The purpose of this study was to compare physical activity in fifth-grade primary school children using a questionnaire and an accelerometer. A total of 34 participants (15 boys and 19 girls) aged 10–11 years participated in this study. A questionnaire and an accelerometer were used to assess and exercise time and moderate-to-vigorous physical activity (MVPA), respectively. Participants were classified into two groups, i.e., meeting ≥60 min/day MVPA group and non-meeting MVPA ≥60 min/day MVPA group, based on the results of questionnaire assessment and MVPA was compared. Except for all children and girls on weekdays, the exercise time assessed by the questionnaire was significantly different from the MVPA measured by the accelerometer. There were significant differences in MVPA between the meeting ≥60 min/day MVPA group and non-meeting MVPA ≥60 min/day MVPA group on weekends in all children and on weekdays and all-days in boys. Agreement between physical activity guideline meeting and non-meeting, as assessed by questionnaire and accelerometer, showed significant agreement only for all children in weekends (φ=0.35, p<0.05). In conclusion, our study suggested that it is not appropriate to use the exercise time assessed by the questionnaire and MVPA assessed by the accelerometer as equivalent measures of activity for fifth-grade students.

The physical strength and motor ability of children in Japan and South Korea have tended to decline due to a decrease in physical activity and the lack of acquisition of basic movements. This study aimed to measure the physical and motor abilities during early childhood in Japan and This study aimed to measure the physical and motor abilities during early childhood among children in Japan and South Korea and to examine the physical measurement values, physical fitness, and motor skills during early childhood in both We found that 4-year-old girls, 5- and 6-year-olds in South Korea were slightly taller than children of the same age in Japan, but the difference was not significant. The average body weight of a 5-year-old child in South Korea was significantly higher than that in Japan. In terms of motor ability, Japan had a significantly higher average body support endurance time and ball catching for 4-year-olds; tennis ball throwing, repeated South Korean 6-year-olds were faster than the Japanese ones only in the 25 m run. In addition, although no significant difference was found in the comprehensive judgment results of motor ability, it decreased as age increased in the 25 m run. In addition, although no significant difference was found in the comprehensive judgment results of motor ability, motor ability decreased among children in Japan but remained consistently low at all ages among children in South Korea. In conclusion, in terms of physique, Korean children weighed more than the Japanese in the bracket age of 5 years, but in terms of motor ability, the Japanese children had better motor abilities than the South Koreans in most items.

This study determined differences in sleep habits of fifth through ninth graders by taking into account the school management level to which the children belonged to. A group of 21 researchers from 15 research institutes administered a questionnaire survey to 21,491 fifth to ninth graders, who were attending 76 schools from all regions of Japan. Among the questionnaire respondents, a total of 6,556 fifth to ninth graders (3,245 boys and 3,311 girls) attending municipal or national schools located in medium-sized cities and with no deficiencies in the questionnaire items were included in the analysis. Basic details (such as sex), information on sleep habits (such as waking time, bedtime, sleeping hours on weekdays and holidays, sleep debt, and daytime sleepiness), screen time, and moderate-to-vigorous physical activity was collected via the questionnaire. Children attending national schools had poorer sleep habits for both school type, and the differences were particularly prominent on weekdays. Furthermore, children attending national schools were more likely to exhibit daytime sleepiness. It was also suggested that children attending municipal schools had delayed sleep phase due to long screen time, while children attending national schools had advanced sleep phase due to short screen time, particularly on holidays. In the future, random sampling and longitudinal studies in schools from cities other than medium-sized are required.

(1)We conducted Item Response Theory analysis on the data from the survey of 82 Kayan (Lahwi) women regarding their acquisition of skill selected from inventory of clothes-making skills demonstrated by Kayan abutase-atatase. From this analysis, we measured the difficulty and discrimination of each clothes -making skills elements.

(2)This analysis discovered a clear regularity in the Kayan clothes making process. More specifically, we found that learning process of Kayan clothes-making skills elements of highly resembles the learning curve discovered by Sgaw Karen Survey (Shimoda, 2019), and acknowledging this regularity, we can find the latent order and sequentiality of the oral transmission of Kayan clothes-making skills.

(3)Furthermore, Kayan clothes making process were divided into 7 categories, and we discovered the sequentiality of learning items within these difficulty of each technical elements in 7 categories.

From a practical standpoint, we considered at what kind of sequence should execute for each skill element. In this way, it became possible to systematize the learning of ethnic clothes -making.

This study aimed to clarify the developmental characteristics of hopping, one of the fundamental locomotion skills among children, through a qualitative evaluation of their movements. The acquisition of the movement and the process of its mastery in early childhood were evaluated. Hopping tasks were conducted with the leg easier to use for hopping (chosen leg) and the other leg (non-chosen leg). Upper and lower limb movements during hopping were evaluated based on a previous study's evaluation criteria. The results obtained were as follows:

(1) There was no clear laterality in the choice of the leg used for hopping. This suggests that the role of the lower limb in hopping in early childhood is not lateralized.
(2) The movement evaluation of hopping was different for both legs. Evaluation of the chosen leg tended to be higher than that of the non-chosen leg.
(3) Most children were evaluated as immature in hopping for both the lower and upper limb evaluations, and there were few mature movement patterns among children under 6 years of age.
(4) Comparing the evaluation of hopping movement by age, the evaluation increased with age. Notably, there was a significant difference between 4- and 5–6-year-olds. It is suggested that there was a greater change in improvement between 4- and 5-year-olds.
(5) Hopping as a whole-body movement combining both upper and lower limbs suggests that the movements gradually change with age to be used effectively for postural stability and forward propulsion.

In summary, this study indicates that the development of hopping movement in early childhood is a process of acquiring the initial movement pattern at the age of 4 years and becoming proficient at it during the age of 5–6 years.

The purposes of this study were to examine the Japanese parameters (JP) of the BTT model (Bock, 1992) and measure the accuracy of the predicted adult stature (PAS) estimation using the height data of Japanese children (6 to 17 years old). The subjects of this study were 1,508 boys and 1,308 girls. Among them, 1,137 boys and 1,102 girls with good fitting on the BTT model were analyzed. BTT parameters were created for Japanese subjects and compared to default parameters (DP), followed by an error estimation comparison between PAS using JP and PAS using DP. Additionally, growth data was artificially generated by subtracting the newest year from the 12-year data and calculating PASs from that data set. Finally, we compared the difference between the PAS of the growth data and the PAS from the full 12 years of data. The following findings were obtained from the analyzes:

1) Initial parameters for Japanese (JP) in the BTT model of height development for predicting adult heights of athletes were obtained for males and females separately.
2) Highly accurate predictions can be made when using 8 years of developmental data from 6 to 13 years of age, but the prediction accuracy is significantly reduced when the developmental data is less than 13 years of age.
3) In stunting data, there is a regression effect whereby a lower PAS is predicted for taller individuals and conversely a higher PAS is predicted for shorter individuals.
4) In the growth data, both boys and girls with developmental characteristics such as abrupt stalls in growth and growth spurts resulted in an estimation error of ± 10 cm or more.

This study aimed to classify the body composition of puberty students into six categories, using Fat Mass Index (FMI) and Fat Free Mass Index (FFMI), and to identify the characteristics of their physical fitness and motor capacity in each category. FMI and FFMI are body composition (FM; Fat Mass, FFM; Fat Free Mass) divided by height squared. The participants were 1,482 high school students (815 males and 667 females) aged 15-17 years old. The body measurements were height, weight, and FFM (Fat Free Mass). In addition to the calculation of Body Mass Index, fat mass (FM) was calculated from fat free mass (FFM) and body weight, and FMI and FFMI were calculated FM, FFM and height. The students body were categorized into six groups using cluster analysis with FMI and FFMI as variables: low FFMI and low FMI (Category 1), low FFMI and normal FMI (Category 2), high FFMI and low FMI (Category 3), high FFMI and normal FMI (Category 4), high FFMI and high FMI (Category 5), and high FFMI and very high FMI (Category 6). Among the categories, Categories 3 and 4 showed significantly higher scores in total physical fitness and all the physical fitness factors, revealing endurance sports type and power sports type respectively.

This study aimed to determine the developmental characteristics and sex differences of running performance and motions in 82 current male and female infants aged 3-5 years and compare the results with those in infants around 1980 from a kinematic point of view.

In the experiment, the time taken to run 25 m was measured, and body motions during running were videorecorded (120 fps) to analyze the step length, step frequency, and running motion factors. In both male and female participants in this study, the running velocity, step length, velocity index, step frequency index, and step length index increased with age from 3 to 5 years; however, the step frequency did not change. The non-stance time and jumping ratio also increased with age, while the stance time decreased with age from 3 to 5 years in both male and female subjects.

The running velocity in the subjects in this study did not differ clearly from that in infants around 1980, except for 5-year-old girls; however, the step frequency and step length measurements in infants aged 3-5 years indicated a larger step frequency and a smaller step length of the participants in this study than the respective values of infants around 1980. Moreover, the running motion data revealed a greater vertical movement of the body’s center of gravity in the male and female subjects in this study than in infants around 1980. Furthermore, there were no sex differences in the running motion among the male and female subjects in this study, suggesting that the running motions of boys have become similar to those of girls. No changes over time in the running motion were found in the male and female subjects in this study, suggesting that the running motions remained immature in both boys and girls.