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.

Breaking Barriers: An Innovative Tool to Assess the National and City-Level Physical Activity Policy Development to Practice Disconnect.

BACKGROUND: Population-level physical activity increases are improbable without intersectoral collaboration across government levels and sectors to develop and implement physical activity promotion policies. This study aims to provide information about the development of the Interaction between National and Local Government Levels in Development and Implementation of Physical Activity Policies Tool (INTEGRATE PA-Pol). A framework was created to examine the development and implementation of national and subnational physical activity policies and the (mis)alignment between government levels. METHODS: The work was conducted in 3 phases: (1) a scoping review was carried out to identify local government physical activity promotion policies and instruments for assessing them, (2) an expert group designed 6 questionnaires, and (3) cognitive response testing was employed for validity testing and item modification with a panel of research and policy experts. RESULTS: The INTEGRATE PA-Pol Tool consists of 6 questionnaires assessing how national and subnational governments collaborate to develop and implement physical activity promotion policies. CONCLUSION: This tool can assist in better understanding the development and implementation of a public policy monitoring system that will allow for benchmarking and priority setting to comprehend how physical activity promotion policies are designed and executed.

Physical activity and life satisfaction among adolescents before and during the COVID-19 pandemic.

The negative impact of the COVID-19 pandemic and distance education has significantly affected adolescents' lives. The restrictive policies negatively affected their physical and mental health and life satisfaction. It is therefore desirable to look for ways to eliminate similar negative impacts on adolescents in the future. This study aimed to identify the differences in the association between physical activity and life satisfaction in Polish adolescents before and during the pandemic. The study included 1541 participants (891 before the pandemic and 650 during the pandemic) aged 15-19 years. The International Physical Activity Questionnaire-Long Form questionnaire was used to assess physical activity, and the Bern Subjective Well-Being Questionnaire was used to evaluate life satisfaction. The objectivity of data collection and analysis before and during the pandemic was ensured by the web application the International Database for Research and Educational Support. During the pandemic, we found lower physical activity and life satisfaction in both boys and girls compared to before the pandemic. Girls with low and high physical activity levels showed significantly lower life satisfaction during the pandemic than they did before. Low life satisfaction was associated with lower physical activity, and high life satisfaction was associated with greater total physical activity. Both boys and girls with low and high life satisfaction achieved significantly fewer physical activity recommendations during the pandemic. High life satisfaction increased the likelihood of meeting the recommendations for physical activity before and during the pandemic. This study provides new insights into the differences and associations between life satisfaction and physical activity in adolescent boys and girls before and during the pandemic. It provides suggestions for the prevention of possible future restrictions in the school settings. Support for post-pandemic life satisfaction in adolescents should focus mainly on increasing vigorous physical activity and improving adolescent participation in organized physical activity settings.

Trends in physical activity in adolescents participating and not participating in organized team or individual physical activity.

INTRODUCTION AND OBJECTIVE: Participation of adolescents in organized physical activity (PA), together with physical education, is essential for the development of a habit of regular PA, achievement of PA recommendations and adoption of physical literacy. The aim of the study is to identify the trends and differences in PA levels between adolescents participating in organized team PA, organized individual PA, and those not participating in organized PA. Another aim is to formulate proposals to eliminate the negative effects of the pandemic on adolescents' participation in organized PA. MATERIAL AND METHODS: The research took place between 2012-2021 in 51 secondary schools and involved a total of 1,202 boys and 1,561 girls. Participation in organized PA was examined using the 'Sports preferences survey'. Weekly PA was investigated by means of the 'International Physical Activity Questionnaire-Long Form'. RESULTS: The results confirmed the negative trend in participation in organized PA. However, this was predominantly caused by the negative effects of the pandemic in 2020-2021. Boys participating in organized team and individual PA had more school PA, recreation PA, vigorous PA, moderate PA and overall PA during the week, compared with boys not participating in organized PA (girls had more vigorous PA, moderate PA and overall PA). CONCLUSIONS: Participation in organized team PA and individual PA plays an important role, primarily in supporting vigorous PA but also in overall weekly PA among boys and girls. The negative effects of the pandemic should be eliminated by increasing adolescents' participation in various forms of organized PA with an emphasis on organized individual PA which can be regularly pursued, even under restrictive measures at home, in the countryside or in nature.

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.

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.

Associations between preference and participation in team sports: Physical activity promotion among adolescents.

Background: The level of physical activity (PA) in adolescents is highly dependent on their PA preferences. PA preferences among adolescents are dominated by team PA, mostly team sports (TS). The aim of this study is to identify (a) the status and trends in the preferences of TS among Czech and Polish boys and girls in different educational and sports environments, and (b) the impact of the agreement between the preferred and simultaneously pursued TS on the structure of weekly PA and on the meeting of PA recommendations. Methods: The research was carried out between 2009 and 2022 in the Czech Republic and Poland and included 2,939 boys and 4,427 girls aged 15-19 years. Preferences and participation in TS were identified using a PA preference questionnaire and weekly PA using the International Physical Activity Questionnaire-Long Form. Trends in TS preferences were analyzed over 27-year periods. The participants were divided into groups by agreement and disagreement between the preferred and pursued TS, and by agreement and disagreement between the preferences of TS and participation in organized TS. Results: Throughout the 14-year study period, boys in both countries preferred soccer, whereas girls favored volleyball. Agreement between preferences and participation in TS increased vigorous PA in Czech and Polish boys and girls. The agreement between the preferences for TS and participation in organized TS had the most significant effect on increasing vigorous PA in Czech and Polish boys and girls and on total PA in boys in both countries. Those who preferred and participated in TS were more likely to meet PA recommendations. Conclusion: Respecting the status and trends of TS preferences in supporting participation in TS increases adolescents' PA and their achievement of PA recommendations. Increasing active participation in organized TS among boys and girls may support regular PA and help eliminate the negative effects of the pandemic on adolescents' PA.

Time Trends of Step-Determined Physical Activity Among Adolescents With Different Activity Levels in Czech Republic.

BACKGROUND: This study aimed to present step-determined physical activity trends in adolescents with different activity levels over a period of 10 years. METHODS: Pedometers were used to monitor weekly physical activity in 1855 boys and 2648 girls aged 15-19 years recruited from 155 schools in the Czech Republic between 2009 and 2018. Trends for average steps/day and percent of accumulating various levels of steps/day (<10,000, 10,000-13,000, and >13,000 steps/d) were analyzed by sex. RESULTS: There was a statistically significant decrease in average steps/day between 2009-2010 and 2017-2018 in boys from 12,355 (3936) steps/d to 10,054 (3730) steps/d and girls from 11,501 (3278) steps/d to 10,216 (3288) steps/d. The percent accumulating <10,000 steps/d increased by 21% in boys and 12% in girls. The percent achieving >13,000 steps/d decreased by 17% in boys and 10% in girls. CONCLUSIONS: Objectively collected evidence indicates an overall decrease in Czech adolescents' steps/day over a 10-year period concurrent with an increase in the percent of boys and girls accumulating <10,000 steps/d. These trends are concerning as they portend a decline in physical activity as adolescents transition to adulthood and continue to age, which also may have major health implications.

The Impact of Distance Education during the COVID-19 Pandemic on Physical Activity and Well-Being of Czech and Polish Adolescents.

BACKGROUND: The aim of this study was to identify the changes in the structure of weekly physical activity (PA) and well-being among adolescent boys and girls between habitual education (HE) and distance education (DE) during the pandemic in secondary schools. METHODS: The research was carried out in 12 Czech and 18 Polish schools during 2019 to 2020 academic session for HE and 2020 to 2021 academic session for DE. The research involved 723 girls and 626 boys aged 15 to 18 years. The structure of the weekly PA was assessed using the International Physical Activity Questionnaire-Long Form, while well-being was assessed using the World Health Organization-5 Well-Being Index. RESULTS: There was a statistically significant decrease of PA among boys in school PA, transportation PA, recreation PA, vigorous PA, moderate PA, walking, and overall weekly PA during the DE resulting from the pandemic. In girls, during DE, a decrease was observed in school PA, vigorous PA, and overall PA. During DE, a high level of well-being was reported by only 34.9% of girls (43.8% during HE) and 50% of boys (65.6% during HE). CONCLUSIONS: The observed low PA and high incidence of depressive symptoms in adolescents in distance education during pandemic constraints are a challenge for schools to change in supporting physical activity, eliminating similar negative impacts on school life in the future.

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.

Differences and Associations between Physical Activity Motives and Types of Physical Activity among Adolescent Boys and Girls.

Interventions aimed at motivation for physical activity (PA) are mostly beneficial, but the effects on preventing the decrease in PA are not entirely clear, especially in girls. The main aim of this study was to identify the differences and associations between PA motives and types of PA in boys and girls and between low and high motivated boys and girls. Another aim is to identify the types of motivation and PA that increase the likelihood of achieving PA recommendations and to propose ways of increasing PA among low motivated adolescents. The research carried out before the COVID-19 pandemic (2010-2019) and involved 2,149 Czech and 1,927 Polish adolescents aged 15-19 years. The International Physical Activity Questionnaire-Long Form was used to identify the level of PA types, while PA motivation was examined through the Motives for Physical Activities Measure-Revised. During the ten years, a decline was observed in enjoyment, fitness, and social motives. An increase in appearance motives was observed in girls, while no significant changes were seen in boys. Boys showed a higher motivation for PA than girls in enjoyment, competence, fitness, and social motives, while girls were high motivated in appearance motives. The greatest statistically significant differences between low and high motivated individuals were found in the associations between recreation/vigorous PA and between all types of motivation in boys and girls in both countries. The strongest associations in both genders were observed between enjoyment/competence motives and recreation/vigorous PA. Respecting and using the associations between the types of PA motives and types of PA in low and high motivated boys and girls can support feelings of PA enjoyment, increase PA, support the achievement of PA recommendations, and positively affect adolescents' healthy lifestyles.

Time Trends in Physical Activity Using Wearable Devices: A Systematic Review and Meta-analysis of Studies from 1995 to 2017.

INTRODUCTION: Conflicting evidence exists on whether physical activity (PA) levels of humans have changed over the last quarter-century. The main objective of this study was to determine if there is evidence of time trends in PA, from cross-sectional studies that assessed PA at different time points using wearable devices (e.g., pedometers and accelerometers). A secondary objective was to quantify the rate of change in PA. METHODS: A systematic literature review was conducted of English-language studies indexed in PubMed, SPORTDiscus, and Web of Science (1960-2020) using search terms (time OR temporal OR secular) AND trends AND (steps per day OR pedometer OR accelerometer OR MVPA). Subsequently, a meta-analytic approach was used to aggregate data from multiple studies and to examine specific factors (i.e., sex, age-group, sex and age-group, and PA metric). RESULTS: Based on 16 peer-reviewed scientific studies conducted between 1995 and 2017, levels of ambulatory PA are trending downward in developed countries. Significant declines were seen in both males and females (P < 0.001) as well as in children (P = 0.020), adolescents (P < 0.001), and adults (P = 0.004). The average study duration was 9.4 yr (accelerometer studies, 5.3 yr; pedometer studies, 10.8 yr). For studies that assessed steps, the average change in PA was -1118 steps per day over the course of the study (P < 0.001), and adolescents had the greatest change in PA at -2278 steps per day (P < 0.001). Adolescents also had the steepest rate of change over time, expressed in steps per day per decade. CONCLUSIONS: Evidence from studies conducted in eight developed nations over a 22-yr period indicates that PA levels have declined overall, especially in adolescents. This study emphasizes the need for continued research tracking time trends in PA using wearable devices.

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.

Does Vigorous Physical Activity Contribute to Adolescent Life Satisfaction?

BACKGROUND: Physical and mental health are the basis of life satisfaction (LS), even during adolescence. The aim of this study was to identify the associations between LS and types of physical activity (PA) in Czech and Polish boys and girls. METHODS: The research involved 933 girls and 663 boys aged 15-19 years. LS was diagnosed using the Bern Subjective Well-Being Questionnaire and the WHO-5 Well-Being Index. The International Physical Activity Questionnaire-long form (IPAQ-LF) questionnaire was used to identify the types of weekly PA. RESULTS: Adolescents with the highest LS had more recreational, moderate, vigorous, and total weekly PA. The strongest associations between LS and PA were in the Czech and Polish boys and girls who participated in vigorous PA (VPA). The recommendations for VPA were fulfilled by 45% of Czech and 46% of Polish boys and 40% of Czech and 50% of Polish girls, with the highest LS. The most significant positive moderator between LS and PA was participation in organized PA. Boys with the highest LS were 1.94 times more likely to meet the weekly recommendation of VPA than boys with the lowest LS. Similarly, girls with the highest LS were 1.77 times more likely to meet these recommendations. CONCLUSIONS: Promoting both current subjective well-being and organized PA, with an emphasis on achieving the VPA recommendations, may support general LS and a healthy lifestyle in adolescents.

The Association between Participation in Organized Physical Activity and the Structure of Weekly Physical Activity in Polish Adolescents.

The main aim of the study was to determine the associations of participation in organized physical activity (OPA), and the structure of weekly physical activity (PA) with meeting the PA recommendations among Polish boys and girls. The research was conducted between 2012 and 2019 in the Silesian region of Poland among 3499 secondary school students. To determine the structure of PA (school, transportation, home, recreation, vigorous moderate, and walking), the International Physical Activity Questionnaire-Long Form (IPAQ-LF) questionnaire was used. Adolescents participating in OPA showed significantly more PA (p < 0.001) than non-participating adolescents. The strongest associations were observed between participation in OPA and vigorous PA. The weekly recommendation of vigorous PA was met by 61% of the students with three or more lessons of OPA per week, 29% of students with one or two lessons of OPA per week, and 24% of students not participating in OPA. Therefore, boys and girls with no OPA are at greatest risk of health issues. Schools, sports clubs, and leisure institutions should increase the participation of adolescents in OPA, especially non-participants. Comprehensive school PA programs should especially include those forms of OPA that respect health weaknesses, individual talents for specific types of PA, and preferred types of PA among adolescents.

Physical Activity Recommendations in the Context of New Calls for Change in Physical Education.

The current social, health, and educational changes in society require an adequate response in school-based physical activity (PA), including physical education (PE) lessons. The objective of this study was to identify the real average step counts of Czech and Polish adolescents during PE lessons, and propose recommendations for improving PE programs. This research was carried out in 143 Czech and 99 Polish schools. In the research, a total of 4911 adolescents aged 12-18 years were analyzed as part of teaching practice and 1827 in the context of habitual school practice. Steps were monitored using pedometers. The average step count per PE lesson was 2390 in Czech and Polish boys, while girls achieved 1851 steps. In both countries, boys were subject to greater physical strain in PE lessons compared to girls, both in teaching practice (F(4088,3) = 154.49, p < 0.001, ηp2 = 0.102) and school practice (F(1552,3) = 70.66, p < 0.001, ηp2 = 0.103). Therefore, the priority in PE lessons is to increase the amount of PA for girls, achieve the objectives of PE during PA, and use wearables to improve awareness of PA and improve physical literacy, as well as to support hybrid and online PE as a complement to traditional PE.

International Physical Activity and Built Environment Study of adolescents: IPEN Adolescent design, protocol and measures.

INTRODUCTION: Only international studies can provide the full variability of built environments and accurately estimate effect sizes of relations between contrasting environments and health-related outcomes. The aims of the International Physical Activity and Environment Study of Adolescents (IPEN Adolescent) are to estimate the strength, shape and generalisability of associations of the community environment (geographic information systems (GIS)-based and self-reported) with physical activity and sedentary behaviour (accelerometer-measured and self-reported) and weight status (normal/overweight/obese). METHODS AND ANALYSIS: The IPEN Adolescent observational, cross-sectional, multicountry study involves recruiting adolescent participants (ages 11-19 years) and one parent/guardian from neighbourhoods selected to ensure wide variations in walkability and socioeconomic status using common protocols and measures. Fifteen geographically, economically and culturally diverse countries, from six continents, participated: Australia, Bangladesh, Belgium, Brazil, Czech Republic, Denmark, Hong Kong SAR, India, Israel, Malaysia, New Zealand, Nigeria, Portugal, Spain and USA. Countries provided survey and accelerometer data (15 countries), GIS data (11), global positioning system data (10), and pedestrian environment audit data (8). A sample of n=6950 (52.6% female; mean age=14.5, SD=1.7) adolescents provided survey data, n=4852 had 4 or more 8+ hours valid days of accelerometer data, and n=5473 had GIS measures. Physical activity and sedentary behaviour were measured by waist-worn ActiGraph accelerometers and self-reports, and body mass index was used to categorise weight status. ETHICS AND DISSEMINATION: Ethical approval was received from each study site's Institutional Review Board for their in-country studies. Informed assent by adolescents and consent by parents was obtained for all participants. No personally identifiable information was transferred to the IPEN coordinating centre for pooled datasets. Results will be communicated through standard scientific channels and findings used to advance the science of environmental correlates of physical activity, sedentary behaviour and weight status, with the ultimate goal to stimulate and guide actions to create more activity-supportive environments internationally.

Physical Activity Recommendations for Segments of School Days in Adolescents: Support for Health Behavior in Secondary Schools.

School physical activity (PA) is an indispensable part of daily PA, the foundation for developing lifelong PA and fitness, and an easy way to gain physical and health literacy. School PA is equally important for understanding the continuity of physical and mental health, even in broader psychosocial aspects. Regarding long-term outcomes, significant attention has been paid to the determination of daily and weekly recommendations for adolescent PA. However, comprehensive approaches suggesting recommendations for PA in segments of the school day are rare. This study aimed to (a) provide a rationale for PA recommendations in segments of school days and incorporate it into generally accepted PA recommendations, and (b) promote radical changes in the educational process toward a healthy school lifestyle through PA recommendations in segments of school days. The results of research conducted in 98 secondary schools in the Czech Republic and 104 secondary schools in Poland from 2009 to 2017 were used in this study. In total, 3,860 boys and 5,237 girls from the Czech Republic and 3,052 boys and 3,329 girls from Poland, all aged 15-19, participated. We recommended at least 2,000 steps (or 10 min of moderate-to-vigorous PA) for the before school segment and at least 6,000 steps (or 30 min of moderate-to-vigorous PA) for the after-school segment. For the time spent at school, we further recommended at least 500 steps/h (alternatively, at least 3,000 steps/school time), 20 min of moderate-to-vigorous PA (≥3METs or 60% HRmax), and at least one HRsubmax/max response to significant stress during PA to mitigate educational stress and high levels of sedentary behavior in schools. PA should account for at least 25% of school time, even on days with no scheduled physical education lessons. We propose using PA recommendations in segments of school days to achieve positive changes in the educational process and school lifestyle. Acceptance of PA recommendations in segments of school days theories on physical education could help refine and concretize demands for changes in PA and lifestyle in secondary schools. In practice, it could support the creation of innovative and comprehensive school PA programs. Future research should focus on obtaining evidence in support for adolescent PA by applying PA recommendations in segments of school days.

Do physical activity and sedentary time mediate the association of the perceived environment with BMI? The IPEN adult study.

The study's main aim was to examine whether adults' accelerometer-based physical activity and sedentary time mediated the associations of neighbourhood physical environmental perceptions with body mass index (BMI) and weight status across 10 high- and middle-income countries. Data from the IPEN Adult study, an observational multi-country study (n = 5712) were used. Results showed that sedentary time was a non-significant or inconsistent mediator in all models. MVPA mediated the associations of street connectivity, land use mix-diversity, infrastructure/safety for walking and aesthetics with BMI in single models. In the multiple model, MVPA only fully mediated the relation between land use mix-diversity and BMI. This finding was replicated in the models with weight status as outcome. MVPA partially mediated associations of composite environmental variables with weight status. So, although MVPA mediated some associations, future comprehensive studies are needed to determine other mechanisms that could explain the relation between the physical environment and weight outcomes. Food intake, food accessibility and the home environment may be important variables to consider. Based on the consistency of results across study sites, global advocacy for policies supporting more walkable neighbourhoods should seek to optimize land-use-mix when designing and re-designing cities or towns.