Minoru Adachi

Importance of both fatness and aerobic fitness on metabolic syndrome risk in Japanese children.

Associations between body mass index (BMI), peak oxygen consumption (VO2peak), and metabolic syndrome (MetS) risk factors have not been adequately studied in Japanese children. Here the relationships between these parameters and the threshold aerobic fitness level necessary for low MetS risk were determined. The participants (299 children; 140 boys and 159 girls, aged 9.1 ± 0.3 years) were divided into four groups using the medians of predicted VO2peak (pVO2peak) and BMI. MetS risk scores were calculated using z-scores. Receiver Operating Characteristic analysis was used to determine the threshold aerobic fitness level necessary for low MetS risk. The MetS risk score of the High BMI group was significantly higher than that of the Low BMI group for both sexes (p < 0.0001). However, the High BMI/High Fitness group had a significantly lower MetS risk score than the High BMI/Low Fitness group for both sexes. The pVO2peak cut-off values for low MetS risk were 47.9 and 44.9 ml/kg/min for boys and girls, respectively. Our results suggest that improvements in both fatness and aerobic fitness are important for decreasing MetS risk. We also confirmed the pVO2peak of cut-off values necessary for low MetS risk in Japanese children.

Patterns of Physical Activity Outside of School Time among Japanese Junior High School Students.

BACKGROUND Physical activity is beneficial for adolescent health. The physical activity patterns of Japanese adolescents are relatively unknown. Therefore, this study aimed to describe the current patterns of physical activity and to identify sex and grade differences among them. METHODS The participants comprised 714 Japanese adolescents aged 12 to 15 years old (boys N = 372, girls N = 342) from a public junior high school in Okayama, Japan. Physical activity at school, outside of school after hours, and during lunch recess as well as the total leisure time in a usual week was assessed with a 5-item questionnaire. To assess the differences in the physical activity patterns by sex and grade, independent t tests and analysis of variance (ANOVA) were conducted, respectively. RESULTS Boys spent significantly more time in physical activity both inside and outside of school settings than girls (p < .05). Higher grade students were significantly less active than lower grade students (p < .05). Furthermore, the physical activity patterns across the grades differed between settings (at school, outside of school during the after-school period, lunchtime recess, and at home). CONCLUSION To increase physical activity levels among Japanese adolescents, implementation of after-school programs or environmental modifications developed within the school setting could be effective strategies.

Objectively measured sedentary behavior, obesity, and psychological well-being: A cross-sectional study of Japanese schoolchildren

BACKGROUND Sedentary behaviors (SB) are associated with health indicators; however, there are currently very few studies that have examined these associations, especially in conjunction with psychological factors, in children. The current study examined the independent relationship between objectively assessed SB, and indicators of obesity and psychological well-being, among Japanese children. METHODS A total of 967 elementary-school children completed a cross-sectional survey. SB was measured with accelerometers for 7 consecutive days. Psychological well-being data (eg, anxiety and behavior problems) were collected via a self-report questionnaire. To determine the relationship of SB with degree of obesity and psychological well-being, linear regression analyses were conducted to relate the indicators of obesity and psychological well-being on SB, adjusted by gender, grade, percentage of moderate-to-vigorous physical activity per day, duration spent wearing the accelerometer, and degree of obesity. RESULTS SB was significantly related to behavioral/emotional problems (β = .280, P = .010, R2 = .015). There was a statistically significant relationship between SB and anxiety (β = .206, P = .059, R2 = .007). No significant association with degree of obesity was found. CONCLUSIONS Excess SB relates higher levels of behavioral/emotional problems and anxiety. These results can inspire the development of interventions that promote well-being and enhance psychological health, by focusing on SB in Japanese children.

Association of physical activity and sedentary behavior with psychological well-being among japanese children: A two-year longitudinal study

Data on the effect of increased or decreased physical activity on children’s psychological status are scarce, and effect sizes are small. This study conducted two-year longitudinal research to identify associations between physical activity, sedentary behavior, and psychological well-being in Japanese school children through a mail survey completed by 292 children aged 6–12 years. Data on sociodemographics, physical activity, sedentary behavior on weekdays and the weekend, and psychometrics (self-efficacy, anxiety, and behavioral/emotional problems) were collected using a self-reported questionnaire. A logistic regression analysis was performed, calculating odds ratios for physical activity, psychometrics, and baseline age and physical activity and sedentary behavior changes. For boys, a negative association was found between increased physical activity outside school and maintained or improved self-efficacy as opposed to a positive association in girls. Increased sedentary behavior on weekdays and long periods of sedentary behavior on weekends were associated with maintained or improved behavioral/emotional problems in girls only. This two-year longitudinal study is the first of its kind conducted in Japan. Although effect sizes were small, these results may nevertheless assist in intervention development to promote psychological well-being.