Where Are Czech Adolescents Active? The Patterns of Movement and Transport Behavior in Different Active Living Domains.

To understand the environmental determinants of physical activity (PA), precise spatial localization is crucial. This cross-sectional study focuses on the spatiotemporal distribution of PA among Czech adolescents (n = 171) using Global Positioning System loggers and accelerometers. The results showed that adolescents spent most of their time in sedentary behavior, with 57.2% and 58.5% of monitored time at home and school, respectively. The park and playground had the lowest proportion of sedentary behavior but also the lowest amount of moderate to vigorous PA (MVPA). However, when considering the time spent in each domain, the highest proportion of MVPA was seen in publicly accessible playgrounds (13.3% of the time). Chi-square analysis showed that the relative distribution of different PA intensities did not differ across spatial domains. Based on these results, the authors propose 2 key strategies for increasing MVPA in adolescents: Increase the time spent in activity-supportive environments, such as parks and playgrounds, and design techniques to increase MVPA at home and school settings.

The Effect of Sedentary Behaviour on Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis.

BACKGROUND: Cardiorespiratory fitness (CRF) is an important indicator of current and future health. While the impact of habitual physical activity on CRF is well established, the role of sedentary behaviour (SB) remains less understood. OBJECTIVE: We aimed to determine the effect of SB on CRF. METHODS: Searches were conducted in MEDLINE, Embase, PsycINFO, CINAHL and SPORTDiscus from inception to August 2022. Randomised controlled trials, quasi-experimental studies and cohort studies that assessed the relationship between SB and CRF were eligible. Narrative syntheses and meta-analyses summarised the evidence, and Grading of Recommendations, Assessment, Development and Evaluation (GRADE) certainty was based on evidence from randomised controlled trials. RESULTS: This review included 18 studies that focused on youth (four randomised controlled trials, three quasi-experimental studies, 11 cohort studies) and 24 on adult populations (15 randomised controlled trials, five quasi-experimental studies, four cohort studies). In youth and adults, evidence from randomised controlled trials suggests mixed effects of SB on CRF, but with the potential for interventions to improve CRF. Quasi-experimental and cohort studies also support similar conclusions. Certainty of evidence was very low for both age groups. A meta-analysis of adult randomised controlled trials found that interventions targeting reducing SB, or increasing physical activity and reducing SB, had a significant effect on post-peak oxygen consumption (mean difference = 3.16 mL.kg-1.min-1, 95% confidence interval: 1.76, 4.57). CONCLUSIONS: Evidence from randomised controlled trials indicates mixed associations between SB and CRF, with the potential for SB to influence CRF, as supported by meta-analytical findings. Further well-designed trials are warranted to confirm the relationship between SB and CRF, explore the effects of SB independent from higher intensity activity, and investigate the existence of such relationships in paediatric populations. CLINICAL TRIAL REGISTRATION: PROSPERO CRD42022356218.

How Czech Adolescents Perceive Their Physical Activity.

Adolescence is a critical stage in the development of an individual's physical activity (PA) habits and preferences. Adolescents' perceptions of PA can influence their motivation to engage in PA and, consequently, their overall level of PA. Thus, our primary aim was to investigate whether Czech adolescents misperceive their peers' PA. Our dataset comprised cross-sectional data on 1289 adolescents aged 11-15 years. PA was measured using self-reported items used in the HBSC study. To describe the gender and school grade differences in VPA, independent samples T, ANOVA, Mann-Whitney U, and Kruskal-Wallis H tests were performed. To analyze the effect of gender, school grade, school, and participants' own PA on the underestimation of PA, binomial regression models were used. Our study points out that there is a discrepancy between self-perceived levels of PA and the perceived descriptive norms of peers' PA. Adolescents underestimate the prevalence of sufficient PA, and thus perceived descriptive norms in PA as being worse than levels of own PA. These findings indicate room for targeted interventions based on social-norms-based approaches to increase the PA of adolescents or at least strengthen their actual positive behavior.

A 24-h activity profile and adiposity among children and adolescents: Does the difference between school and weekend days matter?

BACKGROUND: Twenty-four-hour movement behaviours are gaining attention in the research community. However, no study has addressed how 24-h activity profiles vary between structured and less structured days and whether an unfavourable activity profile is associated with childhood obesity. We aimed to analyse differences between school day and weekend day 24-h activity profiles and their associations with adiposity indicators among children and adolescents. METHODS: Participants were 382 children and 338 adolescents who wore wrist accelerometers for 24 hours a day for seven consecutive days. The 24-h activity profile expressed by the average acceleration (AvAcc) and intensity gradient (IG) were estimated from multi-day raw accelerometer data. Adiposity indicators included body mass index (BMI) z-score, fat mass percentage (FM%), fat mass index (FMI), and visceral adipose tissue (VAT). Multiple linear regression of activity profile metrics and adiposity indicators was performed separately for school and weekend days. RESULTS: Weekend days AvAcc and IG were lower compared to school days in both age groups (p <0.001 for all). Specifically, AvAcc was lower by 9.4% and 11.3% in children and adolescents, respectively. IG on weekend days was lower (more negative) by 3.4% in children and 3.1% in adolescents. Among children, on school days AvAcc and IG were negatively associated with FM%, FMI, and VAT, whilst on weekend days AvAcc was positively associated with BMI z-score, FMI, and VAT (p < 0.05 for all). Among adolescents, negative associations were found between weekend day AvAcc and IG and FM% and FMI (p < 0.05 for all), respectively. CONCLUSIONS: This study confirms the importance of 24-h activity profile as a potentially protective factor against excess adiposity. The variability of movement behaviours during structured and less structured days should be considered when optimizing the 24-h movement behaviours to prevent childhood obesity.

European fitness landscape for children and adolescents: updated reference values, fitness maps and country rankings based on nearly 8 million test results from 34 countries gathered by the FitBack network.

OBJECTIVES: (1) To develop reference values for health-related fitness in European children and adolescents aged 6-18 years that are the foundation for the web-based, open-access and multilanguage fitness platform (FitBack); (2) to provide comparisons across European countries. METHODS: This study builds on a previous large fitness reference study in European youth by (1) widening the age demographic, (2) identifying the most recent and representative country-level data and (3) including national data from existing fitness surveillance and monitoring systems. We used the Assessing Levels of PHysical Activity and fitness at population level (ALPHA) test battery as it comprises tests with the highest test-retest reliability, criterion/construct validity and health-related predictive validity: the 20 m shuttle run (cardiorespiratory fitness); handgrip strength and standing long jump (muscular strength); and body height, body mass, body mass index and waist circumference (anthropometry). Percentile values were obtained using the generalised additive models for location, scale and shape method. RESULTS: A total of 7 966 693 test results from 34 countries (106 datasets) were used to develop sex-specific and age-specific percentile values. In addition, country-level rankings based on mean percentiles are provided for each fitness test, as well as an overall fitness ranking. Finally, an interactive fitness platform, including individual and group reporting and European fitness maps, is provided and freely available online (www.fitbackeurope.eu). CONCLUSION: This study discusses the major implications of fitness assessment in youth from health, educational and sport perspectives, and how the FitBack reference values and interactive web-based platform contribute to it. Fitness testing can be conducted in school and/or sport settings, and the interpreted results be integrated in the healthcare systems across Europe.

Top 10 International Priorities for Physical Fitness Research and Surveillance Among Children and Adolescents: A Twin-Panel Delphi Study.

BACKGROUND: The measurement of physical fitness has a history that dates back nearly 200 years. Recently, there has been an increase in international research and surveillance on physical fitness creating a need for setting international priorities that could help guide future efforts. OBJECTIVE: This study aimed to produce a list of the top 10 international priorities for research and surveillance on physical fitness among children and adolescents. METHODS: Using a twin-panel Delphi method, two independent panels consisting of 46 international experts were identified (panel 1 = 28, panel 2 = 18). The panel participants were asked to list up to five priorities for research or surveillance (round 1), and then rated the items from their own panel on a 5-point Likert scale of importance (round 2). In round 3, experts were asked to rate the priorities identified by the other panel. RESULTS: There was strong between-panel agreement (panel 1: rs = 0.76, p < 0.01; panel 2: rs = 0.77, p < 0.01) in the priorities identified. The list of the final top 10 priorities included (i) "conduct longitudinal studies to assess changes in fitness and associations with health". This was followed by (ii) "use fitness surveillance to inform decision making", and (iii) "implement regular and consistent international/national fitness surveys using common measures". CONCLUSIONS: The priorities identified in this study provide guidance for future international collaborations and research efforts on the physical fitness of children and adolescents over the next decade and beyond.

Normative-referenced values for health-related fitness among Czech youth: Physical fitness data from the study IPEN Adolescent Czech Republic.

OBJECTIVES: The aim of this study was to developed sex- and age-specific normative-referenced percentile values for health-related fitness among 12 to 18 years old Czech youth. METHODS: This study included cross-sectional data from 1,173 participants (50.7% boys) collected between 2013 and 2016. Participants were recruited from 32 elementary or secondary schools across eight cities located in the Czech Republic. Health-related fitness was objectively measured using both anthropometric (height, body mass, and sum of skinfolds) and performance (20-m shuttle run for cardiorespiratory endurance, modified push-ups for muscular strength/endurance, and V sit-and-reach for flexibility) tests. Sex- and age-specific normative values were calculated using the Lambda Mu Sigma method. Sex- and age-related differences in means were expressed as standardized effect sizes. RESULTS: Normative percentiles were tabulated and displayed as smoothed curves. Among boys, measures of health-related fitness generally increased with age, except for an age-related decline in the sum of skinfolds and a plateau in V sit-and-reach. Among girls, most measures of health-related fitness increased from age 12 to 16 years before stabilizing, except for the sum of skinfolds, which remained stable from age 12 to 18 years. The sex-related differences were large with boys having higher cardiorespiratory endurance and muscular strength/endurance than girls. Girls compared to boys had higher flexibility. CONCLUSIONS: This study presents the most up-to-date sex- and age-specific normative-referenced percentile values for health-related fitness among Czech youth. Normative values may be useful for fitness and public health screening and surveillance, for example, by helping to identify youth with low fitness who might benefit from a fitness-enhancing intervention.

The Czech Republic's 2022 Report Card on Physical Activity for Children and Youth: A rationale and comprehensive analysis.

Background/Objective: The second edition of the Czech Republic's Report Card on Physical Activity for Children and Youth was released in 2022. This paper describes the development of the Report Card and presents a comprehensive summary of the main findings. Methods: The multi-level search strategy was developed by the national expert panel to identify the available sources that provide data related to the physical activity of Czech children and adolescents. The data were used to assign grades to ten core and two additional indicators. Results: A total of 28 sources provided data that allowed grades to be assigned to 11 out of the 12 indicators. Grade B was assigned to six indicators (School: B+, Community and Environment: B, Organized Sport and Physical Activity: B-, Active Transportation: B-, Family and Peers: B-, Sleep: B-), grade C to three indicators (Overall Physical Activity: C+, Active Play: C, Physical Literacy: C), and grade D to two indicators (Government: D+, Sedentary Behaviors: D). No grade for the "Physical Fitness" indicator could be assigned due to a lack of data collected in the reference period 2018-2019. Conclusions: Although the family, school, and built environment provided a variety of opportunities to be physically active, a high proportion of children and adolescents did not meet the current physical activity guideline and were exposed to excessive sedentary behavior. A multisectoral and multidisciplinary response is required to reduce the health and economic burden of physical inactivity and excessive sedentary behavior among Czech children and adolescents.

Associations of accelerometer measured school- and non-school based physical activity and sedentary time with body mass index: IPEN Adolescent study.

BACKGROUND: This study examined the strength, shape and direction of associations of accelerometer-assessed overall, school- and non-school-based moderate-to-vigorous physical activity (MVPA) and sedentary time (ST) with BMI among adolescents across the world. Second, we examined whether these associations differed by study site and sex. METHODS: Cross-sectional data from the IPEN Adolescent study, an observational multi-country study, were used. Participants wore an accelerometer for seven days, reported height and weight, and completed a socio-demographic survey. In total, 4852 adolescents (46.6% boys), aged 11-19 years (mean age = 14.6, SD = 1.7 years) were included in the analyses, using generalized additive mixed models. RESULTS: Adolescents accumulated on average 41.3 (SD = 22.6) min/day of MVPA and 531.8 (SD = 81.1) min/day of ST, and the prevalence of overweight and obesity was 17.2% (IOTF), but these mean values differed by country. Linear negative associations of accelerometer-based MVPA and ST with standardized BMI scores and the likelihood of being overweight/obese were found. School-based ST and non-school-based MVPA were more strongly negatively associated to the outcomes than non-school based ST and school-based MVPA. Study site moderated the associations; adolescent sex did not. No curvilinear associations were found. CONCLUSIONS: This multi-country study confirmed the importance of MVPA as a potential protective factor against overweight/obesity in adolescents. Non-school-based MVPA seemed to be the main driver of these associations. Unexpected results were found for ST, calling for further examination in methodologically sound international studies but using inclinometers or pressure sensors to provide more precise ST measures.

Changes in sedentary behavior patterns during the transition from childhood to adolescence and their association with adiposity: a prospective study based on compositional data analysis.

BACKGROUND: To date, no longitudinal study using a compositional approach has examined sedentary behavior (SB) patterns in relation to adiposity in the pediatric population. Therefore, our aims were to (1) investigate the changes in SB patterns and adiposity from childhood to adolescence, (2) analyze the prospective compositional associations between changes in SB patterns and adiposity, and (3) estimate the changes in adiposity associated with substituting SB with physical activity (PA) of different intensities. METHODS: The study presents a longitudinal design with a 5-year follow-up. A total of 88 participants (61% girls) were included in the analysis. PA and SB were monitored for seven consecutive days using a hip-worn accelerometer. Adiposity markers (fat mass percentage [FM%], fat mass index [FMI], and visceral adiposity tissue [VAT]) were assessed using the multi-frequency bioimpedance analysis. The prospective associations were examined using compositional data analysis. RESULTS: Over the follow-up period, the proportion of time spent in total SB increased by 154.8 min/day (p < 0.001). The increase in total SB was caused mainly by an increase in middle and long sedentary bouts, as these SB periods increased by 79.8 min/day and 62.0 min/day (p < 0.001 for both), respectively. FM%, FMI, and VAT increased by 2.4% points, 1.0 kg/m2, and 31.5 cm2 (p < 0.001 for all), respectively. Relative to the remaining movement behaviors, the increase in time spent in middle sedentary bouts was significantly associated with higher FM% (ßilr1 = 0.27, 95% confidence interval [CI]: 0.02 to 0.53) at follow-up. Lower VAT by 3.3% (95% CI: 0.8 to 5.7), 3.8% (95% CI: 0.03 to 7.4), 3.9% (95% CI: 0.8 to 6.9), and 3.8% (95% CI: 0.7 to 6.9) was associated with substituting 15 min/week spent in total SB and in short, middle, and long sedentary bouts, respectively, with an equivalent amount of time spent in vigorous PA. CONCLUSIONS: This study showed unfavorable changes in SB patterns and adiposity status in the transition from childhood to adolescence. Incorporating high-intensity PA at the expense of SB appears to be an appropriate approach to reduce the risk of excess adiposity in the pediatric population.

Smart Watch Versus Classic Receivers: Static Validity of Three GPS Devices in Different Types of Built Environments.

In order to study the relationship between human physical activity and the design of the built environment, it is important to measure the location of human movement accurately. In this study, we compared an inexpensive GPS receiver (Holux RCV-3000) and a frequently used Garmin Forerunner 35 smart watch, with a device that has been validated and recommended for physical activity research (Qstarz BT-Q1000XT). These instruments were placed on six geodetic points, which represented a range of different environments (e.g., residential, open space, park). The coordinates recorded by each device were compared with the known coordinates of the geodetic points. There were no differences in accuracy among the three devices when averaged across the six sites. However, the Garmin was more accurate in the city center and the Holux was more accurate in the park and housing estate areas compared to the other devices. We consider the location accuracy of the Holux and the Garmin to be comparable to that of the Qstarz. Therefore, we consider these devices to be suitable instruments for locating physical activity. Researchers must also consider other differences among these devices (such as battery life) when determining if they are suitable for their research studies.

Associations of novel 24-h accelerometer-derived metrics with adiposity in children and adolescents.

BACKGROUND: Further research is required to explore the associations between 24-h movement behaviours and health outcomes in the paediatric population. Therefore, this study aimed to examine the associations between novel data-driven 24-h activity metrics and adiposity among children and adolescents. METHODS: The sample included 382 children (8-13 years) and 338 adolescents (14-18 years). The average acceleration (AvAcc) of activity, intensity gradient (IG), and metrics representing the initial acceleration for the most active time periods of the 24-h cycle were calculated from raw acceleration data. Adiposity measures included body mass index z-score, fat mass percentage (FM%), and visceral adipose tissue (VAT). Data analysis was performed using multiple linear regression adjusted for wear time, sex, maternal education level, and maternal overweight and obesity. RESULTS: Children demonstrated higher values in all 24-h activity metrics than did adolescents (p < 0.001 for all). For children, the initial acceleration for the most active 2, 5, 15, and 30 min of the 24-h cycle were negatively associated with FM% (p ≤ 0.043 for all) and VAT (p <0.001 for all), respectively. For adolescents, the IG was negatively associated with FM% (p = 0.002) and VAT (p = 0.007). Moreover, initial acceleration for the most active 2, 5, 15, 30, 60, and 120 min were associated with FM% (p ≤ 0.007 for all) and with VAT (p ≤ 0.023 for all). CONCLUSIONS: The intensity distribution of activity and initial acceleration for the most active 2, 5, 15, 30, 60, and 120 min within the 24-h cycle are beneficial for the prevention of excess adiposity in the paediatric population.

Replacing school and out-of-school sedentary behaviors with physical activity and its associations with adiposity in children and adolescents: a compositional isotemporal substitution analysis.

BACKGROUND: Little is known on how context-specific sedentary behaviors (SB) affect adiposity. This study aimed to investigate compositional associations between context-specific SB and adiposity and estimate the differences in adiposity associated with replacing school and out-of-school SB with physical activity (PA). METHODS: This study included 336 children and adolescents. Time spent in SB and PA was estimated using multi-day 24-hour raw accelerometer data. SB and PA were specified for school and out-of-school times. Fat mass percentage (FM%) and fat mass index (FMI) were used as adiposity indicators. A compositional isotemporal substitution model was used to estimate differences in adiposity associated with one-to-one reallocations of time from context-specific SB to PA. RESULTS: Participants spent approximately two thirds of their school and out-of-school time being sedentary. Relative to the remaining 24-h movement behaviors, significant associations between out-of-school SB and adiposity were found in both boys (ßilr1 = 0.63, 95% confidence interval [CI] = 0.03-1.22 for FM%; ßilr1 = 0.76, 95% CI = 0.03-1.49 for FMI) and girls (ßilr1 = 0.62, 95% CI = 0.25-0.98 for FM%; ßilr1 = 0.80, 95% CI = 0.28-1.32 for FMI). Replacing 30 min/day of out-of-school SB with out-of-school light PA decreased FM% by 10.1% (95% CI = 3.3-17.9) and FMI by 14% (95% CI = 2.7-24) in girls. No significant associations were found for school SB. CONCLUSIONS: A reduction of out-of-school SB in favor of light PA should be advocated as an appropriate target for interventions and strategies to prevent childhood obesity.

Prevalence and correlates of adherence to the combined movement guidelines among Czech children and adolescents.

BACKGROUND: There are limited studies on the prevalence of adherence to the combined guidelines for physical activity (PA), sedentary behavior, and sleep in children and adolescents. Moreover, little is known about correlates of adherence to the guidelines. Therefore, the main aim of this study is to examine the prevalence and identify the correlates of adherence to the combined movement guidelines among children and adolescents. METHODS: A total of 355 children aged 8-13 years (44% boys) and 324 adolescents aged 14-18 years (43% boys) from the Czech Republic participated in this study. PA and sleep duration were estimated using multi-day 24-h raw data from wrist-worn accelerometers. Recreational screen time was parent proxy-reported in children and self-reported in adolescents. Seventeen potential correlates were grouped into three homogenous categories for biological and cognitive, behavioral, and family correlates. The multi-level multivariable logistic regression was applied to identify correlates of adherence to combined movement guidelines and to specific combinations of any of two recommendations. RESULTS: Approximately 6.5% of children and 2.2% of adolescents met all recommendations of the combined movement guidelines. In children, girls (OR = 0.4; 95% CI = 0.1-0.9) and participants with overweight or obese fathers (OR = 0.3; 95% CI = 0.1-0.7) had significantly lower odds of adherence to the combined movement guidelines. Additionally, children had higher odds of meeting specific combinations of two recommendations if they reported regular fruit and vegetable intake, participated in organized PA, or if their fathers had a university degree. Meanwhile, paternal overweight and obesity, and high sleep efficiency were associated with lower odds of meeting specific combinations of recommendations. In adolescents, sex, fruit and vegetable intake, organized PA, and active play were correlates of meeting specific combinations of any two recommendations. CONCLUSIONS: A low proportion of children and adolescents met the combined movement guidelines and several correlates related to family were identified. Family is a key source of influence for healthy movement behaviors during childhood and adolescence.

How do short sleepers use extra waking hours? A compositional analysis of 24-h time-use patterns among children and adolescents.

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 (ßilr1 = 0.46, 95% confidence interval [CI] = 0.29 to 0.62) and lower amounts of time spent in sporadic SB (ßilr1 = - 0.17, 95% CI = -0.24 to - 0.10), sporadic LPA (ßilr1 = - 0.09, 95% CI = -0.14 to - 0.04) and sporadic MVPA (ßilr1 = - 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 (ßilr1 = 0.08, 95% CI = 0.02 to 0.14, p = 0.007) and 10-29 min (ßilr1 = 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.

How Czech Adolescents Perceive Active Commuting to School: A Cross-Sectional Study.

To achieve a healthy lifestyle, adolescents must be physically active and meet physical activity (PA) guidelines. One of the most natural ways of increasing the amount of PA is active commuting (AC) to school. Recent reviews suggest that peer norms have the potential to shape PA during adolescence in particular. Thus, our primary aim was to investigate whether Czech adolescents misperceive their peers' AC behaviors and attitudes towards AC. Our dataset comprised cross-sectional data on 1586 adolescents aged 11-15 years. Basic descriptive statistics, chi-square tests, and correlation analyses were used to analyze the data. Regarding traveling to school, 68% of the Czech adolescents in this study are daily active commuters (walking, cycling, or riding a scooter or skateboard). Less than half of the respondents believed that most of their classmates were commuting to school actively almost daily. The students who believed that most of their classmates commuted to school actively had significantly higher chances of being regular active commuters themselves. The results showed that most of the Czech adolescents misperceived the AC norms of their peers. Thus, there could be potential in using a social norms approach aimed at increasing the level of AC in Czech adolescents through targeted interventions.

Is adherence to the 24-hour movement guidelines associated with a reduced risk of adiposity among children and adolescents?

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-to-vigorous 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.

Robust Compositional Analysis of Physical Activity and Sedentary Behaviour Data.

Although there is an increasing awareness of the suitability of using compositional data methodology in public health research, classical methods of statistical analysis have been primarily used so far. The present study aims to illustrate the potential of robust statistics to model movement behaviour using Czech adolescent data. We investigated: (1) the inter-relationship between various physical activity (PA) intensities, extended to model relationships by age; and (2) the associations between adolescents' PA and sedentary behavior (SB) structure and obesity. These research questions were addressed using three different types of compositional regression analysis-compositional covariates, compositional response, and regression between compositional parts. Robust counterparts of classical regression methods were used to lessen the influence of possible outliers. We outlined the differences in both classical and robust methods of compositional data analysis. There was a pattern in Czech adolescents' movement/non-movement behavior-extensive SB was related to higher amounts of light-intensity PA, and vigorous PA ratios formed the main source of potential aberrant observations; aging is associated with more SB and vigorous PA at the expense of light-intensity PA and moderate-intensity PA. The robust counterparts indicated that they might provide more stable estimates in the presence of outlying observations. The findings suggested that replacing time spent in SB with vigorous PA may be a powerful tool against adolescents' obesity.