The current focus of meeting the physical activity guidelines for children and young people include preventing conditions such as high blood cholesterol, high blood pressure, metabolic syndrome, obesity, low bone density, depression, and injuries. However, the relationship between sleep habits and meeting physical activity guidelines is still unclear. This study aimed to assess this relationship among fifth- to eighth-grade (ages 10–14) Japanese children. This cross-sectional study included 3,123 children (boys: 1,558, girls: 1,565, mean age: 12.5 ± 1.2 years). Questionnaires were used to assess parameters such as moderate-to-vigorous physical activity per day, school and weekend night sleep durations, social jetlag, daytime sleepiness, napping, screen time, and breakfast intake. Participants were divided into an achievement and a non-achievement group depending on their physical activity guideline achievement status (i.e., whether they met the children’s physical activity guideline of 60 min or more of moderate-to-vigorous physical activity per day). Then, to determine the sleep habits in relation to the children’s achievement of guideline-recommended physical activity levels, multivariate logistic regression analyses were conducted. In fifth- and sixth-grade (ages 10–12) boys, an inverse association was observed between physical activity guideline achievement and daytime sleepiness. In seventh- and eighth-grade (ages 12–14) boys, physical activity guideline achievement was inversely associated with social jetlag and skipping breakfast. Additionally, in seventh- and eighth-grade girls, physical activity guideline achievement was inversely associated with inappropriate sleep duration on weekends and screen time. These results suggest that meeting the physical activity guideline is related to favorable sleep habits in Japanese children. However, their relevance may differ by school type and gender.

A survey was conducted to assess physical activity, depression, and sense of coherence among early adolescents. This study used a cross-sectional sample of 12,086 students(G5-G9)from 28 public elementary schools and 22 public junior-high-schools in Japan. A total of 9,424 students(G5-G8)were surveyed from December 2013 to December 2015 using the International Physical Activity Questionnaire ［資 料］ 発育発達研究 第 78 号 (IPAQ) -short form to measure physical activity (PA), the Depression Self-Rating Scale for Children (DSRS-C)for depressive symptoms, and the Sense of Coherence Scale-13-item version(SOC-13).Vigorous PA(VPA)of the G5 boys(4h 20 min)was significantly longer than that of the G5 girls(1h 30 min)and the VPA of the junior-high-school students increased significantly compared with that of the elementary-school students. The VPA of the G8 boys reached 6h 30 min, whereas that of the G8 girls approached 3h, which was a significant difference. Additionally, more junior-high-school students participated in sports-club activities than did elementary-school students.The mean DSRS-C score of the G5 girls(10.24±5.73)was significantly higher than that of the G5 boys (9.31±5.31). No other differences by grade, were found among the elementary-school students. The depressive symptoms of the junior-high-school students indicated they had a greater risk for depression than the elementary-school students did.The mean SOC score of the G8 boys(44.58±8.11)was higher(better)than that of the G8 girls (43.46± 8.30). Furthermore, the elementary-school studentsʼ score on the SOC was higher than that of the juniorhigh-school students；the score tended to decrease as the grade increased. Key words：adolescence, physical activities, depression, sense of coherence, questionnaire 思春期，身体活動量，抑うつ，首尾一貫感覚，質問紙法 Ⅰ はじめに 思春期は二次性徴による身体の変化や認識，感 情等の精神面など，急激な発育発達が起こる時期 であり，様々なストレスの原因となる出来事が増 える時期である．この思春期の健康問題として， 不登校，不定愁訴，自殺行為などが挙げられてお り，うつ病に関しても，わが国の思春期の子ども における有病率は 2.0-8.0％であり，大人とほぼ 同程度であるといわれている(傳田，2007) ．

The International Physical Activity Questionnaire (IPAQ) is a self-reported questionnaire for assessment of physical activity and has been validated in many countries among adults. However, there are few studies about the validity of IPAQ for children. The purpose of this study was to investigate the validity of moderate to vigorous physical activity according to the modified version the IPAQ for Japanese Early Adolescents (IPAQ-JEA). Ninety-two adolescents aged 10-13 years participated in this study. The validity of the IPAQ-JEA criteria was tested using an activity monitor (Active style Pro, HJA-350IT; ASP). Daily physical activity was continuously monitored for one week by ASP. The participants were asked to complete the IPAQ-JEA after wearing the ASP. The epoch length of ASP was set at 1-min in this study (ASP 1-min ). According to the minute by minute METs values, time spent on moderate intensity physical activity (MPA, 3 to 6 METs), vigorous intensity PA (VPA, > 6 METs), and moderate to vigorous intensity PA (MVPA, > 3 METs) was calculated. In addition, we also calculated bout physical activity maintained for 10 minutes or longer (ASP bout ). Weekly time spent on MVPA assessed by IPAQ-JEA (MVPA_IPAQ-JEA) was significantly correlated with that assessed by ASP bout (MVPA_ASP bout ) (ρ=0.359, p<0.01) and ASP 1-min (MVPA_ASP 1-min ) (ρ=0.399, p<0.01). However, MVPA_IPAQ-JEA was significantly higher than that of MVPA_ASP bout and MVPA_ ASP 1-min (p<0.001). Although time spent on VPA assessed by IPAQ-JEA (VPA_IPAQ-JEA) was also significantly correlated with that assessed by ASP bout (VPA_ASP bout ) (ρ=254, p<0.05) and ASP 1-min (VPA_ASP 1-min ) (ρ=438, p<0.01), time spent on VPA_IPAQ-JEA was significantly higher than that for VPA_ASP bout and VPA_ASP 1-min (p<0.001). These results support the use of the IPAQ-JEA as a relative measure of physical activity among 10-13-year-old children.

Objective: This study examined the relationship between neighborhood food and physical activity environment, and obesity among elementary and junior high school students in Japan. Methods: The participants were fifth- to ninth-grade children (n=7277), who were attending municipal schools in Japan. Percent overweight (POW) was calculated using their age, gender, height, and weight, which were collected through a questionnaire. A POW of < 20% was considered non-obese, while ≥ 20% was considered obese. Furthermore, using a geographic information system, we investigated the density of convenience stores, fast-food stores, casual restaurants, supermarkets and department stores, parks, sports facilities, stations, and intersections in the school district. Additionally, from the census, we obtained information regarding the population density of the municipality where the participants’ schools were located. Multiple logistic regression analysis was used to examine the relationship between obesity and food environment (the food environment model), between obesity and physical activity environment (the physical activity environment model), and among obesity, food, and physical activity environment (the food and physical activity environment model). Results: In the food environment model and the food and physical activity environment model, the density of convenience stores showed a significant positive association. In the physical activity environment model, the density of stations showed a significant negative association. Conclusion: This study’s findings can contribute to the development of appropriate community interventions for improving children’s health in Japan and similar areas.

A questionnaire survey was conducted to assess the physical activity, health-related QOL and depression of junior high school students. The subjects were 1,332 students from 5 public junior high schools in a certain city；valid responses were obtained from 1,289 students. The International Physical Activity Questionnaire（IPAQ）was used for assessing physical activity, the Pediatric Quality of Life Inventory （PedsQL TM ）for health-related quality of life（QOL), and the Depression Self-Rating Scale for Children （DSRS-C）for depression tendency.With regard to physical activity between males and females and among different grades, there was a significant difference in the amount of vigorous-intensity activity（in terms of days, hours, and total activity time of 1 week). However, no significant difference was observed in walking. In the different age groups, the difference was observed in moderate-intensity activity（time, total activity time of 1 week）and energy expenditure. No significant difference was observed between males and females in holiday time is sitting activity was not observed in the grades. With regard to health-related QOL, a significant difference was observed between male and female students in the emotional function. The percentage calculated for each grade revealed that the female students showed higher depression tendency than the male students and that the number of students exceeding the cut-off score, which was determined to indicate depression tendency, increased as they advanced to the next grade. While the score maintained around 30％ from the 1st year to 3rd year in the female students, it showed about 30％ only in the 3rd year in the male students. Furthermore, one in three male and female 3rd year junior high school students was determined to have depression tendency. Therefore, it is necessary to reconsider the current cut-off score when using it to assess junior high school students.Key words：Junior high school students, physical activity, health-related QOL, depression, questionnaire 中学生，身体活動量，健康関連 QOL，抑うつ，アンケート