Journal of High Performance Sport
Online ISSN : 2434-7302
Print ISSN : 2434-7299
Volume 10
Displaying 1-14 of 14 articles from this issue
  • Yuzaburo Kojima, Masahiro Hagiwara, Taisuke Kinugasa
    2022 Volume 10 Pages 1-10
    Published: 2022
    Released on J-STAGE: March 13, 2022
    JOURNAL OPEN ACCESS
    It has been known that athlete development pathway is a long-term process determined by a complex interplay of various factors and elements of athlete development. It is important to develop athletes holistically and systematically for improving international competitiveness. Understanding the age of peak performance of elite athletes could provide important information for long-term development and high performance strategic planning. The aim of this study was to estimate training periods of Rio de Janeiro 2016 Summer Olympic Games and PyeongChang 2018 Winter Olympic Games medalists (n=1,471) based on the sports categorization (cgs, artistic, combat, game, target, and others) by analyzing the starting age of main sport and age of winning the first medal at Olympic Games. The data suggest that the characteristics of Olympic medalists were as follow: (1) the lower the starting age, the longer the training period, and the higher the starting age, the shorter the training period; (2) the starting age was higher and the training period was shorter in the cgs sports compared with other sports; and (3) the starting age was lower and the training period was longer in the artistic and game sports compared with the other sports.
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  • Saeko Takahashi, Jumpei Sasadai, Reia Shimizu, Akira Suzuki, Naomi Tak ...
    2022 Volume 10 Pages 11-23
    Published: 2022
    Released on J-STAGE: May 22, 2022
    JOURNAL OPEN ACCESS
    In order to investigate the effect of sports activities restriction during the COVID-19 pandemic on physical function among athletes, this study compared the physical measurements of athletes from immediately after lifting the restriction of activities with their measurements after returning to competition. The subjects were twenty-nine Japanese top-level athletes (male: 14, female: 15). Measurements of the upper limbs, trunk, and lower limbs were performed from the viewpoint of injury prevention. The results showed that in female athletes, the upper limb functions of external rotation at maximum elevation and scapular adduction, and lower limb muscle power and muscle mass were significantly improved after returning to competition compared to immediately after the lifting of restrictions. There was no significant difference observed in the trunk measurements of both male and female athletes. In the future, these results will be useful in conditioning athletes if sports activities are once again restricted.
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  • Toshiharu Yokozawa, Yuya Kimura, Fuminori Saikawa, Takanori Kato, Dais ...
    2022 Volume 10 Pages 24-35
    Published: 2022
    Released on J-STAGE: May 22, 2022
    JOURNAL OPEN ACCESS
    This study aimed to investigate the average speed, estimated propulsive force, and excess distance in each section of the 500m race for men at a senior international competition and to assess the race patterns of world-class speed skaters. The motion of the top 12 speed skaters who started in the inner and outer lanes (IL and OL), respectively (n=24), was captured at 60 frames/s using a local position measurement system that automatically identifies the skaters’ trajectory and speed. The 500m lane was divided into six sections, and the average speed in each section was calculated. Additionally, the propulsive force for each section was estimated by the change in the speed and assumed magnitude of the air resistance during the corresponding section. The excess distance in the curved sections was calculated as the difference between the actual skating distance and official lane distance. As a result, for both the IL and OL, the skaters with an overall greater average speed had a greater average speed from the crossing straight to the second curved section and a greater estimated propulsive force to the first curved section. Among the excellent skaters, sections for which estimated propulsive forces were larger differed depending on the skater in both the IL and OL. Skaters with a higher official record for the IL had a smaller excess distance. Our observations suggest that the higher average speed in a particular section could be attributed to the larger propulsive force in the previous section, and the propulsive force to the first curved section was important for the 500m race for men.
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  • A case study of a targeted sports project
    Shuhei Yamashita
    2022 Volume 10 Pages 36-49
    Published: 2022
    Released on J-STAGE: May 29, 2022
    JOURNAL OPEN ACCESS
    With the decision to host the 2020 Olympics in Tokyo, several projects were launched as measures to achieve fifth place in the ranking of the number of gold medals won in this competition. As part of these measures, a targeted sports project was implemented to increase the number of sports in which medals can be won by implementing the PDCA cycle and building a new system to develop athletes’ performance. The historical development of this project is reviewed in this paper, and its prospects are also discussed. This project was designed using a structure that aims to increase the number of athletes with the potential to win medals as well as develop medal-winning sports. A further goal was to create a new performance enhancement system through activities that build a PDCA cycle for the target sports that were selected through evidence-based analysis. A review of this project shows that it was implemented in conjunction with a variety of policies and measures. In the future, the results of this project should also be taken into account for evaluation and verification. Although we have been aiming to build a new system using the PDCA cycle, it is also necessary to consider a system that can be adapted to the environment of high-performance sports while considering the limitations of the PDCA cycle.
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  • : The perspectives of strategic planning and research of bidding for and hosting international sport events.
    Takahiro Waku, Jun Kubota, Masafumi Hara
    2022 Volume 10 Pages 50-63
    Published: 2022
    Released on J-STAGE: December 18, 2022
    JOURNAL OPEN ACCESS
    The purpose of this study was to obtain fundamental knowledge for a strategic approach in future sport policies to bid for and host international sport events and to explore the potential for the application of social network analysis in the field of international sport event research. We attempted to reveal the worldwide network structure among the international federations and countries hosting senior-class high level international sport events (Olympic sports only) like world championships and/or world-cups, for the past twenty years from 2001 to 2020. We defined the host countries and international federations of 647 international sport events as nodes, and measured the total numbers of nodes and ties of the network, the density of the network, and the degree of nodes using social network analysis. Furthermore, we used NetDraw to create a network map of hosting countries and international federations. The network consisted of 114 nodes and 878 ties with the density of 0.068. Countries with higher degree centrality were Germany, the United States, China/Spain, Italy, France, Japan/Russia, Great Britain, Canada, Hungary, and Australia throughout the past 20 years. The degree centralities in the first decade were higher for Germany/the United States, Spain/Italy, Canada/Japan, France, China, Australia, and Russia/Great Britain, while during the last decade China, France/Russia, Germany, the United States, Hungary/Spain, Italy/Japan, Great Britain, the Netherlands and Korea had a higher degree centrality. The international federations for sailing, cycling, swimming, gymnastics, athletics, wrestling, canoe, handball, modern pentathlon, and volleyball had a higher degree centrality throughout the past 20 years. In the second decade, the international federations for boxing, table tennis and taekwondo also had a higher degree centrality. These findings revealed the worldwide network structure and property among stakeholders related to hosting international sport events. Our findings provided basic evidences for understanding of market scale of international events and identification of competitive countries or potential sports/events in strategic planning of bidding for and hosting international sport events in the future. Social network analysis can be applied to researches in relation to high performance sport development, influence to international sports, and social effects on constancy of hosting international events in the field of international sport event research.
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  • Kanako Hirano, Taro Iizuka
    2022 Volume 10 Pages 64-73
    Published: 2022
    Released on J-STAGE: December 18, 2022
    JOURNAL OPEN ACCESS
    This paper reports the support using videos that was provided to the Japanese national badminton team in preparation for the Tokyo 2020 Olympic Games. As with the preparation for the Rio de Janeiro 2016 Games, we have continued to provide coaches and players with match analysis data and match videos of international tournaments. In addition, to help enhance the quality of their training for the Tokyo 2020 Games, we provided them with training videos along with a delay playback video tool for checking their performance during training camps. Match analysis was intended to determine the play tendencies of the opponents of the Japanese players, and to evaluate the performances of Japanese players for further training. To achieve these purposes effectively, we selected a suitable procedure from four options: specific play scene extraction from match videos, scoring analysis, spatial analysis, and temporal analysis. In particular, the use of temporal analysis was expanded to solve the problems of each player and the team as a whole.
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  • Naoyuki Kobatake, Hideyuki Nagao, Tomokazu Miura
    2022 Volume 10 Pages 74-84
    Published: 2022
    Released on J-STAGE: December 18, 2022
    JOURNAL OPEN ACCESS
    This study aimed to identify the characteristics of snatch lift in top-class Japanese female weightlifters. The hypothesis was that lifters who are good at the snatch had lower barbell velocity in the 1st pull and longer heel contact time based on their weightlifting coaching points. Female lifters who competed in the 2021 All Japan Women's Weightlifting Championships were included in the study. Lifters who had a small difference in scores between the best attempts in snatch and clean & jerk lifts comprised Group A (good at snatch), while those who had a greater difference in scores comprised Group B (NOT good at snatch). The two-dimensional position coordinates of the barbell of each athlete's best snatch attempt during competition were calculated from video analysis to determine the kinematic variables of the barbell. Heel contact time was also determined from video images and compared between groups. The results supported the hypothesis: athletes in Group A had a significantly smaller mean vertical velocity of the barbell in the 1st pull phase than the athletes in Group B (0.45±0.05[m/s], 0.52±0.05[m/s], p<0.001, d=1.179). However, there were no significant differences in mean vertical velocity of the barbell in the 2nd pull phase or in vertical maximum velocity between groups. Heel contact time was also significantly larger in Group A (0.61±0.04[s], 0.53±0.06[s], p<0.001, d=1.347). Finally, there was a negative relationship between the mean vertical velocity of the barbell during the 1st pull phase of the snatch and the best snatch attempt that standardized body weight (r=-0.287, p<0.05). These results suggest that slow and careful execution of the 1st pull and keeping the feet flat in the snatch positively affect the performance.
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  • Fumitake Okabe, Toshinobu Kawai, Toshiharu Yokozawa, Nobuhiko Akazawa, ...
    2022 Volume 10 Pages 85-94
    Published: 2022
    Released on J-STAGE: February 08, 2023
    JOURNAL OPEN ACCESS
    The purpose of this study is to clarify the factors for shortening lap times in the short track speed skating. Eight male skaters skated three laps at maximum effort, and the second half of the second lap having the minimum lap time was extracted for analysis. Both straight and curve sections were divided into the first and second parts which were defined as S3, C3, C4, and S4 in the order of skating, respectively, using the track markers set on the track and the cushion. From C3 to S4, skaters performed a crossing motion, which was the push-off movement with crossing their legs. In addition, a carrying motion, in which the right leg is held deeply flexed in the middle of the crossing motion and attempts to change direction boldly, was used in the curve sections. Parameters were the lap time, section speed calculated by the length and time of each section, time and percentage of the carrying motion (ToC and PoC) during the curve, change of section speed from S3 to C3 and C4 to S4, and left and right stroke frequency after the carrying motion. The results were as follows: 1) The section speed significantly increased from C4 to S4 and significantly decreased from S3 to C3. 2) The skaters who skated at a shorter lap time tended to have a higher section speed in the curve and the former part of the straight section with the crossing and carrying motion. 3) There were significant negative relationships among lap time, section speed from C3 to S4. There was a positive relationship between lap time and PoC. To shorten the lap time, it would be important to acquire a higher speed in the curve and S4 using the crossing and carrying motion.
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  • Junpei Sasadai, Masuyo Oishi, Shogo Okamoto, Kazuya Fukami, Reia Shimi ...
    2022 Volume 10 Pages 95-106
    Published: 2022
    Released on J-STAGE: February 08, 2023
    JOURNAL OPEN ACCESS
    The Total Conditioning Support Program (TCSP) provides comprehensive medical/scientific support concurrently in multiple disciplines (rehabilitation, nutrition, psychology, high performance gym, and training gym) to athletes who need rehabilitation due to sports injury or illness. The goal is to accelerate the return to play and improve upon the pre-injury performance level. We provided support through the TCSP to a para-alpine ski racer following an anterior cruciate ligament reconstruction. A multi-disciplinary collaborative approach was followed to implement interventions to strengthen muscles in addition to those of the affected leg and improve the aerobic and anaerobic capacity using ergometers. As a result, the athlete was able to compete again after confirming the effectiveness of the training exercises. Thus, multi-disciplinary collaboration was able to resolve problems such as lack of expertise and time constraints that usually arise in a single rehabilitation approach.
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  • ― Toward Tokyo 2020 Olympic Games: a case study ―
    Takeo Matsubayashi, Kai Kobayashi, Ryo Yamanaka, Hayato Onuma, Keisuke ...
    2022 Volume 10 Pages 107-124
    Published: 2022
    Released on J-STAGE: February 08, 2023
    JOURNAL OPEN ACCESS
    This study described the case application of video analysis for the baton-exchange practice of Japanese men's athletics 4×100m relay team toward the Tokyo 2020 Olympic Games, assessing the team's baton-exchange technique. The study also verified the relevance of various indices related to baton-exchange technique and discussed the challenges in future analysis. The passer and receiver were filmed from the side, then their sprinting time and velocities were measured every 5 meters. Some indices relevant to baton-exchange technique were also calculated, e.g., 40m time, from the passer entering into the takeover zone to the receiver passing the point 10m ahead of the zone exit; acceleration of the receiver; baton-exchange duration; baton-exchange position; free distance. The data suggested the team had a high standard of baton-exchange technique. It also indicated that the acceleration of the receiver is important, that shortened baton-exchange duration might not necessarily be required for receiver’s successful acceleration, and that the running speed adjustment of passer toward baton exchange and the free distance should be assessed comprehensively considering various factors such as the approach of passer to the receiver. For appropriate interpretation, it appeared essential to carefully check the data and its situation in detail for each trial. Several issues remain to be tackled in future analysis, with further data collection.
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  • Masahiro Hagiwara, Taisuke Kinugasa
    2022 Volume 10 Pages 125-139
    Published: 2022
    Released on J-STAGE: February 08, 2023
    JOURNAL OPEN ACCESS
    This study reported a case study of building evidence-based athlete development pathway models, which was jointly constructed by the two National Federations (NFs) and Japan Sport Council. As a result, the building procedure of the two pathway models (one Paralympic sport and one Olympic sport) using the Japanese FTEM (Foundation, Talent, Elite, and Mastery) framework were identified as follows: "understanding the concepts", "understanding the current situation", "formulating a hypothetical model", "collecting evidence", "re-building a model ", and "visualizing/publicizing the model". The development of pathway models required constant coordination and collaboration between NFs and key stakeholders by collecting sport-specific insights of the respective athletes and their stakeholders. In addition, the following three trickle-down effects were obtained from the process: (1) sharing the pathway models with athletes and their stakeholders by visualizing the whole of sport pathway with a language that promote common understanding; (2) presenting the visualized pathway models to the stakeholders to facilitate a common understanding and clarify their roles; (3) involving more stakeholders to collaborate and individuals to work together according to the overall aim.The building procedure of the pathway models shown in this study was only a part of the co-designing of the pathway models, and further monitoring is necessary for the full implementation of the pathway models. To our knowledge, this study was the first study to report process of developing the pathway models using the Japanese FTEM framework in Japan. The trickle-down effects, issues, and building procedure obtained from this study might be useful for other stakeholders.
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  • Yasuhiro Suzuki, Yuko Ishida, Eiko Suzuki, Daichi Yamashita
    2022 Volume 10 Pages 152-166
    Published: 2022
    Released on J-STAGE: February 08, 2023
    JOURNAL OPEN ACCESS
    The purpose of this study was to examine the effects of hypoxic sprint interval training using cycle ergometer on energy supply and artistic swimming performance. Two Japan national team artistic swimmers who participate in Tokyo 2020 Olympic performed sprint interval training for 24 sessions under the normobaric hypoxia (FiO2 = 14.4-15.5 %). The training consisted of 10-s and 60-s maximal sprinting, and sprint interval training (9×60-s pedaling, 60-s rest or 9×30-s pedaling, 30-s rest×2sets). At the end of training, a questionnaire was administered regarding changes in performance as perceived during competition and practice. The duration of exposure to hypoxia per session was approximately 90-110 minutes. The highest average power during training for the 60-s maximal pedaling test used to assess anaerobic capacity increased by 18 % and 13 %, respectively, for each subject compared to the first training session. In addition, the results of the questionnaire to the athletes indicated that they were able to swim to the end of the performance and that they felt less fatigued, indicating an improvement in subjective energy supply and delayed fatigue. These findings suggest that the sprint interval training under the normobaric hypoxia improved both anaerobic and aerobic capacities and may be an effective training program for artistic swimmers.
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  • Hiroki Ozaki, Minoru Matsumoto, Hideyuki Nagao, Toshiharu Yokozawa
    2022 Volume 10 Pages 167-182
    Published: 2022
    Released on J-STAGE: February 08, 2023
    JOURNAL OPEN ACCESS
    Pose estimation using deep learning (DL) is expected to solve traditional problems faced by sports biomechanics, including limitations resulting from the application of reflective markers. For sports biomechanists to correctly utilize these pose estimation techniques, there is a need to elucidate the estimation and learning procedures used in pose estimation as well as to consider how to utilize them. Therefore, we aimed to review recently published major pose estimation models and to examine the availability of pose estimation in sports biomechanics. We observed that the main models were developed for simultaneous estimation of multiple persons, but none of the these were designed to rigorously estimate center of joint position which is mainly required in sports biomechanics. Further, all training datasets for these models were digitized positions that appeared as the joint centers of people in “in-the-wild” videos; moreover, these workers were non-professionals termed as “crowd-workers”. Therefore, regardless of the model quality, the dataset accuracy may be a bottleneck that impedes the estimation accuracy required in sports biomechanics. All the metrics used to verify the accuracy involved verification of the average estimation results of multiple joint points across the entire frame or multiple frames. Therefore, even with a high overall estimation accuracy, the accuracy of the estimated positions of the individual joints may be low. Taken together, it is difficult to utilize and calculate kinematic variables based on joint positions obtained through pose estimation. However, the existing pose estimation may help sports biomechanists calculate the movement periodization and number. To expand the utility of pose estimation in sports biomechanics, sports biomechanists should be actively involved in the development of pose estimation models and datasets.
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