Temporal trends in handgrip strength for older Japanese adults between 1998 and 2017

Objective: To estimate temporal trends in handgrip strength (HGS) for older Japanese adults between 1998 and 2017. Design and Methods: Adults aged 60–79 years were included. Annual nationally representative HGS data (n=176,449) for the 19-year study period were obtained from the Japanese Ministry of Education, Culture, Sports, Science and Technology. Temporal trends in mean HGS were estimated by sample-weighted regression models relating the year of testing to mean HGS. National trends in absolute, percent and standardized HGS were estimated by a post-stratified population-weighting procedure. Temporal trends in variability were estimated as the ratio of coefficients of variation (CVs). Results: Collectively, there was a small improvement in mean HGS of 1.4 kg (95%CI: 1.3–1.5), 4.5% (95%CI: 4.3–4.7), or 0.27 standard deviations (95%CI: 0.26–0.28) between 1998 and 2017. The rate of improvement progressively increased over time, with more recent values (post-2008) 1.5-fold larger than earlier values. Gender- and age-related temporal differences were negligible. Variability in HGS declined substantially over time (ratio of CVs [95%CI]: 0.88 [0.86–0.90]), with declines 1.9-fold larger in women compared to men, and 1.7-fold larger in 70–79-year-olds compared to 60–69-year-olds. Conclusions: There has been a small, progressive improvement in mean HGS for older Japanese adults since 1998, which is suggestive of a corresponding improvement in overall strength capacity. The substantial decline in variability indicates that the improvement in mean HGS was not uniform across the population

Temporal trends in 6-minute walking distance for older Japanese adults between 1998 and 2017

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 (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. Conclusions 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

Compliance with a physical activity guideline among junior high school students

Background: There were no nationwide moderate- to vigorous-intensity physical activity (MVPA) data relating to Japanese adolescents. This study assessed compliance with an MVPA guideline by adolescents, using a random sampling survey in Japan. The factors associated with compliance with the guideline were also examined. Methods: Participants were first- to third-grade Japanese junior high school students (307 boys and 255 girls). We analyzed data from the National Sports-Life Survey of Teens 2019, which used the Japanese version of physical activity (PA) questions in the World Health Organization Health Behavior in School-aged Children survey and potential correlates of MVPA. Results: Compliance with the PA guideline by the World Health Organization for Japanese students was 19.0% (95% confidence interval (CI), 15.8–22.3). The compliance of boys was significantly higher than that of girls (23.1%; 95% CI, 18.4–27.8; vs 14.1%; 95% CI, 9.8−18.4). The odds of meeting the PA guideline were significantly higher for boys in the second grade than boys in the first grade (odds ratio (OR) 1.78; 95% CI, 1.02–3.09), liking PA (for all: OR: 2.97; 95% CI, 1.32–6.69; for girls: OR: 2.99; 95% CI, 1.01–8.81), and sports participation (for all: OR: 4.77; 95% CI, 2.32–9.80; for boys: OR: 6.00; 95% CI, 1.81–19.89; for girls: OR: 4.08; 95% CI, 1.63–10.21). Conclusions: The results suggest that more than 80% of junior high school students were insufficiently physically active in Japan. Preferences for PA and sports participation may be important correlates of sufficient PA

Oxytocin Reactivity during a Wilderness Program without Parents in Adolescents

While wilderness programs are recognized as a feasible intervention to promote psychological independence in adolescence, little is known about physiological changes. The present study focused on oxytocin, a key hormone for social cognition and behavior, and investigated changes in OT concentrations during a wilderness program among adolescents. Twenty-one 4th–7th graders were separated from parents and immersed with adventures and challenges in the woodlands of Motegi, Tochigi Prefecture, Japan for 31 days, and dataset of 20 boys aged 9–13 years-old were used for analysis. OT concentrations in early morning saliva samples on days 2, 5, 8, 13, 18, 20, 21, 22 and 30 were determined using ELIZA. We performed multi-level regression analyses to compare the OT concentrations before and after solo and team-based survival challenges, and across the nine observational points, adjusting for potential covariates. We found that adolescents increased OT level in a situation where they needed others’ cooperation and support for survival (coefficient: 2.86, SE: 1.34, p = 0.033). Further, we found that adolescents gradually decreased their basal OT level during a long separation from parents (coefficient: −0.083, SE: 0.034, p = 0.016). A combination of these findings suggest the OT level may be a marker for psychological independence

The Changes in Visual Acuity Values of Japanese School Children during the COVID-19 Pandemic

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 (<0.3)”. An analysis of the relationship between the survey year and eye laterality of VA yielded a significant regression coefficient in the surveyed years for elementary (OR, 1.516; 95% CI, 1.265–1.818) and junior high school students (OR, 1.423; 95% CI, 1.136–1.782). Lifestyle changes during the COVID-19 pandemic might have affected VA and eye laterality in Japanese children