From the results of this study, there was a significant difference (p<0.05) between 2018 and 2022 in the number of back attacks, points, scoring rate, and number of bats for OH players. A significant difference (p<0.05) was observed between 2018 and 2022 in the score ratio of back attacks in the league as a whole and the score ratio of OH players. In 2018, only a significant positive correlation (r=0.708) was observed for the set rate and back attack of each team, but in 2022, each team's A significant positive correlation (r=0.798) was observed between the set rate and the goal scoring rate of the team as a whole, and a strong positive correlation (r=0.779) was also observed for the goal scoring rate of the OH players. A moderately significant correlation (r=0.684) was observed, and a moderately significant correlation (r=0.644) was also observed for OH players' back attack scores. This result suggests that it is necessary to pay attention to the back attack trends of OH players in terms of offensive tactics at the top level of university men's. In addition, in order to incorporate tactics according to the team situation, we believe that it is important to collect information in advance, such as the opponent's tactical tendency and the effective tactical pattern of the own team, and we were able to confirm the necessity of establishing the environment and system.

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In this study, we attempted to introduce the Pythagorean expectation used in baseball to volleyball. We compared the three prediction models: the Pythagorean expectation used in baseball (Model 1), the Pythagorean winning percentage using an index suitable for volleyball (Model 2), and a model predicts winning percentage based on the side-out rate and breakout rate (Model 3). Results indicated that Model1, Pythagorean expectation, had a correlation with winning percentage in volleyball, but the error was large. and Model3 had the highest prediction accuracy. We named this model that based on side-out rate and break rate the "Nambu expectation".

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Acute peripheral fatigue may occur due to muscle damage during volleyball, resulting in a temporary decrease in jump performance. This study aimed to investigate the effect of cold water immersion (CWI) of the lower limbs between volleyball games on jump performance. Twelve university volleyball players participated in this randomized crossover study. The participants played two games, each of three sets, in a gymnasium. There was a 30-minute rest in between the games. During rest time, the participants were assigned to the CON group (30 minutes of seated rest) or the COOL group (15 minutes of CWI (15°) up to the level of the iliac crest and 15 minutes of seated rest). The counter-movement jump (CMJ) after the second game and 24 hours later, and the spike decision rate in the second game were significantly higher in the COOL group (p<0.05). The perceived recovery status before the second game and the session rating of perceived exertion (s-RPE) after the second game were also significantly improved in the COOL group (p<0.05). CWI of the lower extremities between volleyball games suppressed the decline of the CMJ height at the end of exercise and the spike decision rate. The decrease in tissue temperature caused by CWI of the lower extremities may have improved s-RPE and the perceived recovery status, which in turn, affected the jump performance.

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The purpose of this study was to clarify the gazing point of the setter during the tossing motion of college female volleyball players and to obtain data for coaching. Four setters were wearing the eye mark recorder (EMR-9, nac, 30 Hz) and tossed the ball. The setter tossed five times each in the left, center, and right directions. The gaze points were divided into five areas. A chi-square test was used to compare the percentage of areas gazed at by each player. The probability of significance was set at less than 5%. The results showed that player A, a regular player, paid less attention to the ball when tossing to left (p=0.00) and more to the spiker (p=0.00) and others (p=0.02). Player A also made more gazing movements than the other players. Kurokawa et al. (1988) found that in volleyball blocking, the unskilled players' gaze point moved after the ball, while the skilled players paid less attention to the ball. This suggests that player A, an advanced player, spent a smaller percentage of time gazing at the ball.

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The purpose of this study was to clarify to what extent learners understood the key points of spike techniques, in order for instructors to gain insights that can be utilized in planning and practicing volleyball lessons. As a result, it was revealed that both experienced and beginner volleyball players have challenges in understanding spike techniques, specifically, pushing-off in the takeoff phase and hitting the ball before the contact phase.

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In recent years, the state of junior sports has come under scrutiny. In junior high school club activities in particular, problems such as too many hours of activity, the burden on teachers, and the supremacy of winning cannot be overlooked. In order to develop junior sports, it is important to accumulate examples of attractive junior sports activities in Japan. This study focused on a regional junior league called the "Tohoku i-League. This study was based on an interview survey with the person in charge of the tournament. This tournament has special rules that are not found in regular volleyball games, and the development of the players is the first priority. In addition, various efforts are being made to make the games more entertaining with specialized staff, such as play-by-play commentary. Furthermore, the league format of the tournament allows players to challenge themselves again during the tournament. This allows the players to reflect on their own play and develop self-reliant players. This tournament is a very important example of a proposal for junior high school athletic club activities. It is necessary to consider how to promote the event more widely in the future. As described above, we hope that distinctive junior sports activities like those described in this report will be carried out in various parts of the country, leading to the growth of the junior generation.

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