Finite Element Simulation of Head Impacts in Mixed Martial Arts

This study determined brain stress and strain in an unhelmeted sport and correlated this with concussive injuries. Thirteen MMA athletes were fitted with the MiG2.0 Stanford instrumented mouthguard. The mouthguard records linear acceleration and angular velocity in 6 degrees of freedom. Angular acceleration was calculated by differentiation. All events were video recorded, time stamped and reported impacts confirmed. 298 impacts above 10g were recorded during sparring sessions and 153 impacts in competitive events. The competitive events resulted in five concussions which were diagnosed by a medical doctor. The impact with the highest angular acceleration from each sparring session and competitive event was simulated using the GHBMC head and neck model. The model was run on Amazon Web Services using the LS-Dyna explicit solver. The resultant linear acceleration, strain in the corpus callosum and brain stem and shear stress in the corpus callosum were all significantly different in concussed athletes compared to uninjured. Average strain in the corpus callosum of concussed fighters was 0.27 which was 87.9% higher than uninjured fighters and was the best strain indicator of concussion. The best overall predictor of concussion found in this study was shear stress in the corpus callosum which differed by 111.4% between concussed and uninjured athletes. This study is unique in that it measured head accelerations in vivo and determined that high stress and strain in the corpus callosum correlated with the concussive injuries

Concussion and the Severity of Head Impacts in Mixed Martial Arts

Background: Concern about the consequences of head impacts in US football motivated researchers to investigate and develop instrumentation to measure the severity of these impacts. However, the severity of head impacts in unhelmeted sports is largely unknown as miniaturised sensor technology has only recently made it possible to measure these impacts in vivo. Aim: The objective of this study was to measure the linear and angular head accelerations in impacts in mixed martial arts (MMA), and correlate these with concussive injuries. Methods: Thirteen MMA fighters were fitted with the Stanford instrumented mouthguard (MiG2.0). The mouthguard records linear acceleration and angular velocity in 6 degrees of freedom. Angular acceleration was calculated by differentiation. All events were video recorded, time stamped and reported impacts confirmed. Results: 451 verified head impacts above 10g were recorded during 19 sparring events (n=298) and 11 competitive events (n=153). The average resultant linear acceleration was 38.0g ± 24.3g while the average resultant angular acceleration was 2567 ± 1739rad/s2. The competitive bouts resulted in five concussions being diagnosed by a medical doctor. The average resultant acceleration (of the impact with the highest angular acceleration) in these bouts was 86.7 ± 18.7g and 7561 ± 3438rads/s2. The average maximum Head Impact Power (HIP) was 20.6kW in the case of concussion and 7.15kW for the uninjured athletes. Conclusion: The study recorded novel data for sub-concussive and concussive impacts. Events that resulted in a concussion had an average maximum angular acceleration that was 24.7% higher and an average maximum HIP that was 189% higher than events where there was no injury. The findings are significant in understanding the human tolerance to short-duration, high linear and angular accelerations