Is the relationship between sedentary behaviour and cardiometabolic health in adolescents independent of dietary intake? A systematic review

Screen time in the development of type 2 diabetes mellitus (T2DM) : a two-sample Mendelian randomization study

OBJECTIVE

This study aimed to investigate the potential causal relationship between screen time and the risk of developing type 2 diabetes mellitus (T2DM) using Mendelian randomization.

METHODS

Two-sample Mendelian randomization was conducted, utilizing genetic variants associated with different types of screen time as instrumental variables. Single nucleotide polymorphisms (SNPs) were used to assess the primary outcome, which was the risk of developing T2DM.

RESULTS

The analysis revealed a significant positive causal association between television viewing time and the risk of T2DM. Specifically, excessive television viewing time was found to increase the risk of developing T2DM (OR: 2.39, 95% CI: 1.90 to 3.00, P < 0.01). However, no significant causal relationship was observed between computer usage time and the risk of T2DM. Additionally, mobile phone use time showed a positive correlation with the risk of T2DM (OR: 1.31, 95% CI: 1.04 to 1.64, P = 0.02), albeit to a lesser extent than television viewing time.

CONCLUSION

The findings of this study indicate a significant causal association between certain types of screen time, specifically television viewing and mobile phone use, and an increased risk of T2DM.

Longitudinal associations of screen time, physical activity, and sleep duration with body mass index in U.S. youth

BACKGROUND

Youth use different forms of screen time (e.g., streaming, gaming) that may be related to body mass index (BMI). Screen time is non-independent from other behaviors, including physical activity and sleep duration. Statistical approaches such as isotemporal substitution or compositional data analysis (CoDA) can model associations between these non-independent behaviors and health outcomes. Few studies have examined different types of screen time, physical activity, and sleep duration simultaneously in relation to BMI.

METHODS

Data were baseline (2017-2018) and one-year follow-up (2018-2019) from the Adolescent Brain Cognitive Development Study, a multi-site study of a nationally representative sample of U.S. youth (N = 10,544, mean [SE] baseline age = 9.9 [0.03] years, 48.9% female, 45.4% non-White). Participants reported daily minutes of screen time (streaming, gaming, socializing), physical activity, and sleep. Sex-stratified models estimated the association between baseline behaviors and follow-up BMI z-score, controlling for demographic characteristics, internalizing symptoms, and BMI z-score at baseline.

RESULTS

In females, isotemporal substitution models estimated that replacing 30 min of socializing (β [95% CI] = -0.03 [-0.05, -0.002]), streaming (-0.03 [-0.05, -0.01]), or gaming (-0.03 [-0.06, -0.01]) with 30 min of physical activity was associated with a lower follow-up BMI z-score. In males, replacing 30 min of socializing (-0.03 [-0.05, -0.01]), streaming (-0.02 [-0.03, -0.01]), or gaming (-0.02 [-0.03, -0.01]) with 30 min of sleep was associated with a lower follow-up BMI z-score. In males, replacing 30 min of socializing with 30 min of gaming was associated with a lower follow-up BMI z-score (-0.01 [-0.03, -0.0001]). CoDA estimated that in males, a greater proportion of time spent in baseline socializing, relative to the remaining behaviors, was associated with a higher follow-up BMI z-score (0.05 [0.02, 0.08]). In females, no associations between screen time and BMI were observed using CoDA.

CONCLUSIONS

One-year longitudinal associations between screen time and BMI may depend on form of screen time, what behavior it replaces (physical activity or sleep), and participant sex. The alternative statistical approaches yielded somewhat different results. Experimental manipulation of screen time and investigation of biopsychosocial mechanisms underlying the observed sex differences will allow for causal inference and can inform interventions.

Association between Diet and Adiposity in Adults: Influence of Sedentary Behavior Patterns

This study analyzed the influence of sedentary behavior (SB) on the association between dietary patterns and adiposity in community-dwelling adults. Eight hundred and forty-three adults (age: 56.5 ± 18.3 years) participated in this cross-sectional epidemiological study. Dietary patterns were evaluated using self-report questions regarding the weekly frequency of consumption of certain foods. Adiposity was determined using anthropometric measurements of weight, waist circumference, and height. SB was evaluated according to the time spent on screen devices. The usual physical activity level and socioeconomic status were considered confounding factors. Associations were determined using multivariate linear models with simultaneous adjustments for confounding variables. A statistical analysis indicated that fruit consumption was negatively related to the body mass index, regardless of the adjustment for SB domains. Red meat consumption was positively related to the body mass index, and fried food consumption was positively related to the waist-to-height ratio, regardless of the adjustment for SB domains. The consumption of fried food was positively associated with global and central adiposity after the adjustments for confounding factors and time spent on screen devices. We concluded that dietary habits are related to adiposity in adults. However, SB domains seem to influence the relationship between body adiposity and dietary habits, mainly regarding the consumption of fried foods.

Promoting physical activity for children: an audit among Italian family pediatricians

BACKGROUND

This survey aimed to investigate the perception of Italian Pediatricians regarding the promotion of physical activity.

METHODS

From January to May 2015, a survey was conducted among family pediatricians working in Puglia, interviewed by a standardized questionnaire, that investigated demographic information, participation in sporting activity by the pediatrician, opinion on obesity and the promotion of physical activity, and attitude towards enquiring about the physical activity of patients with and without chronic diseases.

RESULTS

We collected 200 questionnaires (35.7% of target population): 51.5% of enrolled pediatricians stated that they were participating in sporting activities at the time of the survey. The average opinion regarding the relevance of the obesity was 9±1.4/10 and about the promotion of physical activity 9.6±0.8. All enrolled pediatricians asked for their patients' physical activity and encouraged inactive children to begin an appropriate activity. Pediatricians who took part in sport had a high probability of encouraging physical activity, among patients affected by chronic diseases.

CONCLUSIONS

Family pediatricians declared a good attitude regarding the promotion of physical activity for their patients according to national and international recommendations. The main concern emerging from our results is the risk of an "inappropriate interdiction" of physical activity in children affected by chronic diseases, in particular physicians that have never participated in a sport.

Are Physical Activity and Sedentary Screen Time Levels Associated With Food Consumption in European Adolescents? The HELENA Study

One of the current main public health problems is the prevalence of obesity in children. Unhealthy lifestyle behaviors such as poor dietary habits, high sedentary screen time (SST), and low levels of physical activity (PA) have a strong tendency to track from childhood into adulthood. The aim of this manuscript is to assess the association between meeting or not meeting the PA and SST recommendations and the consumption of different food groups.

Data were obtained from a sample of European adolescents from the multicenter cross-sectional HELENA study. In all, 1448 adolescents from 8 cities were included. PA was objectively measured by accelerometry and dietary intake by 24-hour dietary records. Adolescents were grouped according to PA and SST recommendations.

In both sexes, intake of savory snacks was higher in those groups who did not meet any of the recommendations (p < 0.05). For males, those who met both recommendations were more likely to drink/eat milk, yogurt, and water (p < 0.05). Those not meeting recommendations were more likely to drink sugar-sweetened beverages (p < 0.05). For females, those not meeting recommendations were less likely to eat fruits and vegetables and more likely to have a higher intake of fats and oils (p < 0.05).

Those adolescents meeting PA and SST recommendations had a higher intake of healthy foods, like fruit and vegetables and dairy products. However, the negative relationship unhealthier food and SST is stronger in males independently of PA. More studies assessing the combined effect of both PA and SST regarding dietary habits in children and adolescents are needed.

Association between Different Domains of Sedentary Behavior and Health-Related Quality of Life in Adults: A Longitudinal Study

Extended periods of time on screen devices and sitting are the main activities that characterize sedentary behavior (SB), which negatively impacts the quality of life. This negative influence was demonstrated mainly by cross-sectional studies performed in high-income countries in which the effects of screen time on health-related quality of life (HRQoL) is not considered. Thus, we analyzed the association between the different domains of SB (i.e., subdomains of screen time-television, computer, cellphone) and the HRQoL in adults that live in Brazil during two years of follow-up. The sample included 331 adults. Subdomains of screen time (i.e., watching television, using computers, and cellphones) and of HRQoL (i.e., physical functioning, role-physical, bodily pain, general health, vitality, social functioning, role-emotional, mental health, and current health perception) were assessed by a structured questionnaire and SF-36, respectively. Our results indicate a significant increase in screen time during the two years of follow-up. Linear regression models indicated that although domains of SB were differently associated with HRQoL, in general, screen time was negatively associated with social functioning and positively associated with physical functioning during locomotion and activities of daily living (ADL), role-physical (i.e., physical issues during work and ADLs), and role-emotional (i.e., emotional issues during work and ADLs) after the two-year follow-up. In conclusion, screen time may positively or negatively influence some domains of HRQoL in adults.

Mealtime media use and cardiometabolic risk in children

OBJECTIVES

To examine the association between mealtime media use and non-HDL-cholesterol as well as other markers of cardiometabolic risk (CMR) in children.

DESIGN

A repeated measures study design was used to examine the association between mealtime media use and CMR outcomes. Multivariable linear regression with generalised estimating equations was used to examine the association between mealtime media use and CMR outcomes. Analyses were stratified a priori by age groups (1-4 and 5-13 years).

SETTING

The TARGet Kids! Practice-based research network in Toronto, Canada.

PARTICIPANTS

2117 children aged 1-13 years were included in the analysis.

RESULTS

After adjusting for covariates, there was no evidence that total mealtime media use was associated with non-HDL-cholesterol in 1-4 year olds (P = 0·10) or 5-13 year olds (P = 0·29). Each additional meal with media per week was associated with decreased HDL-cholesterol in 5-13 year olds (-0·006 mmol/l; 95 % CI -0·009, -0·002; P = 0·003) and log-TAG in 1-4 year olds (β = -0·004; 95 % CI -0·008, -0·00009; P = 0·04). Media use during breakfast was associated with decreased HDL-cholesterol in 5-13 year olds (-0·012 mmol/l; 95 % CI -0·02, -0·004; P = 0·002), while media during lunch was associated with decreased log-TAG (-0·01 mmol/l; 95 % CI -0·03, -0·002; P = 0·03) in children aged 1-4 years. Total mealtime media use was not associated with total cholesterol, glucose or insulin in either age group.

CONCLUSIONS

Mealtime media use may be associated with unfavourable lipid profiles through effects on HDL-cholesterol in school-aged children but likely not in pre-schoolers.

Bikes for Life: Measuring the effects of a bicycle distribution program on 6 to 12-year-old children's BMI and health behaviors

Treating pediatric obesity is challenging. The objective was to evaluate effect of receiving a bicycle on (a) physical activity, (b) sedentary activity, (c) Body Mass Index (BMI), and (d) eating habits. A stepped-wedge randomized controlled trial of 6- to 12-year-old patients with overweight/obesity was conducted April 2012-2018. Participants were randomized to wait 0, 2, 4, or 6 months for a bicycle. Outcomes on activity, BMI and eating were collected at 3, 6, 9- and 12-months after children received a bicycle. A total of 525 participants with 387 (74%) completed 3-month follow-up questionnaire, and 346 (66%) completed 12-month follow-up visit. Participants were mostly Latino/a (71%) and low income (58%), and 31% had never ridden a bicycle. Median baseline BMI was 98th percentile. At 3 months, 62% reported bicycle use last week, on average 3.6 days. Time spent on sedentary activities decreased by 48 min/day (p = 0.04), and time spent playing sports increased by 1.7 h/week (p < 0.01). No reduction in BMI was seen. Consumption of sugary drinks decreased (by 0.59 servings/week, p < 0.01), and consumption of vegetables increased (0.71 servings/week, p = 0.04). At 12 months, sedentary time, sugary drink and vegetable consumption remained significantly more favorable than at enrollment (p < 0.01, p < 0.01, p = 0.04 respectively), but not significantly different (p = 0.47 for sedentary, p = 0.73 for sugary drink) and significantly less favorable (p < 0.01 for vegetables) than at the time of intervention. Participants reported riding bicycle, improved activity and dietary habits, though reversion towards baseline behavior was seen by one year and no change in BMI from enrollment.

The longitudinal association between early-life screen viewing and abdominal adiposity-findings from a multiethnic birth cohort study

IMPORTANCE

Screen viewing in adults has been associated with greater abdominal adiposity, with the magnitude of associations varying by sex and ethnicity, but the evidence is lacking at younger ages. We aimed to investigate sex- and ethnic-specific associations of screen-viewing time at ages 2 and 3 years with abdominal adiposity measured by magnetic resonance imaging at age 4.5 years.

METHODS

The Growing Up in Singapore Towards healthy Outcomes is an ongoing prospective mother-offspring cohort study. Parents/caregivers reported the time their child spent viewing television, handheld devices, and computer screens at ages 2 and 3 years. Superficial and deep subcutaneous and visceral abdominal adipose tissue volumes were quantified from magnetic resonance images acquired at age 4.5 years. Associations between screen-viewing time and abdominal adipose tissue volumes were examined by multivariable linear regression adjusting for confounding factors.

RESULTS

In the overall sample (n = 307), greater total screen-viewing time and handheld device times were associated with higher superficial and deep subcutaneous adipose tissue volumes, but not with visceral adipose tissue volumes. Interactions with child sex were found, with significant associations with superficial and deep subcutaneous and visceral adipose tissue volumes in boys, but not in girls. Among boys, the increases in mean (95% CI) superficial and deep subcutaneous and visceral adipose tissue volumes were 24.3 (9.9, 38.7), 17.6 (7.4, 27.8), and 7.8 (2.1, 13.6) mL per hour increase in daily total screen-viewing time, respectively. Ethnicity-specific analyses showed associations of total screen-viewing time with abdominal adiposity only in Malay children. Television viewing time was not associated with abdominal adiposity.

CONCLUSION

Greater total screen-viewing time (and in particular, handheld device viewing time) was associated with higher abdominal adiposity in boys and Malay children. Additional studies are necessary to confirm these associations and to examine screen-viewing interventions for preventing excessive abdominal adiposity and its adverse cardiometabolic consequences.

Physical activity, screen exposure and sleep among students during the pandemic of COVID-19

This study aimed to determine the levels of health-related behaviours (physical activity, screen exposure and sleep status) among Chinese students from primary, secondary and high schools during the pandemic of COVID-19, as well as their changes compared with their status before the pandemic. A cross-sectional online survey of 10,933 students was conducted among 10 schools in Guangzhou, China, between 8th and 15th March, 2020. After getting the informed consent from student's caregivers, an online questionnaire was designed and used to obtain time spending on health-related behaviours during the pandemic of COVID-19, as well as the changes compared with 3 months before the pandemic, which was completed by students themselves or their caregivers. Students were stratified by regions (urban, suburban, exurban), gender (boys and girls), and grades (lower grades of primary school, higher grades of primary schools, secondary schools and high schools). Data were expressed as number and percentages and Chi-square test was used to analyse difference between groups. Overall, the response rate of questionnaire was 95.3% (10,416/10,933). The median age of included students was 13.0 (10.0, 16.0) years and 50.1% (n = 5,219) were boys. 41.4%, 53.6% and 53.7% of total students reported less than 15 min per day in light, moderate and vigorous activities and 58.7% (n = 6,113) reported decreased participation in physical activity compared with the time before pandemic. Over 5 h of screen time spending on online study was reported by 44.6% (n = 4,649) of respondents, particular among high school students (81.0%). 76.9% of students reported increased screen time compared with the time before pandemic. Inadequate sleep was identified among 38.5% of students and the proportion was highest in high school students (56.9%). Our study indicated that, during the COVID-19 pandemic, the school closure exerted tremendous negative effects on school-aged children's health habits, including less physical activity, longer screen exposure and irregular sleeping pattern.

Clustering of multiple lifestyle behaviors among migrant, left-behind and local adolescents in China: a cross-sectional study

BACKGROUND

Influence of migration on externalized behavioral problems (e.g., aggressive) among adolescents has been well assessed, yet lifestyle behaviors of migrant, left-behind and local adolescents have been largely overlooked by researchers and policy-makers. Therefore, this study aimed to identify clustering of multiple lifestyle behaviors and their associations with migrant status among Chinese adolescents.

METHODS

A cross-sectional survey was conducted in 2015 in Beijing, and Wuhu city (Anhui province). Adolescents self-reported age, gender, family economic status, migrant situation, and lifestyle behaviors (i.e., physical activity, screen time, sleep, smoke, soft-drink, alcohol, fruit and vegetable consumption) via a battery of validated questionnaires. Latent class analysis was conducted to identify behavioral clusters using Mplus 7.1. ANOVA, and multivariable logistic regression were used to examine associations between migrant situations and behavioral clusters using SPSS 22.

RESULTS

Three distinct behavioral clusters were exhibited among 1364 students (mean age: 13.41 ± 0.84 years): "low risk" (N = 847), "moderate risk" (N = 412) and "high risk" (N = 105). The "high-risk" cluster had the highest prevalence of adolescents not meeting healthy behavioral recommendations. There were no significant differences in the prevalence of high-risk lifestyle among migrant, left-behind, rural local and urban local adolescents. But migrant adolescents had the lowest prevalence of low-risk lifestyle, followed by left-behind, rural and urban local adolescents. Moreover, compared with urban local, migrant (OR = 2.72, 95%CI: 1.88,3.94), left-behind (OR = 2.28, 95%CI: 1.46, 3.55), and rural local (OR = 1.76, 95%CI:1.03,3.01) adolescents had a higher risk of moderate-risk lifestyle.

CONCLUSIONS

Clustering of assessed lifestyle behaviors differed by the migrant status. Particularly, migrant and left-behind adolescents were more likely to have moderate-risk lifestyle compared with their counterparts. Interventions that promote moderate to vigorous physical activity and consumption of fruits and vegetables simultaneously are needed among them.

The Prevalence of Insulin Resistance and the Associated Risk Factors in a Sample of 14-18-Year-Old Slovak Adolescents

The prevalence of cardiometabolic risk factors has increased in Slovakian adolescents as a result of serious lifestyle changes. This cross-sectional study aimed to assess the prevalence of insulin resistance (IR) and the associations with cardiometabolic and selected lifestyle risk factors in a sample of Slovak adolescents. In total, 2629 adolescents (45.8% males) aged between 14 and 18 years were examined in the study. Anthropometric parameters, blood pressure (BP), and resting heart rate were measured; fasting venous blood samples were analyzed; and homeostasis model assessment (HOMA)-insulin resistance (IR) was calculated. For statistical data processing, the methods of descriptive and analytical statistics for normal and skewed distribution of variables were used. The mean HOMA-IR was 2.45 ± 1.91, without a significant sex differences. IR (cut-off point for HOMA-IR = 3.16) was detected in 18.6% of adolescents (19.8% males, 17.6% females). IR was strongly associated with overweight/obesity (especially central) and with almost all monitored cardiometabolic factors, except for total cholesterol (TC) and systolic BP in females. The multivariate model selected variables such as low level of physical fitness, insufficient physical activity, breakfast skipping, a small number of daily meals, frequent consumption of sweetened beverages, and low educational level of fathers as significant risk factors of IR in adolescents. Recognizing the main lifestyle risk factors and early IR identification is important in terms of the performance of preventive strategies. Weight reduction, regular physical activity, and healthy eating habits can improve insulin sensitivity and decrease the incidence of metabolic syndrome, type 2 diabetes, and cardiovascular disease (CVD).

Screen time and its effect on dietary habits and lifestyle among schoolchildren

OBJECTIVE

The aim of the study was to determine the associations between recreational screen time and dietary habits and lifestyle factors in a representative sample of schoolchildren.

METHODS

Observational, cross-sectional study data were derived from 177,091 children aged 8 to 17 years participating in a health survey. Recreational screen time, physical activity (PA), and sleeping hours were assessed through self-completed questionnaires. Dietary habits were evaluated via the Mediterranean Diet Quality Index for children and adolescents (KIDMED) test. Anthropometric and physical fitness (PF) estimations were obtained by trained investigators.

RESULTS

Binary logistic regression comparisons between screen time levels (e.g. < 2 vs. ≥ 2 - < 3 h/d, < 2 vs. ≥ 3 - < 4 h/d and < 2 vs. ≥ 4 h/d) and dietary habits showed that the longer the screen time the increased the odds of unhealthy dietary habits such as skipping breakfast, consuming fast food frequently, and eating sweets frequently, and the decreased the odds of healthy dietary habits such as consuming a second fruit every day, consuming fresh or cooked vegetables or/and fish regularly, in both genders, after adjusting for several covariates. Furthermore, the longer the screen time the increased the odds of total and central obesity, insufficient sleep (< 8-9 h/d), and inadequate PA, and the decreased the odds of healthy PF.

CONCLUSIONS

The longer the screen time the unhealthier dietary habits and lifestyle profile among schoolchildren, after adjusting for several covariates.

Electronic Devices as Correlates of Sedentary Behavior and Screen Time Among Diverse Low-Income Adolescents During the School Year and Summer Time

Excessive screen time among adolescents increases risk for overweight and obesity. Having electronic devices in the adolescent's bedroom is associated with more screen time. The present study expanded on previous studies by also examining portable personal electronic devices and social media membership as correlates of screen time use and total sedentary time in the school year and summer among diverse low-income adolescents. Adolescents aged 10-17 years were recruited from lower-income areas; n=150 (34 African Americans, 23 American Indians, 16 Asian/Pacific Islanders, 39 Latinos, and 38 White/non-Hispanics) completed surveys and wore accelerometers in both the school year and summer. Total sedentary time was computed from accelerometers. Recreational screen time was assessed with a 3-item validated scale. Adolescents reported the presence of 6 electronic devices in their bedrooms, ownership of 4 portable devices, and social media membership. General linear modeling was conducted for both time periods, with demographic covariates and interactions with sex and race/ethnicity. More electronic devices in bedrooms were related to more screen time during the school year and summer, and to more total sedentary time in summer. Personal electronics were related only to more screen time in the school year. Social media membership was related to more total sedentary time in summer, but only among African Americans, American Indians, and non-Hispanic Whites. Electronic devices in bedrooms was confirmed as a risk factor for sedentary behavior among low-income adolescents of color. Social media membership and use should be further studied with diverse adolescents.

Sedentary behavior is more related with cardiovascular parameters in normal weight than overweight adolescents

This study analyzed the relationship between sedentary behavior and cardiovascular parameters in normal weight and overweight adolescents. The sample included 449 boys and 555 girls with mean age of 13 years from public schools, which were divided into five geographical regions, with data collections performed in one selected school from each region. Sedentary behavior was assessed by screen time on TV, computer, videogame and cell phone/tablet, with good reliability in adolescents. Physical activity was assessed by Baecke's questionnaire, validated for adolescents. Measures of body weight, height and waist circumference were collected. Adolescents were classified as overweight or normal weight by cut-off points of body mass index for age and sex. Cardiovascular parameters were evaluated by oscillometric device and heart rate by specific monitor. Computer use was positively related to systolic blood pressure (SBP) (β = 0.35; 95%CI = 0.07-0.62) and diastolic blood pressure (DBP) (β = 0.25; 95%CI = 0.05-0.44) in normal weight but not in overweight adolescents. Similar results were observed for cell phone/tablet in SBP (β = 0.46; 95%CI = 0.20-0.72) and DBP (β = 0.36; 95%CI = 0.18-0.54), only for normal weight. The cluster of screen time was related to SBP in normal weight (β = 0.44; 95%CI = 0.03-0.84) and overweight (β = 0.60; 95%CI = 0.01-1.19). Screen time in computer and cell phone/tablet was more related to cardiovascular parameters in normal weight than overweight adolescents.

The association between screen time and cardiometabolic risk in young children

OBJECTIVES

While studies exist on the association between screen time and cardiometabolic risk among adolescents, research examining the effect of screen time on cardiometabolic risk in young children is lacking. The primary objective of this study was to examine the association between daily screen time and cardiometabolic risk (CMR) [sum of age- and sex-standardized z-scores of systolic blood pressure (SBP), glucose, log-triglycerides, waist circumference (WC), and negative high-density lipoprotein (HDL) cholesterol divided by the square root of five] in young children. Secondary objectives included examining individual CMR risk factors, including waist-to-height ratio and non high-density lipoprotein (non-HDL) cholesterol, as well as the individual cut-offs of these risk factors. Additional analyses include examining the association between screen time and CMR by handheld/non-handheld devices.

METHODS

A study was conducted among young children 3 to 6 years from the TARGet Kids! practice-based research network in Toronto and Montreal, Canada. Children with one or more measures of screen time and CMR were included in this study. Generalized estimating equation (GEE) multivariable linear regressions and multivariable logistic regressions, using published cut-offs, were conducted to evaluate these associations.

RESULTS

Data from 1317 children [mean age 52 months (SD = 13.36), 44.34% female] were included for analyses. There was no evidence of associations between screen time and total CMR score or individual risk factors (p > 0.05) after adjusting for confounders. A statistically significant, but small association between daily screen time and non-HDL cholesterol was found (B = 0.046; CI = [0.017 to 0.075]; p = 0.002.

CONCLUSIONS

Though no relationship was reported between daily screen time and the majority of CMR factors in early childhood, there was an association between daily screen time and non-HDL cholesterol. As the relationship between daily screen time and CMR factors may not be apparent in early childhood, studies to evaluate longer-term cardiometabolic effects of screen time are needed. Although there is an evidence-based rationale to reduce screen time in early childhood, prevention of cardiometabolic risk may not be the primary driver.

Determinants of Physical Activity and Screen Time Trajectories in 7th to 9th Grade Adolescents-A Longitudinal Study

Physical activity (PA) in youth tends to decline with increasing age, while sedentary behaviour including screen time (ST) increases. There are adolescents, however, whose PA and ST do not follow this pattern. The aim of this study is (i) to examine trajectories in PA and ST from grade 7-9 among students in Berlin, and (ii) to investigate the relationship of these trajectories with individual factors and school type. For the present analyses, changes in students' PA and ST across three time points from 7th to 9th grade were assessed via self-report questionnaires. Positive and negative trajectories were defined for both PA (positive: increasing or consistently high, negative: decreasing or consistently low) and ST (vice versa). Multivariable logistic regression analyses were performed to identify possible predictors of PA and ST trajectories. In total, 2122 students were included (50.2% girls, mean age 12.5 (standard deviation 0.7) years). Compared to grade 7, less students of grade 9 fulfilled PA and ST recommendations (PA: 9.4% vs. 13.2%; ST: 19.4% vs. 25.0%). The positive PA trajectory included 44% of all students (63% boys), while the positive ST trajectory included 21% of all students (30% boys). Being a boy was significantly associated with a positive PA trajectory, while being a girl, having a high socioeconomic status, and attending a high school, were significantly associated with a positive ST trajectory. Different PA and ST trajectories among adolescents should be taken into account when implementing prevention programs for this target group.

Sedentary Behaviors in Today's Youth: Approaches to the Prevention and Management of Childhood Obesity: A Scientific Statement From the American Heart Association

This scientific statement is about sedentary behavior and its relationship to obesity and other cardiometabolic outcomes in youth. A deleterious effect of sedentary behavior on cardiometabolic health is most notable for screen-based behaviors and adiposity; however, this relation is less apparent for other cardiometabolic outcomes or when sedentary time is measured with objective movement counters or position monitors. Increasing trends of screen time are concerning; the portability of screen-based devices and abundant access to unlimited programming and online content may be leading to new patterns of consumption that are exposing youth to multiple pathways harmful to cardiometabolic health. This American Heart Association scientific statement provides an updated perspective on sedentary behaviors specific to modern youth and their impact on cardiometabolic health and obesity. As we reflect on implications for practice, research, and policy, what emerges is the importance of understanding the context in which sedentary behaviors occur. There is also a need to capture the nature of sedentary behavior more accurately, both quantitatively and qualitatively, especially with respect to recreational screen-based devices. Further evidence is required to better inform public health interventions and to establish detailed quantitative guidelines on specific sedentary behaviors in youth. In the meantime, we suggest that televisions and other recreational screen-based devices be removed from bedrooms and absent during meal times. Daily device-free social interactions and outdoor play should be encouraged. In addition, parents/guardians should be supported to devise and enforce appropriate screen time regulations and to model healthy screen-based behaviors.

Individual and family-based approaches to increase physical activity in adolescents with intellectual and developmental disabilities: Rationale and design for an 18 month randomized trial

Adolescents with intellectual and developmental disabilities (IDD) are less physically active and have lower cardiovascular fitness compared with their typically developing peers. This population faces additional barriers to participation in moderate-to-vigorous physical activity (MVPA) such as reliance on parents, lack of peer-support, and lack of inclusive physical activity opportunities. Previous interventions to increase MVPA in adolescents with IDD have met with limited success, at least in part due to requiring parents to transport their adolescent to an exercise facility. We recently developed a remote system to deliver MVPA to groups of adolescents with IDD in their homes via video conferencing on a tablet computer. This approach eliminates the need for transportation and provides social interaction and support from both a health coach and other participants. We will conduct a 18-mo. trial (6 mos. active, 6 mos. maintenance, 6 mos. no-contact follow-up) to compare changes in objectively assessed MVPA in 114 adolescents with IDD randomized to a single level intervention delivered only to the adolescent (AO) or a multi-level intervention delivered to both the adolescent and a parent (A + P). Our primary aim is to compare increases in MVPA (min/d) between the AO and A + P groups from 0 to 6 mos. Secondarily we will compare changes in MVPA, sedentary time, cardiovascular fitness, muscular strength, motor ability, quality of life, and the percentage of adolescents achieving the US recommendation of 60 min. MVPA/d across 18 mos. We will also explore the influence of process variables/participant characteristics on changes in MVPA across 18 mos. NCT registration: NCT03684512.

Heavy screen users are the heaviest among 10,000 children

This cross-sectional study examined the associations of recreational screen time (viewing TV programs on any screen-based device and computer use, performed while sitting) with body mass index (BMI) categories and waist-to-height ratio (WHtR) tertiles in 10,228 children (mean age 11.1 years, SD 0.8). We categorized the children into Light, Medium and Heavy TV viewers and computer users, and into Low, Medium and High exercise groups. Compared with Light TV viewers, Medium (OR: 1.30, 95% CI: 1.11–1.52, when adjusted for age, sex, language, sleep duration and exercise) and Heavy (OR: 1.57, 95% CI: 1.34–1.83) TV viewers had a higher risk of being overweight. Similarly, Heavy computer users had a higher risk of being overweight (OR: 1.42, 95% CI: 1.21–1.67). We observed interactions between exercise and TV viewing (p = 0.012) or computer use (p = 0.010). However, Heavy TV viewers had a higher risk of being overweight in all exercise groups. The associations of TV viewing and computer use were similar with BMI and WHtR. To conclude, heavy sedentary screen time is associated with overweight and central adiposity in children. Moreover, heavy TV viewers have a higher risk for overweight and central adiposity, regardless of weekly exercise duration.

Sexual Dimorphism of Brown Adipose Tissue Function

OBJECTIVE

To determine whether brown adipose tissue (BAT) activity in school-age children differs between the sexes and to explore the impact of dietary intake, sedentary behavior, and picky/fussy eating.

STUDY DESIGN

Children aged 8.5-11.8 years of age (n = 36) underwent infrared thermography to determine the temperature of the skin overlying the main superficial BAT depot in the supraclavicular region before and after 5 minutes of mild cold exposure (single-hand immersion in cool tap water at about 20°C). The relationships between the supraclavicular region temperature and parental reports of food consumption, eating behavior, and inactivity were explored.

RESULTS

The supraclavicular region temperature was higher in boys (n = 16) at baseline, and after cold exposure. Boys displayed a greater thermogenic response to cold. Strong negative correlations were observed between the supraclavicular region temperature and body mass index percentile, and differences in supraclavicular region temperature between girls and boys persisted after adjustment for body mass index percentile. A negative linear relationship was observed between protein and vegetable intake and supraclavicular region temperature in girls only, but did not persist after adjustment for multiple comparisons. There was no difference in the adjusted supraclavicular region temperature between active or inactive children, or picky and nonpicky eaters.

CONCLUSIONS

These findings indicate sexual dimorphism in BAT thermogenic activity and a sex-specific impact of diet. Future studies should aim to quantify the contribution of BAT to childhood energy expenditure, energy imbalance, and any role in the origins of childhood obesity.

Activity-related behavior typologies in youth: a systematic review

BACKGROUND

Clusters of adolescents differentiated by patterns of physical activity and sedentary behavior (activity-related typologies) are common. Understanding both the characteristics of adolescents and modifiable correlates of these typologies, can help to develop interventions for those most at risk. This systematic review aimed to synthesize the socio-demographic characteristics and modifiable correlates of activity-related behavioral typologies among adolescents.

METHODS

A systematic search of seven electronic databases was conducted to identify quantitative studies using person-oriented statistical approaches to identify activity-related behavioral typologies among 12-18 year-olds. This systematic review was registered in Prospero (registration number: CRD42016046879).

RESULTS

Thirty-six studies met the inclusion criteria and were classified according to three sub-themes based on behaviors included in the typologies (1. physical activity and sedentary behavior only; 2. physical activity, sedentary behavior and risk-related behaviors; 3. physical activity, sedentary behavior and diet). Studies were mostly cross-sectional and relied on self-report measures. Methods were considerably heterogeneous, however results revealed some consistency in typologies within specific groups. For example, typologies characterized by unhealthy behavior patterns (e.g., characterized by physical inactivity, high sedentary behavior and poor diet or high risk-related behaviors) comprised more older adolescents. With the exception of socio-demographics (age, sex, body mass index and socio-economic status), very few correlates have been studied to date (mostly school-related behavioral factors and intrapersonal influences), with evidence largely from typologies comprised of physical activity, sedentary behavior and diet.

CONCLUSIONS

More research is needed to assess a range of modifiable correlates associated with activity-related behavior typologies among adolescents. This will allow for more targeted interventions, to achieve long-lasting, positive behavior change in adolescent populations.

Preschool children's physical activity and cardiovascular disease risk: A systematic review

OBJECTIVES

Higher physical activity (PA) levels in adults are associated with lower cardiovascular disease risk, however it is unclear whether this association is evident in children younger than five years. Given that cardiovascular disease has early life origins, this study systematically reviews evidence of associations between PA and cardiovascular disease risk factors among children aged 3-5.5years.

DESIGN

Systematic review.

METHOD

A systematic search of multiple data bases was conducted to identify published papers reporting associations between any measure of PA and cardiovascular disease risk factors.

INCLUSION CRITERIA

English language; peer-reviewed; original quantitative research; mean age or majority of sample to be between 3.0-5.5years. Studies where the sample was characterised by a health condition (e.g. obese, hypertensive) were not eligible for inclusion.

RESULTS

Twelve papers met the inclusion criteria. At least one study for each cardiovascular disease risk factor except inflammation was included. PA was not associated with insulin resistance, and inconsistently associated with the remaining cardiovascular disease risk factors. Studies were mostly cross-sectional and methodologically heterogeneous. Longitudinal and experimental study designs and objective measurement of PA may help provide a clearer indication of the interplay between PA and cardiovascular disease risk in the preschool population.

Associations between different weight-related anthropometric traits and lifestyle factors in Norwegian children and adolescents: A case for measuring skinfolds

OBJECTIVES

The purpose of this study was to investigate the association between weight-related anthropometric measures and children's eating habits, physical activity and sedentary lifestyle at a population level.

METHODS

Data from the Bergen Growth Study were used to study the association of z-scores of waist circumference (WC), weight-to-height ratio (WHtR), subscapularis (SSF) and triceps (TSF) skinfolds and BMI, with lifestyle factors in 3063 Norwegian children (1543 boys) aged 4-15 years, using linear regression analysis. Each sex was analyzed separately.

RESULTS

In a fully adjusted model with additional correction for BMI z-scores, the consumption of vegetables was associated with higher WC (b = 0.03) and TSF (b = 0.05) z-scores in girls. Sedentary behavior was not associated with any of the anthropometric measures. Physical activity was negatively associated with SSF (b = -0.07) and TSF (b = -0.07) z-scores in boys, while a significant negative association was observed with WC (b = -0.02), WHtR (b = -0.03), SSF (b = -0.04) and TSF (b = -0.06) in girls.

CONCLUSION

Physical activity was negatively associated with skinfolds in both sexes. The BMI was not related to the level of physical activity, and should be complemented with direct measures of fat tissue, like skinfolds, when studying the effect of physical activity on body composition in children.

Relationship between screen time and nutrient intake in Japanese children and adolescents: a cross-sectional observational study

Background

Sedentary behaviors have recently become an important public health issue. We aimed to investigate the relationship between screen time and nutrient intake in children and adolescents.

Methods

The present study was conducted in 2013. Data were collected from children and adolescents aged between 6 and 15 years old in Shika town. Questionnaires were distributed to 1459 subjects, 1414 of whom participated in the study (96.9%). Sedentary behaviors were assessed based on participants’ screen behaviors (television (TV) viewing, personal computer (PC) use, and mobile phone (MP) use). The main outcomes were the intake of nutrients from a validated food frequency questionnaire. Analysis of covariance (ANCOVA) was used to examine the significance of differences in nutrient intake estimates. Multivariate linear regression analyses, adjusting for age, BMI, and physical activity, were used to provide parameter estimates (β) and 95% CI for the relationship between screen time and nutrient intake.

Results

In boys, longer TV viewing times correlated or tended to correlate with a lower intake of protein, potassium, calcium, iron, vitamin K, vitamin B-2, and total dietary fiber. In girls, longer TV viewing times correlated with a lower intake of protein, sodium, calcium, vitamin D, and vitamin B-2. Longer TV viewing times correlated with a higher intake of n-6 fatty acids in girls. PC use was related or tended to be related to a lower intake of potassium, iron, vitamin K, and folic acid in boys, but not in girls. A relationship was observed between MP use and a lower intake of vitamin K in boys, and MP use and a higher intake of vitamin D in girls.

Conclusions

The present results revealed that longer TV viewing times are associated with less protein, minerals, vitamins, and total dietary fiber intake in children and adolescents. It was also revealed that boys with PC use have less minerals and vitamins. These results support the need to design intervention programs that focus on decreasing TV viewing time in both sexes and PC use in boys while encouraging adherence to dietary guidelines among children and adolescents.

The Associations between Dietary Patterns and Sedentary Behaviors in Polish Adults (LifeStyle Study)

Sedentary behavior, a low physical activity level, and unhealthy dietary patterns are risk factors for major chronic diseases, including obesity. The aim of this study was to assess the associations of dietary patterns (DPs) with sedentary behaviors (SB) and self-reported physical activity (PA). The data was collected in November 2016 through a cross-sectional quantitative survey amongst 1007 Polish adults. Principal components analysis (PCA) was conducted to derive DPs. Logistic regression analysis was used to verify associations between PA and SD (independent variables), and DPs (dependent variables). Five DPs ('Fast foods & sweets'-FF&S; 'Meat & meat products'-M&MP; 'Fruit & vegetable'-F&V; 'Wholemeal food'-WF; 'Fruit & vegetable juices'-F&VJ) were identified. Representing M&MP independently increased the chance of watching TV at least once a day (by 73%). There was no such relationship between the FF&S and sedentary behaviors. Being in the upper tertiles of pro-health DPs increased the chance of reading books (by 177%-F&V, 149%-WF, 54%-F&VJ) and watching TV (by 71%-F&V). On the other hand, belonging to the upper tertile of WF reduced the chance of using the computer for more than 4 h a day. Belonging to the upper tertile of healthy DPs (WF and F&VJ) increased the chances of moderate or high physical activity, both at work/school and during leisure time. Within F&V, there was a lower chance of moderate or high physical activity at work/school. Being in the upper tertile of unhealthy DPs (FF&S and M&MP) did not show any significant association with physical activity. The study indicated the associations between both healthy and unhealthy DPs and some sedentary behaviors. Association between F&V and watching TV and reading books/newspapers should be recognized as potentially efficient in education. Association between M&MP and watching television can be indicative of the mutual overlap of a negative lifestyle resulting in the development of overweight and obesity, especially since the extent of occurrence of sedentary behaviors is high.

Eating breakfast and snacks while television viewing are associated with some cardio metabolic risk factors among Iranian children

AIM

We aimed to investigate the association of eating meals while television viewing (TVV) and screen-based behaviors with cardio metabolic risk factors (CRFs) among school-aged children in Shiraz.

MATERIALS AND METHODS

This cross-sectional study was done on 409 primary school children (217 boys), aged 6-9 years. Physical activity, time spent on screen-based behaviors and frequency of eating meals while TVV were measured using a questionnaire. Anthropometric indices, fasting blood sugar (FBS), blood lipids, blood pressure (BP), dietary intakes and physical activity were assessed. Association of eating while TVV with CRFs were assessed using linear regression, adjusted for potential confounders. All statistical analysis were conducted using the Stata 13 software.

RESULTS

Fully adjusted model showed that TVV time had significant positive association with waist circumferences (WC), and BP (p <0.05). Also, we found an inverse relationship between using Computer and Video games with TG level (β=-0.3; CI: -0.64, -0.09). Children who ate two or more breakfast meal while TVV had higher WC (β=2.02; CI: 0.51, 3.53) and FBS (β=3.58; CI: 0.39, 6.78) compared to who never ate breakfast while TVV. After adjustment for Screen time and BMI, eating snacks while TVV was positively associated with FBS and systolic BP. However, Eating dinner and lunch while TVV were not significantly associated with any of CRFs after adjustment for confounders.

CONCLUSIONS

We found that both eating breakfast and snacks while TVV were associated with WC, FBS and BP in children. Also, excessive TVV was associated with WC and BP.

Conflicting relationship between dietary intake and metabolic health in PTSD: A systematic review

Posttraumatic stress disorder (PTSD) is a disabling psychological condition associated with significant physical comorbidities. There has been growing evidence to support the relationship between PTSD and cardiometabolic disease. Disordered eating behaviors often seen in people with PTSD symptoms may explain increased cardiometabolic risk. This systematic review aimed to assess the quality of evidence surrounding dietary intake of individuals with symptoms or a diagnosis of PTSD and their associated risk with cardiometabolic health outcomes. Online databases Scopus, ProQuest (Health), Embase, Medline, PsycINFO, and CINAHL with Full Text were searched for peer-reviewed English articles prior to December 2017 that examined dietary intake and cardiometabolic health outcomes in adults with PTSD symptoms or diagnosis. The quality of each study was graded based on the design and methodology using adapted quality assessment tools. Seven studies with five unique participant samples were included in the review. Study methods, design, populations, and outcomes were inconsistent across studies. Dietary intake was considerably varied and limited associations were demonstrated between dietary intake and cardiometabolic risk factors in the PTSD cohorts. Due to the variability of measures and study outcomes, there was insufficient evidence to determine the relationship between dietary intake and PTSD-related cardiometabolic health outcomes. Future studies are needed to examine these associations in individuals with PTSD: specifically higher quality descriptive studies are necessary to confirm a link between diet and cardiometabolic disease in PTSD.

Association of eating while television viewing and overweight/obesity among children and adolescents: a systematic review and meta-analysis of observational studies

The objective of this systematic review and meta-analysis was to examine the association between eating while television viewing (TVV) and overweight or obesity in children (<18 years). A systematic search of PubMed, Scopus, Web of science, PreQuest and Embase was conducted up to April 2017; pooled odds ratio (OR) and 95% confidence intervals (CI) were calculated using a random effects model. Of 4,357 articles identified, 20 observational studies met inclusion criteria (n = 84,825) and 8 of these 20 (n = 41,617) reported OR. Eating while TVV was positively associated with obesity-related anthropometric measurements in 15 studies (75%). The meta-analysis revealed that eating while TVV was positively associated with being overweight (OR = 1.28; 95% CI: 1.17, 1.39). Subgroup analyses showed similar positive associations in both girls and boys, as well as in children who ate dinner while TVV. There was no evidence of publication bias. The present systematic review and meta-analysis suggests that eating while TVV could be a risk factor for being overweight or obese in childhood and adolescents.

From Diabetes Care to Diabetes Cure-The Integration of Systems Biology, eHealth, and Behavioral Change

From a biological view, most of the processes involved in insulin resistance, which drives the pathobiology of type 2 diabetes, are reversible. This theoretically makes the disease reversible and curable by changing dietary habits and physical activity, particularly when adopted early in the disease process. Yet, this is not fully implemented and exploited in health care due to numerous obstacles. This article reviews the state of the art in all areas involved in a diabetes cure-focused therapy and discusses the scientific and technological advancements that need to be integrated into a systems approach sustainable lifestyle-based healthcare system and economy. The implementation of lifestyle as cure necessitates personalized and sustained lifestyle adaptations, which can only be established by a systems approach, including all relevant aspects (personalized diagnosis and diet, physical activity and stress management, self-empowerment, motivation, participation and health literacy, all facilitated by blended care and ehealth). Introduction of such a systems approach in type 2 diabetes therapy not only requires a concerted action of many stakeholders but also a change in healthcare economy, with new winners and losers. A "call for action" is put forward to actually initiate this transition. The solution provided for type 2 diabetes is translatable to other lifestyle-related disorders.

Association between overweight/obesity and eating habits while watching television among primary-school children in the city of Shiraz, Iran

OBJECTIVE

It has been reported that television (TV) viewing is associated with childhood obesity in Western countries. The present study aimed to investigate the relationship between obesity and eating habits while watching TV among primary-school children in the Middle East.

DESIGN

Cross-sectional.

SETTING

Children were recruited from primary schools of four educational districts in Shiraz, Iran. Anthropometric indices of mass (kg) and height (m) were measured, and BMI (percentile) was calculated. Demographic characteristics, TV viewing behaviours and physical activity data were collected from parents during face-to-face interviews and a 3d dietary record was completed. Subject Children (n 607) aged 6-10 years.

RESULTS

Mean (sd) age of children was 8·16 (1·37) years, of whom 9·1 and 8·4 % were overweight and obese, respectively. Children who spent ≥2 h watching TV on weekdays (OR=1·99; 95 % CI 1·09, 3·60) and weekend days (OR=1·86; 95 % CI 1·01, 3·43) had higher odds of being obese, even after adjusting for physical activity. Children who ate breakfast while watching TV had higher odds of being overweight v. those who did not watch TV while eating breakfast (OR=2·70; 95 % CI 1·02, 7·60). There were no associations between TV viewing during other meals (lunch and dinner) and overweight/obesity.

CONCLUSIONS

TV viewing for ≥2 h daily increases the risk of being obese in Iranian children aged 6-10 years, independent of physical activity. Further, breakfast consumption while watching TV may increase the risk of overweight/obesity, independent of total TV viewing time.

Sedentary behaviours and health-related quality of life. A systematic review and meta-analysis

Researchers have speculated that sedentary behaviour may reduce health-related quality of life (HRQOL), but the extent to which this is true remains unknown. Our study sought to systematically review and synthesise research on the relationship between sedentary behaviours and HRQOL and to investigate if these relationships are moderated by age, health status, and HRQOL domain. The review was registered with PROSPERO (no. CRD42016036342). We searched six electronic databases. The selection process resulted in including k = 27 original studies; k = 18 were included in a meta-analysis. Data were synthesised twice, using the methods of systematic review and meta-analysis, in order to reduce biases related to a small number of included studies. Both the systematic review and meta-analytical methods indicated that lower levels of sedentary behaviours were associated with higher physical HRQOL (estimate of average effect: r = -.140; 95% CI -.191, -.088). Moderator analyses indicated that associations between the physical HRQOL domain and sedentary behaviours may be similar in strength across age- and health status groups. Causal inferences could not be drawn as most studies were cross-sectional. Concluding, sedentary behaviours were related to better physical HRQOL but not reliably to mental and social HRQOL.

Cross-sectional and prospective mediating effects of dietary intake on the relationship between sedentary behaviour and body mass index in adolescents

BACKGROUND

Cross-sectional evidence suggests TV viewing, but not objectively-measured sedentary time or bouts of sedentary time, is consistently associated with body mass index (BMI) in adolescents. However, it is unclear whether dietary intake is a potential mediator of these relationships. The aim of this study was to explore the cross-sectional and prospective mediating effects of dietary intake on the association of sedentary behaviour with BMI z-score (zBMI) in a cohort of Australian adolescents.

METHODS

Cross-sectional and prospective analyses were conducted in adolescents aged 12-15 years participating in the 2002/03 (baseline) and 2004/05 (follow-up) Nepean Growing Up Study. The independent variables were television (TV) viewing, an objective measure of total sedentary time and average sedentary bout duration, and the outcome variable zBMI. Using the Sobel-Goodman method with bootstrapping, mediation analyses were conducted examining three dietary components (discretionary foods, sugar-sweetened beverages [SSB] and takeaway foods) as mediators of associations between TV viewing and zBMI (n = 259) and between total sedentary time and average sedentary bout duration with zBMI (n = 140).

RESULTS

No significant cross-sectional or prospective total or direct associations were observed for TV viewing, total sedentary time and average sedentary bout duration with zBMI. However, TV viewing was positively associated with consumption of takeaway foods cross-sectionally (β = 0.06; 95% CI 0.01 to 0.12), prospectively at baseline (β = 0.07; 95% CI 0.01 to 0.12) and prospectively at follow-up (β = 0.10; 95% CI 0.04, 0.16), and average sedentary bout duration was inversely associated with SSB consumption both cross-sectionally (β = -0.36; 95% CI -0.69 to -0.02) and prospectively at baseline (β = -0.36; 95% CI -0.70 to -0.02). No mediation effects were identified.

CONCLUSIONS

TV viewing, total sedentary time and bouts of sedentary time were not associated cross-sectionally or prospectively with adolescents' zBMI, and three elements of dietary intake (e.g. intake of discretionary foods, SSB and takeaway foods) did not mediate this relationship. The role of dietary intake and sedentary behaviour in relation to adolescent health requires further clarification.

Standing Classrooms: Research and Lessons Learned from Around the World

Children spend between 50 and 70 % of their time sitting while at school. Independent of physical activity levels, prolonged sitting is associated with poor health outcomes in adulthood. While there is mixed evidence of health associations among children and adolescents, public health guidelines in the USA, UK, Australia and Canada now recommend young people should break up long periods of sitting as frequently as possible. A potentially effective approach for reducing and breaking up sitting throughout the day is changing the classroom environment. This paper presents an overview of a relatively new area of research designed to reduce youth sitting time while at school by changing the classroom environment (n = 13 studies). Environmental changes included placement of height-adjustable or stand-biased standing desks/workstations with stools, chairs, exercise balls, bean bags or mats in the classroom. These 13 published studies suggest that irrespective of the approach, youth sitting time was reduced by between ~44 and 60 min/day and standing time was increased by between 18 and 55 min/day during classroom time at school. Other benefits include increased energy expenditure and the potential for improved management of students' behaviour in the classroom. However, few large trials have been conducted, and there remains little evidence regarding the impact on children's learning and academic achievement. Nevertheless, with an increasing demand placed on schools and teachers regarding students' learning outcomes, strategies that integrate moving throughout the school day and that potentially enhance the learning experience and future health outcomes for young people warrant further exploration.

Augmented Reality Video Games: New Possibilities and Implications for Children and Adolescents

In recent years, the video game market has embraced augmented reality video games, a class of video games that is set to grow as gaming technologies develop. Given the widespread use of video games among children and adolescents, the health implications of augmented reality technology must be closely examined. Augmented reality technology shows a potential for the promotion of healthy behaviors and social interaction among children. However, the full immersion and physical movement required in augmented reality video games may also put users at risk for physical and mental harm. Our review article and commentary emphasizes both the benefits and dangers of augmented reality video games for children and adolescents.

Impact of school policies on non-communicable disease risk factors - a systematic review

BACKGROUND

Globally, non-communicable diseases (NCDs) are identified as one of the leading causes of mortality. NCDs have several modifiable risk factors including unhealthy diet, physical inactivity, tobacco use and alcohol abuse. Schools provide ideal settings for health promotion, but the effectiveness of school policies in the reduction of risk factors for NCD is not clear. This study reviewed the literature on the impact of school policies on major NCD risk factors.

METHODS

A systematic review was conducted to identify, collate and synthesize evidence on the effectiveness of school policies on reduction of NCD risk factors. A search strategy was developed to identify the relevant studies on effectiveness of NCD policies in schools for children between the age of 6 to 18 years in Ovid Medline, EMBASE, and Web of Science. Data extraction was conducted using pre-piloted forms. Studies included in the review were assessed for methodological quality using the Effective Public Health Practice Project (EPHPP) quality assessment tool. A narrative synthesis according to the types of outcomes was conducted to present the evidence on the effectiveness of school policies.

RESULTS

Overall, 27 out of 2633 identified studies were included in the review. School policies were comparatively more effective in reducing unhealthy diet, tobacco use, physical inactivity and inflammatory biomarkers as opposed to anthropometric measures, overweight/obesity, and alcohol use. In total, for 103 outcomes independently evaluated within these studies, 48 outcomes (46%) had significant desirable changes when exposed to the school policies. Based on the quality assessment, 18 studies were categorized as weak, six as moderate and three as having strong methodological quality.

CONCLUSION

Mixed findings were observed concerning effectiveness of school policies in reducing NCD risk factors. The findings demonstrate that schools can be a good setting for initiating positive changes in reducing NCD risk factors, but more research is required with long-term follow up to study the sustainability of such changes.

Sedentary behaviour and adiposity in youth: a systematic review of reviews and analysis of causality

Background

Sedentary behaviour (sitting time) has becoming a very popular topic for research and translation since early studies on TV viewing in children in the 1980s. The most studied area for sedentary behaviour health outcomes has been adiposity in young people. However, the literature is replete with inconsistencies.

Methods

We conducted a systematic review of systematic reviews and meta-analyses to provide a comprehensive analysis of evidence and state-of-the-art synthesis on whether sedentary behaviours are associated with adiposity in young people, and to what extent any association can be considered ‘causal’. Searches yielded 29 systematic reviews of over 450 separate papers. We analysed results by observational (cross-sectional and longitudinal) and intervention designs.

Results

Small associations were reported for screen time and adiposity from cross-sectional evidence, but associations were less consistent from longitudinal studies. Studies using objective accelerometer measures of sedentary behaviour yielded null associations. Most studies assessed BMI/BMI-z. Interventions to reduce sedentary behaviour produced modest effects for weight status and adiposity. Accounting for effects from sedentary behaviour reduction alone is difficult as many interventions included additional changes in behaviour, such as physical activity and dietary intake. Analysis of causality guided by the classic Bradford Hill criteria concluded that there is no evidence for a causal association between sedentary behaviour and adiposity in youth, although a small dose-response association exists.

Conclusions

Associations between sedentary behaviour and adiposity in children and adolescents are small to very small and there is little to no evidence that this association is causal. This remains a complex field with different exposure and outcome measures and research designs. But claims for ‘clear’ associations between sedentary behaviour and adiposity in youth, and certainly for causality, are premature or misguided.

The mediating role of energy intake on the relationship between screen time behaviour and body mass index in adolescents with obesity: The HEARTY study

Adolescents spend up to 6-8 h/day in sedentary screen behaviour and screen time is an independent risk factor for obesity. However, the mechanisms by which screen time confers obesity risk remain unclear. Via community level recruitment this study examined whether the relationship between screen time behaviours and body mass index (BMI: kg/m²) was mediated by total energy intake or macronutrient consumption. In a cross-sectional study of post-pubertal adolescents (N = 283: 86M, 197F) with overweight or obesity at baseline of an intervention for weight control, we examined self-reported total energy intake (mean Calories from 3 day food diary), macronutrient intake (grams/day of carbohydrate, fat, protein) and total screen time (aggregate of hours/day watching TV, playing seated video games, and recreational computer use). BMI was objectively measured and converted to standardized scores (z-BMI). Simple and multiple mediation analyses were conducted using the bootstrapping approach described by Preacher and Hayes. Covariates included age, sex, ethnicity, parental education, Tanner stage, and self-reported physical activity. The relationship between screen time and z-BMI was significantly mediated by energy intake. Higher levels of carbohydrate intake, but not fat or protein intake, significantly mediated the relationship between screen time and z-BMI (95% bias-corrected and accelerated confidence interval [0.0004, 0.0074]). Higher carbohydrate intake mediated the relationship between TV viewing and z-BMI, and video gaming and z-BMI. In conclusion, the relationship between screen time and BMI appears to be mediated by increased energy intake, primarily in the form of higher carbohydrate intake. It is possible that reducing time spent watching TV and playing video games may reduce food intake and help promote dietary adherence needed for weight management in obese adolescents.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov ID: NCT00195858.