791 BO14 – Mixed martial arts vs rugby: which sport produces larger deformation of brain white matter?

Background Head impacts in sports produce brain deformation, which can damage brain white matter leading to short/long-term effects. Quantifying white matter deformation (strain) in different sports allows developing tailored prevention and treatment strategies. Objective We tested whether white matter tracts are subjected to different strains during impacts in two contact sports, rugby and mixed martial arts (MMA). Design The PROTECHT instrumented mouthguard (iMG) was used to measure head kinematics. Information on the measurement settings, filtering and validation can be found in [1]. We used the Imperial College finite element model of brain injury biomechanics to predict brain deformation. This model has been validated against recent experiments on post-mortem human subjects[2]. Participants Five professional male MMA fighters and eight elite male rugby players were instrumented. Athletes wore the iMG to capture head impacts during the entire match. Total 296 head impacts were collected, all video-verified, with 150 from MMA and 146 from rugby. Outcome measurements We calculated peak linear and rotational accelerations. The distribution of maximum principal strain within the brain was predicted using the brain model. 90th percentile strain was calculated in 14 white matter tracts which usually associated with cognitive deficits. Results Peak kinematics and brain strain were considerably larger in MMA than rugby. This may be associated with MMA's higher percentage of direct head impact (Table.1). Two-way ANOVA analysis confirmed a significant strain difference between the two sports but not between tracts. In both sports, largest strains were predicted in three white matter tracts, SLF, SLFT and ILF (Fig.1). Conclusions Our results show larger brain strain in MMA than rugby head impacts, suggesting higher risk of injury in MMA. These results can help aid the direction of guidelines of these sports to prevent brain injury. 1. [1]Jones CM. et al., Sensors. 2023 2. [2]Zimmerman KA. et al., J Biomech. 2021