Purpose

  In recent years, karate, a traditional martial art native to Japan, has gained global popularity. However, limited research exists on specific psychological factors and motivations behind continued practice of karate. Therefore, this study explored these factors through open-ended questionnaires to extract and categorize factors related to psychological motivation for sustained karate practice. The objective was to develop a psychological measurement scale tailored for future karate practitioners.

Methods

  An online survey was conducted between July and August 2022 using Google Forms and open-ended questions to explore the “motivations of adult karate practitioners” about their reasons and desires for practicing karate. The study participants involved 11 adult karate practitioners（7 males, 4 females, aged 20–40 years）from the Wado-kai branch of the All Japan Karatedo Federation in Tokyo. The collected data underwent text mining analysis, wherein the textual data was segmented into word units and parts of speech were analyzed for frequent word extraction via “word segmentation（morphological analysis）.” Co-occurrence network analysis was used to validate the relevance and cluster structure of frequent words, visualizing them through a diagram. Moreover, the co-occurrence network analysis results were integrated with findings from the previous literature on karate and judo to formulate an integrated motivation model.

Results

  The data analysis yielded 20 frequent words from a total of 572 words. Furthermore, co-occurrence network analysis revealed that descriptions of motivations among adult Japanese karate practitioners could be classified into five categories: 1） Coaching and Instruction，2）Awareness for Body and Mind，3）Collective Effort，4）Anti-Aging，5）Learning and Training.

Discussion/Conclusion

  The studyʼs findings classified karate practitionersʼ motivations into the following factors: 1）Relationships and social connections with instructors, 2）Perception of physical and mental well-being, 3）Peer collaboration and competitiveness, 4）Youth preservation, and 5）Learning derived from the discipline. This study effectively identified motivational factors that are unique to karate practice by employing an unconventional approach. Future research should encompass wider age groups and practitioners with different expertise levels to quantitatively validate these findings by establishing psychological measurement indicators.

[Introduction]

  Marine microplastics are a global environmental concern and originate from several sources. We previously reported the release of microplastics, namely synthetic turf fibers（TF）and rubber infill（rubber tips, RT）from artificial turf sports fields. In the present study, we created traps using a wire mesh to prevent TF and RT from flowing into the environment. We also examined whether the depth of the drainage basin affected the release of TF and RT owing to water flow.

[Methods]

1）Simulation experiments were conducted using a plastic container as a model for the drainage basin. The container had an opening on one side and a trap made of wire mesh attached to the opening from the inside. The TF or RT was placed in the container, and water was allowed to flow through the container. The amount of TF and RT caught and remaining in the container with or without the trap was measured. The cost of making each trap varied from 360 to 11,000 Japanese yen, depending on the wire mesh count.

2）A verification test was conducted by setting a trap in a drainpipe in the drainage basin of an artificial turf sports field. The TF and RT migrated from the ditch of the field to the drainage basin, flowed into the sewage pipe via rainwater, and eventually reached the sewage treatment plant. We measured and compared the TF and RT amounts in the drainage basin with or without the trap during the experimental period.

3）Simulation experiments were conducted to determine whether the depth of the drainage basin affected the release of TF and RT from the plastic container owing to water flow.

[Results]

1）The wire mesh traps effectively caught the TF and RT under the applied water flow, and the amount of TF and RT that passed through the container decreased.

2）When the trap was attached to the drainpipe, larger amounts of TF and RT remained in the drainage basin compared to that with the drainpipe without a trap.

3）The amount of TF and RT remaining in the containers increased with increasing depth of the drainage basin.

[Discussion]

  Our wire mesh traps prevented the release of TF and RT into the environment. Because the structure of the trap is simple, fabrication is possible at low cost. Further experiments are required for the practical use of the trap in terms of its durability and maintenance.

  There are two types of official balls（Company A's product: Ball A, Company B's product: Ball B）used in volleyball games. These balls are known to be different in their subjective ease of use, e.g., color, bounciness, surface friction, etc. Among student athletes, ball B is preferred to ball A in its subjective ease of use（Washo et al., 2018）. In the present study we aimed to clarify the functional characteristics of playersʼ predictive ability, that would be crucial for the game play, particularly by investigating the effects of volleyball experience（experienced & inexperienced）and ball manufacturer. In the experiment, participants were asked to answer the predictive spatial location of the falling point of a given ball after watching a short video clip of serving a ball. The participants were then asked to report their answer confidence level concerning the prediction. The absolute errors（i.e., direct distance between the predicted- and actual-falling points）and confidence level obtained were analyzed. Our results indicated that both the accuracy and confidence level in the experienced group were higher compared to those in the inexperienced group. The effect of the temporal occlusion was also observed, implying an improved prediction accuracy due to acquisition of further visual information. The accuracy for ball A was higher than that for ball B and this was irrespective of volleyball experience. Further analysis revealed that both ball types were predicted to fall nearer to the observer than the actual falling point was: Ball A appeared to be judged relatively closer to the endline compared to ball B, whereas ball B, which is recognized to be easy to use, was judged closer to the centerline compared to ball A. Although the prediction accuracy for ball B was lower than that for ball A, our results suggest that depending on the manufacture different prediction biases with respect to depth（y-axis）direction are evoked.

  This study delves into a legal case involving an injury sustained by a student in a public high schoolʼs baseball club, shedding light on the appropriate conduct expected of a teacher in the role of a club advisor.

  The aim of this study is to provide educators with insights that encourage them to carefully acknowledge their duties as club advisors, which include providing guidance and supervision aimed at safeguarding studentsʼ wellbeing and physical safety（a duty to maintain safety）and anticipating and preventing accidents（a duty to avoid consequences）.

  The outcome of the trial went against the school（club advisor）. The school（club advisor）was found to have breached its duty to maintain safety（please refer to the main text for details）.

  Teachers should keep a notebook or use the notes app on their smartphones to check for and handle any “negligence” or “laxity” on their part, such as “doing things as usual carries no risks” or “accidents wonʼt happen.” They should also check for and handle any “omissions” in terms of guidance and any “oversights” from the perspective of preventing accidents. In the event of an accident resulting in legal action, teachers should be aware that these notes could be used as “evidence” in their defense.