In baseball pitching, breaking balls are often evaluated using the word Kire, which means the sharpness of the ball or how well-pitched the ball is. However, it is not obvious if the players have a common perception regarding the Kire of the breaking balls, and if the breaking balls can be expressed by their kinematic characteristics, such as speed and trajectory displacement. Therefore, we investigate the degree of agreement among the evaluators on the evaluations of breaking balls using Kire, and demonstrate the relationship between the Kire and the kinematic characteristics of those balls in this study. For this purpose, 12 high school and 20 collegiate pitchers threw balls of every pitch type as they would normally throw in a game. The pitched-ball velocities and trajectory displacements were calculated. Six high school and six collegiate catchers of the same team as the pitchers evaluated each breaking ball (curveball, slider, changeup, and cutter). The evaluation system corresponded to a five-point grade system. From the results, we found that the players had common perceptions of the Kire of some pitch types but not of the others. In addition, we were able to quantify Kire using the kinematic characteristics for the curveballs and cutters, but not for the sliders and changeups.
The present study examined factors related to variations in approach time, focusing on step frequency, ground contact time, and flight time for each step in the approach. The participant, a university male 110-m hurdler, performed 22 hurdle runs with three hurdles set at the competitive standard for 110-m hurdles. Trials were held once a week, three times. They were conducted in July, which corresponds to the match season. The number of runs per occasion ranged from 6 to 12. Changes in the step frequency, ground contact time, and flight time for each step in the approach were measured. The correlations between approach time and step frequency, ground contact time, and flight time in each step were also analyzed. The main results were as follows: (a) A significant negative correlation (r=-0.638, p=0.008) was found between approach time and step frequency for each step, but only for the frequency of the fifth step. (b) A significant negative correlation (r=-0.718, p=0.002) was found between step frequency and the flight time of the fifth step. (c) A significant negative correlation (r=-0.607, p=0.013) was found between approach time and foot-to-hurdle distance on the take-off side. These results suggest that increasing step frequency by shortening the flight time of the third step before the takeoff may be related to increasing the foot-to-hurdle distance on the take-off side; this may, in turn, lead to a reduction in approach time.
In sports, one method for improving competitive performance is skills acquisition. Athletes spend a significant amount of time each day honing their skills in this regard. The objective of this study was to identify the factors that influence skills acquisition in Japanese elite cheerleading athletes. The survey’s participants comprised seven
active female Japanese cheerleading athletes who have previously won national or international championships. The SCAT(steps for coding and theorization) qualitative data analysis method was used to analyze the data collected from these participants via semi-structured interviews. The findings revealed that the skills acquisition factors
were(a) “cognitive strategies” for clarifying goals and internalizing motives,(b) “training contents” pertaining to the quality and quantity of training,(c) “transference of skills” acquired through basic skills training and specialized training, and(d) “learning as an athlete,” which is acquired through feedback and analysis. These factors included those that are related to the concept of deliberate practice theory, psychological features of elite athletes, motor learning, and movement theory. Thus, it is reasonable to assume that the following are key to the acquisition of cheerleading skills: setting goals based on psychological development and practicing internalizing motives training, working on basic skills training and specialized training to transition to higher difficulty skills, and learning to acquire the skills through feedback and analysis.
The purpose of this study was to clarify the effects of swing training simulating hammer throw on the morphology of the lateral abdominal muscles and swing velocity. Seventeen male baseball players (Age 19.5 ± 1.5 yrs, Height 169.8 ± 4.0 cm, Body mass 66.9 ± 6.4 kg）participated in this study. In this study, the subjects were divided into two groups: eight subjects who additionally worked on hammer swing in addition to normal training (Tr) and nine subjects who only worked on normal training (Con). Swing speed was measured using a bat swing analysis system consisting of an inertial sensor unit, an attachment, and a smartphone application. Muscle thickness of the lateral abdominal muscles (external oblique, internal oblique, and transversus) on the side of the stepping leg was measured. Hammer swing training was performed for 4 weeks. The results showed that there was an interaction between the Tr group and the Con group in terms of swing speed, and only the Tr group showed a significant increase in swing speed. In conclusion, it was obvious that the swing speed was improved by the hammer swing training conducted in this study.
The present study aimed to develop and test a teaching plan for tag rugby, which is a new type of ball sport for elementary school physical education classes. The teaching plan consisted of nine 1-hour activities, including mathematical and computational thinking and a combination of science, technology, engineering, arts, and mathematics (STEAM), in order to improve the students' ability to recognize and judge each phase of the game's tactics from various angles. The participants in the test of the plan were 52 students in two 5th-grade classes at one public elementary school in Tokyo. The students' life skills and tag rugby performance, their attitude toward education and sports, and their ability to express emotions and understand problems were measured. Significant improvement was found in life skills and tag rugby performance, such as the number of tags made and passes (p<0.01), as well as the students' problem solving ability and ability to form personal relationships (p<0.05). This new teaching plan for physical education, which was developed using a programming style of thinking, meets the current elementary school curriculum guidelines from the Ministry of Education.
In this study, we focused on the open turn used in butterfly stroke and breaststroke, and clarified the relationship between the turn movement and the jump performance. The subjects were nine male university swimmers who specialize in butterfly stroke and breaststroke. The swimming turn measurement was performed at the open turn. The subjects swam with maximum effort from 5 m before the turn to 5 m after the turn. In order to evaluate turn motion, the rotation time of the turn motion, the wall contact time, and the push-off velocity were measured. For the evaluation of jump performance, squat jump, vertical jump, and standing long jump were measured. As a result, a significant correlation was found between the push-off velocity at the turn and the peak power in squat jump(r=0.857，p<0.01). In addition, a significant correlation was found between the push-off velocity at turn and peak speed(r=0.805，p<0.05). From the above results, it was clarified that the applied squat jump training may contribute to the performance improvement in the turn phase.
In the Physical Education (P.E.) teacher training curriculum, it is necessary to teach students who want to become P.E. teachers the basic skills for safely teaching junior high school students techniques in judo. However, there is a relatively high risk of infection in lessons of judo courses during the COVID-19 pandemic. In this study, we examined the trials for securing learning outcomes in judo courses such as practice of adopting the buddy system as a prevention measure against COVID-19. In the university where the first author of this report works as a teaching assistant in judo courses, hybrid classes were held from May 17th and online classes were held from May 31st as prevention measures against COVID-19 in the spring semester of 2021. However, in the case of judo courses, in-person education was permitted as an exception, since it was difficult to gain learning outcomes without in-person education. In the classes, an attempt was made to cover the course teaching content as soon as possible at the beginning of the semester. However, due to concerns about the lack of depth of learning of judo techniques, another idea was used aimed at maximizing the learning outcomes, namely adopting a buddy system with fixed pairs during learning activities that involve pair learning and physical contact. We also told students to reduce the amount of contact with other persons with a risk of infection in order to reduce the risk of transmission to their buddies, by recording the number of such contacts in their daily life. As a result, adopting the buddy system enabled students to develop awareness of their responsibility to avoid exposing their buddy to the risk of infection during the COVID-19 pandemic.
This study is a case study of whether it is possible to correct running motions by training using an anti-gravity treadmill for middle-distance college female runner who could not derive the corrections of running motions as expected. The subject was trained 25 times in about five months using an anti-gravity treadmill for the purpose of correcting running motions. As a result, there were changes in the ankle joint angle tends to flex the sole during jog, shortening of contact time, and increase in flight time before and after training for running motion correction using an anti-gravity treadmill. In addition, there was a change in the waveform of the ground reaction force from the heel strike tendency to the forefoot tendency. Also, the subject’s 800m self-record was updated for about 4 seconds. These changes were roughly the contents that the subject herself aimed at correcting the running motion before the training for the running motion correction using the anti-gravity treadmill. From the above, it is considered that there is a possibility that the running motion can be effectively corrected by using the anti-gravity treadmill.
Right heel pain is one of the most common injuries in kendo. This study examined differences in the forward stepping movement and its ground reaction force and sound between collegiate kendo players who were divided into groups based on whether they had experienced right heel pain in competitive activity, taking clues from a case that utilized a retrospective approach in which an athlete ameliorated the right heel pain by modifying the forward stepping movement (Shimokawa et al., 2020). The results revealed that collegiate kendo players who had no previous experience of pain in the heel had acquired forward stepping movements that did not cause heel pain despite having a stronger force than did the movements of those who had experienced heel pain. The forwardstep form of these players who had not experienced heel pain was one in which the knee joint flexed just before stepping forward and the heel was positioned further back than the knee. In addition, the stepping sounds of the players who had not experienced heel pain were high and loud, corroborating the report by Shimokawa et al. (2020) and suggesting that the stepping sounds may be taken into consideration for approaches to form-modification aimed to ameliorate right heel pain.
The purpose of this study was to determine the effects of a MotoTiles exercise on balance ability in communitydwelling older adults. The participants were 11 women who lived in T city and had performed a community-group exercise. The exercise was carried out twice a week for a period of 12 weeks using the local community center. For the balance index, a 20-sec stepping test was performed with the eyes open, and the total head movment distance (TMD), maximum movment distance (MMD), and the distance of the knee joint point (KMD) were used using KINECTTM infrared sensor. The pace of both legs (PACE left and right) and its coefficient of variation (CV) were used using Optogait infrared sensor system. Functional reach (FR), up-and-go (TUG), and 30sec-chair stand (30-CS) were also examined. As a result of 12 weeks of exercise, there was significant improved on TMD, MMD, PACE left CV, FR, TUG, and 30-CS (effect size were moderate to large). No significant changes were observed in other infrared sensor-related indexes, but overall, the head and knee sway during the stepping test and the variation when raising the legs tended to be smaller. The MotoTiles Exercise appears to be useful for assessing one of balance ability in older adults.
In this study, we conducted a comparative experiment of four types of caps (the new cap, breathable brim cap, mesh cap, and normal cap) to verify the effects of the new cap developed for defense against the heat. In the test simulating the cap’s internal environment when running outdoors, the new cap had a temperature increase of only 28.4 ℃ , compared with 31.3 ℃ for the mesh cap, which had the most striking increase in inside temperature. Likewise, outdoor running test (10,000m run, 8 subjects) under the blazing sun, the tympanic temperature of subjects wearing the other three caps had increased significantly after the run, while that of those wearing the new cap had not increased significantly. Furthermore, subjects felt less stifling and superior head coolness with the new cap than the other caps during practical running tests. In addition, runners wearing the new cap in the Marathon Grand Championship in September 2019 also gave high ratings for breathability, head coolness, and reduced stuffiness. This has suggested that the new cap effectively provides defense against the heat when running.