Description

Abstract: Concussion poses a major risk in any sport, especially in contact sports such as
rugby and soccer. While these contact sports are well researched and have seen
improvements in protective gear, there exist few to no reported data investigating the
effectiveness of kendo helmets against blunt forces/concussion. Kendo is a Japanese martial
art involving bamboo swords with traditional armor originating from the 11th century. In this
study, we evaluate the effectiveness of the traditional cotton pad commonly inserted into
kendo helmets to protect against head trauma and to find viable alternatives using modern-day materials. We asked multiple kendo practitioners to deliver strikes to a mannequin fitted
with a kendo helmet. The helmet was equipped with either a commonly used and
commercially available cotton pad, a 3D-printed pad, an electric insulator foam, or no inserts.
The force of each strike was measured. All inserts offered some protection against head
trauma, with force readings below 62.4 g-force (the threshold for the risk of concussion).
Surprisingly, the cotton pad insert yielded minute additional protection than wearing the
helmet alone (36.3 g-force vs 36.5 g-force respectively). The 3D-printed pad offered the best
protection with 34.9 g-force. The electrical insulation foam performed worst with 38.2 gforce. These results are statistically significant with a p-value of 0.007. 3D-printed pads
mitigate blunt forces better than traditional commercial cotton pads. Future research may
explore 3D-printed pads of different shapes, sizes, and materials. 

Keywords: Kendo, Concussion, 3D-Printed, Efficacy