著者

國部 雅大

出版者

日本バレーボール学会

雑誌

バレーボール研究 = Journal of volleyball sciences (ISSN:13449524)

巻号頁・発行日

vol.19, no.1, pp.51-57, 2017-06

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The present study aimed to clarify the types and situations of play which are difficult for referees to judge by reviewing the results of video challenge system introduced in volleyball competition. The data analyzed were all the challenge requested from 76 matches in volleyball competition in the 2016 Rio de Janeiro Olympics. The success rate of challenges was calculated from the number of successful challenges divided by the number of challenges for each type of play.As results, the following findings were obtained:1) The total number of challenges was 400 times, the number of successful challenges (i.e., the number of errors in referee's judgment) was 163 times, and the success rate of challenges was 40.8%. There was no difference in these variables between men’s and women’s competitions.2) The number of successful challenges and the success rate of challenges for the blocker’s ball contact were higher than those for the other types of play, suggesting that it is one of the most difficult judgments for volleyball referees to determine the contact between the blocker and the ball.3) Regarding the judgment on the ball contact of the blocker, the frequency of judgment corrected from no touch to touch was larger than that corrected from no touch to touch. Regarding the judgment on ball in/out, the frequency of judgment corrected from ball out to ball in was larger than that corrected from ball in to ball out.The present study revealed the types and situations of play which are likely to be erroneously judged in volleyball competition for the first time. These findings would be useful for improving the technique of referees from the viewpoint of using visual information and for the future application of video challenge system in volleyball.

著者

岡野 憲一 谷川 聡

出版者

日本バレーボール学会

雑誌

バレーボール研究 = Journal of volleyball sciences (ISSN:13449524)

巻号頁・発行日

vol.18, no.1, pp.27-31, 2016-01

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The main purpose of this study was to evaluate the frequency and rate of jump types in male volleyball games. Sixteen professional volleyball games in eight teams were recorded by the digital videos(60f/s). The offensive and defensive jumps in each position were separated into the five jump types(attack, block, jump toss, serve and trick jump) by a professional coach. The frequency and rate of jump types in each position were as followings1) In the frequency of the jumps While setter(S) jumped more than wing spiker(WS) and opposite(OP) did(p <0.01),libelo(L) jumped less than wing spiker(WS), middle blocker(MB) and opposite(OP)(p<0.001).2) The type of jumps S(block 21. 2%, jump toss 68.1%) and L(jump toss 100%) mostly performed their own positions. WS(attack 38. 9%, block 41. 0%, serve 19.8%), MB(attack 8.4%, trick jump 26.2%, block 53.5%, serve 11.9%) and OP(attack 49.3%, block 34.2%, serve 16.5%) performed various jumps. The results showed that volleyball is an intermittent sport that combines offensive and defensive phases of play. While players should be required to jump vertically as high as they are capable of doing, it is necessary for players to develop various jump abilities depending on their positions.