Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.11648/j.ss.20130201.11.

Language：English   Publishing type：Research paper (scientific journal)   Publisher：PUBLIC LIBRARY SCIENCE  

This study aimed to clarify the cause of rugby head and spinal cord injuries through a network centrality analysis of 14-year (2004-2018) longitudinal data in Japan. The study hypothesis is that understanding the causal relationship among the occurrence of serious injuries, the quality of player experience and play situation as a network structure could be possible to obtain practical knowledge on injury prevention. In this study, bipartite graphs are used to make it easier to understand the situation of players and injuries. This would also help to elucidate more characteristic subgroup. A network bipartite graph and subgroup (cluster) analyses were performed to clarify the injured players' experience and the cause of injury. We used the algorithm of R program, IGRAPH, clustering edge betweenness. For subgroup extraction, the modularity Q value was used to determine which step to cut. The Japanese rugby population was 93,873 (2014-2018 average), and 27% were high school students. The data showed that careful attention would be particularly needed for groups of inexperienced Japanese high school players. Our study suggests that we should consider introducing rules that prohibit "head-on collisions" in youth rugby.

DOI： 10.1371/journal.pone.0235035

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PubMed

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Routledge  

Purpose: The goal of this study was to clarify the defensive structures that play a decisive role in the game of Rugby football, which is a competitive team sport. Method: The study used data from games played under the Rugby Union code, and particularly on turnovers made during defensive plays in the 2015 Rugby World Cup. Social network centrality analysis was applied to analyse organisational strategies. A correspondence analysis performed using centering resonance techniques was shown to deepen our understanding of relationship structures in network mapping, while the application of network analysis was able to improve the description of complex passages of play. Result: Eigenvector centrality would reflect the specific network structures of one’s neighbour vertexes. It also reflects the centrality of all other vertexes that can be further reached from directly involved ones. Team sports rely on cooperation between teammates. The applications of network analysis would be one viewpoint of representing a society in which decision-making behaviours are taken on the basis of human relationships.

File： Network centrality analysis to determine the tactical leader of a sports team.pdf

DOI： 10.1080/24748668.2017.1402283

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.54647/cm32766

Authorship：Lead author   Language：English  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：World Neurosurgery  

Objectives: Acute subdural hematoma (ASDH) is known to be devasting sport-related head injury but it is relatively rare in rugby compared with other contact sports. Certain cases of ASDH have happened in high school rugby players in Japan. To prevent them from the injury we report a background of the players. Methods: Data of high school rugby players who suffered ASDH were extracted from injury reports in the Japan Rugby Football Union between April 2004 and March 2020. The number of injured players, diagnosis on the report, school year, phase of play where the injury occurred, and playing career were analyzed. Results: There were 30 cases of ASDH including 16 cases in the first year, 9 in the second year, and 5 in the third year of playing. Phase of play was mainly being tackled in 11 (37%), and tackling in 13 (43%). Novice players, defined as a player having less playing experience of rugby during junior high school, accounted for 77% of phase of tackling, 82% of being tackled. First year novice players accounted for 100% of phase of being tackled. Outcome within 6 months after injury was recovery in 14, morbidity in 6, mortality in 2, and unknown in 8. Conclusions: Playing experience in high school rugby players should be considered as an important factor for prevention of ASDH—in particular, phase of being tackled is riskier than that of tackling for first year novice players.

DOI： 10.1016/j.wneu.2021.05.042

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author,　Corresponding author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：English   Publishing type：Research paper (scientific journal)   Publisher：Journal of Human Sport and Exercise  

There is little study concerned game structure of women's sevens rugby. Because the game time is only 14 minutes (7 minutes half), the temporal performance would be a decisive factor. It might suggest the characteristics of current world women's sevens rugby and each union. This study clarified the temporal structure of "try scoring rate" (frequency of tries in own possession (secs)), and "try conceding rate" (frequency of tries in oppose possession (secs)). With adding two manipulated factors from "opposition 22m entry try success (attack)" and "own 22m entry try success (defence)", total four factors were investigated for the world ranking clusters. Data were picked up from opened homepage of World Rugby game analysis 2016-2017 women's sevens series. Two-dimensional space showed the relationship of "try scoring rate" and "try conceding rate" (avg. = 79 secs) with mapping the world fifteen union's performances. It suggested world ranking structure. Non-hierarchical cluster analysis was attempted in order to explore the possibility of grouping. Interesting differences were observed among the number of iterations. The 5-iteration process setting showed top group by top 7 unions. The 1000-iteration process setting showed top group by top 3 unions. (explained 96% of point variability). Clustering the world women's sevens rugby was tried from the temporal structure analysis of some attack-defence performances. In non-hierarchical cluster analysis, the number of clusters needs to be determined by the analyst, and there is no established method to calculate the optimal number of clusters automatically. The number of women's sevens games is also limited. Development of the optimal algorithm under this condition would be desired.

DOI： 10.14198/jhse.2019.14.Proc5.63

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Language：Japanese   Publishing type：Research paper (scientific journal)  

File： バイメカ研究.pdf

Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

A game analysis is the practical approach for the performance evaluation and the structure of modern rugby. The longitudinal data gathering could verify the concerned unique structure of the specific league. That relates to the solution of a subject to contribute to the improvement in the quality of the competition of the league as well. In this study, Japanese domestic league was analyzed from 2003 until 2005. Analytic contents were the score profile, the actual exhaustion condition by the long season and try structure. As a source of try, the turnover play was focused in the detail. This defense performance which is connected to quick attacking phase would be common strategic and tactic facet for world second tier union like Japan which has been forced the physical disadvantage constantly. And also that kind of contest and continuity situation would make one of the dynamic mechanisms of rugby union game.

Authorship：Lead author   Language：Japanese  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：Japanese  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Language：Japanese   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)  

Authorship：Lead author   Language：Japanese   Publishing type：Research paper (scientific journal)  

Language：Japanese