Previous studies have investigated the relationship between muscle strength and swimming power in postures assuming catching and pulling movements in front crawl swimming in collegiate swimmers. Muscle strength and physique develop rapidly in the youth period. Therefore, it is important to propose specific training to efficiently improve competitiveness from the young age group. The purpose of this study was to clarify the relationship between isometric shoulder joint muscle strength and front crawl swimming speed and/or swimming power in youth swimmers.

　The subjects of this study were 10 youth swimmers. Shoulder joint muscle strength was measured using a handheld dynamometer. Shoulder joint muscle strength were measured in extension and internal rotation. Extension force was measured at maximal abduction and internal rotation force was measured at abduction-external rotation. Swimming power was measured using a simplified swimming power measuring device (Drag Boat). The Drag Boat is a device that can be converted into 5 levels of load.

　As a result of this study, the extension force on the right side was significantly positively correlated with MSV, MSP, MSP/BM, and MTF. The internal rotation force on the right side was significantly positively correlated with MSP, MSP/BM, and MTF. There was a significant positive correlation between left extension strength and MSP and MTF. The internal rotation force on the left side was significantly positively correlated with MSP, MSP/BM, and MTF.

　These results suggest that improving muscle strength in a position similar to a pull motion during swimming may increase MSP and MSV in youth swimmers.

　This study aimed to determine the double- and single-leg jumping abilities of junior high school track and field club team members versus non-members. Thirty-six track and field club team members and 40 non-members (all aged 13-15 years) were included. Countermovement jump (CMJ), rebound jump (RJ), single-leg CMJ (SCMJ), and single-leg RJ (SRJ) moves were performed on a mat switch. RJ index and jump heights for CMJ, SCMJ, RJ, and SRJ were calculated. All variables except SRJ-index, RJ and SRJ jump heights for first-year junior high school students, CMJ and SCMJ jump heights for second-year junior high school students, and CMJ jump height for third-year junior high school students were significantly higher in track and field club members than in non-members (p < 0.05). The RJ and SRJ ground times were also significantly lower in junior high school students who belonged to a track and field club team than in those who did not (p < 0.05). These results suggest that junior high school students belonging to track and field club teams have better double and single-leg treadmill jumping abilities than those who do not. Therefore, an improvement in the lower limb stretch-shortening cycle performance equal to or greater than that observed with track and field club activities can be expected through activities in a track and field club team.

　Sports teams periodically conduct physical fitness tests to evaluate the improvements in their athletes' physical elements and the effects of their training regimens. However, in the actual sports setting, in addition to the true data, measurements are impacted by accidental errors that are randomly generated, thereby making it difficult to reach a definite conclusion solely based on the commonly employed evaluation methods. Thus, this report demonstrates an evaluation method to detect meaningful changes in the physical elements of athletes in a sports team, as well as actual measurement instances. The participants were female college volleyball players, and the measurement data on countermovement jump (CMJ) obtained in physical fitness testing were used as a case report. The evaluation was done using a method that employs the smallest meaningful change based on the concept of magnitude-based inference. The degree of change in CMJ was evaluated against fluctuations attributed to the measurement method and equipment, as well as the biological biases of the athletes, to examine the presence of definite changes. The results suggested that, compared with conventional methods, this method may more suitably detect improvements in physical elements. We hope this report will be useful for professionals engaged in data analysis in the sports setting and, thus, contribute to advancing evidence-based practice.

　Wing shots are shots taken by sprinting from the corner of the court and jumping from outside defenders into the goal area. It is crucial to change the throwing arm position from the top to the waist for sliced shots in order to succeed with wing shots. Many players, however, lack such a shooting skill. Therefore, this case study aimed to report a coaching experience in instructing sliced shots that other coaches could apply. The author instructed the player to (1) lean the upper body toward the shooting arm during forward swing, (2) keep the elbow position at the maximum external rotation of the shoulder and ball release position in front of the chest, and (3) take backswing raising from the elbow. As a result, the player was able to take wing shots from beside her waist with great power. With regard to the instructions (1) and (2), since the author plays sliced shots tacitly, he was not able to instruct at the beginning. This indicates that even if coaches themselves can play the technical elements, they may not be able to teach them. Regarding (3), the backswing was improved only after the player had understood its necessity. It is therefore considered crucial for coaches to ensure that players understand the need for the technical elements before instructing them. These findings from this case study can help other coaches in coaching shooting techniques such as sliced shots.

　The purposes of this study were to analyze serving motions of twenty-eight Japanese male college tennis players during matches and to compare kinematics for two racket speed groups of different foot-stance styles. Twelve players whose racket speed was higher than 39.00±3.67 m/s were classified as a high speed group and sixteen players with the lower one as a low speed group. The significant differences between the two groups were observed in the racket speed and ball speed. The players of the foot-up stance style showed differences between the high and low speed groups in the torso backward tilt and the hip flexion from toss-up to the forward-swing phase, and the right shoulder abduction angle during the serving motion. The foot-back style players showed differences between the two groups in the horizontal abduction angle of the right shoulder. The results suggested that the low group players of the foot-up style should reduce the backward tilt of the torso in the back-swing phase and raise the right arm in a later timing than the left arm, and that the foot-back style players should horizontally abduct the right shoulder in the forward-swing phase.

　In this study, the characteristics of step length increase during the acceleration phase of the 100 m dash were examined in elementary school students and senior male sprinters (athletes) by means of segmented regression analysis of the step length per height (SL index). The 100 m running times of the 24 athletes analyzed ranged from 10.12 to 11.19 s, and those of the 25 elementary school students ranged from 14.51 to 20.70 s. The SL index at the maximum running speed (SL index･vmax) ranged from 0.99 to 1.41 height times.

　The results showed that the characteristics of step length increase during the acceleration phase of the 100 m dash were indicated by three regression lines (L1, L2, and L3). The SL index･vmax was determined by the number of steps to which the regression lines L1 and L2 was extended in the case of athletes and L1 in the case of elementary school students，respectively. The trend of increasing step lengths of L2 and L3 was almost constant among elementary school students and athletes, regardless of the SL index･vmax. On the other hand, the increasing trend of L1 was found to be greater in athletes than in elementary school students, but it varied with the number of steps taken in L1 section. Furthermore, a method for setting a specific target step length to increase the SL index･vmax was also proposed, taking such characteristics into consideration.

　This study investigated psychological changes caused by watching a motivational video (MV) just before the match in the Hakone Ekiden team.

　Immediately before and after watching the video, the runners took the Japanese Collective Efficacy Questionnaire for Sports (JCEQS), the Psychological Conditioning Inventory for Motivational Video (PCI for MV) test, and the circle commitment scale test, and wrote a response to an open-ended question about their current feelings.

　A paired t-test was performed on the results of the subscale scores and the total scores of each of the JCEQS, the PCI for MV, and the circle commitment scale tests taken before and after the MV viewing.

　In the JCEQS, significant differences were confirmed in mental and physical skills, teamwork, and total scores. Also, in the PCI for MV, significant differences were confirmed in the categories of general vitality, technical efficacy, fighting spirit, and total score. For the circle commitment scale, a significant difference was not confirmed.

　Text mining analysis of the open-ended questionnaire responses revealed that the word “anxiety” was frequently used just before watching the video, but the words “team” and “do your best” were frequently used immediately after watching the video. This suggests that watching the motivational video brought about a positive change to the runners’ mental states.

　The aim of this study was to present a detailed instructional case study on enhancing the performance times of two male collegiate sprinters in the 200m Flying Time Trial (FTT), as well as to establish a standardized method for documenting 200m FTT results. The approach to reducing time focused on optimizing gear ratios, refining flying start techniques, and enhancing strength and power. This comprehensive effort led to Cyclist A improving his time from 10.440 seconds in his sophomore year to 10.110 seconds in his graduate year, and Cyclist B improving from 10.450 seconds to 10.040 seconds over the same period. Analysis of these outcomes identified three critical factors for improving 200m FTT performance: 1) race-specific variables such as gear ratio and flying start techniques, 2) general and specific strength/power development, and 3) physiological attributes including body weight and fat-free mass. These findings suggest that coaching strategies for the 200m FTT should integrate these three aspects both individually and collectively, offering a promising new methodology for field coaching.