Most kendo practitioners, from beginners to experts, repeatedly practice striking by making a large swing of the shinai overhead and then cutting down. We call this a “basic men-uchi”. In actual matches, however, no expert practitioner raises the shinai overhead but instead makes a compact swing, which we call a “practical men-uchi”. We addressed a fundamental question: is it really necessary to practice basic men-uchi in order to master practical men-uchi? We began by theoretically reanalyzing the dynamics of a single bar model, which showed that for obtaining a fast shinai tip speed, it is not effective to press the shinai in opposite directions with the right and left hands. This result suggested that the efficient motion of the shinai is composed of three processes: a quasi-translational motion, a 2-step braking motion, and an axis-free seesaw motion. Considering each process carefully, we found several advantages of practicing basic men-uchi in order to acquire skill in practical men-uchi. For example, to perform the quasi-translational motion well in the practical men-uchi, it is important to move the shoulders forcefully instead of moving the elbows or wrists. Repeating large swings is an appropriate training method for beginners to learn proper shoulders motions. However, practicing only basic men-uchi is not sufficient because some players have difficulty mastering practical men-uchi despite many years of training. We therefore propose that even beginners should practice practical men-uchi. Developing a coaching method based on our results is a pressing issue and progress in this matter is being made.

In budo and sports, to understand complex movements scientifically, it is necessary to reduce them into simple models and to analyze them on the basis of mechanical laws. As the first step in the theoretical study of movements, Sakai et al. (2016) initiated the study of bar mechanics, which are applicable to various movements in sports. In particular, they focused on the effects of inertial force on human movements. One of the important consequences is the “braking effect”, which explains the phenomena that decelerating one end of a moving bar causes instantaneous acceleration of the other end. In this paper, as an extension of the previous work on the braking effect, we study the multistep braking effect on a single bar. This is motivated by the men-uchi (strike to the head) movement in kendo in which a time difference appears in the extensions of the left and right arms. We find that multistep brakes actually accelerate the end of a bar more efficiently. As the number of braking steps increases, the final velocity of the end point increases, but there is an upper limit. While a single brake increases the final velocity of the end point maximally by 150 percent, and by 162 percent with double brakes, as the number of the braking steps are infinite the final velocity approaches 172 percent of the initial velocity. We also discuss how we can apply these results to men-uchi movements.

This study assessed the ability of physical education (PE) teachers and university students (US) undertaking a PE major to judge the safety or danger involved with some judo movements. The subjects were 285 US (96 males, 189 females) aiming to become PE teachers, and 107 school PE teachers (85 males, 22 females). The participants were divided into three groups: teachers with judo experience (TJ); teachers without judo experience (TN); and US. All the subjects were shown a video of the same 18 judo movements, and were then asked if they considered the movements to be safe or dangerous. If they believed the movements were potentially dangerous, they were asked to identify the body parts that could possibly be injured. The average scores for safety, danger, and potentially injured body parts were calculated for each group. The rate of correct answers was also calculated for each movement. The scores in each group and the rates of correct answers in each movement were compared among the three groups.

The findings for recognizing safe situations were as follows:

1)The TN group recognized greater danger with nage-waza to the front than did the TJ group.

2)The US group recognized greater danger with nage-waza to the front and back than did the TJ and TN groups.

3)The US group recognized greater danger with katame-waza than did the TJ and TN groups.

The findings for recognizing dangerous situations were as follows:

4)The TJ group recognized greater danger with the lower posture of the thrower (tori) than did the TN and US groups.

5)The TJ group recognized the greater danger of the receiver (uke) putting their hand to the floor than did the TN and US groups.

6)All three groups recognized the danger with the tori putting their head to the floor; however, the TN and US groups did not identify possible injuries to the head or neck.

7)With regard to possible damage to the spinal column in katame-waza, the TJ and TN groups recognized greater potential danger than did the US group. The US group did not identify possible injuries to the neck.

This study aimed to examine a teaching method of basic striking actions for kendo beginners by applying rhythmic movements.

14 university students were randomly divided into two groups: the ‘rhythm group’ (n=7) was taught basic striking actions through rhythmic movements, and the ‘point group’ (n=7) was taught basic striking actions through traditional explanations and demonstrations of technical points.

Both groups learned and practised basic striking actions such as men, kote and do in four 20 minute sessions as a part of 90-minute university kendo classes. The rhythm group was taught striking actions divided into eight movements and practised these movements along with a rhythm.

Before and after the first class, and after the second to the fourth class, the students’ performance of basic striking actions was assessed with three grades consisting of ① how they swing up the shinai; ② how they simulate the strike of each target; ③ the timing which they strike and take a step forward with the right foot; ④ how they follow through after striking; and ⑤ how they come back to chudan-no-kamae.

The results suggested that the rhythm group acquired men striking actions after the third class, and kote and do striking actions after the second class. The point group did not acquire skills that met all of the criteria of any striking action during any of the four classes. The criterion that the point group did not meet was ⑤. The criteria that took the point group longer to acquire than the rhythm group were ②, ③, and ④ for the men striking action, and ② and ④ for the kote and do striking actions.

As expected, the rhythm group seemed to acquire the basic striking actions more quickly than the point group. Thus it is suggested that the teaching method that applies rhythmic movements would help beginners in kendo acquire skills in a shorter period of time than the other conventional method.

The first World Championship for judoka with an intellectual disability, to which I was dispatched as a member of the All Japan Judo Federation team, was held from October 10-22, 2017, in Cologne, Germany. Officially supported by the International Judo Federation (IJF) and the International Federation for Athletes with Intellectual Impairments (INAS), this event became the first world championship which enabled judo athletes with intellectual impairments to compete on the world stage under special refereeing regulations that are recognized by the IJF. Therefore, this pioneering event served as a historic milestone for the future development of judo for intellectually impaired athletes. Despite many remaining issues, this world championship can be considered a huge success for the future of competitive judo for intellectually impaired athletes. The support of the IJF will be crucial for the further development of judo for the intellectually impaired in the future.