Abstract
Judo is the martial arts that can lead to severe head injuries. Bruising on the back of the head and acute subdural hematoma commonly occur in beginners thrown by Osotogari. Sports-related head injuries were studied by using head protective equipment, which has been evaluated previously. However, these studies treated the head as a rigid body, and evaluated only the impact on the head. As these studies did not consider the behavior of the neck in soft impacts - a major factor in acute subdural hematoma - their utility is limited. Therefore, in the present study, we examined the efficacy of protective equipment that suppresses neck extension, equipment that protects the head, and equipment with both the neck and head. Three shock-absorbing materials (hard urethane, soft urethane, low rebound material) were used. The cranial model used polycarbonate to enable the observation of the behavior of the brain, whereas the brain parenchyma model used silicone gel with similar physical qualities to the brain. Black marker was applied to the surface of the brain parenchyma model and the cranial model. The experimental apparatus was collided while maintaining the velocity of the head at 3.5 m/s. The behavior of this collision was captured by a high-speed camera and relative changes in marker distance were measured. The results indicated that the equipment with both head and neck protection suppressed the relative displacement. Thus, while developing equipment in the future, not only protection the head, but also suppression of neck extension should be considered.
