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Increased screen time is a ubiquitous part of adolescent life and is adversely associated with their well-being. However, it remains unclear whether different types of screen time have equivalent associations, or if relationships are dose-dependent.The data were from 2 nationally representative Health Behaviour in School-aged Children (2010, 2014) surveys across 44 European and North American countries. Psychosomatic health was assessed using 8 complaints and dichotomized as high or low. Discretionary time spent on passive (e.g., TV) and mentally active (e.g., electronic games, computer use) screen-based activities was categorized into 3 groups. Data were analyzed in 2021.The study included 414,489 adolescents (average age, 13.6 [SD=1.63] years; 51.1% girls). Multilevel modeling showed that psychosomatic complaints increased monotonically once all forms of screen time exceeded 2 hours/day. Adolescents reporting high (4 hours/day) TV time, compared with those reporting low (≤2 hours/day), had higher odds of reporting psychosomatic complaints with 67% higher odds (OR=1.67, 95% CI=1.62, 1.72) in boys and 71% (OR=1.71, 95% CI=1.66, 1.75) in girls. High electronic game use was associated with psychosomatic complaints, with odds being 78% higher in boys (OR=1.78, 95% CI=1.73, 1.84) and 88% higher in girls (OR=1.88, 95% CI=1.82, 1.94). Similar associations were found between computer use and psychosomatic complaints.Passive and mentally active screen time are adversely associated with psychosomatic complaints in a dose-dependent manner, with associations slightly stronger for active than passive screen time. This study supports limiting any type of screen time, either passive or active, to 2 hours/day to foster well-being.

Objective This study determined the prevalence of adolescents meeting the individual and combinations of the Australian 24-Hour Movement Guidelines, and their associations with the health related quality of life (HRQoL). Methods The participants were 3096 adolescents (mean age: 12.4 years; 49% female) from wave 7 of the birth-cohort of the Longitudinal Study of Australian Children. The outcome was parent-reported HRQoL. Meeting the 24-Hour Movement Guidelines was defined as: ≥60 min/day of moderate to vigorous physical activity (MVPA), ≤2 hour/day of recreational screen time, and 9-11 hour/night of sleep. Generalised estimating equations were used to examine the associations between meeting vs. not meeting recommendations and HRQoL outcomes. Results The prevalence of adolescents meeting all three recommendations was 2.4%, with 23% meeting two, and 57% meeting one recommendation. Meeting all three recommendations was associated with higher overall HRQoL score (β = 4.96, 95% CI: 2.54–7.38) as well as physical (β = 5.22, 95% CI: 2.61–7.83) and psychosocial (β = 4.76, 95% CI: 1.77–7.75) scores. Meeting combinations of screen time with MVPA or sleep recommendations were associated with higher scores for all HRQoL outcomes, while meeting MVPA and sleep recommendations was associated with overall HRQoL score. Compared to meeting no recommendation, meeting more recommendations was significantly and incrementally associated with higher scores for all HRQoL outcomes (ptrend Conclusions Overall, meeting more recommendations within the 24-Hour Movement Guidelines was associated with better HRQoL outcomes. However, only a small percentage of adolescents met all the recommendations, which underscores the need for promoting and supporting adherence to these behaviours.

Highlights • This study provides the prevalence estimates of physical activity, sedentary behavior, and sleep duration (isolation and combination) in a nationally representative sample (n = 114,072) of Chinese children and adolescents of grades 4–12. • Only about 5% of Chinese children and adolescents show the most ideal combination of 24-h movement behaviors. • Chinese children and adolescents with younger ages, higher parental education levels, and higher family incomes exhibit favorable 24-h movement behaviors. • Chinese children and adolescents with the most ideal 24-h movement behaviors have lower risks of overweight and obesity, especially in children of grades 4–6 and girls of grades 7–9., Background Meeting 24-h movement guidelines by children and adolescents has been associated with improved indicators of health, although it has been under-studied in China. Hence, this study aimed to investigate the prevalence of meeting the 24-h movement guidelines, its correlates, and its relationships with body mass index in children and adolescents in China. Methods Cross-sectional data from the 2017 Youth Study in China of 114,072 children and adolescents (mean age = 13.75 years, 49.18% boys) were used. Meeting 24-h movement guidelines (≥60 min of daily moderate-to-vigorous physical activity, ≤2 h of daily leisure screen time, 9–11 h and 8–10 h nightly sleep duration for 6–13-year-olds and 14–17-year-olds, respectively) and height and weight of all participants were assessed. The prevalence of meeting the 24-h movement guidelines and World Health Organization weight status categories were determined. Generalized linear models were used to determine the correlates of meeting the 24-h movement guidelines and the relationships of meeting the 24-h movement guidelines with overweight (OW) and obesity (OB). Results Only 5.12% of Chinese children and adolescents met the 24-h movement guidelines, and 22.44% were classified as OW/OB. Older children and adolescents were less likely to meet the 24-h movement guidelines. Parental education level and family income were positively related to meeting the 24-h movement guidelines. Children and adolescents meeting the 24-h movement guidelines showed lower odds ratios for OW/OB. Compared with participants meeting the 24-h movement guidelines, boys in 4th–6th grades met none of the recommendations (OR = 1.22, 95%CI: 1.06–1.40), met the screen time recommendation only (OR = 1.13, 95%CI: 1.01–1.28), met the nightly sleep duration recommendation only (OR = 1.14, 95%CI: 1.03–1.28), and had significantly higher odds ratios for OW/OB. Similar trends were observed for girls in 4th–6th grades: meeting none of the guidelines (OR = 1.35, 95%CI: 1.14–1.59), meeting sleep duration guidelines only (OR = 1.23, 95%CI: 1.08–1.39), and meeting moderate-to-vigorous physical activity + nightly sleep duration guidelines (OR = 1.24, 95%CI: 1.01–1.54). For girls in 7th–9th grades, the following trend was observed: meeting none of the guidelines (OR = 1.30, 95%CI: 1.01–1.67). Conclusion Very few Chinese children and adolescents met the 24-h movement guidelines. Age (negatively correlated), parental education level, and family income (both positively correlated) were correlates of meeting the 24-h movement guidelines. Children and adolescents meeting the 24-h movement guidelines were more likely to have lower risks for OW/OB, especially in the youngest age group (Grades 4–6); and girls in the middle age group (Grades 7–9) were also more likely to have lower risks for OW/OB. Further research studies should explore additional correlates and determinants for meeting the 24-h movement guidelines. Also, future studies should use longitudinal or interventional designs to determine the relationships between meeting the 24-h movement guidelines and OW/OB and other health indicators, while taking sex and age differences into account., Graphic Abstract Image, graphical abstract

Highlights • The 24-h composition of movement behaviors may have important implications for health at all ages. • Children and youth who meet the 24-h movement guideline recommendations generally report more favorable health indicators than those who do not. • Adherence rates to the 24-h movement guideline recommendations were low. • Sociodemographic, lifestyle, and environmental factors were associated with guideline adherence. • A healthy composition of 24-h movement behaviors and meeting the recommended guidelines are important for disease prevention and health promotion across the lifespan., Background New research suggests that the composition (mix) of movement behaviors within a 24-h period may have important implications for health across the lifespan. Consistent with this integrated movement behavior paradigm, a number of countries across the world have developed and released 24-h movement guidelines for specific age groups. The purpose of this systematic review was to examine the associations between the 24-h time-use composition of movement behaviors, or adherence to 24-h movement guidelines, and multiple health indicators across the lifespan. Methods Five online databases (PsycINFO, PubMed, SPORTDiscus, Web of Science, and Ovid MEDLINE) were searched for relevant peer-reviewed studies published between January 2015 and January 2020 that met the a priori inclusion criteria, with no study design limits. The methodological quality of research evidence for each individual study and for each health indicator was assessed by using a modified version of the Downs and Black checklist. Results A total of 51 studies from 20 different countries met the inclusion criteria. A total of 31 studies examined adherence (meeting vs. not meeting) to 24-h movement guidelines, and 20 studies used compositional analyses to explore the 24-h time-use composition of movement behaviors. Findings indicated that meeting the 24-h movement guidelines were (1) not associated with adiposity among toddlers, (2) favorably associated with health-related quality of life, social-cognitive development, and behavioral and emotional problems among preschoolers, (3) favorably associated with global cognition, health-related quality of life, and healthy dietary patterns in children, and (4) favorably associated with adiposity, fitness, and cardiometabolic, mental, social, and emotional health among children and youth. Significant associations were also found between the composition of 24-h movement behaviors and indicators of (1) adiposity and bone and skeletal health among preschoolers, (2) health-related quality of life among children, (3) adiposity, fitness, and cardiometabolic, social, and emotional health among children and youth, (4) cardiometabolic health in adults, (5) adiposity and fitness among adults and older adults, and (6) mental health and risk of mortality among older adults. The quality of the available evidence ranged from poor to good. Conclusion The current evidence indicates that the composition of movement behaviors within a 24-h period may have important implications for health at all ages and that meeting the current 24-h movement guidelines is associated with a number of desirable health indicators in children and youth. Future studies should employ longitudinal and experimental designs, include valid and reliable measures of 24-h movement behaviors, and examine a wide array of health indicators across all age groups. Such studies would confirm the results from the primarily cross-sectional evidence drawn from studies included in our review and further advance our understanding of the relationships between 24-h movement behaviors and health., Graphical Abstract Image, graphical abstract

Background/Objective This study examined the validity of the FitnessGram® criterion-reference cut-points for cardiorespiratory fitness (CRF) based on two samples of US adolescents (aged 12–15 years). This study also established the CRF cut-points for metabolically healthy weight status based on a recent national fitness survey for the purposes of cross-validating with pre-existing cut-points including FitnessGram. Methods Two cross-sectional data from the 2003–2004 National Health and Nutrition Examination Survey (NHANES) (n = 378) and 2012 NHANES National Youth Fitness Survey (NNYFS) (n = 451) were used. CRF (estimated V ˙ O2max in mL/kg/min) was estimated from a submaximal exercise test. CRF categories based on FitnessGram cut-points, a clustered cardiometabolic risk factors score and weight status were used. A series of Receiver Operating Characteristic (ROC) curve analyses were conducted to identify age- and sex-specific CRF cut-points that were optimal for metabolically healthy weight status. Results Based on FitnessGram cut-points, having high risk CRF, but not low risk CRF, was associated with high cardiometabolic risk (OR = 3.17, 95% CI = 1.14–8.79) and unhealthy weight status (OR = 5.81, 95% CI = 3.49–9.68). The optimal CRF cut-points for 12-13-year-olds and 14-15-year-olds were 40 and 43 mL/kg/min in males and 39 and 34 mL/kg/min in females, respectively. Compared to meeting new CRF cut-points, not meeting new CRF cut-points was associated with higher odds of showing high cardiometabolic risk (OR = 2.91, 95% CI = 1.47–5.77) and metabolically unhealthy weight status (OR = 4.47, 95% CI = 2.83–7.05). Conclusion FitnessGram CRF cut-point itself has rarely been scrutinized in previous literature. Our findings provide partial support for FitnessGram based on two samples of US adolescents. CRF cut-points established in this study supports international criterion-referenced cut-points as well as FitnessGram cut-points only for males. FitnessGram should be continuously monitored and scrutinized using different samples.

Highlights • High parental perceived capability to restrict children's screen time best predicted children's and youth's adherence to all movement recommendations as well as the screen time recommendation. • Increases in children's and youth's outdoor physical activity/sport since the COVID-19 pandemic best predicted adherence to the physical activity recommendation. • No to little changes in children's and youth's sleep duration since the COVID-19 pandemic best predicted adherence to the sleep recommendation., Purpose The purpose of this study was to use decision tree modeling to generate profiles of children and youth who were more or less likely to meet the Canadian 24-h movement guidelines during the COVID-19 outbreak. Methods Data for this study were from a nationally representative sample of 1472 Canadian parents (Meanage = 45.12, SD = 7.55) of children (5–11 years old) or youth (12–17 years old). Data were collected in April 2020 via an online survey. Survey items assessed demographic, behavioral, social, micro-environmental, and macro-environmental characteristics. Four decision trees of adherence and non-adherence to all movement recommendations combined and each individual movement recommendation (physical activity, screen time, and sleep) were generated. Results Results revealed specific combinations of adherence and non-adherence characteristics. Characteristics associated with adherence to the recommendation(s) included high parental perceived capability to restrict screen time, being a boy, increases in children's and youth's outdoor physical activity/sport since the COVID-19 outbreak began, having parents younger than 43 years old (for adherence to screen time recommendation), having no to little change in sleep duration since the COVID-19 outbreak began, and having parents older than 35 years old (for adherence to the sleep recommendation). Characteristics associated with non-adherence to the recommendation(s) included low parental perceived capability to restrict screen time, decreases in children's and youth's outdoor physical activity/sport since the COVID-19 outbreak began, primary residences located in all provinces except Quebec, low parental perceived capability to support children's sleep, and increases in sleep duration since the COVID-19 outbreak began. Conclusion Our results show that specific characteristics interact to contribute to (non)adherence to the movement behavior recommendations. Results highlight the importance of targeting parents’ perceived capability for the promotion of children's and youth's movement behaviors during challenging times of the COVID-19 pandemic, paying particular attention to enhancing parental perceived capability to restrict screen time., Graphical abstract Image, graphical abstract

Background/objective Participation in the Active Healthy Kids Global Alliance (AHKGA) Global Matrix initiative represents a significant work and resource investment for Report Card teams. The objective of this paper was to evaluate the process and findings of the Global Matrix 3.0 and formulate recommendations for improvement. Methods The evaluation of the Global Matrix 3.0 was planned prior to its development and a list of potential process, impact, and outcome indicators were pre-identified. These indicators were informed by online surveys, direct reports, MailChimp’s statistics, Google Analytics of the AHKGA website, and emails sent to the AHKGA Board of Directors. Results Five online surveys were completed by 88%–100% of the targeted respondents. High satisfaction ratings were observed for most of the Global Matrix 3.0 methods, key steps, concepts, and the resources (e-blasts and website) provided by the AHKGA. A total of 496 open-ended comments were provided in the five surveys, including 199 comments reporting issue(s), and 38 reporting both positive feedback and issue(s). The participating Report Card teams successfully assigned a grade to each physical activity indicator, produced a Report Card document, and wrote a short Report Card article. Conclusion This evaluation process allowed for the identification of needed improvements and the formulation of recommendations for future Global Matrix initiatives. This work highlighted the need for the development of physical activity behavior assessment tools that would be internationally adopted and culturally adaptable to varying contexts to improve the standardization of physical activity surveillance at the global scale.

Background 24-h movement guidelines were recently developed to improve both the present and future health of children. The purpose of the present study was to evaluate adherence to the three recommendations strongly associated with health in 24-h movement guidelines and their relationship with weight status (overweight/obesity or underweight) in Japanese primary school children. Methods This cross-sectional study was based on 902 children. Weight status according to measured body mass index (BMI) was classified by the WHO growth reference. Meeting the 24-h movement guidelines was defined as: 9–11 h/night of sleep, ≤2 h/day of screen time, and at least 60 min/day of moderate-to-vigorous physical activity (MVPA). Results The prevalence of children meeting the all three recommendations was 10.5% and 13.2% met none of the three recommendations. Children meeting all three behaviors recommendation, screen time and MVPA or sleep recommendations, or only screen time recommendation had lower odds ratios adjusted for age, gender and socioeconomic status of each school for overweight/obesity compared to children meeting none of the 3 recommendations. Conclusions The screen time recommendation or combinations including screen time recommendation were associated with overweight/obesity. On the other hand, none of the recommendations was associated with underweight.

Prolonged periods of sedentary behaviour, for instance, engendered by home confinement in Shenzhen city, has led to negative mental health consequences, especially in adolescents. Previous research suggests, in general, that sedentary behavior can increase negative emotions. However, the specific mechanism driving the relationship between sedentary behavior and negative emotions is still relatively unclear. Social support and sleep quality might partly explain the effect of sedentary behavior on negative emotions. Thus, the current study aimed to examine the associations between sedentary behavior and negative emotions, and to investigate if social support and sleep quality mediate such a relationship.During home confinement due to the COVID-19 Omicron variant outbreak, 1179 middle and high school students in Shenzhen were invited to voluntarily complete an e-questionnaire, including the 21-item Depression Anxiety Stress Scale (DASS-21), the short form of the International Physical Activity Questionnaire (IPAQ-SF), the Social Support Rating Scale (SSRS) and the Pittsburgh Sleep Quality Index (PSQI). Data from 1065 participants were included in the analysis.We observed significant sex-related and demografic-related differences in emotional (e.g., anxiety, stress and social support) and other outcome variables (e.g., sitting duration and PSQI score). Furthermore, sedentary behavior, social support, and sleep quality were associated with negative emotions (The findings of the current study suggest that social support and sleep quality partially mediate the relationship between sedentary behavior and negative emotions in middle and high school students during home confinement in Shenzhen city.

Summary Background Disease severity in paediatric obesity is usually defined using the body-mass index (BMI). Although informative at the population level, its usefulness on an individual level has limitations. The use of a clinical staging system—Edmonton Obesity Staging System for Pediatrics (EOSS-P)—in identifying health risk has been proposed. This study aimed to examine the association between BMI class and EOSS-P stage. Methods This cross-sectional study was done in children with obesity aged 5–17 years who enrolled in the Canadian Pediatric Weight Management Registry (CANPWR) between May 31, 2013, and Oct 27, 2017, involving ten multidisciplinary paediatric weight management clinics in Canada. We classified participants into WHO BMI classes (class I as 2–3 SD scores, class II as >3 SD scores, and class III as >4 SD scores above the WHO growth standard median), and applied the EOSS-P staging system (stages 0, 1, and 2/3) based on the clinical assessment of coexisting metabolic, mechanical, mental health, and social milieu issues. Clinical information was extracted from medical records and reported using standardised case report forms. Associations of BMI class with EOSS-P stage were examined in children with complete data. Findings Of the 847 children with complete data, 546 (64%) had severe obesity based on BMI class (ie, class II or III) and 678 (80%) were EOSS-P stage 2/3. Stage 2/3 obesity-related health issues were common; mental health concerns were most common (520 [61%] of 847 children), followed by metabolic (349 [41%] of 847 children), social milieu (179 [21%] of 847 children), and mechanical (86 [10%] of 847 children) health issues. Mental health issues (eg, anxiety and attention-deficit hyperactivity disorder) were equally distributed across BMI classes, metabolic health issues were slightly more common in higher BMI classes, and mechanical (eg, musculoskeletal issues and sleep apnoea) and social milieu (eg, bullying and low household income) issues increased with increasing BMI class. Of children with class I obesity, 206 (76%) of 270 had overall EOSS-P stage 2/3, compared with 195 (85%) of 229 with class III obesity. Interpretation Physical and mental health issues were highly prevalent among children with obesity irrespective of BMI class. Participants with class III obesity carried the greatest health risk across subcategories of the EOSS-P. As BMI class increased, a concomitant increased disease burden in mechanical and social milieu issues was observed, whereas metabolic and mental health risks were high across BMI classes. Funding Canadian Institutes of Health Research, Ontario Ministry of Health, McMaster University, and McMaster Children's Hospital.

Background Previous reviews show a favourable relationship between physical activity (PA) and brain health in children and youth. The purpose of this systematic review was to extend the generalizability of previous findings using only studies that employed randomized controlled designs in a wider age range. Methods After registration in PROSPERO, PRISMA guidelines were followed. Studies must have used a randomized controlled design; manipulated PA once (i.e., acute) or more (i.e., chronic) in apparently healthy children (1 month-17.99 years); and examined cognitive function, brain function, or brain structure as outcomes. Articles were reviewed for inclusion and data extraction were performed in duplicate. Results Overall, 84 studies from 83 papers with 12,600 unique participants were included (nrange = 10–1,224, Mrange = 0.77–17 years). Studies were mostly rated as low risk of bias. The majority of studies (n = 52) reported at least one favourable cognitive function outcome associated with a PA intervention. Few studies (n = 6) reported an unfavourable outcome. Examining the multiple cognitive function outcomes within each study, PA had mostly no effect (nacute = 29, nchronic = 47) or a mix of favourable and no effects (nacute = 20, nchronic = 27). For brain function, acute PA was associated with no change (n = 2) whereas chronic PA was associated with a mix of increases, decreases, or no change (n = 3). For brain structure, two overlapping studies found either favourable or no effects of chronic PA. Discussion PA is unlikely to harm brain health in children and youth and may confer some benefits. More research is needed to examine the relationship between PA and brain structure and function.

The purpose of this study was to examine whether meeting movement behavior recommendations (i.e.,≥60 min of moderate-to-vigorous physical activity [MVPA] per day, ≤2 h of recreational screen time per day, and between9 and 11 h of nightly sleep), and combinations of these recommendations, are associated with dietary patterns of children. This cross-sectional study was conducted between 2011 and 2013 and included 5873children 9–11 years of age from 12 countries around the world. MVPA and nightly sleep duration were measured using 24-hour waist-worn accelerometry. Screen time habits were assessed via self-report. A food frequency questionnaire was used to assess dietary patterns, and the whole diet was described by two components derived from principal component analysis: “healthy” and “unhealthy” dietary pattern scores. Covariates included in the multilevel statistical models included age, sex, highest parental education, and body mass index z-score. A healthier dietary pattern score was observed when more movement behavior recommendations were met. Among the three movement behaviors, limiting screen time habits to the recommended amount was most strongly associated with healthier dietary patterns. Similarly, a less unhealthy dietary pattern was observed when more movement behavior recommendations were met. Surprisingly, the highest unhealthy dietary pattern was associated with children meeting the MVPA recommendation alone. Combinations including ≤2 h of screen time per day were those most strongly associated with a less unhealthy dietary pattern. Findings were similar across study sites and in boys and girls. In conclusion, meeting more movement behavior recommendations is generally associated with better dietary patterns in children from around the world, with limiting screen time habits showing the strongest relationships. Refereed/Peer-reviewed

Background: There is a paucity of data from low- and middle-income countries on sedentary behaviour (SB) levels and patterns during early childhood. The purpose of this study was to examine how device-measured SB in young children differed across geographically, economically, and socio-demographically diverse populations, in an international sample. Methods: This multinational, cross-sectional pilot study included data from 1071 3–5-year-old children from 19 countries, collected between 2018 and 2020 (pre-COIVID). SB was measured for three consecutive days using activPAL accelerometers. Sedentary time, sedentary fragmentation and seated transport duration were calculated using PAL Analysis Algorithms and a custom-made analysis program. Linear mixed models were used to examine the differences in SB variables between sex, country-level income groups, caregiver education levels, urban/rural settings, and population density. Findings: Children spent 56% (7.4 hrs) of their waking time sedentary, and 42% accrued at least one sedentary bout/day lasting ≥60 min. The longest average bout duration was 81.1±45.4 min, and an average of 61.1±50.1 min/day was spent in seated transport. Children from upper-middle-income and high-income countries spent a greater proportion of the day sedentary, accrued more sedentary bouts, had shorter breaks between sedentary bouts, and spent significantly more time in seated transport, than children from low- and lower-middle-income countries. Few differences were found in SB patterns between urban/rural settings and caregiver education levels within each country-level income group, while multiple significant differences were found when comparing between country-level income groups. Higher population density was correlated with several higher SB measures. Interpretation: These data advance our understanding of young children’s SB patterns globally and the influences of country income, urban/rural setting, caregiver education levels, and population density. Country income levels and population density appear to be stronger drivers of the observed differences, than sex, rural or urban residential setting or caregiver educational attainment. Funding: American Council on Exercise, USA Beijing Health System High Level Talents Training Project, China 13 Biomedical Research Foundation, Dhaka, Bangladesh Canadian Institutes of Health Research Planning and Dissemination Grant Conselho Nacional de Pesquisa e Desenvolvimento Cientifico e Tecnologico - CNPq Research Department of National Planning and Monitoring, PNG Government Early Start, University of Wollongong, Australia Faculty of Health Sciences at the University of the Witwatersrand, Johannesburg, South Africa Global Challenges Program, University of Wollongong, Australia Harry Crossley Foundation, South Africa National Health and Medical Research Council, Australia NIH - International Research Training Grant Pham Ngoc Thach University of Medicine, Vietnam Research University Grant (GUP), Universiti Kebangsaan Malaysia Sasakawa Sports Research Grant, Sasakawa Sports Foundation, Japan Stella de Silva Research Grant, Sri Lanka College of Paediatricians, Sri Lanka The DST-NRF Centre for Excellence in Human Development at the University of Witwatersrand, Johannesburg, South Africa The International Society of Behavioral Nutrition and Physical Activity, Pioneers Program Declaration of Interest: The authors have no competing financial or personal interests to declare. Ethical Approval: Ethical approval was obtained from the University of Wollongong, Australia (ref: 2018/044) and the appropriate ethics committee(s) in each country.

Summary Background Childhood and adolescence are crucial periods for brain development, and the behaviours during a typical 24 h period contribute to cognitive performance. The Canadian 24-Hour Movement Guidelines for Children and Youth recommend at least 60 min physical activity per day, 2 h or less recreational screen time per day, and 9–11 h sleep per night in children aged 8–11 years. We investigated the relationship between adherence to these recommendations and global cognition. Methods In this cross-sectional observational study, we obtained data from the first annual curated release of the Adolescent Brain Cognitive Development study, a 10-year longitudinal, observational study. Data were collected from 21 study sites across the USA between Sept 1, 2016, and Sept 15, 2017. The participants were 4524 US children aged 8–11 years from 20 study sites. Exposures of interest were adherence to the physical activity, recreational screen time, and sleep duration guideline recommendations. The primary outcome was global cognition, assessed with the NIH Toolbox (National Institutes of Health, Bethesda, MD, USA), which we analysed with multivariable linear mixed-effects models to examine the relations with movement behaviour variables. Findings Complete movement behaviour data were available for 4520 participants. The mean number of guideline recommendations met was 1·1 (SD 0·9). Overall, 2303 (51%) participants met the sleep recommendation, 1655 (37%) met screen time, and 793 (18%) met the physical activity recommendation. 3190 (71%) participants met at least one recommendation, whereas 216 (5%) of participants met all three recommendations. Global cognition was positively associated with each additional recommendation met (β=1·44, 95% CI 0·82–2·07, p Interpretation Meeting the 24 h movement recommendations was associated with superior global cognition. These findings highlight the importance of limiting recreational screen time and encouraging healthy sleep to improve cognition in children. Funding National Institutes of Health.

Watching television or listening to music while exercising can serve as motivating factors, making it more pleasant to exercise for some people. However, it is unknown whether these stimuli influence food intake and/or physical activity energy expenditure (PAEE) for the remainder of the day, potentially impacting energy balance and weight control. We examined the effects of watching television or listening to music while exercising on post-exercise energy intake and expenditure. Our study was a randomized crossover design, in which 24 male adolescents (mean age: 14.9 ± 1.1 years) completed three 30-min experimental conditions consisting of walking/jogging on a treadmill at 60% of heart rate reserve while (1) watching television; (2) listening to music; or (3) exercising with no other stimulus (control). An ad libitum lunch was offered immediately after the experimental conditions, and a dietary record was used to assess food intake for the remainder of the day. An Actical accelerometer was used to estimate PAEE until bedtime. The primary outcome measure was post-exercise energy intake and expenditure (kJ). We found that exercising while watching television or listening to music did not significantly affect post-exercise energy intake or energy expenditure. Exercising on a treadmill was found to be significantly more enjoyable while watching television than with no stimulus present. Ratings of perceived exertion were not significantly different between conditions. Overall, our results suggest that watching television or listening to music while exercising does not impact post-exercise energy intake or expenditure in male adolescents, which may have positive implications for adolescents who may need additional motivation to participate in physical activity.

Brain derived neurotrophic factor (BDNF) is a protein that plays a critical role in modulating cognition in animals and humans. Aerobic exercise often increases BDNF in adults, but effects of this exercise modality and others among adolescents remain uncertain. This study examined the effects of aerobic training, resistance training, and combined training on resting serum BDNF levels in adolescents with overweight and obesity. After a 4-week pre-randomization treatment, 304 post-pubertal, adolescents with overweight or obesity (70% females) aged 14–18 years were randomized to one of four groups for 22 weeks: aerobic training (N = 75), resistance training (N = 78), combined aerobic and resistance training (N = 75), or non-exercising control (N = 76). All participants received dietary counseling targeting a daily energy deficit of 250 kcal. The exercise prescription was 4 times per week, progressing to 45 min/session for the aerobic and resistance groups and 90 min/session for the combined group. Resting serum BDNF levels were measured at baseline and 6-months. Results showed that in both intention-to-treat (ITT) and per protocol (≥70% adherence to prescribed sessions) analyses, there were no significant within- or between-group changes in BDNF. Findings indicate that aerobic training, resistance training or their combination did change serum BDNF levels in adolescents with overweight and obesity. Trial Registration: ClinicalTrials.Gov NCT00195858 http://clinicaltrials.gov/show/NCT00195858, September 12, 2005 (Funded by the Canadian Institutes of Health Research).

Missing data is a universal research problem that can affect studies examining the relationship between physical activity measured with accelerometers and health outcomes. Statistical techniques are available to deal with missing data; however, available techniques have not been synthesized. A scoping review was conducted to summarize the advantages and disadvantages of identified methods of dealing with missing data from accelerometers. Missing data poses a threat to the validity and interpretation of trials using physical activity data from accelerometry. Imputation using multiple imputation techniques is recommended to deal with missing data and improve the validity and interpretation of studies using accelerometry.

Background This study preliminarily examined the relationship between physical activity, sedentary time, and social emotional functioning in children aged 4–6 years. Methods Eighty children attending kindergarden classes in Ottawa, Canada wore Actical accelerometers for 1-week to directly assess their physical activity and sedentary time. Physical activity was quantified as minutes per day in light intensity or moderate intensity, and steps per day, while sedentary time was quantified as minutes per day. Social emotional functioning attributes were assessed by teachers using the Devereux Students Strengths Assessment. Results After controlling for age, sex, household-income and school clustering using multilevel regression models, steps per day were positively associated with social awareness β = 1.537, CI = 0.115–2.959) self-awareness (β = 1.285, CI = 0.014–2.555), relationship skills (β = 1.729, CI = 0.238–3.219), personal responsibilities (β = 1.689, CI = 0.101–3.276), and optimistic thinking (β = 1.091, CI = 0.251–2.157). Moderate physical activity was positively associated with relationship skills (β = 1.598, CI = 0.065–3.131) and optimistic thinking (β = 1.515, CI = 0.069–2.234). Time spent in light physical activity and sedentary time were not associated with social emotional functioning indicators. Conclusions Physical activity as measured by steps per day and time spent in moderate physical activity was associated with better social emotional functioning. Future research is needed to verify these preliminary findings and determine the directionality of relationships observed, and experimental studies are needed to determine whether promoting either increased steps per day or intensity of physical activity can improve social emotional functioning in the early years.

Introduction Active transportation (AT) and independent mobility (IM) represent promising avenues for increasing children's physical activity and minimizing car use. However, there are limited data on the psychometric properties of measures of AT and IM. Methods 94 child and parent dyads living in Ottawa (Canada) consented to complete a questionnaire twice, approximately two weeks apart, in English or French language. They were questioned on children's travel to/from places (e.g., school, parks, shops) and on the extent of the child's IM. The weekly volume of AT to/from school was calculated by multiplying the number of active trips by the home-school distance. An IM index consisting of six “mobility licenses” (to travel home from school, travel to other places within walking distance, cross main roads, cycle on main roads, go out after dark, and travel on local buses without adult supervision) was computed. Test-retest reliability and convergent validity between children and parents were assessed with Cohen's kappa or intra-class correlation coefficients (ICC). Results The volume of AT to/from school showed high test-retest reliability and convergent validity in both languages (ICC range=0.81–0.97). Similarly, test-retest reliability was also high for the number of active trips to/from all destinations (ICC range=0.60–0.94) and the IM index (ICC range=0.63–0.88). Convergent validity for trips to/from all destinations was fair in the English language subsample (ICC range=0.22–0.25), but substantial in the French language subsample (ICC range=0.60–0.82). The IM index showed substantial validity at both test and retest and in both languages (ICC range=0.61–0.80). Coefficients were generally lower when examining single destinations or mobility licenses. Conclusion With minor modifications, the child and parent mobility questionnaires can provide valid and reliable estimates of AT to/from a broad range of destinations and IM among English and French speaking grade 4–6 children.

The study objective was to examine whether meeting the new Canadian 24-hour movement guidelines was associated with health indicators in a representative sample of Canadian children and youth. Cross-sectional findings are based on 4157 (1239 fasting subsample) children and youth aged 6-17years from cycles 1-3 of the Canadian Health Measures Survey (CHMS). Sleep and screen time were subjectively measured while moderate- to vigorous-intensity physical activity (MVPA) was accelerometer-determined. Health indicators in the full sample (body mass index (BMI) z-scores, waist circumference, blood pressure, behavioral strengths and difficulties score (lower=better), and aerobic fitness) and fasting subsample (triglycerides, high-density lipoprotein (HDL)-cholesterol, C-reactive protein, and insulin) were measured. Meeting the overall guidelines was defined as: 9-11 hour/night (5-13years) or 8-10 hour/day (14-17years) of sleep, ≤2 hour/day of screen time, and ≥60 minute/day of MVPA. Compared to meeting all three recommendations, meeting none, one, and two recommendations were associated with a higher BMI z-score, waist circumference, and behavioral strengths and difficulties score and lower aerobic fitness in a gradient pattern (Ptrend

Summary Background Physical activity has many health benefits for young people. In 2018, WHO launched More Active People for a Healthier World, a new global action on physical activity, including new targets of a 15% relative reduction of global prevalence of insufficient physical activity by 2030 among adolescents and adults. We describe current prevalence and trends of insufficient physical activity among school-going adolescents aged 11–17 years by country, region, and globally. Methods We did a pooled analysis of cross-sectional survey data that were collected through random sampling with a sample size of at least 100 individuals, were representative of a national or defined subnational population, and reported prevalence of of insufficient physical activity by sex in adolescents. Prevalence had to be reported for at least three of the years of age within the 10–19-year age range. We estimated the prevalence of insufficient physical activity in school-going adolescents aged 11–17 years (combined and by sex) for individual countries, for four World Bank income groups, nine regions, and globally for the years 2001–16. To derive a standard definition of insufficient physical activity and to adjust for urban-only survey coverage, we used regression models. We estimated time trends using multilevel mixed-effects modelling. Findings We used data from 298 school-based surveys from 146 countries, territories, and areas including 1·6 million students aged 11–17 years. Globally, in 2016, 81·0% (95% uncertainty interval 77·8–87·7) of students aged 11–17 years were insufficiently physically active (77·6% [76·1–80·4] of boys and 84·7% [83·0–88·2] of girls). Although prevalence of insufficient physical activity significantly decreased between 2001 and 2016 for boys (from 80·1% [78·3–81·6] in 2001), there was no significant change for girls (from 85·1% [83·1–88·0] in 2001). There was no clear pattern according to country income group: insufficient activity prevalence in 2016 was 84·9% (82·6–88·2) in low-income countries, 79·3% (77·2–87·5) in lower–middle-income countries, 83·9% (79·5–89·2) in upper–middle-income countries, and 79·4% (74·0–86·2) in high-income countries. The region with the highest prevalence of insufficient activity in 2016 was high-income Asia Pacific for both boys (89·0%, 62·8–92·2) and girls (95·6%, 73·7–97·9). The regions with the lowest prevalence were high-income western countries for boys (72·1%, 71·1–73·6), and south Asia for girls (77·5%, 72·8–89·3). In 2016, 27 countries had a prevalence of insufficient activity of 90% or more for girls, whereas this was the case for two countries for boys. Interpretation The majority of adolescents do not meet current physical activity guidelines. Urgent scaling up of implementation of known effective policies and programmes is needed to increase activity in adolescents. Investment and leadership at all levels to intervene on the multiple causes and inequities that might perpetuate the low participation in physical activity and sex differences, as well as engagement of youth themselves, will be vital to strengthen the opportunities for physical activity in all communities. Such action will improve the health of this and future young generations and support achieving the 2030 Sustainable Development Goals. Funding WHO.

Phosphodiesterase 4 (PDE4) inhibitors are approved for the treatment of some moderate to severe inflammatory conditions. However, dose-limiting side effects in the central nervous system and gastrointestinal tract, including nausea, emesis, headache, and diarrhea, have impeded the broader therapeutic application of PDE4 inhibitors. We sought to exploit the wealth of validation surrounding PDE4 inhibition by improving the therapeutic index through generation of an antibody-drug conjugate (ADC) that selectively targets immune cells through the CD11a antigen. The resulting ADC consisted of a human αCD11a antibody (based on efalizumab clone hu1124) conjugated to an analog of the highly potent PDE4 inhibitor GSK256066. Both the human αCD11a ADC and a mouse surrogate αCD11a ADC (based on the M17 clone) rapidly internalized into immune cells and suppressed lipololysaccharide (LPS)-induced TNFα secretion in primary human monocytes and mouse peritoneal cells, respectively. In a carrageenan-induced air pouch inflammation mouse model, treatment with the ADC significantly reduced inflammatory cytokine production in the air pouch exudate. Overall, these results provide compelling evidence for the feasibility of delivering drugs with anti-inflammatory activity selectively to the immune compartment via CD11a and the development of tissue-targeted PDE4 inhibitors as a promising therapeutic modality for treating inflammatory diseases.

To comprehensively review all observational and experimental studies examining the relationship between physical activity and cognitive development during early childhood (birth to 5 years).Systematic review.Electronic databases were searched in July, 2014. No study design, date, or language limits were imposed on the search. Included studies had to be published, peer reviewed articles that satisfied the a priori determined population (apparently healthy children aged birth to 5 years), intervention (duration, intensity, frequency, or patterns of physical activity), comparator (various durations, intensity, or patterns of physical activity), and outcome (cognitive development) study criteria. Study quality and risk of bias were assessed in December 2014.A total of seven studies, representing 414 participants from five different countries met the inclusion criteria, including two observational and five experimental studies. Six studies found increased or higher duration/frequency of physical activity had statistically significant (p0.05) beneficial effects on at least one cognitive development outcome, including 67% of the outcomes assessed in the executive function domain and 60% in the language domain. No study found that increased or higher duration/frequency of physical activity had statistically significant detrimental effects on cognitive development. Six of the seven studies were rated weak quality with a high risk of bias.This review provides some preliminary evidence that physical activity may have beneficial effects on cognitive development during early childhood. Given the shortage of the information and the weak quality of available evidence, future research is needed to strengthen the evidence base in this area.

Resume Introduction Le concept de pharmacie clinique a ete developpe a partir des annees 1960 en Amerique du Nord. Bien qu’il existe une grande disparite de programmes de soins avec presence decentralisee (i.e. au chevet des patients) des pharmaciens, tant en externe qu’en hospitalisation, la pediatrie a profite de la presence decentralisee de pharmaciens des les annees 1970. L’objectif principal de cet article etait de decrire la methode utilisee pour la mise a niveau d’un secteur de soins pharmaceutiques dans un service de pediatrie. Methode Il s’est agi d’une etude descriptive de la mise a niveau des soins pharmaceutiques pratiques par 2 equivalents temps-plein dans 2 secteurs de pediatrie comprenant 81 lits d’un etablissement tertiaire mere-enfant. La demarche de mise a niveau proposee comportait trois etapes : une revue structuree de la documentation, une description du profil du secteur et une description de la mise a jour du niveau de pratique proposee par l’equipe de recherche, apres consensus avec l’equipe de pharmacie clinique. Resultats Des 236 articles recenses, 13 ont ete retenus pour l’evaluation de l’impact et la description du role du pharmacien en pediatrie. Nous avons recense neuf activites pharmaceutiques specifiques reposant sur des donnees de tres bonne qualite. La reflexion menee par les pharmaciens de l’equipe et les chercheurs a permis d’identifier, en sus des donnees de la litterature, une quinzaine d’ameliorations de la pratique sans modifier les ressources humaines existantes. Conclusion Il existe des donnees sur l’impact du pharmacien en pediatrie. Cette etude descriptive propose une demarche de mise a niveau de la pratique pharmaceutique en pediatrie au sein d’un centre hospitalier universitaire quebecois.

The purpose of this research was to evaluate a population level mass media campaign using implicit (i.e., automatic) and explicit (i.e., non-automatic) measures of evaluations and to determine if discrepant or summed evaluations were associated with endorsing campaign objectives: that physical activity can improve relationship-related, mind-related, or body-related outcomes. Participants (N = 1600) completed an online survey which included a single-category implicit association task that measured more automatic or implicit evaluative responses of images from the campaign. The survey also included questions assessing prompted awareness of the campaign, explicitly measured evaluations of the advertisements, and evaluations of whether participating in physical activity makes one’s relationships, mind, or body better. Results showed participants who rated the advertisements as more appealing exhibited more positive implicit evaluations of the campaign. Evaluating the ads as offensive was negatively related to explicit evaluations of whether physical activity makes relationships, mind, or body better; past behaviour and sum and discrepancy scores were positively related to endorsing relationship, mind, and body outcomes. By including implicit evaluation of a playful and creative campaign designed to influence perceptions of what physical activity can make better, this research highlighted that campaign creators should carefully consider what to include. Discrepant evaluations may indicate benefits that could be highlighted because evaluation of them is more amenable to change. Based on current findings, one possible focus of such campaigns may be the relationship-related benefits of PA.

This study investigated associations between screen-use (time and type) and cognition in children and tested the hypothesis that across all screen types, time spent on screens is negatively associated with cognition. Methods This study presents cross-sectional data from 11,875 US children aged 9–10 years. Exposures were self-reported daily recreational screen-use. The primary outcome was global cognition measured by the Youth NIH Toolbox®. Covariates included child education, pubertal development, parental education, household income, race/ethnicity, physical activity, and sleep duration. Findings The mean (SD) daily recreational screen time was 3.8 (3.1) hours and 99.7% of children reported using some form of screen daily. More screen time was accumulated on weekends compared to weekdays [4.6 (3.6) vs. 3.5 (3.1) hours, d = 0.34, p Conclusions Higher daily screen time is associated with lower cognition in children. These findings suggest moderating screen-use for promoting cognitive development in children.

Background: Childhood is a critical period for brain development, and the behaviours that comprise a typical 24-hour day contribute to cognitive performance in children. This study investigated the relationship between cognition and meeting the 24-hour movement behaviour guidelines of ≥60 minutes of physical activity, ≤2 hours of recreational screen time, and 9-11 hours of sleep per day in 9-10 year olds. Methods: This study presents cross-sectional data from the first annual curated release of the Adolescent Brain Cognitive Development Study (ABCD) - a 10-year longitudinal, observational study investigating brain development in American children. Data were collected from 21 study sites across the United States between September 2016 and 2017. Participants were 4,524 American children aged 9-10 years. Exposures were physical activity, recreational screen time, and sleep duration. The primary outcome was global cognition and secondary outcomes were crystallized and fluid intelligence. Findings: The mean (SD) number of guideline recommendations met was 1·1 (0·9). Overall, 50·9% of participants met the sleep recommendation, 36·5% met screen time, and 17·5% met the physical activity recommendation. 65·3% of participants met at least 1, whereas 4·7% of participants met all 3 recommendations. Multi-level regression analysis revealed a significant positive gradient between global cognition and each additional recommendation met [β=1·48 (95% CI: 0·86, 2·11), p

Background Active transportation (AT; e.g., walking and cycling) is increasingly promoted to increase youth physical activity (PA). Most previous research focused solely on school trips, and associations among AT and cardiovascular risk factors have seldom been examined in adolescents. Purpose To address these important research gaps using data from the nationally representative 2007–2009 Canadian Health Measures Survey. Methods A total of 1,016 adolescents aged 12–19 years reported their weekly time spent utilitarian walking and cycling, and wore an Actical accelerometer for 7 days. They underwent a series of physical tests (measures of fitness, body composition, blood pressure, and blood sampling) following standardized protocols. In 2013, differences in PA and health-related outcomes across levels of walking and cycling were assessed with ANCOVA analyses adjusted for age, gender, parental education, and usual daily PA. Results Greater walking and cycling time was associated with higher moderate-to-vigorous PA (MVPA). Compared to adolescents reporting walking 1–5 hours/week, those reporting 5 hours/week had better grip strength, lower total cholesterol, and total cholesterol/HDL ratio. Compared to adolescents reporting no cycling, those reporting ≥1 hour/week accumulated more light PA, had greater aerobic fitness, and lower BMI, waist circumference, and total cholesterol/HDL ratio; those who reported cycling Conclusions Utilitarian walking and cycling were associated with higher daily MVPA in youth. Cycling was associated with a more consistent pattern of health benefits than walking.

Sedentary behaviour (e.g. TV viewing, seated video game playing, prolonged sitting) has recently emerged as a distinct risk factor for cardiometabolic diseases in children and youth. This narrative review provides an overview of recent evidence in this area and highlights research gaps. Current evidence suggests that North American children and youth spend between 40% and 60% of their waking hours engaging in sedentary pursuits. Although data are lacking concerning temporal trends of objectively measured sedentary time, self-reported sedentary behaviours have increased over the past half century, with a rapid increase since the late 1990s. Excessive sedentary behaviour has been found to have independent and deleterious associations with markers of adiposity and cardiometabolic disease risk. These associations are especially consistent for screen-based sedentary behaviours (TV viewing, computer games, etc), with more conflicting findings observed for overall sedentary time. The above associations are possibly mediated by the influence of screen-based sedentary behaviours on energy intake. Although excessive sitting has been reported to have adverse acute and chronic metabolic impacts in adults, research on children is lacking. Research is particularly needed to investigate the impact of characteristics of sedentary behaviour (i.e. type/context, sedentary bout length, breaks in sedentary time, etc), as well as interventions that examine the health and behavioural impacts of sitting per se.

The hierarchical model posits that acute leukemias arise from leukemia stem cells (LSCs), which display stem cell-like properties like long-term self-renewal and differentiation to generate the heterogeneity observed in the tumor at diagnosis. Elimination of LSCs and their ancestral clones, pre-leukemic stem cells (pre-LSCs), is critical for long-term cure as they are the source of relapse. How these cells survive high-dose therapy remains poorly defined, but may include quiescence and pro-survival signals provided by the microenvironment. Strategies to interfere with specific signals from the niche have shown promising results, but may be subject to compensatory mechanisms due to the inherent plasticity of LSCs. The transactivation of signalling pathways downstream of growth factors from the niche is dependent on receptor-mediated endocytosis, a generic process dependent on Dynamins. Given the important role of the microenvironment for relapse-inducing cells, we postulated that inhibition of Dynamin might impair their properties and sensitize them to chemotherapy. Here, we show that the Dynamin small molecule inhibitor Dynole 34-2 blocks multiple signalling pathways in pre-LSCs and LSCs by preventing endocytosis. Using the Lmo2-transgenic mouse model of T-cell acute lymphoblastic leukemia (T-ALL), we found that Dynole 34-2 impairs self-renewal of pre-LSCs and sensitizes relapse-inducing cells to chemotherapy. We also found that Dynole 34-2 delayed leukemia onset in mice treated with high-dose therapy. Treatment of different patient-derived xenografts revealed that that inhibition of Dynamin activity with Dynole 34-2 represents an effective therapeutic strategy for different subtypes of human T-ALL. In summary, our finding that Dynamin activity is essential for LSC activity and chemoresistance in acute leukemia paves the way for novel therapeutic strategies.

Objective: To determine if a point-of-decision prompt (PODP) targeting sedentary behaviour influenced the proportion of standing individuals during presentations at an academic conference. Methods: Twelve, one-hour groups of presentation sessions (Global Summit on the Physical Activity of Children conference, May 2014) were included in this study; half were randomly assigned to the intervention group and half to the control group. The intervention group was exposed to an oral PODP at the beginning and middle of the presentations. Researchers performed three counts: beginning (e.g. first 10 min), middle (e.g. 30–40 min), and end (e.g. 50–60 min); each count included the number of individuals in the audience and the number of standing individuals. Results: A significantly larger proportion of individuals chose to stand during intervention group presentations (16.9 ± 2.0%) compared to control group presentations (10.5 ± 1.5%; chi2 = 7.13; p < 0.05). Conclusions: This study demonstrated the effectiveness of PODPs at decreasing sedentary behaviour during an academic conference. PODPs are simple, cost-effective interventions that require minimal time commitment, and represent a population health intervention that could reduce sedentary behaviour in a large group setting.

Context Opportunities for young people to be sedentary have increased during leisure time, study time, and transportation time. Purpose This review paper focuses on sedentary behaviors among young people aged 2–18 years and includes evidence of the relationship between sedentary behavior and health risk indicators, an overview of public health recommendations, the prevalence of key sedentary behaviors, evidence of correlates of sedentary behavior and the effectiveness of interventions to reduce sedentary behaviors. Evidence acquisition Although this is a narrative style review and not systematic, where possible, findings from relevant review papers were summarized and a search of more recent literature was performed using computer-based databases such as PubMed, Google Scholar, ERIC, PsycINFO, Social Science Index, SportDiscus, and Health Reference Center – Academic. Evidence synthesis Young people spend 2–4 hours per day in screen-based behaviors and 5–10 hours per day sedentary. Ethnicity, sociodemographic status, having a TV set in the bedroom, and parental behavior appear to be the most consistent correlates of TV viewing time; however, few recent studies aiming to reduce TV viewing or sedentary time among young people have been successful. Conclusions A growing body of evidence supports the development of public health recommendations to limit the time spent in screen-based behaviors. More research is needed to examine the prospective and experimental evidence of associations between overall sedentary time and health, determinants of sedentary behaviors other than screen-based behaviors, and interventions to reduce overall sedentary time or even alternative sedentary behaviors, such as transport- or education-related sitting time.

Research is now required on factors influencing adults' sedentary behaviors, and effective approaches to behavioral-change intervention must be identified. The strategies for influencing sedentary behavior will need to be informed by evidence on the most important modifiable behavioral determinants. However, much of the available evidence relevant to understanding the determinants of sedentary behaviors is from cross-sectional studies, which are limited in that they identify only behavioral "correlates." As is the case for physical activity, a behavior- and context-specific approach is needed to understand the multiple determinants operating in the different settings within which these behaviors are most prevalent. To this end, an ecologic model of sedentary behaviors is described, highlighting the behavior settings construct. The behaviors and contexts of primary concern are TV viewing and other screen-focused behaviors in domestic environments, prolonged sitting in the workplace, and time spent sitting in automobiles. Research is needed to clarify the multiple levels of determinants of prolonged sitting time, which are likely to operate in distinct ways in these different contexts. Controlled trials on the feasibility and efficacy of interventions to reduce and break up sedentary behaviors among adults in domestic, workplace, and transportation environments are particularly required. It would be informative for the field to have evidence on the outcomes of "natural experiments," such as the introduction of nonseated working options in occupational environments or new transportation infrastructure in communities.

Mutations in one of the 13 Fanconi anemia (FA) genes cause a progressive bone marrow failure disorder associated with developmental abnormalities and a predisposition to cancer. Although FA has been defined as a DNA repair disease based on the hypersensitivity of patient cells to DNA cross-linking agents, FA patients develop various developmental defects such as skeletal abnormalities, microphthalmia, and endocrine abnormalities that may be linked to transcriptional defects. Recently, we reported that the FA core complex interacts with the transcriptional repressor Hairy Enhancer of Split 1 (HES1) suggesting that the core complex plays a role in transcription. Here we show that the FA core complex contributes to transcriptional regulation of HES1-responsive genes, including HES1 and the cyclin-dependent kinase inhibitor p21cip1/waf1. Chromatin immunoprecipitation studies show that the FA core complex interacts with the HES1 promoter but not the p21cip1/waf1 promoter. Furthermore, we show that the FA core complex interferes with HES1 binding to the co-repressor transducin-like-Enhancer of Split, suggesting that the core complex affects transcription both directly and indirectly. Taken together these data suggest a novel function of the FA core complex in transcriptional regulation.

A 1:20 scale model of a low-rise naturally ventilated building was tested in a wind tunnel. External pressure coefficients were determined for an open model with various combinations of ridge, sidewall and end wall openings, as well as for a sealed model. The pressure distribution is influenced by all structural modifications at various wind angles. The differences between the open and sealed models were pronounced especially at the ridge and the leeward sidewall. In general, the more opening areas a building has, the larger is the discrepancy in pressure determined for the open versus sealed model.