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Abstract Background Social restrictions associated with the COVID-19 pandemic have altered children’s movement behaviours and impacted their mental health. However, the influence of social restrictions on subjective health complaints remains inadequately understood. This study compared adherence to 24-hour movement behaviour guidelines and the prevalence of subjective health complaints during school closure and one year after reopening. We also examined how combinations of adherence to movement behaviour recommendations relate to subjective health complaints. Methods A repeated cross-sectional survey was conducted at two points. The first survey in May 2020 included 1535 (766 boys and 769 girls) participants during school closures, while the second survey from May to July 2021 involved 1125 (583 boys and 542 girls) participants one year after school reopening. The questionnaire covered socio-demographics, physical activity, screen time, sleep, and subjective health complaints. Differences between periods were analysed using chi-square tests. Logistic regression models assessed the association between adherence to guidelines and subjective health complaints. Results During school closure, children were more likely to meet ‘only sleep’ recommendations and have irritability and lethargy symptoms. Irrespective of sex, those adhering to two or all three recommendations (excluding physical activity and screen time) had a lower risk of symptoms related to physical and mental pain, fatigue, irritability, and lethargy as compared to those who met none of the recommendations. Conclusions Children should meet at least one physical activity or screen time recommendation in addition to sleep recommendations for subjective health. Strategies considering the priority of each movement behaviour are crucial, even during abnormal situations, such as pandemic-related social restrictions. This study offers insightful findings concerning children’s mental health issues during unprecedented and massive disasters or crises.

Abstract Background It is known that the circadian rhythm phase in adults can be advanced in a natural light-dark cycle without electrical lighting. However, the effect of advanced sleep-wake timing according to the natural light-dark cycle on children’s circadian phase is unclear. We investigated the effects of approximately 2 weeks of camping life with little access to artificial lighting on children’s circadian phases. We also conducted an exploratory examination on the effects of wake time according to natural sunrise time on the manner of the advance of their circadian phases. Methods Twenty-one healthy children (mean ± SD age, 10.6 ± 1.4 years) participated in a camping program with wake time (4:00) being earlier than sunrise time (EW condition), and 21 healthy children (10.4 ± 1.1 years) participated in a camping program with wake time (5:00) being almost matched to sunrise time (SW condition). Salivary dim light melatonin onset (DLMO) before the camping program and that after approximately 2 weeks of camping were compared. Results DLMO was advanced by approximately 2 h after the camping program compared with the circadian phase in daily life in both conditions. In addition, the advances in DLMO were significantly correlated with mid-sleep points before the camp in both conditions (EW: r = 0.72, p < 0.01, SW: r = 0.70, p < 0.01). These correlations mean that the phase advance was greater for the children with delayed sleep habits in daily life. Furthermore, in the EW condition, mean DLMO after the camp (18:09 ± 0:33 h) was earlier than natural sunset time and there was no significant decrease in interindividual variability in DLMO. On the other hand, in the SW condition, mean DLMO after the camp (18:43 ± 0:20 h) matched natural sunset time and interindividual variability in DLMO was significantly lower than that before the camp. Conclusions Camping with advanced sleep and wake timing under natural sunlight advances children’s circadian phases. However, DLMO earlier than sunset in an early waking condition may lead to large interindividual variability in the circadian rhythm phase.

Physical fitness (PF) is significantly associated with current and future health. Routine assessment of PF is important not only to understand the overall health of the population, but also to predict future disease burden. While the annual national PF testing conducted by the Japan Sports Agency is well known domestically, the existence of this surveillance strategy is seldom recognized internationally, as only a few published studies have used this PF surveillance dataset. This short review has three aims. First, we briefly summarize the history and test battery of the annual national PF surveillance system for Japanese people. Second, we discuss published research, including our recent work that utilized data from the Japanese PF surveillance database. Third, we propose a priority research agenda for Japanese PF surveillance. While annual PF surveillance appears to be “normal” for Japan, such surveillance efforts are extremely rare internationally. Promoting Japan’s national PF surveillance dataset in international publications provides an important opportunity for other countries to develop similar cost-effective public health surveillance strategies.

Background: The 6-minute walking distance (6MWD) is an excellent measure of both functional endurance and health. The primary aim of this study was to estimate temporal trends in 6MWD for older Japanese adults between 1998 and 2017; the secondary aim was to estimate concurrent trends in body size (i.e., height and mass) and self-reported participation in exercise/sport. Methods: Adults aged 65–79 years were included. Annual nationally representative 6MWD data (n = 103,505) for the entire period were obtained from the Japanese Ministry of Education, Culture, Sports, Science and Technology. Temporal trends in means (and relative frequencies) were estimated at the gender–age level by best-fitting sample-weighted linear/polynomial regression models, with national trends estimated by a post-stratified population-weighting procedure. Temporal trends in distributional variability were estimated as the ratio of coefficients of variation. Results: Between 1998 and 2017 there was a steady, moderate improvement in mean 6MWD (absolute = 45 m (95% confidence interval (95%CI): 43–47); percent = 8.0% (95%CI: 7.6%–8.4%); effect size = 0.51 (95%CI: 0.48–0.54)). Gender- and age-related temporal differences in means were negligible. Variability in 6MWD declined substantially (ratio of coefficients of variation = 0.89, 95%CI: 0.87–0.92), with declines larger for women compared to men, and for 75–79-year-olds compared to 65–74-year-olds. Correspondingly, there were moderate and negligible increases in mean height and mass, respectively, and negligible increases in the percentage who participated in exercise/sport at least 3 days per week and at least 30 min per session. Conclusion: There has been a steady, moderate improvement in mean 6MWD for older Japanese adults since 1998, which is suggestive of corresponding improvements in both functional endurance and health. The substantial decline in variability indicates that the temporal improvement in mean 6MWD was not uniform across the distribution. Trends in 6MWD are probably influenced by corresponding trends in body size and/or participation in exercise/sport.

BackgroundJapanese children face critical psychological challenges that urgently need to be addressed.ObjectiveThis study aimed to clarify performance differences in go/no-go tasks among Japanese elementary and junior high students by sex and grade and comprehensively investigate the relationship between children's lifestyle habits and performance.MethodsIn total, 4,482 (2,289 males, 2,193 females) 1st grade elementary to 3rd grade junior high students (6–15 years old) participated. We conducted a survey and the go/no-go experiments in the participating schools on weekday mornings from November 2017 to February 2020. We collected data on the number of errors in the go/no-go tasks in response to visual stimuli (commission errors in the no-go tasks; omission errors in the go tasks); and on lifestyle habits (i.e., sleep, screen time, and physical activity) using questionnaires.ResultsFor the commission errors, the results demonstrated differences by sex and grade; for the omission errors, differences were only observed by grade. Additionally, we analysed the relationship between both types of errors and sex, grade, sleep conditions, screen time, and physical activity using binomial logistic regression analysis. Commission errors were significantly related to sex and grade whereas omission errors were related to grade, bedtime, screen time, and physical activity.ConclusionsOur results highlighted that children's cognitive functions are related to their lifestyle habits (i.e., sleep conditions, screen time, and physical activity) in addition to sex and grade.

This study aims to examine the immediate and lasting effects of resident summer camp on movement behaviors among children with repeated pre-, during-, and post-intervention measurements. In total, 21 children (aged 10.3 ± 1.2 years, 17 boys and 4 girls) participated in a 31-day nature-based resident summer camp in Japan. Daily children's movement behaviors (moderate-to-vigorous physical activity (MVPA), sedentary behavior (SB), and sleep) were continuously monitored before, during, and after the summer camp (i.e., 75 continuous days). It was found that the children engaged more time in MVPA (9.6%), less time in SB (58.0%), had more steps (22,405 steps/day), and an earlier midpoint of sleep (0:24 a.m.) in the summer camp as compared to the other periods (before and after the camp). However, the children engaged in unfavorable behaviors [reduction in MVPA (3.6%), increased SB (67.3%), and a later midpoint of sleep (1:32 a.m.)] during the summer vacation after the camp. This study indicates that the resident summer camp was effective in improving children's movement behaviors during the camp. However, the lasting effects were negligible or at least limited after its completion.

The purpose of this study was to examine the associations between different types of screen behavior and depression, taking into account exercise and sleep among children and adolescents. A total of 23,573 Japanese children and adolescents (aged 8–15 years) participated in this cross-sectional study. Different types of screen behavior, weekly exercise time, sleep duration, and prevalence of depression were assessed using a questionnaire. Independent associations between various types of screen behavior and prevalence of depression were examined using logistic regression analyses after adjusting for age, school, sleep duration, exercise time, and other screen behavior types. A two-way analysis of covariance was conducted to examine whether exercise and sleep can attenuate the negative effects of screen behavior. The associations between screen behavior and depression varied by screen behavior types and participant characteristics. More time spent engaging in newer types of screen behavior, including social media, online games, and online videos, was associated with a higher prevalence of depression. In contrast, more time spent on TV was associated with a lower prevalence of depression. Sufficient exercise can lower the prevalence of depression, regardless of the length of time and content of the screen, and its associations were particularly significant for junior high school girls. Sleep was not associated with the prevalence of depression among any participant group except elementary school boys. Our findings suggest that age- and sex-specific intervention strategies that also consider screen-based behavior can effectively lower the risk of depression in children and adolescents.

Studies have presented data regarding the effects of short-term (weeks) and long-term (one year) use of standing desks in classrooms on children's health, cognition, and musculoskeletal symptoms. However, no previous study has examined such effects in an extremely short-term period such as one classroom lesson. This study aimed to examine the effects of using standing desks for 45 minutes on elementary school students' stress and executive function. For this experiment, 56 students were recruited from public elementary schools in Setagayaku, Tokyo, Japan. There were three conditions involving the use of standing desks (standing, sitting, and mixed), and all students performed tasks for 45 minutes in each condition. Measurements of stress and executive function were performed before and after the students engaged with each condition. Stress levels did not differ between the sitting and standing conditions for the full 45 minutes. The number of correct answers in the Stroop test, an interference task, was higher in the standing and mixed conditions (switching between standing and sitting) than in the sitting condition (interaction: F(1,37) = 3.340, p = 0.04, η2 = 0.05). These results indicate that using standing desks for 45 minutes improved the 'inhibition' of executive function without excessively increasing stress levels.

The coronavirus disease 2019 (COVID-19) pandemic may result in a greater decrease in visual acuity (VA) among Japanese children. Our study aimed to examine Japanese children’s VA during the pandemic. VA data were collected using standard eye tests during school health check-ups conducted in 2019 and 2020 on 5893 children, in seven public elementary schools and four public junior high schools in Tokyo, Saitama, Kanagawa, and Shizuoka. VA changes were statistically analyzed. The relationship between the survey year and poor VA yielded a significant regression coefficient for the surveyed years in elementary and junior high school students. The 2019 VA value and VA change from 2019 to 2020 demonstrated a significant regression coefficient in elementary school students with VAs of “B (0.7–0.9)” and “C (0.3–0.6)”, and junior high school students with VAs of “B”, “C”, and “D (

Aerobic fitness is considered to be an important marker of current health and even a predictor of future health. The aim of this study was to systematically analyse the available scientific information on temporal changes in maximal long-distance running performance (a widely and long-used marker of aerobic fitness) of Asian children. A systematic review of the scientific literature was undertaken to locate studies explicitly reporting on temporal changes (spanning a minimum of 5 years) in maximal long-distance running of apparently healthy (free from known disease or injury) Asian children aged 9-17 years. Studies were located up to October 2010 via computerized searching of bibliographical databases, reference list searching and personal communication with international experts. Temporal changes were analysed at the country by sex by age by test level using best-fitting linear or polynomial regression models relating the year of testing to long-distance running performances expressed as average running speeds. Changes in means were expressed as percent changes and as standardized effect sizes. Eight studies reporting temporal changes in the long-distance running performance of 23 897 571 children aged 9-17 years from four Asian countries over the period 1964-2009 were included. Overall, there was a large decline in long-distance running performance equivalent to -16.6±1.3% (mean change±95% confidence interval) or -1.2±0.1 standard deviations. Temporal changes were generally consistent for different sex and age groups, but not for different countries, with large declines observed for children from China and the Republic of Korea, small declines for children from Japan and very small declines for children from Singapore. There is overwhelming evidence of meaningful declines in the maximal long-distance running performance of Asian children in recent decades, which are probably caused by a network of social, behavioural, physical, psychosocial and physiological factors. These declines highlight the need for regular surveillance of Asian children's health-related fitness and proactive public health strategies. [ABSTRACT FROM AUTHOR]