INTRODUCTION: The collision-dominant nature of rugby union exposes players to head acceleration events (HAEs), which are a potential risk factor for the development of brain injuries, such as concussion. Instrumented mouthguards enable direct measurement of the magnitude of these HAEs during training and competition. The differences in physical demands of the game, and physical characteristics of males and females, suggests that they might experience different magnitudes of head accelerations owing to a collision; however, this has not been investigated among elite rugby players. The aims of this preliminary study were to compare the magnitude of peak linear and angular head accelerations i) experienced by male vs. female players and ii) during head vs. body impacts. METHODS: Using the PROTECHT instrumented mouthguard system (Sports & Wellbeing Analytics, UK), a total of 822 HAEs were recorded across 100 male (27 ± 4 years, 103 ± 14 kg, 1.86 ± 0.10 m, 659 HAEs) and 37 female (26 ± 4 years, 73 ± 22 kg, 1.68 ± 0.107 m, 163 HAEs) rugby union players from match collisions during the English Premiership, United Rugby Championship and Premier 15s 2021/2022 and 2022/2023 seasons. All HAEs were video-identified and classified into direct head or body impacts according to the anatomical location of initial impact on the player being monitored. Linear and angular acceleration signals were filtered using a zero-phase lag 4th order Butterworth filter, with a low-pass cut-off frequency of 160 Hz. Linear acceleration signals were transformed to the head centre of mass. Peak linear (PLA) and angular acceleration (PAA) values were defined as the resultant signal maxima. Data were log-transformed and grand-mean centred prior to performing multi-level linear models, comparing the magnitude of PLA and PAA, with player as a random factor and sex (male/female) and impact location (head/body) as fixed factors. Significance was set at P < 0.05 and significant fixed effects were followed up with Bonferroni post-hoc tests. RESULTS: There were no differences in PLA nor PAA (P > 0.05) between males (24.0 ± 16.8 g, 1703 ± 1948 rad/s^2, n = 659 [80%]) and females (PLA; 22.2 ± 14.7 g, PAA; 1719 ± 1365 rad/s^2, n = 163 [20%]). Both PLA and PAA were significantly greater (P < 0.001) in HAEs resulting from impacts imparted to the head (PLA; 33.7 ± 23.6 g, PAA; 2304 ± 2384 rad/s^2, n = 141 [20%]) vs. body (PLA; 20.9 ± 12.0 g, PAA; 1494 ± 1358 rad/s^2, n = 581 [80%]). There were no interaction effects to indicate differences between male and females at the two anatomical locations. CONCLUSION: This preliminary analysis, comparing males and females, demonstrated no differences in the peak linear and angular head acceleration magnitudes during match HAEs, despite the physical differences typically observed between sexes. The higher magnitudes during direct head impacts compared to body impacts warrants further investigation into the contextual factors surrounding a direct head impact to better understand the potential causes.
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