著者

広瀬 健一 大山卞 圭悟 尾縣 貢

出版者

The Japan Journal of Coaching Studies

雑誌

コーチング学研究 (ISSN:21851646)

巻号頁・発行日

vol.30, no.1, pp.65-72, 2016-10-20 (Released:2019-09-04)

参考文献数

24

---

This study reports a coaching case of a men's hammer throw athlete (abbreviated to “T athlete” after this) who had a problem with the acceleration of the hammer during the turn phase. T athlete’s personal record was 45.75m at the start of coaching. The theme of the training program was “hammer throw without using preliminary swings”. And T athlete practiced to accelerate the hammer during the turn phase. The training was carried out for about three and a half months. The procedure of the approach was divided into two stages. The approach ① was the 1st training process until T athlete learned “the hammer throw without using preliminary swings”. The approach ② was a training process after learning “the hammer throw without using preliminary swings”. During the approach ①, T athlete was able to learn the timing to accelerate the hammer from the right back during “the hammer throw without using preliminary swings”. In addition, the approach ② conducted the inclined plane of the hammer orbit of the actual throw to get closer to the one of “the hammer throw without using preliminary swings”. Finally, T athlete improved the personal record approximately 7m (45.75 to 52.67m). “The hammer throw without preliminary swings” is considered to be effective as one of the convincing training method to improve the turn technique of hammer throw.

著者

太田 和希 九鬼 靖太 奥平 柾道 吉田 拓矢 前村 公彦 谷川 聡

出版者

The Japan Journal of Coaching Studies

雑誌

コーチング学研究 (ISSN:21851646)

巻号頁・発行日

vol.33, no.2, pp.145-159, 2020-03-20 (Released:2020-06-11)

参考文献数

38

---

This study aimed to clarify the step variables and three-dimensional joint kinematics of the pelvis while increasing running speed on a treadmill. Sixteen male track and field athletes ran on an instrumented treadmill at three different running speeds: 4.0, 6.0, and 8.0 m/s. The step variables, such as step frequency, step length, contact time, and flight time, and the kinematic data of each running speed were recorded using a high-speed video camera (300 fps) and a Vicon T20 system (250 Hz). In addition, the pelvic angular displacement (Δ) was calculated by subtracting the minimum from the maximum values of the pelvic angle in the stance phase. The results were as follows: (1) Stride length and step frequency were significantly greater at higher running speeds. Although contact time was significantly shorter at the faster speeds, flight time was significantly shorter when transitioning from 6.0 to 8.0 m/s and from 4.0 to 8.0 m/s. (2) The pelvis of the swing leg side elevated from toe off to early half of swing phase with increasing running speeds. In addition, the pelvis of the stance leg side rotated to the swing leg side from mid stance phase to toe off with increasing running speeds. (3) Δelevation showed a significant negative correlation with step frequency but a significant positive correlation with stride length for each running speed. In addition, Δrotation showed a significant positive correlation with step frequency but a significant negative correlation with stride length at 8.0 m/s.     Therefore, increased pelvic elevation improves the stride when transitioning from a low to high speed, and increased pelvic rotation leads to a higher step frequency during the stance phase when running at 8.0 m/s. In addition, it was suggested that it is necessary to run at minimum 8.0 m/s for the pelvis to behave differently compared with running at slower speeds to learn the high speed running movement.

著者

升 佑二郎

出版者

The Japan Journal of Coaching Studies

雑誌

コーチング学研究 (ISSN:21851646)

巻号頁・発行日

vol.31, no.2, pp.219-230, 2018-03-20 (Released:2019-09-02)

参考文献数

12

---

This study compared the patterns of upper limb motion when delivering forehand (the hand holding the racket) straight/cross-court clear, drop, and smash shots from the backcourt in badminton.     Seven male badminton players, belonging to a team that was third in the All Japan Intercollegiate Badminton Championships, delivered these shots to record the pattern of motion in each case using MAC 3D System Cameras.     On comparison between straight and cross-court shots, the velocity of the wrist was significantly higher in the latter in all cases (p<0.05). The shoulder horizontal flexion angle was also markedly greater in the latter in all cases (p<0.05). On wrist motion trajectory analysis, the lateral (X-Z) plane at impact was shifted forward in the latter in all cases. Similarly, the frontal (Y-Z) plane was displaced inwards in the latter, while it was displaced outwards in the former from immediately before impact in all cases.     Based on the results, the velocity of the wrist may be higher at a greater shoulder horizontal flexion angle when delivering cross-court compared with straight shots. Furthermore, during the phase immediately before impact, the probabilities of straight and cross-court shots being delivered are high when the wrist moves out- (the distance from the trunk increases) and inwards (it decreases), respectively.

著者

吉田 康成 西 博史 福田 隆 遠藤 俊郎 橋原 孝博

出版者

The Japan Journal of Coaching Studies

雑誌

コーチング学研究 (ISSN:21851646)

巻号頁・発行日

vol.28, no.2, pp.183-197, 2015-03-20 (Released:2019-09-02)

参考文献数

17

---

The purpose of this study was to investigate the read blocking techniques against quick attacks with combination attacks in volleyball. 28 occurrences of blocking motions in 4 games (Poland vs Iran, Poland vs Japan, Cuba vs Argentina, Cuba vs Serbia) from the 2011 Men’s World Cup Volleyball were analyzed by the Direct Linear Transformation Method.     The findings were as follows: (1) The number of occurrences of double blocking (Middle blocker with side blocker) was 11 (Right-side blocker 5 times, Left-side blocker 6 times). Most blocks were single blocks by the middle blocker.     The average of the highest finger-tip heights for blocking motions were right-side 2.80m, middle block 2.97m, and leftside 2.84m. (2) In 11 occurrences of when a middle blocker touched the ball, the average of the finger-tip height for the right fingertip was 2.91m (range: 2.76 to 3.04m), and the left finger-tip height was 2.85m (range: 2.70 to 2.99m). In 8 occurrences, the middle blocker took off -0.016 to -0.134 seconds before the quick spiker hit the ball. (3) When the quick spiker took off, the distance from the net to the middle blocker’s position averaged 0.90m (range: 0.38 to 1.91m). On the other hand, when the quick spiker hit the ball, the distance from the net to the middle blocker’s position averaged 0.66m (range: 0.31 to 1.34m). There was a significant difference between the distance at the time the quick spiker took off and the distance at the time the quick spiker hit the ball (p<0.01). Middle blockers took off 0.150 seconds later when their stance was usually wider than 0.6m.

著者

森本 吉謙 入澤 裕樹 坪井 俊樹 小野寺 和也 川村 卓

出版者

The Japan Journal of Coaching Studies

雑誌

コーチング学研究 (ISSN:21851646)

巻号頁・発行日

vol.32, no.2, pp.203-210, 2019-03-20 (Released:2019-09-02)

参考文献数

23

---

The purposes of this study were to investigate the relationship between competitive result and environmental factors in high school baseball. A questionnaire survey was conducted on 533 university students who belonged to the baseball club when they were in high school. The survey content was the following 11 items; 1. Highest competitive result, 2. Presence or absence of the sports recommendation entrance examination, 3. Presence or absence of the sports scholarship system, 4. Occupation of the head coach, 5. Presence or absence of the assistant coach, 6. Number of the assistant coach, 7. Occupation of the assistant coach, 8. Presence or absence of the selection system for enter the club, 9. Number of the members, 10. Type of school (public or private), 11. Presence or absence of the private facility. In case of high school duplication, only one answer was adopted, and other inappropriate invalid answers were excluded for totalization. Finally, 435 students were divided into national group (n=89), block group (n=82) and prefecture group (n=264), based on the best result of the team at the time of high school, and examined the relationship between the competitive result and each environmental factor. As a result, regarding the occupation of the head coach, the proportion of teachers in all groups was high, but in the other items, the relationship with the competitive result was indicated, and the possibility that the difference in these environments could affect the competitive result was shown.