[Objective] This study established guidelines for treatment and proposed more specific treatment methods for low back pain(LBP). [Method] Participants suspected LBP due to piriformis contracture were 8 athletes of Passive Therapy (PT) group who received only PT once a week for six consecutive times and 8 athletes of PT+Active Exercise Therapy(AET) group who performed daily active exercise(DAE) in addition to PT. The elasticity of piriformis muscle was measured before and after treatment using ultrasound-elastography. The examinations of SLR, FABER, and NRS were developed to enable comparison between participants’ scores before and after each PT, same as in comparison to PT+AET and PT group’s scores, in order to examine efficacy of PT and DAE. [Results] There were significant differences in the elasticity, SLR, FABER, and NRS values between values before the first treatment and values before treatment 3 weeks later in PT+AET group. In PT group, values 1 week later returned to values before the first treatment. [Discussion Conclusion] This study clarified that the measurements’ values 1 week later of athletes who received only PT returned to values before the first treatment. However, it is expected to make a significant progress toward cure of LBP in 2 weeks by adding DAE.

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On the hypothesis that differences in rule understanding among basketball players are found based on the experiences of practice sites, i.e., leading factors such as teams, positions, and games by gender, this study aimed to examine the relationship between the structure of rule understanding among basketball players and their teams, gender, and positions. Subjects were 234 basketball players who belonged to three universities participating in nationwide competitions. They were asked to answer 72 questions, which were categorized after that into 14 items based on their similarities. Principal factor analysis and Biquartimin oblique rotation were applied to the data. Then, the differences in structural factor scores obtained in teams, positions, and gender were examined using t-tests and ANOVAs. Furthermore, in order to examine the association while holding other leading factors constant, Quantification Theory Type One (multiple regression analysis using dummy variables as independent variables) was used. As a result, the following findings were obtained: 1) The following four structural factors were extracted: F1 (the first factor): Understanding of rules regarding offensive and defensive plays in the high position or various kinds of fouls; F2: Understanding of rules regarding offensive time and fouls in shooting; F3: Understanding of rules regarding scrambling for the ball and plays when a game clock stops; and F4: Understanding of five-second rules and the rules of ball possession. Out of these leading factors, complicated structural factor patterns that included some items showing significant loadings on two structural factors were found. 2) Gender was the most impactful leading factor among teams, positions, and gender, and male players were superior to female players in F1 (Understanding of rules regarding offensive and defensive plays in the high position or various kinds of fouls), but female players were superior to male players in F2 (Understanding of rules regarding offensive time and fouls in shooting) and F3 (Understanding of rules regarding scrambling for the ball and plays when a game clock stops). 3) No significant association was found in F4 (Understanding of five-second rules and the rules of ball possession) in all three leading factors and positions with all four structural factors.

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The purpose of this study was to obtain suggestions for training when aiming for a return to competition by a 400m sprinter following hamstring injury through observations of muscle strength recovery, emotional changes, and training content in a series of rehabilitation processes. Knee flexion/extension torque measurements using Cybex, subjective evaluation of pain, and range of motion tests of the hamstrings were investigated longitudinally for 72 days. The subject was able to return to competition early and updated his 400-m university best without reinjury. We were able to obtain the suggestions for training, as shown below. 1) receiving acupuncture treatment from a rest period enables early resumption of training, 2) middle power training using a bicycle ergometer is effective in improving speed endurance, 3) evaluation of knee flexion/extension muscle strength ratio and left/right difference using Cybex can be used as a guideline for return to competition, 4) psychological fear can be dispelled by participating in a competition, and 5) in order to achieve high performance without reinjury in the return competition, the 400-m sprinter should adopt a race pattern that maintains the sprinting speed in the second half of the race.

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The aim of the present study was to investigate the effective use of ankles in terms of duration and load on the lower extremities of the Hike-out test, which mimics the full Hike-out posture in Sailing competition. The duration and electromyography (EMG) of the knee extensors were compared between the two forms of the Hikeout test: ankle dorsiflexion with the toe-strap over the navicular bone (NAV) and ankle plantar flexion with the toe-strap over the metatarsals (MET) . EMG electrodes were attached over muscle bellies of the vastus medialis (VM) , vastus lateralis (VL) and rectus femoris (RF) muscles. The duration of hiking postural maintenance was significantly longer in MET (95 ± 18 s, mean and standard deviation) than in that of NAV (73 ± 20 s) . All subjects ended the measurement when they could not maintain the hip angle, suggesting that it is the muscular endurance of the hip flexor muscle group that determines the duration of the full Hike-out. However, there was no significant difference in the EMG of each muscle between forms. For the RF, which also contributes to hip flexion, the amplitude of EMG was found to increase with time. We concluded that MET with ankle plantar flexion is an effective form to sustain the full Hike-out posture.

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To of basket toss techniques of cheerleading include “Salt backwards tucked” and more difficult “Salt backwards tucked with straddle cut (generally called “X-out”)”. In addition, there is “technique with a twist on X-out” as a technique set with even higher difficulty. The learning process for these techniques is generally in ascending order of difficulty, from “Salt backwards tucked” to “X-out” and then “technique with a twist on X-out”. The purpose of this study was to obtain knowledge for changing from “X-out” to “technique with a twist on X-out” that enables “Salt backwards tucked”. One example in the coaching field, summarized the exercise self-observations of “Salt backwards tucked” and “X-out” were compared from the viewpoint of morphology for one elite top-position player of cheerleading. As a result, differences were shown in the take-off phase, the tap phase, the kick-out phase, and the cut phase of two techniques.

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The purpose of this study was to clarify the effects of inter-set static stretching on force production and flexibility in multiple sets of multi joint exercise. Seven healthy men underwent static stretching of gluteus muscles and quadriceps femoris for 30 seconds each between 4sets × 12reps of back squats. The number of repetitions to the failure in the fifth set and the flexibility before and after back squats were measured. We found that the number of repetitions in the fifth set was greater and the flexibility was maintained compared to nonstretching. These results suggest that inter-set static stretching in multiple sets of back squats may improve the training effect.

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This was a case study about serve training and the effectiveness for a collegiate female tennis player. She is 175cm in height and recognizes her serve is strong point in her play. She also wants to improve her serve in this training. Coaches also evaluates her serve as strong point, and they try to improve her serve. The goal of this training was to improve speed of 1st serve and spin rate of 2nd serve. The training period was approximately five months. The contents of training were 1) to improve swing speed, 2) to adjust the swing direction to improve spin rate, 3) to adjust the impact angle to improve spin rate, and so on. Trackman was used for the serve tests. We analyzed speed, spin rate, impact height and impact depth. As a results, the speed of 1st serve became faster, and 2nd serve became slower after the training. The spin rate of 2nd serve tended to be large at the post test. Impact height was significantly low after the training. The change of impact height was contributed to the speed of 1st serve. The adjustments of technical issues were contributed to the spin rate of 2nd serve.

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The purpose of this study was to clarify the characteristics of soccer tactics utilizing a “half-space” based on the five-lane theory systematized by Pep Guardiola. Data were obtained from 18 official games in the England Premier League and the UEFA Champions League, including eleven games against Manchester City FC (ManC) coached by Pep Guardiola and seven games between the other teams. Thirteen items that were related to tactics using halfspace were analyzed (ex. number of attacking using half-space) on each game. ManC had more penetration into the penalty area, and more received the ball in the half-space (pockets) within the PA. However, the large number of defensive players in the PA was existed due to possession attacking tactics (spent time to attack) in ManC. Therefore, although soccer tactics utilizing a half-space can make more opportunities to penetrate the PA and shoot, the large number of defensive players in PA makes it more difficult in the shooting situation. Therefore, the team’s score may depend on the shooting ability of the player who shoots (the finisher).

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Despite many sports athletes feeling anxious before a match, there are limited studies focusing on how sports players cope with anxiety from the training period to the match. This study aimed to clarify how top-level national college players cope with anxiety from the training period to the day of the match. Two top-level college Kendo players in Japan were chosen as participants (hereafter Participant 1 and 2) based on the demonstration of their abilities in past matches. The Sporting Characteristic Anxiety Scale and the Sporting State Anxiety Scale were used to track the changes in the players’ anxiety in specific sport situations. The participants were also asked to fill in a practice diary to analyze the behavior and thoughts associated with the changes in anxiety. The results demonstrated that Participant 1 easily felt anxiety and that her state of anxiety increased 10 days before the match and remained high until the match. Participant 2 did not feel anxiety throughout the study period. However, despite this difference, both players demonstrated their abilities equally in matches held during the study period. In this regard, the participants’ practice diaries revealed that Participant 1 prepared for the match more carefully than Participant 2 by focusing on aspects in which she lacked during practice. This motivated her and contributed to her performance. These findings suggest the importance of utilizing anxiety, rather than reducing it, for a positive effect on performance.

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Research on flight characteristics and rotational characteristics, which are technical and tactical elements of table tennis competition, is underway, but research on ball distribution characteristics is not very advanced. In this study, we analyzed 14 matches for a male college student with a right-handed shake hand attack, clarified the ball distribution that affects the point, and used it for improving player’s performance and planning of training. The purpose was to examine whether it was possible. The method uses six ultrasonic sensors and a digital video camera to collect the binding position of the ball during the match and perform ABC analysis and correspondence analysis. As a result, the ABC analysis revealed the ball distribution that affects the score of the target players and the ball distribution that is an issue, suggesting that it can be used for tactical changes and making new plans for athlete training. Correspondence analysis created a two-dimensional map obtained from the ball distribution data, and it became clear that the ball distribution that has a strong relationship with the opponent can be visually grasped. For future tasks, it is desirable to analyze by adding factors such as the direction of rotation and the striking method, and to verify whether it is possible to analyze the game in detail.

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In this research, in order to consider on the performance analysis of the top sprinters in the regional rankings regarding to the 100m sprint and the construction of a support structure for the future. Analysis targets are totally 660 data available which were ranked within 10th in each year from 1955 to 2020. As a result, each time was 11.59 ± 0.25s (1955s), 10.90 ± 0.21s(1990s), 10.72 ± 0.12s (2015s). However, this turning point of performances was appeared in 1990-1995 compared with 1955-1990. Especially, posterior performances were no significant difference, and then it was cleared that athletes performances were not improved since 1995. Ranked athletes were consisted almost high school students(55.4％，1955-1990 年), but it was changed to university students(50.8%) for latest 26 years. For the reason, it can be said the issue is that the period of performance maintenance is as short as 3 to 4 years. It is necessary to construct a support structure so that adult athletes can continue to join every competition in the future.

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We examined the longitudinal change of a psychological-competitive ability across three grades in high school baseball players using the Diagnostic Inventory of Psychological Competitive Ability for Athletes (DIPCA). Participants were 109 baseball players in three high schools (five teams) aiming for the “KOSHIEN” tournament. Participants completed the DIPCA every year after each school’s spring tournament (May–June). The longitudinal change of all 109 players showed a decline in scores on the Self-accomplishment subscale in the third grade. However, scores on other factors and subscales did not change significantly across the three grades. A comparison between the regular group (n=64) and the non-regular group (n=45) showed that psychological-competitive ability was higher in the regular group than in the non-regular group. The regular group maintained a high level of psychological-competitive ability from the first grade until the third grade, whereas the non-regular group showed a decline in the Competitive motivation factor in the third grade. Confirming the longitudinal change of the regular group for each team, not only did the teams show positive changes, but also showed negative changes. In addition, the type of longitudinal changes in psychological-competitive ability varied by year, even in the same school.

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This study is based on the hypothesis that the Japanese elite male long jumper（personal best was 7,93 m） will improve the performance by “restricting the stride length from 4 steps before the take-off” in the approach run, and intentionally 4 steps before the take-off. The validity of the hypothesis was verified by analyzing the approach run velocity and motion from 4 steps before the take-off between the 2010 season, which tried to shorten the ground contact distance, and the 2009 season, which was the previous year. Although the 2steps before take-off, approach run velocity was reduced in the 2010 season, 1 steps before the take-off, the approach run velocity was comparable to that of the 2009 season, and the approach run with less deceleration was possible. In addition, since the swing leg was attracted at a high speed and was heading for the take-off a high stride frequency, it was possible to perform an effective take-off preparation motion. From these facts, in the subjects of this study, it is effective to intentionally shorten the ground contact position 4 steps before the take-off and to “limit the stride from 4 steps before the take-off” with less speed reduction and effective approach run. It has been shown that it can be a useful method for eliciting preparation take-off movements.

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Theoretically, the importance of each point count is different in tennis, but there is no study for a specific player so far. The purpose of the present study was to examine the importance of the point counts in the service games of Novak Djokovic who was men’s world ranking No.1 player and to find out the problems that Djokovic has to work on. The analysis subject were 67 men’s singles matches (176 sets, 827 games, 4,761 points) in Davis cup, Gland Slams, ATP Tour Finals and Masters 1000 played at hard-court from January 2018 to January 2020. The results were as follows: The set of top five high important point counts and the set of top four low important point counts agreed with the theoretical ones given that the point won rate was constant regardless of the status. However, the importance of 0-40 was 0.286 which was lower than the theoretical value 0.403 and even if the next point was won, the game won rate was 11.7% lower than the theoretical value. Moreover, in every top five important point counts, the point won rates were lower than the theoretically expected values in spite of the fact that the game won rate should become higher when points are won.

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The purpose of this study was to determine the effect of the different orientations of the strategy board on the perception of player arrangement, and to investigate more effective ways of conducting tactical meetings. In this study, 15 university soccer players were asked to answer whether or not the player arrangement in the recognition phase was the same as that in the viewing phase presented in advance. The images were presented in two conditions, vertical and horizontal, and the decision time and the response accuracy were compared between the two conditions. The results showed that there was no significant difference in the response accuracy among the conditions, while the decision time in the vertical condition was significantly faster than that in the horizontal condition. This result indicates that it is easier for soccer players to recognize the player arrangement presented in the vertical orientation. These results suggest the effectiveness of using the strategy board in a vertical orientation when conducting tactical meetings. The findings of this study are important in that they can be directly applied to coaching in the field.

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This study investigated the characteristics of visual behavior during ball trapping among skilled soccer players. A total of 24 expert and 22 novice soccer players were asked to trap a grounder ball and pass it back to the place where the passer had moved. Simultaneously, the participants’ eye movements were recorded at 30 Hz, and the location where their gaze was directed was identified. Additionally, the pupil area was calculated for each frame. On assessment, the novice players tended to keep looking at the ball until just before the trapping. In contrast, the expert players tended to focus on the person to whom they will return the pass or to the areas where the ball will be passed. Furthermore, the pupil areas of the novice players were larger than those of the expert players during the phase immediately before ball trapping. The gaze behavior specific to expert soccer players, such as looking at the opponent or the area around the ball and not paying too much attention to where they are looking, may be due to their proficiency of ball control.

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This study clarified the “advantages of aggressively pushing forward during a match” and the “effects of grip strength exertion” for judo players by examining the simple whole body reaction time under different positions of center of gravity and with and without grip strength exertion. The results outlined below can be utilized for judo coaching. 1.The simple whole body reaction time when the center of gravity regardless of whether or not the grip strength was exerted, it was faster in the order of more forward, natural stance, and backward. 2.The simple whole body reaction time was delayed when grip strength was exerted compared to when grip strength was not exerted, regardless of the position of the center of gravity.The results indicate that aggressively stepping forward to push an opponent in a match or using a stronger or weaker grip on the judo uniform by devising kumite can be tactics to gain an advantage by facilitating quicker reactions, which can result in quicker techniques and defensive act.

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This study aims to clarify effect of competitive level on collective variables and technical plays within same team in soccer-specific ball possession training with attacking direction. Twenty-two collegiate male soccer players were assigned into two groups: regular group (N = 11) and non-regular group (N = 11). Both groups conducted a ball possession training consisting of 4 on 4 with 3 floaters in the court with 12 m long and 24 m wide. Number of technical plays were quantified by notational analysis. Players’ coordinates were recorded with a local positioning system. The area enveloped by four players within same team was estimated by using a convex envelope algorithm. The amount of packing rate during the ball possession was higher in regular group than in non-regular group. Number of passes tended to be higher in regular group than in non-regular group. The area surrounded by four players within same team was larger in offense team than in defense team, regardless of competition level. The area of offense team in regular group was greater than that in non-regular group, but the area of defense team was higher in non-regular group than in regular group. Therefore, the current results indicate that, in the ball possession training, high competition level’s players get higher packing rate compared to low competition level’s players, and it may depend on the difference in players’ positioning to receive a ball when the ball is held in same team.

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We devised physical training and practical training to improve agility and lower limb power exertion for each 9 male university athletes who specialize in fencing épée and saber, and examined the training effect for 8 weeks. In the pre-training value our results showed that the saber group (32.4 times) was significantly higher than the épée group (27.2 times) in side stepping (P <.05). The comparison of consecutive jumping exhibited a similar result, with saber athletes (13.63 m) again being significantly higher than épée athletes (12.43 m) (P <.05). After 8 weeks, side-stepping in the saber group showed a significantly higher post-training value (35.7 times) than the pre-training value (32.4 times) (P <.01). Saber athletes also displayed a statistically higher jumping performance (14.01m) compared to the pre-training value (13.63 m) (P <.01), whereas there was no significant difference between the pre-training value and the post-training value in the épée group. As mentioned above, the training effect was manifested in both abilities by the practical training only for the saber athletes.

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Athletes of long-term participation in specific sports tend to develop different forms, body shapes, and rhythms depending on the sports they play. In this study, we investigated the characteristics of specific adaptations affected by long-term participation in competitive sports. As a result of the better adaptation of athletes, some neuromuscular functions may be suppressed. In this study, we focused on the frequency of cyclic motion. Fortyfive female athletes and eight controls took part in this study. They performed four cyclic exercises (walking, ropejump, dribble, side-step) with their own natural rhythms. In each trial, the motion of subjects was recorded for sagittal and frontal plane movements and each touchdown was confirmed. We measured the motion-frequency of these cyclic movements using motion analysis software (Kinovea). Motion-frequency was calculated by dividing the number of steps by the time required． All motion-frequencies were calculated by extracting 5 or 10 sequences of steps/dribbles with a constant beat. The swimmer’s group had a significantly lower walking velocity than most other groups (p<0.05). Additionally, they had a significantly lower walking frequency than most other groups. The results of the side-steps and rope-jump movements were similar to those trends of walking. In all the cyclic and rhythmic exercises, the swimmers showed a remarkably low motion-frequency. Understanding the characteristics of athletes’ motion-frequency is considered to be an important factor.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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