The purpose of this study was to investigate the effect of different collar widths of judogi on the tsurite (right hand in a right-handed judo style) movement of youth judo players in the execution of seoi-nage, in order to clarify the problems of existing judogi from the viewpoint of preventing upper limb injuries in judo.
The participants in the study were ten elementary school judo athletes. In the experimental trials, the participants executed seoi-nage (yakusoku-renshu) from two different uke postures in a situation where both tori and uke were gripping. Only uke wore four different types of judogi: a judogi for children, an approved judogi in the 2020 International Judo Federation (IJF) regulations, and judogi made of IJF approved material with custom-made collar widths of 2cm and 3cm.
This study demonstrated that the shoulder’s external rotation angle in seoi-nage was not significantly different between the judogi of different types. However, the shoulder horizontal abduction angle was approximately 20° larger with the approved judogi than that of the other judogi at the transition moment between the turning and throwing phases. Furthermore, the vertical distance between the wrist and the shoulder joint on the tsurite side when performing seoi-nage against uke wearing an approved judogi was significantly larger than against uke wearing a children’s judogi. These results suggest that the tori could not use tsurite effectively to keep the uke off-balance with the approved judogi, leading to a greater imposed stress to the elbow in the seoi-nage throw. This study also demonstrated that the forward tilt angle of the trunk at the moment of maximum external rotation of tori’s shoulder was significantly larger with the approved judogi when compared with the children’s judogi, with a forward tilt angle of more than 50° being shown, which potentially lowers performance and increases the risk of injury. In conclusion, using judogi with the 2020 regulations’ collar widths make it difficult to perform proper seoi-nage, leading to an increased risk of elbow injuries for youth judo athletes.
