People are constantly required to acquire new skills and further improve the skills acquired in sports, music, and work. Practice is an indispensable element in the development of these skills; however, the important thing is to not blindly spend time on the activity, but to use time well. In previous studies related to the duration of practice in sports, prolonged practice has been cited as one of the problems of club activity. This seems to be based on the premise that practicing more is necessary for skill improvement. However, research on the relationship between performance and time management, has revealed that, the proper management of time is beneficial for work efficiency and performance improvement. Therefore, the present study aimed to clarify the influence on the behavior during practice depending on the presence or absence of time notification. Findings revealed that the presence or absence of time notice did not affect the improvement of short-term exercise performance. However, there was a significant difference in the behaviors exhibited during the practice. Notice of practice time has shown to promote behaviors related to practice. On the other hand, when the practice time was not announced, it was confirmed that participants spent a lot of time on behaviors unrelated to practice. These findings suggest that notifying the time during practice not only aids time management by determining the practice duration, but also greatly affects how one approaches the practice. These results may add a new viewpoint on sports practice method.

This study examined the relationship between competitive level and information processing in male kendo Practitioners. Eight top-level students and eight lower-level students in a university kendo club were selected according to their competition records. In this study, S1-S2 selection-reaction to visual stimulation tasks were conducted with two types of task conditions (CT condition, Task1 condition). Brain waves (event-related potential) induced by the experiment tasks were recorded and the characteristics of each group's P300 were compared and examined. Furthermore, participants completed the task by pressing a button with the dominant hand. After calculating the electromyogram reaction times, the following results were obtained:

① In both task conditions, the electromyogram reaction times of the top-level group were significantly shorter than those of the lower-level group.

② In Task1 conditions, the top-level group's NoGo-P300 amplitude was significantly higher than the amplitude for the lower-level group.

Based on these findings, it is evident that top-level kendo Practitioners had shorter reaction times in selection-reaction tasks. Additionally, it is suggested that higher competitive level kendo Practitioners have superior information processing when controlling their movements.

The present study examined the influence of attentional focus on performance of long-distance throwing using dominant and non-dominant hands with different skill levels. Twenty eight participants (22 males and 6 females, mean age: 22. 4 ± 3. 1 years) who showed significant difference between the performance of dominant and non-dominant hand executed three maximum-effort throwing attempts with dominant and non-dominant hands under three different conditions of attentional focus: (1) internal focus on the wrist (wrist internal focus condition; W-INT) , (2) internal focus on separation between pelvis and upper torso orientations (torso internal focus condition; T-INT) , and (3) external focus on ball trajectory (external focus condition; EXT) . Skill level for each hand was defined as the throwing distance. The results related to throwing distance revealed, through a two-way ANOVA, a significant interaction between hand and attentional focus. With the dominant hand, throwing distance became longer in the T-INT (38. 72 ± 1. 85 m) and EXT (38. 63 ± 1. 9 m ) conditions than in the W-INT (36. 80 ± 1. 77 m ) condition. With the non-dominant hand, throwing distance was shorter in the W-INT (18. 33 ± 0. 80 m ) and T-INT (18. 49 ± 0 .86 m ) conditions than in the EXT (19. 93 ± 0. 93 m) condition. In addition, the results related to release angle also showed a significant interaction between hand and attentional focus. These results suggest that the influence of attentional focus on long-distance throwing differs depending on skill level, and that the variation of throwing distance are related to release angle.

Kendo is a type of Japanese traditional physical activity referred to as budo. Kendo is mainly practiced to develop one's mind and body. Kangeiko is a common style of traditional kendo practice that is held during the early morning in winter. Many kendo practitioners think that kangeiko training can improve patience, mental energy, personality, and morality. This belief is described in published kendo literature from premodern Japan. This study examined whether kendo practitioners were able to improve their mental and moral states through kangeiko by applying three psychological scale tests. The research was conducted in two stages. The first involved a literature review to examine the traditional budo mentality as well as the associated features that kendo practitioners expected to develop through kangeiko. This review confirmed two aspects about the budo mentality. The first was related to morals and ethics, while the second applied to psychology. The literature review also confirmed that kangeiko was expected to improve both of these aspects. However, premodern kendo literature tended to place more emphasis on the psychological aspects as opposed to the moral and ethical. Three psychological scale tests were then conducted to evaluate any mental improvements achieved through kangeiko regarding the two mental aspects of budo. These tests were given to kendo practitioners who participated in kangeiko from January 6 to January 13 of 2017. Scores were analyzed using a paired t-test. Posttraumatic Growth Inventory results revealed that the factors of “Relating to Others," “Personal Strength," and “Spiritual Change" significantly changed as a result of kangeiko practice. This may support the traditional belief that kangeiko is a useful way to achieve mental improvements.

This work was supported by JSPS KAKENHI Grant Number JP16H03223.

Quantification of serve ball speed and spin rate in Japanese male Paralympian Wheelchair Tennis Players.

Research on wheelchair tennis in Japan has mostly used sports medicine and game analysis approaches. However, to gain an overall understanding of wheelchair tennis, research in the field of sports biomechanics is essential. In the present study, we used a TRACKMAN ball-tracking device to measure the serve speed and spin rate among Japanese Paralympian wheelchair tennis players, for use in improving serve performance.

The results are as follows:

1. A male Paralympian wheelchair tennis player (P1) exhibited serve speeds and spin rate of 134.6±3.9 (km/h) and 2,369.0±196.8 (rpm) for flat serves, 123.7±3.9 (km/h) and 3,210.0±353.8 (rpm) for slice serves, and 116.1±3.4 (km/h) and 3,410.9±88.7 (rpm) for kick serves.

2. A male Paralympian wheelchair tennis player (P2) exhibited serve speeds and spin rate of 129.5±1.7 (km/h) and 1,413.1±91.2 (rpm) for flat serves, 113.5±4.7 (km/h) and 2,529.6±249.5 (rpm) for slice serves, and 107.9±3.1 (km/h) and 2,676.2±180.9 (rpm) for kick serves.

3. The serve speeds of Japanese Paralympian wheelchair tennis players were highest for flat serves, followed by slice and kick serves in actual measurement value. The spin rate were highest for kick serves, followed by slice and flat serves in actual measurement value.

4. A significant negative correlation between the speed at which a ball is served and its spin rate (trade-off relationship) was observed in a P1, P2 and UT group as measured using TRACKMAN.

5. By providing feedback of the serve ball speed and the spin rate scores to each of the participants, it was found from their inner reflection that, since their hitting perception almost matched the scores, they were able to concretely imagine the next step for their ball speed and spin rate scores, leading to stronger motivation. From these results, it can be implied that this research can contribute to the development of wheelchair tennis players serve performance.