEs in sport; however, little is known about HAE incidence and mechanisms in Australian Rules football. We aimed to measure HAEs in elite Australian Rules football players, and evaluate the influence of playing position and match event on the incidence and magnitude of HAEs in men and women. iMG data were collected from Australian Football League (AFL) and AFL Women’s (AFLW) players in 2023 utilising the HIT-IQ Nexus Gen III iMG, targeting 500 player-matches per sex. Match footage was synchronised with iMG data for video verification and match play coding. Results Three hundred and eleven players contributed iMG data in the analyses, including 126 men (median matches per player: 3 (interquartile range [IQR: 2–6]) and 185 women (median: 3 [IQR: 1–4]). Men had a higher mean incidence of HAEs ≥ 8 g per match than women (5.7 [95% confidence interval CI: 5.0–6.4] vs. 3.0 [95% CI: 2.8–3.3]), however the incidence was comparable when adjusted for time (3.6/hour [95% CI: 3.2–4.1] vs. 3.1/hour [95% CI: 2.9–3.4]). Men recorded higher maximum single-impact peak linear acceleration (PLA; median 31 g vs. women: median 22 g; p  < 0.001) and peak rotational acceleration (PRA; median 3.0 krad/s² vs. women: 2.4 krad/s²; p  < 0.001) per match. Conversely, women experienced greater PRA per impact (median 1.4 krad/s² vs. men: 1.2 krad/s²; p  < 0.001), while PLA was similar (men: median 14 g, women: median 13 g; p  = 0.330). The leading match events resulting in HAEs were marking contests (1.0/hour) in men and contested ball situations (0.8/hour) in women. HAE incidence and magnitude were generally comparable across playing positions, except for men’s rucks, who experienced significantly higher incidence of HAEs (6.5/hour) than forwards (3.6/hour), midfielders (3.2/hour), and defenders (2.7/hour). Conclusions This study highlights differences in HAE incidence, magnitude, and mechanisms by sex, playing position, and match events in elite-level Australian Rules football. These findings provide insight into impact exposure patterns and may inform targeted skill development and policy adjustments to enhance player safety. Key Points In elite-level Australian Rules football, men sustained more instrumented mouthguard-measured head acceleration events (HAEs) per match compared to women; however, incidence was similar after adjusting for time played. Men experienced higher maximum single-impact peak linear and rotational accelerations values per match, while women experienced greater peak rotational acceleration per HAE. Men’s rucks had a significantly higher incidence of HAEs than defenders, midfielders, and forwards, primarily due to more frequent low-magnitude impacts from ruck and marking contests.

Background Advances in instrumented mouthguards (iMGs) allow for accurate quantification of single high-acceleration head impacts and cumulative head acceleration exposure in collision sports. However, relationships between these measures and risk of brain cell injury remain unclear. Aim The purpose of this study was to quantify measures of non-concussive head impact exposure and assess their association with blood glial fibrillary acidic protein (GFAP), neurofilament light (NfL) and phosphorylated-tau-181 (p-tau-181) levels in male Australian football players. Methods A total of 31 athletes underwent in-season (24 h post-match) and post-season (> 5 weeks) blood collections and/or wore HITIQ Nexus A9 iMGs measuring peak linear (PLA) and rotational (PRA) acceleration. Match footage was used to verify and code impacts. Blood GFAP, NfL, and p-tau-181 were quantified using Simoa and natural log transformed for analysis. Associations between post-match biomarkers and within match maximum single impact and cumulative PLA/PRA were assessed with linear mixed models. Results In-season versus post-season elevations were found for GFAP (mean difference 0.14, 95% CI 0.01–0.26, p  = 0.033), NfL (mean difference = 0.21, 95% CI 0.09–0.32, p  = 0.001) and p-tau-181 (mean difference = 0.49, 95% CI 0.33–0.65, p  < 0.001). Post-match GFAP was associated with maximum single impact PLA ( B  = 0.003, 95% CI 0.0002–0.005, p  = 0.036), cumulative PLA ( B  = 0.001, 95% CI 0.0002–0.002, p  = 0.017), cumulative PRA ( B  = 0.01, 95% CI 0.002–0.02, p  = 0.014), and impact number ( B  = 0.03, 95% CI 0.003–0.05, p  = 0.029) within a single match. Change in NfL levels between two-matches correlated with cumulative PLA ( r  = 0.80, 95% CI 0.38–0.95, p  = 0.005), PRA ( r  = 0.71, 95% CI 0.19–0.92, p  = 0.019) and impact number ( r  = 0.63, 95% CI 0.05–0.89, p  = 0.038). Conclusion Maximum and cumulative head accelerations in Australian football, measured by iMGs, were associated with elevated blood biomarkers of brain injury, highlighting the potential of both technologies for head impact management in collision sports.

Advances in instrumented mouthguards (iMGs) allow for accurate quantification of single high-acceleration head impacts and cumulative head acceleration exposure in collision sports. However, relationships between these measures and risk of brain cell injury remain unclear. The purpose of this study was to quantify measures of non-concussive head impact exposure and assess their association with blood glial fibrillary acidic protein (GFAP), neurofilament light (NfL) and phosphorylated-tau-181 (p-tau-181) levels in male Australian football players. A total of 31 athletes underwent in-season (24 h post-match) and post-season (> 5 weeks) blood collections and/or wore HITIQ Nexus A9 iMGs measuring peak linear (PLA) and rotational (PRA) acceleration. Match footage was used to verify and code impacts. Blood GFAP, NfL, and p-tau-181 were quantified using Simoa and natural log transformed for analysis. Associations between post-match biomarkers and within match maximum single impact and cumulative PLA/PRA were assessed with linear mixed models. In-season versus post-season elevations were found for GFAP (mean difference 0.14, 95% CI 0.01-0.26, p = 0.033), NfL (mean difference = 0.21, 95% CI 0.09-0.32, p = 0.001) and p-tau-181 (mean difference = 0.49, 95% CI 0.33-0.65, p < 0.001). Post-match GFAP was associated with maximum single impact PLA (B = 0.003, 95% CI 0.0002-0.005, p = 0.036), cumulative PLA (B = 0.001, 95% CI 0.0002-0.002, p = 0.017), cumulative PRA (B = 0.01, 95% CI 0.002-0.02, p = 0.014), and impact number (B = 0.03, 95% CI 0.003-0.05, p = 0.029) within a single match. Change in NfL levels between two-matches correlated with cumulative PLA (r = 0.80, 95% CI 0.38-0.95, p = 0.005), PRA (r = 0.71, 95% CI 0.19-0.92, p = 0.019) and impact number (r = 0.63, 95% CI 0.05-0.89, p = 0.038). Maximum and cumulative head accelerations in Australian football, measured by iMGs, were associated with elevated blood biomarkers of brain injury, highlighting the potential of both technologies for head impact management in collision sports.

PurposeTo compare instrumented mouthguard (iMG)-measured head kinematics between elite Australian football players who undergo a head injury assessment (HIA), and are either medically cleared (HIA−) or diagnosed with concussion (HIA+).MethodsHead kinematic data were collected over four men’s and women’s seasons, with impacts leading to an HIA verified through video and timekeeper records. Peak linear acceleration (PLA) and peak rotational acceleration (PRA) were compared between HIA− and HIA+ cases.ResultsFive-hundred and nine men and 612 women had an iMG fitted and participated in at least one season. Twenty-nine HIA+ cases (17 men, 12 women) and 86 HIA− cases (24 men, 62 women) had kinematic data verified. In men, HIA+ cases had higher median PLA than HIA− cases (68 g [interquartile range (IQR): 49–87] vs. 41 g [IQR: 28–71]; p=0.04), with area under the curve (AUC) analysis indicating fair discriminative ability (AUC = 0.69). Similarly, HIA+ cases had higher PRA (6.6 krad/s² [IQR: 4.6–9.0] vs. 3.7 krad/s² [IQR: 2.3–6.2]; p=0.01), with an AUC of 0.73. In women, HIA+ cases had higher median PLA (62 g [IQR: 48–85] vs. 36 g [IQR: 23–55]; p=0.001) and PRA (6.7 krad/s² [IQR: 4.1–8.8] vs. 3.0 krad/s² [IQR: 1.8–4.7]; p=0.001), both with an AUC of 0.78.ConclusionHigher PLA and PRA measurements were observed in athletes diagnosed with concussion compared to those who were cleared following HIA. Ultimately, iMG kinematics may assist in the identification of players at risk of concussion who require medical screening.

PurposeTo quantify head acceleration events (HAEs) in elite Australian football.MethodsInstrumented mouthguard (iMG) data were collected from elite Australian football players (2021–2023), with primary analysis on 2023 data from an updated HITIQ iMG, targeting 500 player matches per sex. HAE incidence, magnitude (peak linear acceleration [PLA] and peak rotational acceleration [PRA]), and causes were compared by sex and within each sex for match-play skills.ResultsPrimary analysis included 126 men (median matches per player: 3 [interquartile range (IQR): 2–6]) and 185 women (median matches: 3 [IQR: 1–4]). Men had a higher mean incidence of HAEs with a PLA ≥8 g per match than women (5.7 [95% confidence interval (CI): 5.0–6.4] vs. 3.0 [95% CI: 2.8–3.3]), but incidence was comparable when normalised for time on ground (3.6/hour [95% CI: 3.2–4.1] vs. 3.1/hour [95% CI: 2.9–3.4]). Men recorded higher maximum single-impact PLA (median 31 g [IQR: 19–50] vs. 22 g [IQR: 14–37]; p<0.001) and PRA (median 3.0 krad/s² [IQR: 1.8–5.4] vs. 2.4 krad/s² [IQR: 1.5–3.9]; p<0.001) per match. Conversely, per impact analysis revealed that PRA was greater in women (median 1.4 krad/s² [IQR: 0.9–2.2]) than men (1.2 krad/s² [IQR: 0.8–2.0]; p<0.001), while PLA was similar. Leading HAE causes were marking contests (29.8%) and contested balls (21.3%) in men, and contested balls (26.4%) and tackling (22.5%) in women.ConclusionThis study identifies differences in HAE exposure by sex and match-play skills in elite Australian football.