A novel equestrian helmet testing method: helmet liner performance in highly realistic simulation.

Objective: Employ a novel testing method to assess Multi Directional Impact Protection System (MIPS) helmet technology on rotational velocity and acceleration during head impact.

Methods: An optimization study was completed utilizing a 50th percentile male Hybrid III anthropomorphic test device (ATD). Helmets included expanded polystyrene foam (EPS) and two different MIPS helmets (MIPS 1, MIPS 2). A 24.38-m-long elevated track with rails and a motorized sled was utilized to replicate a fall from approximately 2.13 m. The sled was set to a speed of 20.92 kph, where a tripping mechanism induced rotation in the ATD from the sled and onto a sand surface. During impact of the ATD with the sand surface, head kinematics were measured using resultant acceleration (peak G's), duration of impact (ms), and rotational velocity (rad/s).

Results: A total of three trials for each helmet did not demonstrate a significant difference between the EPS vs. MIPS 1 group with, peak (G's) for resultant acceleration (p = 0.100), duration (ms) for resultant acceleration, (p = 0.100), peak (G's) for rotational velocity, (p = 0.700), and duration (ms) for rotational velocity (p = 0.700). Similarly, the EPS vs. MIPS 2 testing demonstrated no significant differences between the MIPS 2 helmet compared to the EPS helmet, with resultant acceleration (p = 0.400), duration acceleration (p = 0.200), rotational velocity (p = 0.400) and duration velocity (p = 0.400). However, when the MIPS helmet data were pooled, and the EPS helmet data were compared, a statistically significant difference in the duration of acceleration was found (p = 0.048).

Conclusions: Current testing uses a helmeted head form which is dropped or rolled from a prescribed height. These methods discount the loading placed on the neck and head through the angular momentum of the body. Our novel testing method did not find significant differences between the helmet types in diminishing peak rotational forces to the brain; however, our data suggests that MIPS helmet liners may reduce duration of impact. The reduction of acceleration duration could indicate less rotation of the neck, due to the dampening of these forces by the MIPS liners.