Research Journal of Sports Performance
Online ISSN : 2187-1787
Current issue
Displaying 1-6 of 6 articles from this issue
  • Sho Nakazawa, Masaaki Sugita
    2025 Volume 17 Pages 66-73
    Published: 2025
    Released on J-STAGE: February 20, 2025
    JOURNAL FREE ACCESS
    The aim of this study was to investigate the effects of EPA intake over 6 months on EPA concentration, EPA/AA ratio and 5000 m running performance. The results of 58 male collegiate long-distance runners (5000 m: 14 min 30.6 s. ± 30.0 s.) showed that the group that were administered EPA had higher EPA concentration and EPA/AA ratio than the group that were not administered EPA. In addition, EPA concentration, EPA/AA ratio, and 5000m running performance of the administered EPA group improved from pre to post intake and a case analysis of the athletes who were administered EPA demonstrated that EPA concentration, EPA/AA ratio, and 5000 m running performance improved after EPA intake. These results suggest that EPA intake can increase EPA concentration, EPA/AA ratio, and can be predicted to be safe and good for training, and as a result, improve running performance.
    Download PDF (472K)
  • Kosaku Tanaka, Hisashi Mori, Yohei Takai, Masayoshi Yamamoto
    2025 Volume 17 Pages 59-65
    Published: 2025
    Released on J-STAGE: February 20, 2025
    JOURNAL FREE ACCESS
    This study aimed to determine whether a drill alternating between uphill and horizontal running reduced knee flexion on ground contact during running on level ground in long-distance runners. Seven long-distance runners ran on a treadmill at 12 km/h, alternating four times between a 6% incline and a level surface. Before and after this intervention, running videos were captured in the sagittal plane to calculate the coordinates of the hip, knee, and ankle joints, and to determine the knee joint angle. Knee collapse was represented by the amount of knee flexion from ground contact to the position of maximum flexion. As a result, knee collapse was significantly reduced from 21.6 ± 6.0 degrees before the intervention to 18.5 ± 4.6 degrees after the intervention. Additionally, the degree of knee collapse before the intervention was significantly correlated with the relative change after the drill (r = 0.82, p < 0.05) . These findings suggest that alternating between uphill and level running reduces knee joint flexion during level running, with the greatest improvement observed in runners who exhibited greater joint flexion during level running before the drill.
    Download PDF (568K)
  • Comparison of Ascending Motion at Different Levels of Proficiency
    Masao Higashiyama
    2025 Volume 17 Pages 48-58
    Published: 2025
    Released on J-STAGE: February 04, 2025
    JOURNAL FREE ACCESS
    Supplementary material
    This study aimed to clarify the differences in walking techniques between skilled and unskilled mountaineers through a speed-controlled stair walking experiment and gain useful knowledge for understanding and mastering walking techniques in mountaineering. The subjects were 2 males: an experienced mountaineer with instructional skills and the other was an unskilled mountaineer with little experience. In the experiment, subjects carried a backpack with 20% of their body weight and were instructed to walk up 11 steps of stairs at an ascent speed of 300 m/h, and their whole-body motions were recorded by a high-speed video camera (60fps) from the side. Kinematic data were calculated using data recorded with a motion capture system. The results are summarized below: 1) The skilled subject had a greater hip extension range compared to the unskilled. In addition, it was confirmed that the skilled one may have efficiently raised the center of gravity by using stretch-shortening cycle movement(SSC) . 2) The skilled subject had a stopping phase that suppressed the body’s center of gravity velocity after the foot of the forward-stepping leg touched the ground. It is considered that the accumulation of fatigue is suppressed, and the subject moves more efficiently by adding a phase of muscle relaxation during walking. 3) The skilled subject showed less plantar flexion of the ankle joint during the foot release of the back support leg. This may suppress the kicking motion that leads to falls in mountaineering and realize a highly stable walking motion. These results suggest that skilled mountaineers may achieve more efficient and stable walking movements than unskilled mountaineers, even when walking up stairs at the same height and speed.
    Download PDF (785K)
  • Yutaro Yamaguchi, Nakaba Akiyama
    2025 Volume 17 Pages 24-47
    Published: 2025
    Released on J-STAGE: January 29, 2025
    JOURNAL FREE ACCESS
    In order for Japan’s volleyball to develop tactically, it is important to analyze teams on a worldwide level, though it is also vital to look domestically. ‘Attacks’ are considered to have a significant impact on the outcome of a match. Using the V-League (2019-2020 season), which is the top league within Japan, as the subject, I have analyzed the correlation between ‘attacks’ and the outcome of a game. The purpose of this study was to obtain guidelines to create better teams, etc. by subdividing the attack (apart from the situational aspect) and analyzing each data set. The results showed that using the Middle on a good pass, its kill percentage and error percentage, as well as the right-side player, known as the Opposite, has a significant impact on the result of a game. The team that uses their middle effectively on a good pass and has an opposite that can put the ball away even on a broken play wins. This study was very meaningful as it clarified the structure of volleyball within Japan. Most of the foreign athletes within the V-League are Opposites, and it is reasonable to state that the foreign athlete’s ability determines the outcome of a team. Based on this research, it is necessary to come up with a structure that not only wins games domestically, but on an international level as well.
    Download PDF (872K)
  • Yurie Shishime, Eiji Fujita, Yuji Ozawa, Isamu Nakamura
    2025 Volume 17 Pages 17-23
    Published: 2025
    Released on J-STAGE: January 24, 2025
    JOURNAL FREE ACCESS
    This study aimed to examine the impact of icing the forearm muscle groups of judo athletes on their grip time if holding onto their opponent’s judogi during kumite (grappling). The participants were seven female university judo athletes (age: 20.0 ± 1.2 years, competitive experience: 12.3 ± 2.5 years). They performed an exercise to induce forearm muscle fatigue, followed by a simulated judo match with rules for visually impaired athletes and a 5-min rest period in between. The study compared the gripping time from “hajime” (start) to “mate” (halt) if a hikite (sleeve grip) was broken and the number of times a hikite was broken between two conditions: immersing the forearm muscles in an ice bath during the rest period and resting exclusively in a seated position. The results showed that judogi gripping time was significantly longer in the icing condition than in the resting condition (icing: 18.8 ± 6.2 sec, resting: 13.9 ± 3.9 sec), with fewer grip breaks (icing: 11.0 ± 2.6 times, resting: 16.0 ± 5.4 times). These findings suggest that icing the forearm muscles during rest may improve recovery from fatigue and prevent decreased grip endurance during matches.
    Download PDF (634K)
  • For Tokyo Olympics Japan Athlete
    Riho Sekiyama, Ryuichiro Yamashita, Hirofumi Kintaka
    2025 Volume 17 Pages 1-16
    Published: 2025
    Released on J-STAGE: January 15, 2025
    JOURNAL FREE ACCESS
    Many of the research findings and instructional books on artistic gymnastics turning techniques are already more than 30 years old. The rules and techniques are very different today than they were 30 years ago, and the techniques and how to do it have changed accordingly. Therefore,this study aimed to clarify the practical knowledge about kinesthesia of the 3 turns in tuck stand on one leg on balance beam for skilled player. The subject was an athlete representing Japan in the 2021 Tokyo Olympics, and two interviewers conducted the interview survey. The results of the interview revealed the structure of the subject’s sense of movement in this turn, and it was inferred that the swinging arm movement determines the success or failure of the technique. It was found that the subject swung his arms less than maximum to keep the axis intact and compensated for the creation of rotational force by swinging his floating legs.
    Download PDF (813K)
feedback
Top