Kendo Martial Art Concussion Prevention

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 3Dprinted 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 3Dprinted pad offered the best protection with 34.9 g-force. The electrical insulation foam performed worst with 38.2 g-force. 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.