This study aimed to clarify the differences between the previously reported mechanisms of sports-related concussion (SRC) injuries without a loss of consciousness in contact and collision sports and the mechanisms of SRC injuries in our cases. Based on two videos of SRC injuries occurring during a men's rhythmic gymnastics competition (three people were injured), the risk of SRC occurrence was estimated from various parameters using a multibody analysis and eight brain injury evaluation criteria. In the present study, the three SRC impacts that occurred in men's rhythmic gymnastics showed significant characteristics in duration compared to previously reported cases in the contact sports. This suggests that the occurrence of SRC may have been caused by a different type of impact from that which causes SRC in contact sports (e.g., tackling). In addition, calculation of the strain indicating the rate of brain deformation suggested a risk of nerve swelling in all cases involving type 2 axonal injuries. Therefore, when reexamining sports-related head injuries, it is important to recognize the characteristics and mechanisms of SRC that occur in each different sport, as well as the symptoms and course of SRC after injury.
Keywords: diffuse axonal injury; impact analysis; motion analysis; trauma brain injury.