The purpose of this study was to investigate whether swing velocity affects the ball kicking performance of male soccer players. The study participants included 309 Japanese male soccer players aged from 10 to 22 years. Participants who were of the same age were classified into 1 group. The participants were further classified into 4 groups on the basis of their school category (elementary school group, junior high school group, high school group, and university group). The ball distance (BD) was measured by the tape measure. The ball velocity (BV) was measured using a speed gun. By using a custom-made speed meter, we measured the maximal swing velocity of the lower limb (SV) while the players were kicking the ball. With respect to BD and BV, there were significant differences between 12 and 15, and 17 and 18 years old, respectively. The SV significantly increased from 12 to 16 years old. It was found that SV significantly correlated with the BV and BD in all participants and all school categories. The BD and BV were significantly increased due to school categories. However, there was no significant difference between the high school group and the university group with respect to SV. Further, BV and BD were significantly higher in the university group than in the high school group. Therefore, the kicking performance may vary depending on differences in skill level. These results suggested that the ball kicking performance may be affected by not only swing velocity but also an individual's ball kicking skills.
The purpose of this study was to investigate the effectiveness of an exercise programs on an unstable support surface designed to develop motor ability in pre-school children. For 86 children (43 four-year-olds and 43 five-year-olds), we configured 10-weeks control period and 10-weeks exercise period. During the exercise period, we carried out an exercise programs on an unstable support surface. In this study, we used a JP cushion as an unstable support surface. The exercise programs were conducted for 12 days over a period of 10 weeks, for 30 minutes per day, under the instructor's guidance. All children were subjected to 2 measurements (height and weight) and 4 performance tests (foot balance, standing broad jump, side jump, hopping on unstable support surface ; HUS task) around the each period. We found that in standing broad jump, side jump and HUS task, the children performed remarkably improve during the exercise period. Second, interaction was found between the effectiveness in the HUS task and grade, however in other tests, no correlation was found between effectiveness and gender and between effectiveness and grade. From these results, as in the case of exercise on an unstable support surface, we get that the exercise programs on an unstable support surface was effective in improving the children's motor ability. Furthermore, the exercise programs are effective regardless of the differences in gender.
The aim of this study is to clarify the correlation of children's feelings of life enrichment and independence with any dark experiences they may encounter. A total of 1393 students of both genders were randomly selected for the survey from fourth, fifth, and sixth graders in Tokyo elementary schools. Data was collected from two series of questions : 1) dark experiences (ten questions, four-point rating scale) and 2) their life enrichment and independence feelings (ten questions, five-point rating scale). Of the three grades, the fourth grade students had the highest number of dark experiences as well as the best feelings in their daily lives. The factor-analysis revealed four factors, which were “dark experiences from outside,” “dark experiences from inside the house,” “factors of life enrichment feelings,” and “factors of a child's independence.” According to the SEM model (with the four factors), the effects of dark experiences on children's independence indicated approximately a 26% rate of variance of the final dependent factor, i.e., children's independence. Therefore, these results suggest that dark experiences could affect a child's independence.