BACKGROUNDThis study investigates school lifestyle among adolescents in terms of physical activity (PA) structure: (1) adolescents participating in a physical education lesson (PEL) versus (2) aggregate recess time exceeding 60 minutes.METHODSThe research was conducted in 24 secondary schools in the Czech Republic (boys N = 208, girls N = 433). For the whole day (1-3 days) participants wore the ActiTrainer accelerometer, which monitored PA, and heart rate. A total of 1122 school days were recorded.RESULTSBoth boys and girls participating in a PEL reported significantly better results compared with nonparticipating individuals regarding all indicators of volume and intensity of school PA (SPA). In most SPA indicators, longer aggregate recess time (>60 minutes) had a statistically significant effect, particularly on the volume of SPA. The recommended 500 steps/hours for SPA was achieved by 83% of boys participating in PEL and 69% of girls. In contrast just 32% of nonparticipating boys and 31% of girls reached this level. With longer recess time the recommendation was met by 43% of boys (42% of girls) compared with 26% of boys (23% of girls) with shorter recess time.CONCLUSIONSAn increase in SPA and an improved lifestyle in adolescents on school days are significantly supported more by PELs than by longer recess time.

Background: Little is known about the combined effect of physical activity (PA), recreational screen time (ST), and sleep in preventing childhood obesity. Hence, this study aimed to analyze the associations between meeting the PA, ST, and sleep recommendations within the 24-hour movement guidelines and adiposity indicators among children and adolescents. Methods: A total of 679 children and adolescents aged 8-18 years were included. The time spent in moderate-tovigorous PA and the sleep duration were estimated from raw data from a wrist-worn accelerometer. Recreational ST was reported by the child or parent. Body mass index (BMI) z-score, fat mass percentage (FM%), and visceral adipose tissue (VAT) were used as adiposity indicators. Participants with ≥ 60 min/day of moderate-to-vigorous PA, < 2 h/day of recreational ST, and uninterrupted sleep for 9-11 h/day (for children) or 8-10 h/day (for adolescents) were considered to meet the overall 24-hour movement guidelines. Results: Meeting the ST only recommendation was associated with reduced odds of a high BMI z-score (odds ratio [OR] = 0.38, 95% confidence interval [CI]: 0.17-0.89), excess FM% (OR = 0.34, 95% CI: 0.13-0.93), and excess VAT (OR = 0.27, 95% CI: 0.10-0.74) in adolescents. Significantly reduced odds of a high BMI z-score was associated with meeting the combination of the ST and sleep recommendations (OR = 0.11, 95% CI: 0.01-0.89). Adolescents who met one recommendation (OR = 0.51, 95% CI: 0.27-0.96) or any two recommendations (OR = 0.33, 95% CI: 0.11-0.94) had reduced ORs of having a high BMI z-score. Adolescents had lower odds of having excess VAT if they met one recommendation (OR = 0.39, 95% CI: 0.19-0.81) or any two recommendations (OR = 0.25, 95% CI: 0.07-0.90). No significant associations were found in children. Conclusions: The present study showed no associations between meeting all three recommendations within the 24-hour movement guidelines and adiposity indicators. However, meeting ST only recommendation and the combination of the ST and sleep recommendations was associated with a reduced risk of excess adiposity. This finding should be considered when designing effective strategies and interventions to prevent childhood obesity.

Purpose: School physical activity (SPA) is a significant component of daily PA. We investigated differences in PA between boys and girls in two differing education systems-Poland and the Czech Republic-which have four and two physical education lessons (PELs) per week, respectively. Method: This project was conducted from 2012-2016 at 17 Polish and 23 Czech secondary schools (N = 921; mean age = 16.2 ± 0.7 years). ActiTrainer accelerometers were used to monitor participants' PA and heart rate during school days. Weekly PA was measured using pedometers. Subjective levels of weekly PA were self-reported on the International Physical Activity Questionnaire-long form. Results: The Polish education system enabled adolescents to meet the recommendations for moderate-to-vigorous PA more likely than did the Czech system. SPA also represented a higher portion of daily PA in the Polish (vs. Czech system); however, the differences in total daily step count between Polish and Czech adolescents were non-significant. SPA accounted for 30-37% of the daily PA (as measured by step count) of Polish girls (23-30% of Czech girls) and 28-39% of Polish boys (25-37% of Czech boys). Conclusions: Participation in PELs was associated with a higher rate of meeting SPA recommendations in both countries. Compared with the Czech Republic, more PELs in the Polish education system was associated with increased daily vigorous PA and a greater portion of SPA in daily PA. Differences in overall daily and weekly moderate-to-vigorous PA between Polish and Czech adolescents were non-significant.

Background To examine compositional associations between short sleep duration and sedentary behavior (SB), light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA) among children and adolescents. Methods Multi-day 24-h data on sleep, SB, LPA and MVPA were collected using accelerometers among 343 children (8–13 years old) and 316 adolescents (14–18 years old). Children and adolescents with sleep duration of < 9 and < 8 h, respectively, were classified as short sleepers. Robust compositional regression analysis was used to examine the associations between short sleep duration and the waking-time composition. Results Seventy-one percent of children and 75.3% of adolescents were classified as short sleepers. In children, being a short sleeper was associated with higher SB by 95 min/day ( p < 0.001) and lower MVPA by 16 min/day ( p = 0.002). Specifically, it was associated with a higher amount of time spent in long sedentary bouts (β ilr1 = 0.46, 95% confidence interval [CI] = 0.29 to 0.62) and lower amounts of time spent in sporadic SB (β ilr1 = − 0.17, 95% CI = –0.24 to − 0.10), sporadic LPA (β ilr1 = − 0.09, 95% CI = –0.14 to − 0.04) and sporadic MVPA (β ilr1 = − 0.17, 95% CI = –0.25 to − 0.10, p < 0.001 for all), relative to the remaining behaviours. In adolescents, being a short sleeper was associated with a higher amount of time spent in SB by 67 min/day ( p = 0.001) and lower LPA by 2 min/day ( p = 0.035). Specifically, it was associated with more time spent in sedentary bouts of 1–9 min (β ilr1 = 0.08, 95% CI = 0.02 to 0.14, p = 0.007) and 10–29 min (β ilr1 = 0.10, 95% CI = 0.02 to 0.18, p = 0.015), relative to the remaining behaviours. Conclusions Among children and adolescents, short sleep duration seems to be highly prevalent and associated with less healthy waking time. Public health interventions and strategies to tackle the high prevalence of short sleep duration among children and adolescents are warranted.

BackgroundThe main aim of the study was to examine the cross-sectional associations between objectively measured physical activity (PA) and body fatness in 7–12-year-old children.MethodsWe performed an analysis of 365 children (209 girls). Participant recruitment was performed in eight randomly selected elementary schools in cities and towns with various numbers of inhabitants. The body composition analysis was performed according to a multi-frequency bioelectrical impedance analysis; PA was monitored using an accelerometer.ResultsIn terms of the overall PA, boys were more active than girls. No significant associations (unadjusted and adjusted models) were found between light PA and all body fatness indicators in either sex. Moderate-to-vigorous PA was significantly negatively associated with all body fatness indicators only in girls. These associations strengthened after adjustment for age, height and sedentary time (β ranging from –0.49 to –0.36, P ≤ 0.01). In contrast, vigorous PA was strongly negatively associated with body fatness indicators only in boys. In the fully adjusted model the significant negative associations were found for fat mass percentage (β = –0.15, P = 0.048) and fat mass index (β = –0.15, P = 0.040).ConclusionsThe present study suggests that increasing sex-specific PA of different intensities may be an appropriate approach for decreasing body fatness in children. Longitudinal studies are needed to verify these associations.