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Descriptive analysis of head impact kinetics in a simulated rugby union tackle: preliminary findings

Objective The tackle is a key component in rugby union and carries some of the highest risk for concussions. The purpose this study was to observe the acceleration profile of the head during a simulated tackle and to determine if these forces vary by playing position. Design Observational. Setting Laboratory. Participants Male rugby players (n=41) age 21.8±3.4 years. Protocol Participants were asked to perform 5 tackles with each shoulder. For each tackle the 50 kg bag was released on a pendulum and the players completed a 3 m run-up to make contact with the bag at its peak speed (4.3 ±.13 m/s). For each tackle the linear and rotational acceleration were captured using a head positioning system (HPS) anchored over the mastoid bone. Outcome measures The magnitude and variability of the mean resultant linear and rotational acceleration forces over the 10 tackles were examined using the peak acceleration values and were compared with Mann-Whitney-Wilcoxon tests. Main results The overall mean peak linear force was 82.9 Gz with a range of 20.1–236.6 Gz. For the forwards (n=23) the peak linear and rotational accelerations were 83.0±36.3 Gz and 2537.8±477.7 m/s2, while for the backs (n=18) were 77.6±33.8 Gz and 2501.9±519.6 m/s2. There were no significant differences between forwards/backs, or those with a history of concussion (p≥0.054). Conclusions With growing evidence implicating the importance of sub-concussive impacts in later brain health, understanding the exposure load of players during trainings and games is essential. This is the first study to document the impact forces recorded at the head during a simulated rugby tackle. Competing interests None. Ed Lodge is CEO of CSx Concussion Management Systems, who developed and provided the Head positioning system that was used to measure head impact kinetics in real time.