The Japan Journal of Coaching Studies
Online ISSN : 2434-0510
Print ISSN : 2185-1646
Volume 31 , Issue 2
Showing 1-10 articles out of 10 articles from the selected issue
Original articles
  • Takashi Wataya
    2018 Volume 31 Issue 2 Pages 157-164
    Published: March 20, 2018
    Released: September 02, 2019
    JOURNAL FREE ACCESS

        The purpose of this study was to clarify the characteristic of kicking motion of pivoting leg of softball pitchers who have great velocity of center of gravity during pitching. The study was subject to 19 high school girl softball pitchers who specialize in the windmill pitching and we calculated the kinematic variables concerning the maximum velocity of center of gravity and kicking motion to the pitching direction by two-dimensional motion analysis of their pitching motion. After that, we conducted a correlation analysis between the maximum velocity of center of gravity and the kinematic variables. Our findings through this study concerning the characteristic of pitchers who have a great velocity of center of gravity are as follows.
    1) The height of center of gravity was kept to be low during pitching. In addition, forward lean angle of upper body and hip flexion angle were large at the beginning of kicking.
    2) The average angular velocity of overall leg and the average angular velocity of hip joints were large. Especially, the average angular velocity of hip joints in the latter kicking was large.
    3) The range of motion of thigh was large and the inclination of overall foot and thigh to the pitching direction at the end of kicking were large.
        Including above, this study suggested a potential that it is effective for the instruction of the windmill pitching that we have them do a kicking motion by keeping their height of center of gravity to be lower during kicking and focusing on the extension motion of hip joints in order to enhance velocity of center of gravity.

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  • Tatsuaki Ikeda
    2018 Volume 31 Issue 2 Pages 165-174
    Published: March 20, 2018
    Released: September 02, 2019
    JOURNAL FREE ACCESS

        The purpose of this study was to investigate an effect and utility of the resistance training for individual difference of a training objective and muscle adaptation. Sixteen healthy males were evaluated characteristics of one repetition maximum (1RM) and the total number of repetitions (Ntotal) loaded at 90%, 70% and 50%1RM of a knee extension exercise prior to this study (pre). Subjects carried out training of knee extension exercise for 12 weeks twice a week. In addition, the training accorded with a plan-do-check-act cycle (PDCA cycle). CSA (muscle cross-sectional area of a quadriceps femoris muscle), 1RM and Ntotal were measured every 3 weeks during a training period to evaluate a training effect. Based on these measurement results, subjects chose from two different training methods (strength・power-up type and bulk-up type) according to a personal training objective and degree of a training effect.
        The major findings were:
    ①1RM, 1RM / CSA and Ntotal in all subjects increased significantly after training.
    ② Development transitions of 1RM and Ntotal differed greatly according to the individual difference of a training objective and muscle adaptation.
    ③There is a possibility that a significant increase of 1RM was affected by adaptation of a neuromuscular system.
        These results suggest that the personalized resistance training incorporating a PDCA cycle may become more rational and effective practice, as compared with training which performs the same contents to all subjects.

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  • Estimating physical strength requirement corresponding to throwing distance
    Kei Maeda, Keigo Ohyama Byun, Kenichi Hirose, Mitsugi Ogata
    2018 Volume 31 Issue 2 Pages 175-184
    Published: March 20, 2018
    Released: September 02, 2019
    JOURNAL FREE ACCESS

        The purposes of this study were to clarify the influence of physical strength on throwing distance, and to estimate strength requirement for each target throwing distance of discus. The questionnaire method was used to investigate parameters about morphology and physical strength for 114 male discus throwers. Pearson’s correlation coefficient was calculated to investigate the relationships between the parameters and throwing distance. Then, multiple regression analysis was carried out to clarify influence of the parameters on throwing distance. As a result, all parameters correlated significantly to throwing distance. The parameters of morphology to have great influence on throwing distance were span of arm and body weight. The parameters of physical strength to have great influence on throwing distance were backward over head shot throw, snatch, standing five steps jump, 30m dash, in descending order. In addition, physical strength requirement corresponding to throwing distance of discus was gained by estimating the standard value of each parameter from the regression analysis. Strength requirement shown in this study has a high practicality for coaches and throwers in planning training programs and setting goals.

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  • Comparing with residential camp and nonparticipants
    Masahiro Okada, Akihiro Sakamoto, Taiki Kawata, Masahiro Horimatsu
    2018 Volume 31 Issue 2 Pages 185-195
    Published: March 20, 2018
    Released: September 02, 2019
    JOURNAL FREE ACCESS

        The purpose of this study was to determine the effects of expeditionary camp on attitudes toward nature of elementary and junior high school students. Scale of Attitudes toward Nature was administered three times (before camp, just after camp, and 1-month later) to students who participated in Expeditionary Camp (N=69) and Residential Camp (N=60). The scale was also administered two times (before camp and 1-month later) to students who did not participate in camp (N=91). The results were as follows:
    1. Total scores of Attitudes toward Nature in Expeditionary Camp were significantly higher than those in Nonparticipants at 1-month later. Comparing each factor, there were significant differences in scores of “positive affect” factor and “camp” factor.
    2. Total scores of Attitudes toward Nature in Expeditionary Camp showed significant increase at just after camp and sustained until 1-month later. The other hand, there was no significant change in Residential Camp. Also, total scores in Expeditionary Camp were significantly higher than those in Residential Camp at just after camp, and the difference tended to sustain until 1-month later. Comparing each factor, Expeditionary Camp was significantly higher than Residential Camp in scores of “camp” factor.

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  • The speed and spin of the service
    Nahoko Koya, Tetsu Kitamura, Hiroo Takahashi, Daisuke Mitsuhashi
    2018 Volume 31 Issue 2 Pages 197-208
    Published: March 20, 2018
    Released: September 02, 2019
    JOURNAL FREE ACCESS

        The service is the only shot in tennis that is 100% under control of the player, and the most potentially dominant shot in game. This study investigated the service speed and spin as an indicator of service performance and analyzed the correlation between service performance and physical fitness. Twenty- two male players playing at the elite level of each age in Japan, participated in this study. It was found that:
    1) There was a significant correlation between the speed, both 1st and 2nd services, and physical fitness, while the service spin did not correlate with physical fitness.
    2) Medicine ball throw, which is a test item of throwing type, was the item that we could predict the speed of the 1st service, compared to running and jumping items.
    3) A significant regression in speed between the 1st service speed (Y) and medicine ball throw was found [Y=1.16x+100.24; x: medicine ball throw; r =0.81; p<0.05].

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  • Follow-up of 5000m running performance
    Sho Nakazawa, Kazuki Takizawa, Yoshiki Koto, Koya Yamashiro, Daisuke S ...
    2018 Volume 31 Issue 2 Pages 209-217
    Published: March 20, 2018
    Released: September 02, 2019
    JOURNAL FREE ACCESS

        The purpose of this study was to clarify the relationship between running distance over an 8-month period and both 5000 m running performance and aerobic capacity (VO2max, VO2VT, running economy). The 8-month study period was divided into two segments of 4 months each. It was found that long-distance athletes could run 5000 m in about 15 min 30 s. The analysis also confirmed the following: (1) athletes that ran longer distances in the 8-month period had better 5000m times; (2) they had higher VO2VT; and (3) athletes whose distances were longer in the first half of the study period had better VO2VT and 5000m records in the second half of the period. The anaerobic threshold reached a higher level in runners with greater training distance, resulting in an improvement in race results. Furthermore, based on the fact that the distance run in the first four months effects on VO2VT and 5000 m running times in the latter four months, this study demonstrates the possibility of training effects occurring after a certain latency period. The results implicated that it was important to track running distances as an indicator of race performance.

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  • Yujiro Masu
    2018 Volume 31 Issue 2 Pages 219-230
    Published: March 20, 2018
    Released: September 02, 2019
    JOURNAL FREE ACCESS

        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.

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  • Shinnosuke Uematsu, Yuki Iguchi, Shigeo Kusumoto, Yohei Shimokochi, Ak ...
    2018 Volume 31 Issue 2 Pages 231-237
    Published: March 20, 2018
    Released: September 02, 2019
    JOURNAL FREE ACCESS

        This study investigated the occurrence frequency of accelerations (Acc), decelerations (Dec), and changes of directions (CoD) during the actual handball game and their frequency under high intensity events (HIE) circumstances, using inertial measurement units (IMU).
        Participants were female handball players in Japan. 10 players (Age: 24.7±2.3 years old, height: 167.0±8.1 cm, body weight: 65.2±6.1 kg) belong to womenʼs division of Japan Handball League (upper group), 10 top-level university players (Age: 20.6±0.8 years old, height: 165.1±5.9 cm, body weight: 61.0±5.6 kg) from the division 1 of Japanese university handball league (middle group), and 8 university players (age: 20.0±0.8 years old, height: 157.9±5.8 cm, body weight: 54.3±5.5 kg) from a team belong to division 2 of the league (lower group).
        As a result, the upper group displayed the highest occurrence frequency in all items, the middle group was second highest, and lower group was the lowest. The result indicates that in competition sites, it is important to implement specializing training based on the understanding of the characteristics of handball as a sport and on the scientific knowledge that we could acquire from the actual games.

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  • Naoto Tobe, Ryohei Hayashi, Yasushi Kariyama, Kiyonobu Kigoshi, Mitsu ...
    2018 Volume 31 Issue 2 Pages 239-251
    Published: March 20, 2018
    Released: September 02, 2019
    JOURNAL FREE ACCESS

        This study aimed to present the practical knowledge and investigate effective techniques to improve performance in the high jump. The subject was a male Japanese top class high jumper whose personal record was 2 m31. Progress in high jump performance was shown by an increase from 2 m22 in 2012 to 2 m31 in 2014, and kinematics data were collected at competitions to assess the factors involved in achieving best record. The results were as follows.
    1. The subject focused on high jump technique training during periods between competitions, and on improvement in strength training at without competition periods. Considering effects of training, this training protocol was logical.
    2. The subject changed from single-arm action at takeoff to double-arm action and improved its techniques during this study. This change improved high jump performance by increasing force on takeoff.
    3. The results of this study suggested different from general theory which is provided by previous study. It means that there is possibility to discover new theory by investigating individual case.
        These results suggest the hints to improve high jump performance and indicating the importance of individual longitudinal investigation.

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Research data
  • focusing on psychological modification and exercise intensity
    Satoshi Motoya, Yasuhiko Takahashi, Mizuki Kojima, Aya Horiguchi
    2018 Volume 31 Issue 2 Pages 253-262
    Published: March 20, 2018
    Released: September 02, 2019
    JOURNAL FREE ACCESS

        The purpose of this study is to explore the possibilities of exercises using elastic ropes by proposing an exercise program and set of gymnastics utilizing the characteristics of elastic ropes and verifying the effects of these exercises. 146 university students were the subjects of the study, and the items of the study were examination of the exercise program using the visual analog scale, psychological modification before and after the gymnastics using the two-dimensional mood scale, and the subjective and objective exercise intensity during the gymnastics. As a result: (1) The overall average values on the visual analog scale for all subjects of the study were 78.6 ± 21.4% for attainment, 75.5 ± 20.2% for interest, and 29.1 ± 26.2% for danger. In particular, high values were displayed for interest, similarly to the study using elementary school students as the subjects. (2) Through research using the two-dimensional mood scale, a significant difference (p<.001) was confirmed in all items of the study before and after the gymnastics for all subjects of the study, for which vitality, pleasure, and arousal increased, while stability decreased. (3) For exercise intensity during the gymnastics, the rating of perceived exertion was 8.9 ± 1.6, and the average heart rate, which served as the subjective index for gymnastic intensity, was 102.1 ± 11.4 bpm, resulting in similarly low values for both. As described above, it was found that the proposed gymnastics can be performed by university students with interest, and a positive effect of psychological improvement can be obtained, even though the exercise intensity values were low.

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