Association between screen time and accelerometer-measured 24-h movement behaviors in a sample of Brazilian adolescents.

OBJECTIVES: Different screen time activities may be related to sleep, physical activity, and sedentary behavior. The objective was to examine the association between self-reported screen time activities and accelerometer-measured 24-h movement behaviors. STUDY DESIGN: This was a cross-sectional study. METHODS: Adolescents' (n = 718, 50.4% girls, 16 years) sleep duration, sedentary behavior, light-intensity physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) were estimated with wrist-worn accelerometry. Time spent on screen time activities related to studying, working, watching videos, playing video games, and using social media was self-reported. Multilevel linear regressions were used to test the association between screen time with sleep, sedentary behavior, and physical activity. RESULTS: Boys and girls slept 6.4 and 6.7 h per night, spent 10.4 and 10.1 h/d in sedentary behavior, spent 4.0 and 4.4 h/d in LPA, and spent 34.7 and 29.2 min/d in MVPA, respectively. Studying was inversely related to LPA and MVPA. Working was inversely related to sleep and positively related to LPA. Watching videos was associated with lower LPA and MVPA. For boys, videogames were associated with increased sedentary behavior and lower LPA and MVPA. For girls, studying and/or using social media were associated with lower LPA and MVPA. CONCLUSIONS: Indicators of screen time were associated with different accelerometer-measured 24-h movement behaviors in this sample of Brazilian adolescents.

Adherence to 24-hour movement guidelines and academic performance in adolescents.

OBJECTIVE: The aim of the study was to examine the association between meeting combinations of the Canadian 24-h movement guidelines and academic performance in adolescents. STUDY DESIGN: This cross-sectional study used the 2017 Ontario Student Drug Use and Health Survey, a survey representative of Ontario students in grades 7-12 attending publicly funded schools. A total of 10,160 students were included in the analysis. METHODS: Moderate to vigorous physical activity (MVPA), screen time, sleep duration, and academic performance were self-reported. A multiple linear regression model was used to examine differences in academic performance between adolescents meeting and those not meeting the combinations of movement guidelines (≥60 min/day of MVPA; ≤2 h/day of screen time; 9-11 h/night of sleep for ages 11-13 years, 8-10 h/night for ages 14-17 years, and 7-9 h/night for ages 18 years or older). Covariates included age, sex, ethnicity, subjective socio-economic status, body mass index z-score, and substance use. RESULTS: We found that 5.1% of students met all three movement guidelines, whereas 39.0% did not meet any. Middle school students who met all three guidelines or either the screen time or sleep guideline displayed better academic performance than those who met none of the guidelines. High school students who met the screen time and sleep guidelines displayed better academic performance than those who did not meet any guidelines. CONCLUSIONS: Adhering to screen time and sleep duration recommendations is associated with better academic performance among adolescents.

Association of eating behaviour with clock gene polymorphism 3111 T > C in children based on nutritional status.

Background: The CLOCK (circadian locomotor output cycle kaput) gene is a central regulator of circadian rhythm. The CLOCK gene has been related to energy intake and therefore to nutritional status. However, its specific associations with aspects of food behaviour in children have been scarcely investigated.Aim: To determine the association between the CLOCK gene polymorphism 3111 T > C and eating behaviours in children based on nutritional status.Methods: A cross-sectional study of the association between a CLOCK gene variant and eating behaviour in children (n = 256) was performed. Eating behaviour was evaluated by the Child Eating Behaviour Questionnaire (CEBQ). In addition, the genotype of the CLOCK 3111 T > C (TT, CC, TC) gene polymorphism and BMI were determined.Results: The obese carriers of the C allele of the polymorphism had lower scores in the dimensions "response to satiety" and "slowness to eat" (p < 0.001), both of which constitute an anti-intake dimension and are related to food satiety.Conclusions: The C allele CLOCK gene could be considered a genetic risk factor for satiety-altered eating behaviour dimensions.

Cognitive restriction accentuates the increased energy intake response to a 10-month multidisciplinary weight loss program in adolescents with obesity.

BACKGROUND: Multidisciplinary interventions have shown some merits in weight reduction strategies in youth, however, their impact on subsequent daily energy intake remains largely unknown. The aim of the present study was to evaluate the nutritional responses to a 10-month multidisciplinary intervention among adolescents with obesity, in relation to their eating behavior characteristics. METHODS: Thirty-five adolescents (mean age: 13.4 ±â€¯1.2 years) with obesity took part in a 10-month residential multidisciplinary weight loss program. Anthropometric measurements, body composition (dual-energy X-ray absorptiometry), 24-h ad libitum energy intake (weighted), eating behaviors (Dutch Eating Behavior Questionnaire) and appetite sensations (Visual Analogue Scales) were assessed on three occasions: at their arrival in the institution (T0), after 5 months (T1), and at the end of the 10-month program (T2). RESULTS: The mean weight loss reached 11% of the adolescents' initial body weight, with an important inter-individual variability (-25% to +3% of their initial body weight). Results revealed sex differences change, with boys showing a higher decrease in fat mass percent and increase in fat-free mass compared with girls. Weight loss was accompanied by a significant decrease in emotional (-8.3%, p < 0.05) and external (-14.8%, p < 0.001) eating scores and a significant increase in 24-h ad libitum energy intake (+246 kcal, p < 0.001). The observed subsequent increased 24-h ad libitum energy intake at T2 compared to T0 was significantly higher in cognitively restrained eaters (+492 kcal) compared to unrestrained eaters (+115 kcal, p = 0,015). Dietary restraint score at baseline was inversely correlated with the percentage of weight loss (r = -0.44, p = 0.010). CONCLUSION: A 10-month multidisciplinary weight loss intervention induced an increase in 24-h ad libitum energy intake compared to baseline, especially in cognitively restrained eaters. Moreover, initially cognitively restrained eaters tended to lose less body weight compared to unrestrained ones. These findings suggest that cognitive restriction may be a useful eating behavior characteristic to consider as a screening tool for identifying adverse responders to weight loss interventions in youth.

Integrating sedentary behavior in the theoretical model linking childhood to adulthood activity and health? An updated framework.

About 30 years ago, Blair and collaborators proposed a theoretical model illustrating the relationships between childhood and adulthood physical activity and health. The evolution of our societies has led to a "sedentarisation" of the subsequent generations, and the literature underlines an independent effect of physical activity and sedentary behaviors on health. We propose here an updated version of the model first designed by Blair and colleagues, suggesting the integration of the impact of sedentary behaviors on children and adult health.

Inequality in physical activity, sedentary behaviour, sleep duration and risk of obesity in children: a 12-country study.

OBJECTIVE: Studies examining associations between movement behaviours (i.e. physical activity, sedentary behaviour and sleep duration) and obesity focus on average values of these movement behaviours, despite important within-country and between-country variability. A better understanding of movement behaviour inequalities is important for developing public health policies and behaviour-change interventions. The objective of this ecologic analysis at the country level was to determine if inequality in movement behaviours is a better correlate of obesity than average movement behaviour volume in children from all inhabited continents of the world. METHODS: This multinational, cross-sectional study included 6,128 children 9-11 years of age. Moderate-to-vigorous physical activity (MVPA), total sedentary time (SED) and sleep period time were monitored over 7 consecutive days using waist-worn accelerometry. Screen time was self-reported. Inequality in movement behaviours was determined using Gini coefficients (ranging from 0 [complete equality] to 1 [complete inequality]). RESULTS: The largest inequality in movement behaviours was observed for screen time (Gini of 0.32; medium inequality), followed by MVPA (Gini of 0.21; low inequality), SED (Gini of 0.07; low inequality) and sleep period time (Gini of 0.05; low inequality). Average MVPA (h d-1) was a better correlate of obesity than MVPA inequality (r = -0.77 vs. r = 0.00, p = 0.03). Average SED (h d-1) was also a better correlate of obesity than SED inequality (r = 0.52 vs. r = -0.32, p = 0.05). Differences in associations for screen time and sleep period time were not statistically significant. MVPA in girls was found to be disproportionally lower in countries with more MVPA inequality. CONCLUSIONS: Findings from this study show that average MVPA and SED should continue to be used in population health studies of children as they are better correlates of obesity than inequality in these behaviours. Moreover, the findings suggest that MVPA inequality could be greatly reduced through increases in girls' MVPA alone.

Thresholds of physical activity associated with obesity by level of sedentary behaviour in children.

BACKGROUND: It is unknown whether moderate-to-vigorous physical activity (MVPA) thresholds for obesity should be adapted depending on level of sedentary behaviour in children. OBJECTIVE: The objective of the study is to determine the MVPA thresholds that best discriminate between obese and non-obese children, by level of screen time and total sedentary time in 12 countries. METHODS: This multinational, cross-sectional study included 6522 children 9-11 years of age. MVPA and sedentary time were assessed using waist-worn accelerometry, while screen time was self-reported. Obesity was defined according to the World Health Organization reference data. RESULTS: Receiver operating characteristic curve analyses showed that the best thresholds of MVPA to predict obesity ranged from 53.8 to 73.9 min d-1 in boys and from 41.7 to 58.7 min d-1 in girls, depending on the level of screen time. The MVPA cut-offs to predict obesity ranged from 37.9 to 75.9 min d-1 in boys and from 32.5 to 62.7 min d-1 in girls, depending on the level of sedentary behaviour. The areas under the curve ranged from 0.57 to 0.73 ('fail' to 'fair' accuracy), and most sensitivity and specificity values were below 85%, similar to MVPA alone. Country-specific analyses provided similar findings. CONCLUSIONS: The addition of sedentary behaviour levels to MVPA did not result in a better predictive ability to classify children as obese/non-obese compared with MVPA alone.

Estimating sleep efficiency in 10- to- 13-year-olds using a waist-worn accelerometer.

OBJECTIVE: In field settings, wrist- and waist-worn accelerometers are typically used to assess sleep characteristics and movement behaviors, respectively. There has been a shift in movement behavior studies to wear accelerometers 24 h/d. Sleep characteristics could be assessed in these studies if sleep algorithms were available for waist-worn accelerometers. The objective of this study was to develop and provide validity data for an algorithm/sleep likelihood score cut-off to estimate sleep efficiency in children using the waist-worn Actical accelerometer. DESIGN: Cross-sectional study. PARTICIPANTS: Fifty healthy children aged 10-13 years. MEASUREMENTS: Children wore an Actical on their waist and an Actiwatch 2 on their nondominant wrist for 8 nights at home in their normal sleep environment. Participants were randomized into algorithm/sleep likelihood score "development" and "test" groups (n=25 per group). Within the development group, we assessed sleep efficiency with the Actical using the same algorithm that the Actiwatch 2 uses and selected the sleep likelihood score cut-off value that was the most accurate at predicting sleep efficiency at the nightly level compared with the Actiwatch 2. We applied this algorithm and cut-off value to the test group. RESULTS: Mean (SD) sleep efficiency estimates for the test group from the Actical and Actiwatch 2 were 89.0% (3.9%) and 88.7% (3.1%), respectively. Bland-Altman plots and absolute difference scores revealed considerable agreement between devices for both nightly and weekly estimates of sleep efficiency. CONCLUSION: A waist-worn Actical accelerometer can accurately predict sleep efficiency in field settings among healthy 10- to 13-year-olds.

The adiposity of children is associated with their lifestyle behaviours: a cluster analysis of school-aged children from 12 nations.

BACKGROUND: The relationship between children's adiposity and lifestyle behaviour patterns is an area of growing interest. OBJECTIVES: The objectives of this study are to identify clusters of children based on lifestyle behaviours and compare children's adiposity among clusters. METHODS: Cross-sectional data from the International Study of Childhood Obesity, Lifestyle and the Environment were used. PARTICIPANTS: the participants were children (9-11 years) from 12 nations (n = 5710). MEASURES: 24-h accelerometry and self-reported diet and screen time were clustering input variables. Objectively measured adiposity indicators were waist-to-height ratio, percent body fat and body mass index z-scores. ANALYSIS: sex-stratified analyses were performed on the global sample and repeated on a site-wise basis. Cluster analysis (using isometric log ratios for compositional data) was used to identify common lifestyle behaviour patterns. Site representation and adiposity were compared across clusters using linear models. RESULTS: Four clusters emerged: (1) Junk Food Screenies, (2) Actives, (3) Sitters and (4) All-Rounders. Countries were represented differently among clusters. Chinese children were over-represented in Sitters and Colombian children in Actives. Adiposity varied across clusters, being highest in Sitters and lowest in Actives. CONCLUSIONS: Children from different sites clustered into groups of similar lifestyle behaviours. Cluster membership was linked with differing adiposity. Findings support the implementation of activity interventions in all countries, targeting both physical activity and sedentary time.

Sources of variability in childhood obesity indicators and related behaviors.

The purpose of this study was to describe sources of variability in obesity-related variables in 6022 children aged 9-11 years from 12 countries. The study design involved recruitment of students, nested within schools, which were nested within study sites. Height, weight and waist circumference (WC) were measured and body mass index (BMI) was calculated; sleep duration and total and in-school moderate-to-vigorous physical activity (MVPA) and sedentary time were measured by accelerometry; and diet scores were obtained by questionnaire. Variance in most variables was largely explained at the student level: BMI (91.9%), WC (93.5%), sleep (75.3%), MVPA (72.5%), sedentary time (76.9%), healthy diet score (88.3%), unhealthy diet score (66.2%), with the exception of in-school MVPA (53.8%) and in-school sedentary time (25.1%). Variance explained at the school level ranged from 3.3% for BMI to 29.8% for in-school MVPA, and variance explained at the site level ranged from 3.2% for WC to 54.2% for in-school sedentary time. In general, more variance was explained at the school and site levels for behaviors than for anthropometric traits. Given the variance in obesity-related behaviors in primary school children explained at school and site levels, interventions that target policy and environmental changes may enhance obesity intervention efforts.

Associations between meeting combinations of 24-h movement guidelines and health-related quality of life in children from 12 countries.

OBJECTIVES: To examine whether meeting vs not meeting movement/non-movement guidelines (moderate-to-vigorous physical activity [MVPA], screen time, sleep duration), and combinations of these recommendations, are associated with health-related quality of life (HRQoL) in children from 12 countries in five major geographic regions of the world and explore whether the associations vary by study site. STUDY DESIGN: Observational, multinational cross-sectional study. METHODS: This study included 6106 children aged 9-11 years from sites in Australia, Brazil, Canada, China, Colombia, Finland, India, Kenya, Portugal, South Africa, the United Kingdom, and the United States. Participants completed the KIDSCREEN-10 to provide a global measure of their HRQoL. Sleep duration and MVPA were assessed using 24-h accelerometry. Screen time was assessed through self-report. Meeting the recommendations was defined as ≥60 min/day for MVPA, ≤2 h/day for screen time, and between 9 and 11 h/night for sleep duration. Age, sex, highest parental education, unhealthy diet pattern score, and body mass index z-score were included as covariates in statistical models. RESULTS: In the full sample, children meeting the screen time recommendation, the screen time + sleep recommendation, and all three recommendations had significantly better HRQoL than children not meeting any of these guidelines. Differences in HRQoL scores between sites were also found within combinations of movement/non-movement behaviors. For example, while children in Australia, Canada, and USA self-reported better HRQoL when meeting all three recommendations, children in Kenya and Portugal reported significantly lower HRQoL when meeting all three recommendations (relative to not meeting any). CONCLUSIONS: Self-reported HRQoL is generally higher when children meet established movement/non-movement recommendations. However, differences between study sites also suggest that interventions aimed at improving lifestyle behaviors and HRQoL should be locally and culturally adapted.

Inadequate sleep as a contributor to type 2 diabetes in children and adolescents.

Lack of sleep is a modifiable risk factor for adverse health in humans. Short sleep duration and poor sleep quality are common in the pediatric population; the largest decline in sleep duration over the past decades has been seen in children and adolescents. The objective of the present narrative review was to provide for the first time an overview of the literature on sleep and its association with type 2 diabetes mellitus (T2D) biomarkers in children and adolescents. For this narrative review, 23 studies were retained (21 observational and 2 experimental studies). Notwithstanding the conflicting results found in these studies and despite being attenuated by adiposity level, maturity, sex and age, there is still some compelling evidence for an association between sleep duration (for both objective or subjective measurements of duration) and architecture with one or more T2D biomarkers in children and adolescents. The majority of the studies reviewed did focus on sleep duration and one or more T2D biomarkers in children and adolescents, but sleep architecture, more precisely the suppression of slow wave sleep and rapid eye movement sleep, has also been shown to be associated with insulin resistance. Only two studies looked at sleep quality, and the association between sleep quality and insulin resistance was not independent of level of adiposity. Future experimental studies will help to better understand the mechanisms linking insufficient sleep with T2D. Work also needs to be carried out on finding novel and effective strategies aimed at improving sleep hygiene and health outcomes of children and adolescents.

Perceptions and attitudes about body weight and adherence to the physical activity recommendation among adolescents: the moderating role of body mass index.

OBJECTIVE: We examined the associations between perceptions and attitudes about body weight and adherence to the physical activity recommendation (PAR) for adolescents to achieve ≥60 min/day of moderate-to-vigorous physical activity and tested whether body mass index (BMI) was a moderator of these relationships. STUDY DESIGN: Cross-sectional survey. METHODS: Self-reported data from Canadian adolescents (n = 4299) who participated in the 2013 Ontario Student Drug Use and Health Survey were analysed. RESULTS: Dissatisfaction with body weight was associated with lower odds of adherence to the PAR (odds ratio [OR]: 0.74; 95% confidence interval [CI]: 0.55-0.99). More specifically, those who perceived themselves as overweight/obese had lower odds of adherence to the PAR (OR: 0.59; 95% CI: 0.42-0.81) compared with those who think they were about the right weight. Those who were trying to gain weight were more likely to adhere to the PAR (OR: 1.92; 95% CI: 1.29-2.86) compared to those who were doing nothing about their body weight. BMI was a significant moderator of the association between dissatisfaction with body weight and adherence to the PAR. At low BMI, there were no differences in the adherence to the PAR between adolescents who were dissatisfied with their body weight or not. At high BMI, adolescents who were dissatisfied with their body weight were less likely to adhere to the PAR than those who were not dissatisfied with their weight. Results were not different between males and females. CONCLUSIONS: Results suggest that adolescents who are dissatisfied with their body weight have lower adherence to the PAR, particularly those who are overweight or obese.

Interactions between sleep, movement and other non-movement behaviours in the pathogenesis of childhood obesity.

Research examining the health effects of physical activity, sedentary behaviour and sleep on different health outcomes has largely been conducted independently or in isolation of the other behaviours. However, the fact that time is finite (i.e. 24 h) suggests that the debate on whether or not the influence of a single behaviour is independent of another one is conceptually incorrect. Time spent in one behaviour should naturally depend on the composition of the rest of the day. Recent evidence using more appropriate analytical approaches to deal with this methodological issue shows that the combination of sleep, movement and non-movement behaviours matters and all components of the 24-h movement continuum should be targeted to enhance health and prevent childhood obesity. The objective of this review is to discuss research investigating how combinations of physical activity, sedentary behaviour and sleep are related to childhood obesity. Emerging statistical approaches (e.g. compositional data analysis) that can provide a good understanding of the best 'cocktail' of behaviours associated with lower adiposity and improved health are also discussed. Finally, future research directions are provided. Collectively, it becomes clearer that guidelines and public health interventions should target all movement behaviours synergistically to optimize health of children and youth around the world.

Mid-upper arm circumference as a screening tool for identifying children with obesity: a 12-country study.

BACKGROUND: No studies have examined if mid-upper arm circumference (MUAC) can be an alternative screening tool for obesity in an international sample of children differing widely in levels of human development. OBJECTIVE: Our aim is to determine whether MUAC could be used to identify obesity in children from 12 countries in five major geographic regions of the world. METHODS: This observational, multinational cross-sectional study included 7337 children aged 9-11 years. Anthropometric measurements were objectively assessed, and obesity was defined according to the World Health Organization reference data. RESULTS: In the total sample, MUAC was strongly correlated with adiposity indicators in both boys and girls (r > 0.86, p < 0.001). The accuracy level of MUAC for identifying obesity was high in both sexes and across study sites (overall area under the curve of 0.97, sensitivity of 95% and specificity of 90%). The MUAC cut-off value to identify obesity was ~25 cm for both boys and girls. In country-specific analyses, the cut-off value to identify obesity ranged from 23.2 cm (boys in South Africa) to 26.2 cm (girls in the UK). CONCLUSIONS: Results from this 12-country study suggest that MUAC is a simple and accurate measurement that may be used to identify obesity in children aged 9-11 years. MUAC may be a promising screening tool for obesity in resource-limited settings.

Comparison of ActiGraph GT3X+ and Actical accelerometer data in 9-11-year-old Canadian children.

Accelerometry is the gold standard for field-based physical activity assessment in children; however, the plethora of devices, data reduction procedures, and cut-points available limits comparability between studies. This study aimed to compare physical activity variables from the ActiGraph GT3X+ and Actical accelerometers in children under free-living conditions. A cross-sectional study of 379 children aged 9-11 years from Ottawa (Canada) was conducted. Children wore the ActiGraph GT3X+ and Actical accelerometers on the hip simultaneously for 7 consecutive days (24-h protocol). Moderate-to-vigorous (MVPA), vigorous (VPA), moderate (MPA), and light (LPA) physical activity, as well as sedentary time, (SED) were derived using established data reduction protocols. Excellent agreement between devices was observed for MVPA (ICC = 0.73-0.80), with fair to good agreement for MPA, LPA and SED, and poor agreement for VPA. Bland-Altman plots showed excellent agreement for MVPA, LPA, and SED, adequate agreement for MPA, and poor agreement for VPA. MVPA derived from the Actical was 11.7% lower than the ActiGraph GT3X+. The ActiGraph GT3X+ and Actical are comparable for measuring children's MVPA. However, comparison between devices for VPA, MPA, LPA, and SED are highly dependent on data reduction procedures and cut-points, and should be interpreted with caution.

Use of social networking sites and perception and intentions regarding body weight among adolescents.

OBJECTIVE: Social networking sites (SNSs) not only offer users an opportunity to link with others but also allow individuals to compare themselves with other users. However, the link between the use of SNSs and the dissatisfaction with body weight is largely unknown. We investigated the associations between the use of SNSs and the perception of body weight and related behaviours among adolescent men and women. METHODS: The study sample consisted of 4,468 (48.5% women) 11-19-year-old Canadian students in grades 7 to 12 who participated in the 2013 Ontario Student Drug Use and Health Survey. RESULTS: Overall, 54.6% of students reported using SNSs for 2 h or less per day, 28.0% reported using them for more than 2 h d-1 and 17.4% reported infrequent or no use of SNSs (reference category). After adjustment for covariates, results showed that adolescent women who use SNSs for more than 2 h d-1 had greater odds of dissatisfaction with body weight (odds ratio = 2.02; 95% confidence interval [CI]: 1.30-3.16). More specifically, they were more likely to perceive themselves as overweight (relative risk ratio [RRR] = 2.20; 95% CI: 1.34-3.60) compared with those who reported infrequent or no use of SNSs. Conversely, men who use SNSs for 2 h or less per day presented a lower risk for perceiving themselves as overweight (RRR = 0.68; 95% CI: 0.47-0.98) but not those who use SNSs for more than 2 h d-1. Women who use SNSs for more than 2 h d-1 reported a greater likelihood of trying to lose weight (RRR = 2.52; 95% CI: 1.62-3.90). CONCLUSIONS: Our results showed that heavy use of SNSs is associated with dissatisfaction with body weight in adolescent women.