著者

水島 淳 広瀬 健一

出版者

一般社団法人 日本体育・スポーツ・健康学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.67, pp.297-302, 2022 (Released:2022-05-11)

参考文献数

17

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Communities of practice have been applied in coach development programs around the world. The purpose of the current study was to explore the concept of community of practice, the theoretical background, the literature on community of practice for sport coaches, and the value creation process in community of practice. The findings of this study should offer some insight into how we can implement community of practice for coach learning and development.

著者

水島 淳 広瀬 健一

出版者

一般社団法人 日本体育・スポーツ・健康学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

pp.21158, (Released:2022-03-25)

著者

金堀 哲也 山田 幸雄 會田 宏 島田 一志 川村 卓

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.59, no.1, pp.133-147, 2014 (Released:2014-06-13)

参考文献数

28

被引用文献数

6 2

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The purpose of this study was to clarify the viewpoint of a well-experienced baseball coach when evaluating batting skills using kinematics indices. Method: First, three baseball coaches evaluated sixteen baseball players in their own teams. The players were divided subjectively into a first superior (FG) group and a second superior (SG) group according to batting ability. Next, the hitting motion of all sixteen players was captured using a VICON system (9 cameras, 250 Hz). We measured the speed of the batted and pitched ball, or the timing of release by the pitcher, using three synchronized high-speed cameras (250 Hz). From these kinematics data, we calculated several kinematics indices for each batter, focusing especially on the indices for motion of the lower extremities and trunk. In contrast, a well-experienced expert coach who had never met these players evaluated the hitting motion of each player using only motion films without the above kinematics indices, and similarly divided them into FG and SG. The evaluation of fourteen players agreed between the team coaches and the expert coach. The FG and the SG each comprised seven players. We analyzed these fourteen players using the kinematics indices, and clarified objectively the differences in hitting motion between the two groups. Results & Conclusions: The speed of swing, batted ball speed and physical index were approximately the same in the two groups. However, players in the FG group showed a significantly longer distance of center of gravity migration in step than those in the SG group. This might have been attributable to the hip abduction movement on the pivot side on the basis of kinematics indices (p<0.05). Moreover, players in the FG group took more time in step, and swung in a shorter time after landing on the stepped foot, relative to the players in the SG group (p<0.05). These results suggest that the well-experienced expert coaches paid particular attention to the above hitting motion rather than the speed of swing, batted ball speed and physical index as coaching points.

著者

堀内 元 中島 大貴 桜井 伸二

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

pp.16095, (Released:2017-08-25)

参考文献数

29

被引用文献数

2 4

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The purpose of this study was to evaluate the generation, absorption and transfer of mechanical energy during baseball batting, focusing on the lower extremities and torso. The batting motion and ground reaction forces acting on each foot of 79 amateur baseball players were recorded using a motion capture system and two force plates. The joint forces and joint torques were calculated using inverse dynamics. In addition, the mechanical powers as a function of each joint torque were calculated to assess the generation/absorption of mechanical energy. The mechanical powers as a function of joint forces and joint torques acting on each segment were calculated to assess the transfer of mechanical energy. The main results were as follows:  1. In the phase from contact of the stride foot to the peak lower torso rotational velocity (lower torso acceleration phase), the mechanical energy was generated and flowed into the lower torso as a function of hip joint torque.  2. In the lower torso acceleration phase, the mechanical energy flowed out from the lower torso to the upper torso as a function of torso joint torque.  3. In the phase from the peak lower torso rotational velocity to impact (swing phase), the mechanical energy was generated and flowed into the upper torso as a function of torso joint torque.  4. In the swing phase, the mechanical energy of the bat increased rapidly, and this amount of change was significantly correlated with the bat head speed at impact.  5. Though the analysis phase, the change in the mechanical energy of the torso was small.  These results suggest that both hip joints generate mechanical energy and that the torso acts as a pathway of mechanical energy during baseball batting. In addition, the transfer of mechanical energy from the torso to the upper extremities and the bat contributes to increasing the bat head speed at impact.

著者

小野 雄大 友添 秀則 根本 想

出版者

一般社団法人 日本体育・スポーツ・健康学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

pp.17015, (Released:2017-09-27)

参考文献数

94

被引用文献数

2 5

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In recent years, the way university sports are conducted has been under discussion. In particular, there is some concern about the balance between studies and competitive activities, which is important when considering the future of university sports in Japan. As no previous research has focused on sports recommendation admissions to universities in Japan, the present study first attempted to clarify the way in which this system has developed.  The following findings were obtained:  1. In Japan, even before the recommendation admission system was officially approved, athletes had been given preferential treatment in entrance examinations, which was not disclosed to the public or stipulated in application guides.  2. Soon after the recommendation admission system was officially approved, campus disputes worsened, which caused the preferential admission treatment of athletes to be severely criticized, making it difficult to continue with the conventional system any longer. Accordingly, during the period from the late 1960s to the early 1970s, universities abolished the preferential treatment given to athletes in entrance examinations.  3. Since the recommendation admission system was officially approved in 1967, the faculties of physical education at private universities, among others, started to actively admit athletes based on recommendation. These physical education faculties selected students based on physical skill tests to secure competent athletes. Thus, by matching the admission policy of the faculty with the sporting abilities of athletes, universities were able to secure competent athletes without having to impose a special admission quota for athletes.  4. In the 1980s, private universities played a leading role in conducting entrance examinations with a special admission quota for athletes. Waseda University launched the Special Selection System for Physical Education Major, which introduced a special admission quota for athletes, specified the athletic events and performances, and made the selection process widely known to the public. In conducting this selection, however, the university faced a dilemma of whether or not to employ it as the system for strengthening their sports teams.  5. In 1987, the Ad Hoc Council on Education, an advisory body of the Japanese Government on education, recommended that assessment of sports activities be taken into consideration in entrance examinations. The 1989, the Guidelines for University Entrance Examination, revised in accordance with the Council's recommendation, listed “adequate assessment of activities in sports, culture, etc.” as a selection method for university admission for the first time.

著者

坂口 将太 図子 浩二

出版者

一般社団法人 日本体育・スポーツ・健康学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.58, no.2, pp.599-615, 2013 (Released:2013-12-07)

参考文献数

27

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This study investigated the development of rebound jumping ability in preschool children. The subjects included 100 boys (2 years: 8, 3 years: 19, 4 years: 33, 5 years: 30, and 6 years: 10) and 80 girls (2 years: 11, 3 years: 22, 4 years: 21, 5 years: 18, and 6 years: 8). The measurements used were jumping height in counter movement jumping (CMJ), index (jumping height/ground contact time) of consecutive rebound jumping (RJ), foot length, shank length, Achilles tendon length, relative Achilles tendon length (Achilles tendon length/shank length), relative foot length (foot length/shank length) and calf girth as morphological characteristics. The main results obtained were as a follows.   1)  CMJ jumping height and RJ-index increased with age. Development of RJ-index depended on the increase in jumping height because ground contact time did not change even though jumping height increased with age.   2)  CMJ and RJ ability development types were classified into 3 groups according to ±1 SD of the residual of regression line with age in months (good, equal, and poor groups). For RJ ability, the number of equal groups decreased significantly after 50 months in boy and girls. In addition, for boys, the number of individuals in the good group increased significantly after 50 months, whereas for girls, the number of individuals in the poor group increased significantly after 50 months. No such changes were found in CMJ ability.   3)  RJ jumping height and ground contact time were compared among the 3 groups. The good group showed a significantly higher jumping height and shorter ground contact time than the other 2 groups. In addition, morphological characteristics showed no significant differences among the 3 groups.   These results suggest that the development of RJ ability differs from that of CMJ ability, and that the development difference in RJ ability begins to become evident in infants over 50 months. In addition, it is suggested that this difference is influenced by factors other than morphological characteristics.

著者

田邊 元

出版者

一般社団法人 日本体育・スポーツ・健康学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.66, pp.791-807, 2021 (Released:2021-11-27)

参考文献数

88

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This paper aims to clarify some of the diverse martial arts practices during the Meiji era by identifying martial arts entertainment that was mainly prevalent in that period. It follows the activities of shinto-ryu kenbujutsu, which was founded by Hibino Raifu in the middle of the Meiji period and included performances in its practice. This paper analyzes the martial arts practiced in martial arts performances from the perspective of their performance character. The performance character refers to the nature of martial arts as practiced in a “see/be seen” relationship. How was the martial art practiced in such a relationship? The study examines how Hibino practiced martial arts entertainment while being aware of the audience’s gaze. Chapter 2 gives a detailed description of Hibino’s life. Hibino was different from other martial artists in that he had connections with the regime side, such as soldiers, politicians, and scholars, although his origins are unknown. Throughout the Sino-Japanese War and the Russo-Japanese War, he was supported by many people, and his performances were attended by military and political figures. He actively presented the martial arts to such audiences, including those on the regime side, in the form of entertainment. Chapter 3 clarifies specific details of the practice of shinto-ryu, which included sword dance, practiced by a swaggerer and recognized by the audience as a dance performed by female geisha. Hibino stated that kenbujyutsu and sword dance were different, and that sword fighting represented an extension of “martial arts training”, which through practice showed the “reality and activity of the yamato spirit”. To be more specific, the demonstration was so fierce that the swords broke, and the audience felt as if they were watching a duel, and even cried. Of course, the audience included soldiers and politicians as mentioned earlier. In other words, Hibino’s martial arts performances satisfied both the masses and the critical gaze of soldiers and politicians. As mentioned above, although the martial arts could be perceived as “violent” in the new era, Hibino adapted to the times by actively presenting performances that met the requirements of the audience.

著者

五賀 友継 李 燦雨

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.63, no.1, pp.121-137, 2018-06-10 (Released:2018-06-20)

参考文献数

93

被引用文献数

1

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The aim of this study was to clarify the establishment and development process of Dai Nippon Kyudo Kai (DNKK), which existed from the Meiji to the pre-war Showa era, and its organizational forms. The tasks of the study were to elucidate the establishment and developmental process of the DNKK based on the historical characteristics of the organization, which can be divided into 6 periods. The organizational forms were examined based on the articles of incorporation, and the trends of membership and branch distribution were also clarified. The results were as follows: 1)The DNKK was established as Seinen Kyujutsu Kai under the Toshizane Honda school in 1909, and shortly renamed the Dai Nippon Kyujutsu Kai. When it became an incorporated foundation in 1919, it was renamed the DNKK. The kyudo philosophy of Kako Neya was strongly reflected at the time of its foundation. 2)The DNKK increased its membership by developing its publishing arm, and promoted kyujutsu and kyudo as part of the regular curriculum in the school. 3)Division among DNKK members in 1915 and the death of Toshizane Honda in 1917 led to a schism of Toshizane Hondaʼs pupils, which resulted in diffusion of the Toshizane Honda method among kyudo players. 4)The DNKK was renamed kyudo from kyujutsu when it became an incorporated foundation in 1919. They considered kyujutsu to be a subject within kyudo. 5) The massive promotion of the DNKK was financially supported by kyudo shops. 6)Analysis of the articles of incorporation showed that the kyudo philosophy of Kako Neya was strongly reflected in the policy of the DNKK through a mechanism based on the opinions of the board of councilors. 7) The conflict with Dai Nippon Butoku Kai over kyudoyosoku resulted in further expansion of the DNKK because of the massive promotion program against them, and a medically negative interpretation to kyudoyosoku evident at the Tokyo Provisional First Army Hospital. 8)Kako Neya decided to step down in 1943, and the activity of the DNKK was substantially terminated in 1944 due to the influence of war. 9)The cumulative total DNKK membership was 22,769 between June 1912 and October 1943. The membership trend was affected by various external factors. 10)A total of 426 branches were established domestically and internationally. The trend of branch establishment was similar to that of membership, and 75% of branches were located in Eastern Japan. The DNKK aggressively promoted overseas expansion.

著者

吉田 拓矢 川原 布紗子 福田 有紗 白井 蒼 佐久間 彩 図子 あまね 淺井 武 谷川 聡 平嶋 裕輔

出版者

一般社団法人 日本体育・スポーツ・健康学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

pp.20110, (Released:2021-05-12)

被引用文献数

1

著者

遠藤 俊典 宮下 憲 尾縣 貢

出版者

一般社団法人 日本体育・スポーツ・健康学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.53, no.2, pp.477-490, 2008-12-10 (Released:2009-02-25)

参考文献数

26

被引用文献数

3 8

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The purpose of the present study was to clarify the factors involved in deceleration in the last phase of a 100 m sprint by comparing the kinetics of the lower limb joints between the maximal running velocity phase (Max) and the deceleration phase (Dec). Five male collegiate sprinters, running 60 m and 100 m at maximal effort, were videotaped with high-speed cameras (250 fps) and the ground reaction force (1000 Hz) was measured at the 50-m and 85-m points. The kinematics and kinetics of the lower limb joints were then calculated. The results were as follows: 1) The deceleration of running velocity was due to a decrease of stride frequency. 2) In the Dec, braking impulse increased, but propulsion impulse decreased significantly. 3) Significant decreases were found in joint torque and negative power exerted by ankle plantar flexors. 4) Hip negative work exerted by hip joint torque in the late support phase tended to decrease, and it is thought that this decrease affected the delay of hip-flex movement during the early recovery phase. These results reveal that the function of the ankle has a direct influence on deceleration, and suggest that the negative work exerted by hip joint torque during the support phase may help to maintain hip-flex movement during the early recovery phase in the final phase of the 100-m sprint.

著者

鈴木 楓太

出版者

一般社団法人 日本体育・スポーツ・健康学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

pp.19012, (Released:2020-02-10)

被引用文献数

1

著者

勝又 宏 川合 武司

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.40, no.6, pp.381-398, 1996-03-10 (Released:2017-09-27)

被引用文献数

7

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This study was designed to examine how baseball batters adjust their batting actions to slow-speed and fast-speed pitches by measuring the ground reaction forces. The followings were revealed during different phases of the batting action. 1) At the take-back motion phase, the weight was transferred onto the catcher-side foot. The ground reaction force of the left foot, i.e., the pitcher-side foot, was increased immediately to fix the left foot firmly on the ground at the bat-swing phase. 2) In batting the slow-speed pitches, fixing the stepped left foot on the ground was remained momentarily before the bat-swing action. 3) In batting the slow-speed and fast-speed pitches, the ground reaction force curves of the left foot at the bat-swing phase were almost the saae. 4) The bat swing was started after fixing the left foot on the ground. 5) In each batting for the slow-speed and the fast-speed pitches which were mixed at random, the beginnig-phases of the batting motions were started at the almost same time. These analyses suggest the followings: 1)Ddecision on hitting the pitch is made before fixing the stepped foot firmly on the ground. 2)By momentary fixation of the stepped foot on the ground, the bat-swing action is synchronized to the pitch for correctly timed hitting. 4)When it is difficult for batters to predict whether the next pitch will be fast-speed or slow-speed, batters' actions may be prepared to hit the fast-speed pitches. And when the pitched ball is slow-speed, batters may adjust the start of the bat-swing action by momentary fixation of the stepped foot on the ground.

著者

石井 泰光 山本 正嘉 図子 浩二

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.55, no.1, pp.63-79, 2010 (Released:2010-07-20)

参考文献数

39

被引用文献数

3

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The purpose of this study was to investigate the similarities of upper torso rotation and pelvic rotation around the vertical axis of the global coordinate system with trunk rotation during throwing and striking movements. We enrolled twenty-three right-handed male college students, who performed baseball pitching and batting movements and the golf driver shot. During the throwing and striking movements, 3D coordinates of body landmarks were obtained using the VICON 612 system with 10 cameras operating at 120 frames per second. The ball speed during pitching and the head speed during batting and the driver shot were measured using a high-speed camera at 250 frames per second and analyzed using WINanalyze (2D motion analyzer). The angles of rotation of the upper torso and pelvis were calculated as the angles between the respective segment and the global x-axis. The trunk rotation angle was calculated as the angle between the upper torso segment and the pelvic segment. The sequential data for rotational movement variables were normalized from the onset of the minimum upper torso angle until release or impact. There were significant positive correlations between the ball speed during pitching, head speed during batting, and head speed during the driver shot (pitching vs. batting, r=0.627, p<0.01; pitching vs. driver shot, r=0.670, p<0.01; batting vs. driver shot, r=0.554, p<0.01). There were significant positive correlations between the two striking movements with regard to the maximum angular velocity of upper torso rotation (r=0.567, p<0.01) and pelvic rotation (r=0.523, p<0.05). The batting and driver shot showed similarity of trunk rotation and pelvic rotation in that the contribution of pelvic angular velocity to the maximum upper torso angular velocity was larger than the contribution of trunk rotational angular velocity to the maximum upper torso angular velocity. Upon trunk rotation, there were no significant positive correlations among the pitching, the batting, and the driver shot with regard to maximum angular velocity. These results indicate that the ball and head speeds are strongly related during pitching, batting, and the driver shot. The upper torso rotation and pelvic rotation around the vertical axis of the global coordinate system are related only during batting and the driver shot.

著者

津越 智雄 浅井 武

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.55, no.2, pp.565-576, 2010 (Released:2010-12-28)

参考文献数

24

被引用文献数

5

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This study examined the physique, physical fitness and motor ability of soccer players, especially junior youth and youth players of “J-League” clubs, using relatively common field test items in accordance with the Japan Football Association (JFA) Physical Measurement Guidelines (2006). We also compared the physique, physical fitness and motor ability between those who were promoted and those who retired from clubs for each generational category (top team group and second team group for the professional category) in an attempt to identify factors that significantly influence selection to higher categories. The study subjects were 213 male soccer players who were affiliated to a team (aged 19 years or older) in the Japan Professional Soccer League (J-League) or its subsidiary clubs, including the youth team (16-18 years) and the junior youth team (13-15 years), between 2006 and 2008. All subjects were compared for the following items: body height, body weight, percentage body fat, 10-m run, 30-m run, 50-m run, shuttle run (10 m×5), STEP 50, vertical jump, standing five-step jump, and multi-stage shuttle run. The measurements were also compared between those who were promoted and those who retired from the club for each category using the t-test and discrimination analysis. The results revealed that the factors of physique, physical fitness and motor ability that significantly influenced the promotion or retirement of junior youth and youth players were those related to physique (especially body weight), speed and agility. Power-related factors were more important in youth players, but were less influential than the above-mentioned factors. The influence of endurance-related factors appeared to be even smaller. The field test items used in the present study are considered valuable for use in training practice in that they can be performed relatively easily and allow selective factors for each category to be determined to some extent.

著者

尾縣 貢 高本 恵美 伊藤 新太郎

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.48, no.5, pp.573-583, 2003-09-10 (Released:2017-09-27)

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本研究の目的は,上肢の無気的作業能が400m走中の走速度逓減およびパフォーマンスに及ぼす影響を検討することであった。400m走50.70±1.38秒のタイムを持つ十種競技者10名を対象に,400m走中の40m毎の速度変化,ゴールタイム,30秒間のペダリング中およびクランキング中の最大パワー,平均パワー,パワー低下率,それぞれの運動5分後の乳酸値を測定した。主な結果は次の通りであった。1)クランキング後乳酸値/400m走後乳酸値と400m走タイムとの間には,有意な負の相関関係が認められた。この結果から,高い強度の無気的運動に耐えうる上肢の能力を高めることが,400m走のパフォーマンスを高めることにつながるものと考えられる。2)400m走では,10名全員が80m地点通過後に速度逓減を示し,ゴールまで逓減を続けた。80m以降の速度逓減は直線回帰式で表すことができ,その傾き(絶対値)を速度逓減指標とした。この速度逓減が緩やかな者ほど,400m走タイムは短いという関係が認められた。3)320-360m区間(第8区間)から360-400m区間(第9区間)への速度逓減は,上肢のパワー低下率および下肢のパワー低下率との間に有意な正の相関関係が認められた。これは,上肢のパワー発揮の持続力に優れることがゴール前の速度低下を小さく抑えることにつながることを示唆するものである。以上のことから,上肢のパワー持続能力がゴール前の速度逓減に影響を及ぼしていることが明らかとなった。

著者

那須 大毅 松尾 知之

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

pp.14047, (Released:2015-01-20)

参考文献数

12

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The aim of the present study was to investigate the differences in kinematics between two types of motor strategy for expert dart throwing. We divided eight experts into two groups based on the motor strategies they had demonstrated in a previous study (Nasu et al., 2014): group A were experts who had a longer time window in which a release could result in hitting the bull's eye, and group B were experts who had a shorter time window but greatly reduced their timing error. Each subject performed 60 dart throws, aiming at the center of the dart board (bull's eye). The movement of the dart, index finger, and joint motion of the upper extremity were captured using a motion capture system with 7 cameras (480 Hz, Oqus300, Qualysis Inc.). We compared the shape of the hand trajectory and joint kinematics between the groups. We found that experts in group A demonstrated a smaller shoulder angle (lower elbow height) and a larger angle of elbow flexion through forward swing than those in group B. These differences affected the time window that led to a successful throw, i.e. the time for which the mutually complementary relationship among the release parameters (especially the relationship between velocity and direction of motion) was maintained. These results may be useful as basic data to help clarify how throwing accuracy can be improved in several sports.

著者

阿江 数通 小池 関也 藤井 範久 阿江 通良 川村 卓 金堀 哲也

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

pp.16080, (Released:2017-09-01)

参考文献数

48

被引用文献数

1

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The purpose of this study was to compare the kinematic characteristics of the upper body between baseball tee batting and pitched ball batting in order to gain basic knowledge for improvement of batting skill. Ten male collegiate baseball players (age: 20.7±1.1 yr; height: 1.75±0.05 m; body mass: 76.3±7.1 kg; athletic career: 12.7±2.7 yr) participated. They performed two kinds of batting: tee batting (TB) and machine-pitch batting (MB) using a pitching machine (approximate ball speed 33.3 m/s), which were set at middle ball height for the strike zone. Three-dimensional coordinate data were acquired with a motion capture system. Kinematic variables such as maximum bat-head speed, swing time, bat angle, joint angles of the upper limbs, and segment angle of the upper trunk were calculated. Differences between TB and MB were analyzed statistically using paired t-test (p<0.05.) The maximum bat-head speed was significantly greater in TB than in MB, but swing times divided into two phases showed no significant differences between MB and TB. In the first half of the swing, the bat inclination angle was significantly larger in MB than in TB. The joint angles of the barrel-side shoulder abduction, knob-side shoulder adduction and internal rotation were significantly larger in MB than in TB, and those of the barrel-side shoulder internal rotation and individual elbow pronations were significantly larger in TB than in MB. The clockwise rotational angle of the upper trunk was significantly larger in TB than in MB. In the last half of the swing, the joint angles of the barrel-side shoulder abduction, knob-side shoulder flexion and adduction were significantly larger in MB than in TB, and that of the knob-side elbow pronation was significantly larger in TB than in MB. The changes in upper body movement in MB affected the radius of rotation of the bat about the vertical axis to control the bat easily. The movements in the last half of the swing largely resulted from those in the first half of the swing, and did not contribute to timing adjustment. These results indicate that the initial configuration of the bat and upper limbs, and movements at the beginning of the bat swing contribute to the timing adjustment of the bat for a pitched ball. The results of the present study suggest that it could be useful to pay attention to the movement of the bat and upper body in the first half of the swing as TB practice in order to improve timing adjustment.

著者

宮西 智久 藤井 範久 阿江 通良 功力 靖雄 岡田 守彦

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.40, no.2, pp.89-103, 1995

被引用文献数

3 6

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The purpose of this study was to investigate the differences of the motions between the speed throw and the distance throw, using a three-dimensional(3D) motion analysis. Twenty-four male university baseball players were the subjects of this study. They were asked to throw a ball (mass 0.144kg) horizontally as fast as possible (speed throw: ST), and as far as possible (distance throw: DT). These motions were filmed by two high-speed video cameras. 3D landmark coordinates of the subiects and the ball were calculated by the DLT method. The following kinematic parameters were computed: angle of release, the component velocities of the ball, the 3D angles for the backward/forward lean, right/left lean of the upper torso, and the twist of the torso and those for the abduction/adduction, horizontal flexion/extension, internal/external rotation at the shoulder joint, and the flexion/extension at the elbow joint of the throwing arm. The sequential data were normalized with the time from the stride foot contact to the ball release, and then averaged. Angle of release was significantly larger in the DT than in the ST. Significant difference was not found between the resultant velocity of the ST and the DT. Vertical velocity of the ball was significantly larger in the DT than in the ST during the latter half of the acceleration phase. On the other hand, horizontal velocity of the ball was significantly larger in the ST than in the DT. The backward lean and the left lean angles of the upper torso were also significantly larger in the DT than in the ST throughout the all sequences analyzed. Ranges of these angular displacements between the stride foot contact and the release, however, had no significant difference between the ST and the DT. The shoulder adduction angle was also significantly larger in the DT than in the ST during the latter half of the acceleration phase. These results indicate that the differences in the release parameters between the ST and the DT were caused not only by the throwing arm motions but also by the motions of the upper torso. It has been suggested that the motions to upward and left ward of the upper torso helps to achieve longer throwing distance in the DT, and that forward lean of the upper torso possibly contributes to achieve larger horizontal ball velocity at the release in the ST.

著者

豊嶋 陵司 桜井 伸二

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

pp.17008, (Released:2018-06-15)

参考文献数

47

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This study investigated the relationships between the kinetic factor of the swing leg and step frequency (SF) and step length (SL) during the top speed phase of a sprint. Sixteen male sprinters (age 19.3±0.6 years, height 1.74±0.06 m, weight 66.1±5.2 kg) performed maximum effort 60-m sprints. Video data from the 43.5- to 50-m section of the sprint were collected using a high-speed camera (300 Hz). SF index and SL index were calculated to exclude the influence of body height on the outcomes of interest. Torque and torque power of the hip and knee joints of the right leg were calculated during the swing phase of the right leg. The time of the swing phase of the right leg was normalized so that the take-off of the right foot, touchdown of the left foot, take-off of the left foot, and touchdown of the right foot were 0%, 100%, 200%, and 300%, respectively. For every 5% of normalized time, partial correlation analysis was conducted between the right leg kinetics and SF index (controlling SL index) and SL index (controlling SF index). The SF index was associated with a large hip flexion torque and a large hip extension torque during 10–60% and 250–280% of the swing phase, respectively. Moreover, large peaks of the hip flexion torque and positive power were associated with a high SF index (r = -.718, p <0.01; r = .531, p <0.05, respectively). The SL index was associated with a hip flexion torque during 20–30% of the swing phase, although there was no significant partial correlation between the SL index and peak hip flexion torque (r = -.381, p = .161). In addition, a high SL index was associated with early appearance of the peak hip flexion torque power (r = -.759, p <0.01). In conclusion, throughout the top speed phase of a sprint, a high SF index requires a large torque and hip joint power for the leg swing over a short duration, and a high SL index requires an early increase of hip flexion torque power.

著者

中澤 篤史

出版者

一般社団法人 日本体育学会

雑誌

体育学研究 (ISSN:04846710)

巻号頁・発行日

vol.53, no.2, pp.315-328, 2008-12-10 (Released:2009-02-25)

参考文献数

27

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The Undoukai (Athletic Association) at the Imperial University of Tokyo was a student association that consisted mainly of sports club members. The Undoukai was a departure point for Japanese sports, and led to the establishment of school sports in the Meiji period, being incorporated as a foundation in 1934. The purpose of this study is to describe the process of how the Undoukai was organized as an incorporated foundation from the late Taisho era to the early part of the Showa era, focusing on interactions among students and the university. The main documents are gathered from the Imperial University Newspaper.The results of this study are summarized as follows.1) This study describes the history after establishment of the Undoukai, which was integrated into the Gakuyukai (Athletic and Cultural Association) at the Imperial University of Tokyo in 1920. The Gakuyukai was an all-university association that included cultural activities. However, the members of the sports clubs left the Gakuyukai and organized the Undoukai again in 1928.2) This study clarifies two oppositional relationships among students during the organizational process of the Undoukai. One was between sports club members and the other students, and the other was between the left-wing students and the right-wing students. In both relationships, sports club members would win the understanding of non-athletic students and would distance themselves from the left-wing students. Both practices enabled the Undoukai to become independent from the Gakuyukai.3) This study clarifies that strong assistance from the University contributed to the reorganization of the Undoukai. There were two problems that the University needed to address: one was how to prevent students' illnesses, and the other was how to discourage students from becoming inclined to the politcal left. Therefore, the University expected general students to aspire to “healthy body” and to have “healthy idea”. While the University would recommend sports to general students in order to realize the expectation of “healthy body”, at the same time it would separate general students from left-wing students in order to realize the expectation of “healthy idea”. These expectations and practices of the University provided the impetus that nurtured the Undoukai.