Collisions in junior rugby

Introduction: In recent years there has been increased public and media awareness regarding players’ safety and brain health after a concussion or long-term participation in rugby union. Because of the nature of rugby, players are exposed to repeated collisions which may or may not result in concussion. These impacts are of linear (direct: g) and rotational (indirect: rads/s²) nature. At present there is sparse research investigating the role of collisions in junior rugby on players’ brain health, especially junior female rugby players. Methods: Sixteen U17 female rugby players and twenty U16 male rugby players aged 12-16yrs completed pre-season and post-season assessment which included: advanced magnetic resonance imaging (MRI) of the brain, neurocognitive testing, health history questionnaire and motor control questionnaire. Participants wore instrumented mouthguards during their club and school season (recording collisions > 8g) for all games and contact trainings. The collisions were video verified. Players completed 14-66 contact sessions over the 2022 season. Results: Results are expected in 2024. Results will identify incidence and magnitude of impacts for both teams across their club and school season; we hypothesize higher acceleration forces will be recorded in games compared to trainings. Cognitive testing, motor control questionnaires, and MRI scans will be analysed within-subject; we hypothesize those exposed to a lower incidence and magnitude of collisions will show fewer changes (pre versus post season) in white matter fibre cross sectional area and density, neurocognitive testing scores and conscious motor control than those exposed to higher total exposures. Discussion: There is conflicting research investigating the correlation between magnitude and incidence of collisions and brain health. Our study is the first to investigate this association in male and female adolescent rugby players. Current research shows increased reduction of white matter in older athletes; however white matter is still developing in adolescents, highlighting the importance of investigating adolescent rugby players. Take home message: The study highlights the need for objective data to measure head impact exposure in rugby union. Emerging data shows more impacts in games vs. training, and that non-collision game events, such as lineout lifting or side-stepping, generally do not trigger the 8g mouthguard threshold. Data is beginning to show correlations between game events and levels of linear acceleration