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

Losing sleep influences dietary intake in children: a longitudinal compositional analysis of a randomised crossover trial

BACKGROUND

Although inadequate sleep increases the risk of obesity in children, the mechanisms remain unclear. The aims of this study were to assess how sleep loss influenced dietary intake in children while accounting for corresponding changes in sedentary time and physical activity; and to investigate how changes in time use related to dietary intake.

METHODS

A randomized crossover trial in 105 healthy children (8-12 years) with normal sleep (~ 8-11 h/night) compared sleep extension (asked to turn lights off one hour earlier than usual for one week) and sleep restriction (turn lights off one hour later) conditions, separated by a washout week. 24-h time-use behaviors (sleep, wake after sleep onset, physical activity, sedentary time) were assessed using waist-worn actigraphy and dietary intake using two multiple-pass diet recalls during each intervention week. Longitudinal compositional analysis was undertaken with mixed effects regression models using isometric log ratios of time use variables as exposures and dietary variables as outcomes, and participant as a random effect.

RESULTS

Eighty three children (10.2 years, 53% female, 62% healthy weight) had 47.9 (SD 30.1) minutes less sleep during the restriction week but were also awake for 8.5 (21.4) minutes less at night. They spent this extra time awake in the day being more sedentary (+ 31 min) and more active (+ 21 min light physical activity, + 4 min MVPA). After adjusting for all changes in 24-h time use, losing 48 min of sleep was associated with consuming significantly more energy (262 kJ, 95% CI:55,470), all of which was from non-core foods (314 kJ; 43, 638). Increases in sedentary time were related to increased energy intake from non-core foods (177 kJ; 25, 329) whereas increases in MVPA were associated with higher intake from core foods (72 kJ; 7,136). Changes in diet were greater in female participants.

CONCLUSION

Loss of sleep was associated with increased energy intake, especially of non-core foods, independent of changes in sedentary time and physical activity. Interventions focusing on improving sleep may be beneficial for improving dietary intake and weight status in children.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ANZCTR ACTRN12618001671257, Registered 10th Oct 2018, https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=367587&isReview=true.

Modifiable lifestyle risk factors for overweight and obesity in children and adolescents with type 1 diabetes: A systematic review

This review aims to identify and report epidemiological associations between modifiable lifestyle risk factors for overweight or obesity in children and adolescents with type 1 diabetes (T1D). A systematic literature search of medical databases from 1990 to 2023 was undertaken. Inclusion criteria were observational studies reporting on associations between dietary factors, disordered eating, physical activity, sedentary and sleep behaviours and measures of adiposity in children and adolescents (<18 years) with T1D. Thirty-seven studies met inclusion criteria. Studies were mostly cross-sectional (89 %), and 13 studies included adolescents up to 19 years which were included in this analysis. In adolescents with T1D, higher adiposity was positively associated with disordered eating behaviours (DEB) and a higher than recommended total fat and lower carbohydrate intake. A small amount of evidence suggested a positive association with skipping meals, and negative associations with diet quality and sleep stage. There were no published associations between overweight and physical activity, sedentary behaviours and eating disorders. Overall, the findings infer relationships between DEB, fat and carbohydrate intake and adiposity outcomes in people with T1D. Prospective studies are needed to determine causal relationships and to investigate sleep stages. High quality studies objectively measuring physical activity and include body composition outcomes are needed.

The association between device-measured sitting time and cardiometabolic health risk factors in children

BACKGROUND

There is limited evidence of the associations between postural-derived sitting time, waist-worn derived sedentary time and children's health and the moderation effect of physical activity (PA). This study examined associations of children's device-measured sitting time with cardiometabolic health risk factors, including moderation by physical activity.

METHODS

Cross-sectional baseline data from children (mean-age 8.2 ± 0.5 years) in Melbourne, Australia (2010) participating in the TransformUs program were used. Children simultaneously wore an activPAL to assess sitting time and an ActiGraph GT3X to assess sedentary time and physical activity intensity. Cardiometabolic health risk factors included: adiposity (body mass index [BMI], waist circumference [WC]), systolic and diastolic blood pressure (SBP, DBP), high-density lipoprotein (HDL), low-density lipoprotein (LDL), cholesterol, triglycerides, fasting plasma glucose (FPG), serum insulin, and 25-hydroxyvitaminD (25[OH]D). Linear regression models (n = 71-113) assessed associations between sitting time with each health risk factor, adjusted for different PA intensities (i.e. light [LIPA], moderate-vigorous intensities [MVPA], separately on each model), age, sex, adiposity, and clustering by school. Interaction terms examined moderation. The analyses were repeated using device-measured sedentary time (i.e. ActiGraph GT3X) for comparison.

RESULTS

Sitting time was positively associated with SBP (b = 0.015; 95%CI: 0.004, 0.026), DBP (b = 0.012; 95%CI:0.004, 0.020), and FPG (b = 0.001; 95%CI: 0.000, 0.000), after adjusting for higher PA intensities. The association between sitting time and insulin (b = 0.003; 95%CI: 0.000, 0.006) was attenuated after adjusting for higher PA intensities. When the models were adjusted for LIPA and MVPA, there was a negative association with LDL (b=-0.001; 95%CI: -0.002, -0.000 and b=-0.001; 95%CI: -0.003, -0.000, respectively). There was a negative association of sedentary time with WCz (b=-0.003; 95%CI: -0.005, 0.000) and BMIz (b=-0.003; 95%CI: -0.006, -0.000) when the models were adjusted by MVPA. Sedentary time was positively associated with triglycerides (b = 0.001; 95%CI: 0.000, 0.001) but attenuated after adjusting for MVPA. No evidence of moderation effects was found.

CONCLUSIONS

Higher volumes of sitting and sedentary time were associated with some adverse associations on some cardiometabolic health risk factors in children. These associations were more evident when sitting time was the predictor. This suggests that reducing time spent sitting may benefit some cardiometabolic health outcomes, but future experimental research is needed to confirm causal relationships and identify the biological mechanisms that might be involved.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry: ACTRN12609000715279.

Adherence to a healthy lifestyle behavior composite score and cardiometabolic risk factors in Spanish children from the CORALS cohort

To assess the associations between the adherence to a composite score comprised of 6 healthy lifestyle behaviors and its individual components with several cardiometabolic risk factors in Spanish preschool children. Cross-sectional analyses were conducted in 938 participants included in the CORALS cohort aged 3-6 years. Six recognized healthy lifestyle behaviors (breastfeeding, sleep duration, physical activity, screentime, adherence to the Mediterranean diet, and eating speed) were assessed in a composite score. Multiple linear and logistic regression models were fitted to assess the associations with cardiometabolic risk factors (weight status, waist circumference, fat mass index, blood pressure, fasting plasma glucose, and lipid profile). In the adjusted multiple linear and logistic regression models, compared with the reference category of adherence to the healthy lifestyle behavior composite score, those participants in the category of the highest adherence showed significant decreased prevalence risk of overweight or obesity [OR (95% CI), 0.4 (0.2, 0.6)] as well as significant lower waist circumference, fat mass index (FMI), systolic blood pressure and fasting plasma glucose concentration [β (95% CI), - 1.4 cm (- 2.5, - 0.4); - 0.3 kg/m2 (- 0.5, - 0.1); and - 3.0 mmHg (- 5.2, - 0.9); - 1.9 mg/dL (- 3.5, - 0.4), respectively]. Slow eating speed was individually associated with most of the cardiometabolic risk factors.   Conclusions: Higher adherence to the healthy lifestyle behavior composite score was associated with lower waist circumference, FMI, other cardiometabolic risk factors, and risk of overweight or obesity in Spanish preschool children. Further studies are required to confirm these associations. What is Known: • Lifestyle is a well-recognized etiologic factor of obesity and its comorbidities. • Certain healthy behaviors such as adhering to a healthy diet, increasing physical activity, and decreasing screentime are strategies for prevention and treatment of childhood obesity. What is New: • Higher adherence to the healthy lifestyle behavior composite score to 6 healthy behaviors (breastfeeding, sleep duration, physical activity, screentime, eating speed, and adherence to the Mediterranean diet) was associated with decreased adiposity, including prevalence risk of overweight or obesity, and cardiometabolic risk in preschool children. • Slow eating and greater adherence to the Mediterranean diet were mainly associated to lower fasting plasma and serum triglycerides concentration, respectively.

Decreasing Sedentary Time during Lessons Reduces Obesity in Primary School Children: The Active Movement Study

INTRODUCTION

School-based exercise interventions targeted at reducing obesity are often successful in the short term, but they are resource-heavy and do not always lead to long-lasting behaviour changes. This study investigated the effect of reducing sedentary time, rather than increasing exercise, on physical activity (PA) behaviours and obesity in primary school children.

METHODS

Thirty UK state primary schools participated in this cluster-controlled intervention study (IDACI score = 0.15 ± 0.07, free school meals = 26 ± 9%). Twenty-six intervention and 4 control schools (intervention = 3,529, control = 308 children) completed the Physical Activity Questionnaire for Children (PAQ-C) in terms 1 and 3. Three intervention and 3 control schools (intervention = 219, control = 152 children) also measured waist-to-height ratio (WTHR). The Active Movement Intervention is a school-based programme which integrates non-sedentary behaviours such as standing and walking in the classroom. Data were analysed via ANCOVAs and multiple linear regressions.

RESULTS

WTHR was reduced by 8% in the intervention group only (F(2, 285) = 11.387, p < 0.001), and sport participation increased by 10% in the intervention group only (F(1, 232) = 6.982, p = 0.008). Other PAQ-C measures increased significantly in the intervention group, but there was no group*time interaction. Changes in PAQ-C did not predict reductions in WTHR. Instead, the amount of change in WTHR was predicted by intervention group and by baseline WTHR of the pupil, where children with higher baseline WTHR showed greater reductions (F(2, 365) = 77.21, p < 0.001, R2 = 0.30). Socio-economic status (SES), age, or gender did not mediate any of the changes in the PAQ-C or WTHR.

CONCLUSION

Reducing sedentary behaviours during school time can be an effective obesity reduction strategy for primary school children who are overweight. The lack of demographic effects suggests that this method can be effective regardless of the school's SES, pupil age, or gender.

Are there associations between sedentary time inside and outside preschools with preschoolers' executive function?

Preschool children spend a large part of their day at school, and a large part of that time they spend in sedentary time. Although sedentary time negatively affects regions of the brain responsible for cognition, it is believed that the type of sedentary time performed can favor executive functions' performance. The present study explored the associations between sedentary time inside and outside preschools with executive function (EF) tasks in preschoolers. Seventy-three preschool children (60% girls; 55.0 ± 9.1 months of age) were objectively assessed for sedentary time and physical activity (PA) using accelerometers (wGT3X). EF was evaluated using the Go/No-Go paradigm through the Early Years Toolbox - YET. Go's inverse efficiency (IE) and the No-Go accuracy were analyzed. To establish possible associations between EF and sedentary time, a structural equation model was conducted after adjustments for sex, age, body mass index, and moderate-to-vigorous PA. A significant and positive association between sedentary time on weekend days and IE (b = 0.61; p < .001) was observed. The general model explained 52% of the variation in IE and 2.1% in the accuracy of No-Go. The sedentary time on weekend days seems to be related to worse EI. This result emphasizes a context-dependent association between time being sedentary and preschoolers' EF. Further investigations should focus on exploring the type of sedentary behavior children are engaged in different contexts.

Why don't college freshmen meet the US dietary guidelines for added sugar, refined grains, sodium, and saturated fat?

OBJECTIVE

The objective of the study was to evaluate how well college students meet U.S. dietary guidelines by examining the mean intakes of nutrients to limit (sodium, sugar, refined grains, and saturated fat), and what factors lead to exceeding the dietary recommendations.

PARTICIPANTS

Participants were first-year undergraduate students (N = 269).

METHODS

Diet was assessed using a DHQ-III and estimated with food source composition tables. Multivariable logistic regression analysis was used to model variables associated with exceeding the recommendations. One-sample t-tests were performed to compare the cohort with national intakes.

RESULTS

One-third met added sugar guidelines; only 4% met daily refined grains requirements, Fewer than half met saturated fat guidelines, and slightly over half met recommended sodium guidelines. Level of physical activity, race/ethnicity, and living on campus were the important predictors for exceeding recommended intakes.

CONCLUSIONS

Most students do not adhere to the U.S. dietary guidelines for nutrients to limit.

Evidence for the contribution of the gut microbiome to obesity and its reversal

Obesity has become a worldwide pandemic affecting more than 650 million people and is associated with a high burden of morbidity. Alongside traditional risk factors for obesity, the gut microbiome has been identified as a potential factor in weight regulation. Although rodent studies suggest a link between the gut microbiome and body weight, human evidence for causality remains scarce. In this Review, we postulate that existing evidence remains to establish a contribution of the gut microbiome to the development of obesity in humans but that modified probiotic strains and supraphysiological dosages of microbial metabolites may be beneficial in combatting obesity.

Low movement, deep-learned sitting patterns, and sedentary behavior in the International Study of Childhood Obesity, Lifestyle and the Environment (ISCOLE)

BACKGROUND/OBJECTIVES

Sedentary behavior (SB) has both movement and postural components, but most SB research has only assessed low movement, especially in children. The purpose of this study was to compare estimates and health associations of SB when derived from a standard accelerometer cut-point, a novel sitting detection technique (CNN Hip Accelerometer Posture for Children; CHAP-Child), and both combined.

METHODS

Data were from the International Study of Childhood Obesity, Lifestyle, and the Environment (ISCOLE). Participants were 6103 children (mean ± SD age 10.4 ± 0.56 years) from 12 countries who wore an ActiGraph GT3X+ accelerometer on the right hip for approximately one week. We calculated SB time, mean SB bout duration, and SB breaks using a cut-point (SBmovement), CHAP-Child (SBposture), and both methods combined (SBcombined). Mixed effects regression was used to test associations of SB variables with pediatric obesity variables (waist circumference, body fat percentage, and body mass index z-score).

RESULTS

After adjusting for MVPA, SBposture showed several significant obesity associations favoring lower mean SB bout duration (b = 0.251-0.449; all p < 0.001) and higher SB breaks (b = -0.005--0.052; all p < 0.001). Lower total SB was unexpectedly related to greater obesity (b = -0.077--0.649; p from <0.001-0.02). For mean SB bout duration and SB breaks, more associations were observed for SBposture (n = 5) than for SBmovement (n = 3) or SBcombined (n = 1), and tended to have larger magnitude as well.

CONCLUSIONS

Using traditional measures of low movement as a surrogate for SB may lead to underestimated or undetected adverse associations between SB and obesity. CHAP-Child allows assessment of sitting posture using hip-worn accelerometers. Ongoing work is needed to understand how low movement and posture are related to one another, as well as their potential health implications.

Full-Day Physical Activity and Sedentary Behaviour Levels of Typically Developing Children and Adolescents in the Middle East: A Systematic Review

Physical activity (PA) and sedentary behaviour (SB) are important components of physical behaviour associated with long-term health outcomes. Environmental and cultural factors may influence physical behaviour. To explore full day PA and SB in children and adolescents (2-18 years old) in the Middle East, a systematic literature review was performed including 183 journal articles. A wide range of PA and SB outcomes were reported, in some cases making synthesis of results difficult. As a consequence, results were generally reported narratively (MVPA time, total PA, SB time). Meta-regression of daily step count revealed females took 4600 fewer steps than males, with 3000 fewer steps on weekdays than weekends, and overweight individuals taking 2800 fewer steps/day. Steps decreased with age. Meta-regression for TV viewing time demonstrated an increase by 0.04 h per year of age. Even though environmental and cultural conditions may be different, PA and SB of children and adolescents in the Middle East were largely comparable to those of Europeans and North Americans. The wide range of data collection instruments used (both self-report questionnaire and body-worn devices) and heterogeneity of data made synthesis of reported data across studies very difficult, suggesting a need for greater standardisation of data collection methods.

Sedentary Bout Patterns and Metabolic Health in the Hispanic Community Health Study/Study of Latino Youth (SOL Youth)

Background There is limited evidence on the potential negative metabolic health impacts of prolonged and uninterrupted sedentary bouts in structurally disadvantaged youth. This study investigated associations between sedentary bout variables and metabolic health markers in the Hispanic Community Health Study/SOL Youth (Study of Latino Youth). Methods and Results SOL Youth was a population-based cohort of 1466 youth (age range, 8-16 years; 48.5% female); 957 youth were included in the analytic sample based on complete data. Accelerometers measured moderate-to-vigorous physical activity (MVPA), total sedentary time, and sedentary bout patterns (daily time spent in sedentary bouts ≥30 minutes, median sedentary bout duration, and number of daily breaks from sedentary time). Clinical measures included body mass index, waist circumference, fasting glucose, glycated hemoglobin, fasting insulin, and the homeostasis model assessment of insulin resistance. After adjusting for sociodemographics, total sedentary time, and MVPA, longer median bout durations and fewer sedentary breaks were associated with a greater body mass index percentile (bbouts=0.09 and bbreaks=-0.18), waist circumference (bbouts=0.12 and bbreaks=-0.20), and fasting insulin (bbouts=0.09 and bbreaks=-0.21). Fewer breaks were also associated with a greater homeostasis model assessment of insulin resistance (b=-0.21). More time in bouts lasting ≥30 minutes was associated with a greater fasting glucose (b=0.18) and glycated hemoglobin (b=0.19). Conclusions Greater accumulation of sedentary time in prolonged and uninterrupted bouts had adverse associations with adiposity and glycemic control over and above total sedentary time and MVPA. Findings suggest interventions in Hispanic/Latino youth targeting both ends of the activity spectrum (more MVPA and less prolonged/uninterrupted sedentary patterns) may provide greater health benefits than those targeting only MVPA.

Adolescent sedentary behavior and body composition in early adulthood: results from a cohort study

BACKGROUND

This study investigates the cross-sectional and prospective associations between accelerometer-measured sedentary behavior and body composition from adolescence to early adulthood.

METHODS

Data from the Santiago Longitudinal Study were analyzed (n = 212). Sedentary time was measured at age 16 years, and body composition (body mass index [BMI], waist circumference, waist-to-height ratio [WHtR], fat mass percentage, and lean mass percentage) was examined at both age 16 and 23 years. Adjusted linear regression models estimated associations between sedentary time, sedentary bout duration, and body composition, overall and by sex.

RESULTS

In all analyses, mean sedentary bout duration was not associated with body composition. In cross-sectional analyses, more sedentary time during adolescence was significantly associated with lower BMI, waist circumference, WHtR, fat mass percentage, and higher lean mass percentage (p < 0.05). One standard deviation increase in daily sedentary time was prospectively associated with lower body mass index (β = -1.22 kg/m2, 95% CI: -2.02, -0.42), waist circumference (β = -2.39 cm, 95% CI: -4.03, -0.75), and WHtR (β = -0.014, 95% CI: -0.024, -0.004). Sedentary time at 16 years was not associated with changes in body composition from 16 to 23 years.

CONCLUSIONS

Sedentary behavior in adolescence is not adversely associated with body composition profiles in early adulthood.

IMPACT

Little is known about the effect of device-measured sedentary behavior on body composition during the transition from adolescence to early adulthood. Among participants in the Santiago Longitudinal Study, more accelerometer-measured sedentary time during adolescence was associated with lower BMI, waist circumference, and waist-to-height ratio in early adulthood though point estimates were generally small in magnitude. Sedentary behavior in adolescence was not detrimentally associated with healthy body composition profiles in early adulthood. Public health interventions aimed at reducing obesity rates could consider other behaviors, such as physical activity and healthy diet, instead of sitting time.

Adherence to 24-h movement guidelines in Spanish schoolchildren and its association with insulin resistance: a cross-sectional study

Introduction

Being more active, being less sedentary, and sleeping enough are associated with adequate body weight and adiposity in children. However, few researchers have analyzed these different lifestyle behaviors and the adherence to 24 h movement guidelines with respect to insulin resistance (IR) at school age. Therefore, we aimed to analyse the association between the adherence to 24 h movement guidelines (physical activity, sedentary time, sleep) and IR in Spanish schoolchildren.

Methods

A cross-sectional study of 839 children (8-13 years, 51.1% girls) were studied. Anthropometric, biochemical, and lifestyle behavioral data were collected. IR was defined as HOMA-IR>3.16. Compliance with the 24 h movement guidelines were defined as ≥60 min/day of moderate and/or vigorous physical activity, < 120 min/day of screen time, and 9-11 h/day of sleep time. Associations between adherence to the 24 h movement guidelines and IR were performed by multivariate logistic regression analyses.

Results

The IR in our sample was 5.0%, being higher in girls. Compliance with physical activity or screen time, but not with sleep recommendations, was associated with lower fasting glucose, fasting insulin, and HOMA-IR values. A low adherence to 24 h movement guidelines was associated with a higher risk of IR (odds ratio (95% CI): 2.150 [1.089-4.247]), especially in girls (odds ratio (95% CI): 2.800 [1.180-6.645]).

Conclusion

Higher physical activity levels and lower screen times were associated with a lower risk of IR in schoolchildren, underlining the importance of adhering to as many healthy lifestyle recommendations as possible.

Obesogenic behavior clusters associated with weight status among Brazilian students: a latent class analysis

This study aimed to examine the association between clusters of physical activity (PA), diet, and television viewing (TV) with weight status among a representative sample of Brazilian students. Data from the National Health School-based Survey (PeNSE) 2015 were analyzed (n = 16,521; mean age 14.8, standard deviation 0.03 year). PA (minutes/week spent in leisure-time, and commuting to/from school), TV (hours/day), and weekly consumption of deep-fried empanadas, candies, sodas, ultra-processed foods, fast foods, green salads or vegetables, and fruits were self-reported on the validated PeNSE questionnaire. Latent class analysis defined behavior classes, and binary logistic regression assessed the association between clustering and weight status. Six classes' types with positive and negative behaviors were identified. Adolescents belonging to the "low TV time and high healthy diet" class had higher chances of being overweight (including obesity) compared to their peers in the "moderate PA and mixed diet" class. No associations were found in the other clusters. Mixed classes with healthy and unhealthy behaviors characterized adolescents' lifestyles and these profiles were related to weight status.

Sedentary behaviour profiles and longitudinal associations with academic performance in youth: The UP&DOWN study

The current study evaluated longitudinal associations between profile transitions of context-specific sedentary behaviour (SB) and changes in academic performance (AP) among school-aged youth. Participants were 466 children and 717 adolescents (50.8% males) aged 8-18 years (children = 7.92 ± 0.41 years; adolescents = 11.85 ± 1.53 years). Non-school SBs and AP were evaluated at baseline and two years later. General linear mixed models were implemented, controlling for age, region, parental education, body mass index, and cardiorespiratory fitness. Cross-sectionally, participants with an Educative-profile (i.e., highest scores in doing homework with/without computer and reading for fun) had higher AP when compared to other profiles. Longitudinally, males who changed from a Screen- to an Educative-profile had higher AP than males who changed from an Educative- to a Social- or Screen-SB profile (p < 0.01). No significant differences were found in females. These findings show the importance of analysing SB patterns from a qualitative perspective (i.e., context-specific for boosting school children AP) and highlighting time spent in educative as the most positive for AP, as well the need to implement interventions to reduce time on screen and social behaviours, especially targeting males.

Association between Types of Screen Time and Weight Status during the COVID-19 Pandemic: A Longitudinal Study in Children and Adolescents

BACKGROUND

This study aimed to investigate the changes in distinct types of screen time and explore their longitudinal association with children and adolescents' weight status.

METHODS

A two-wave longitudinal study was conducted among 2228 children and adolescents (6-19 years) in Shanghai, China, before and during the pandemic. Recreational screen time (watching TV/videos, online gaming, using social media, and browsing webpages), educational screen time (online homework and online class), and BMI were measured using a self-reported questionnaire. Mixed-effects models were constructed to assess the associations between screen time and weight status.

RESULTS

The prevalence of overweight and obesity was 20.5% and 10.2% at baseline, respectively. Both recreational and educational screen time increased significantly over two months. While recreational screen time was found to be a risk factor for obesity, it was not the case for educational screen use. Specifically, adolescents who spent more time watching TV/videos had a higher obesity risk (OR = 1.576). No significant associations were found in children.

CONCLUSIONS

Overweight and obesity were prevalent among children and adolescents in China. Reducing screen-based activities is a promising strategy to prevent unhealthy weight gain in Chinese children and adolescents, while it is necessary to consider the content and distinguish between educational and recreational screen use.

Association of normal weight obesity with lifestyle and dietary habits in young Thai women: A cross-sectional study

Background

The risk of lifestyle-related diseases in normal weight obesity (NWO), a condition, in which the body mass index (BMI) is normal but the body fat mass is high, has attracted a lot of attention. However, there are no reports on the association between NWO and lifestyle, eating habits, and other health risks in Thai people. BMI alone cannot be used to identify individuals with NWO; thus, some students with NWO develop metabolic abnormalities without receiving any intervention. This study aimed to examine the differences in anthropometrics, lifestyle, and eating habits among young Thai women and their association with the BMI and the body fat ratio (BFR).

Methods

A total of 250 female Thai university students of normal body type (18.5 ≤ BMI<25.0 kg/m2) were classified as having non-normal weight obesity (NO-NWO) if their BFR was <30.0% or NWO if their BMI and BFR were >30.0%. The lifestyle and eating habits of the two groups were compared. We conducted logistic analysis with the presence or absence of NWO as the dependent variable, and the dietary habit items of "eating greasy foods," "eating ultra-processed foods (UPF)," and "drinking sweetened beverages" as the objective variables.

Results

Among the study participants who were of normal body type, 46.8% were NWO. The participants in the NWO group consumed UPF more frequently (odds ratio [OR], 2.04; p = 0.014) and sweetened beverages more regularly (OR, 1.92, p = 0.041) than those in the NO-NWO group.

Conclusion

UPF and sweetened beverage consumption was more common in individuals with NWO. Identifying the risk factors for NWO is essential to help individuals make lifestyle changes to prevent its progression and complications.

High free leptin index as the risk factor for childhood obesity in Indonesia: A case-control study

Identifying the risk factors is critical in preventing childhood obesity. Leptin concentration is elevated in obesity. High serum leptin levels are believed to reduce soluble leptin receptor (sOB-R) concentrations and are associated with leptin resistance. The free leptin index (FLI) is a biomarker of leptin resistance and the status of leptin action. This study aims to investigate the association between leptin, sOB-R, and FLI with measurements to diagnose obesity in children, such as BMI, waist circumference and waist-to-height ratio (WHtR). We conducted a case-control study in 10 elementary schools in Medan, Indonesia. The case group was children with obesity, while the control group was children with normal BMI. Leptin and sOB-R levels were measured from all the subjects using the ELISA method. Logistic regression analysis was employed to determine which factors were predictor variables of obesity. A total of 202 children between 6 and 12 years old were recruited for this study. Children with obesity showed significantly higher leptin levels and FLI and lower SOB-R levels FLI (p < .05) than control. The cut-off for WHtR in this study was 0.499 (sensitivity 90% and specificity 92.5%). Children with higher leptin levels had a higher risk of obesity based on BMI, waist circumference, and WHtR values.

Screen use, sleep duration, daytime somnolence, and academic failure in school-aged adolescents

In this study, we examined the relationship between screen time use, sleep characteristics, daytime somnolence, and academic performance in school-aged adolescents. We surveyed 1,257 12- to 18-year-old adolescents attending 52 schools in urban or suburban areas of Argentina. We recorded the daily exposure to various screen-based activities, including video- and online-gaming, social media, TV or streaming. Screen time and device type in the hour before bedtime, sleep patterns during weekdays and weekends, somnolence (Pediatric Daytime Sleepiness Scale score), and grades in language and mathematics were also assessed. Structural Equation Modelling was used to identify a path connecting the latent variables. Results are expressed as standardized regression weights (srw). Missing data were present in 393 subjects, and thus the final sample consisted of 864 complete responses. Daytime somnolence (i.e., PDSS score ≥ 15) was observed in 614 participants (71%), and academic failure (i.e., grades < 7/10) in 352 of them (41%). Time spent using video gaming consoles was negatively associated with sleep duration (srw = -0.22, p<0.01) and positively connected with daytime somnolence (srw = 0.11, p<0.01). Use of mobile devices was associated with lower academic performance (srw = -0.11, p<0.01). Sleep duration was inversely related to daytime somnolence (srw = -0.27, p<0.01), which was in turn negatively associated with academic performance (srw = -0.18, p<0.05). Bedtime computer use did not influence any outcome. In summary, among adolescents, screen use adversely affected nighttime sleep, daytime somnolence, and academic performance. These findings call for the implementation of educational public campaigns aimed at promoting healthy sleep and reducing screen exposure among adolescents.

The degree of association between overweight and obesity with the use of electronic media among Bangladeshi adolescents

BACKGROUND

Electronic media usage is recently considered a modifiable risk factor for overweight and obesity among adolescents. The purpose of this present study was to evaluate the association of electronic media (EM) usage with overweight and obesity among school-going adolescents.

METHODS

This cross-sectional study was conducted from October to December 2019 among school-going adolescents (14-16 years old) residing in the Jashore Sadar Upazila, Jashore district of Bangladesh. A standardized questionnaire was used to collect information regarding the socio-economic status, time spent watching television, video games playing, computer, and smart mobile phone use through face-to-face interviews. Age- and sex-specific body mass index (BMI) cut-off values for overweight and obesity were determined for Asian adolescents by the International Obesity Task Force (IOTF). Multinomial logistic regression analysis was carried out to determine the association between electronic media use with overweight and obesity.

FINDINGS

The findings suggest that the overall prevalence of overweight and obesity was 13.5% and 25.2%, respectively. Among the total adolescent students, about 49.1% highly (above 3 hours per day) spent their time on EM use whereas 30.6% moderately (≥121 to 180 min/day) use EM. The regression analysis showed that spending high time using total screen-based electronic devices, television viewing, video game playing, computer use, and smartphone use were significantly associated with overweight (RRR: 7.36, 95% CI: 3.64-11.54; RRR: 4.58, 95% CI: 1.46-7.95; RRR: 4.45, 95% CI: 2.75-6.12; RRR: 3.18, 95% CI: 1.87-4.70; RRR: 2.15, 95% CI: 1.23-3.51) and obesity (RRR: 8.72, 95% CI: 4.64-12.54; RRR: 2.89, 95% CI: 1.31-5.21; RRR: 3.88, 95% CI: 1.74-5.13; RRR: 3.08, 95% CI: 1.32-4.86; RRR: 1.19, 95% CI: 0.93-1.48) in adolescents, respectively.

CONCLUSION

The results support the total time spent using electronic media was associated with an increased risk of being overweight and obesity. Finally, this study strongly suggests the proper use of electronic media may be necessary to reduce the risk of being overweight and obesity in early adolescents.

Associations of physical activity and screen time with adolescent idiopathic scoliosis

BACKGROUND

Adolescent idiopathic scoliosis (AIS) is the most common type of idiopathic scoliosis, affecting approximately 0.61%-6.15% adolescents worldwide. To date, the results on the relationship between moderate-to-vigorous physical activity (MVPA) and AIS were inconsistent, and the association between screen time (ST) and AIS remained unclear. This study aimed to describe MVPA and ST among adolescents, and to explore the independent and joint associations between PA, ST, and AIS.

METHODS

A frequency-matched case-control study based on the 2021 Chinese School-based Scoliosis Screening Program in Shenzhen city, south China, was conducted. The research involved 494 AIS patients (aged 9-17 years) and 994 sex- and age-matched healthy controls. MVPA and ST were measured using a self-administered questionnaire. Logistic regression models estimated associations between PA, ST, and AIS.

RESULTS

Compared to subjects meeting the recommended 60-min daily of MVPA, adolescents reporting daily MVPA time less than 60 min had 1.76 times higher odds of experiencing AIS (95% CI: 1.32-2.35) and adolescents reporting daily MVPA in inactive status had 2.14 times higher odds of experiencing AIS (95% CI: 1.51-3.03). Moreover, participants reporting ST for 2 hours or more had 3.40 times higher odds of AIS compared with those reporting ST less than 2 hours (95% CI: 2.35-4.93). When compared with the adolescents reporting both ST and MVPA meeting the guidelines recommended times (ST < 2 h and MVPA ≥ 60 min/day), those reporting both ST ≥ 2 h and MVPA in inactive status are 8.84 times more likely to develop AIS (95% CI: 3.99-19.61).

CONCLUSIONS

This study reported that the insufficient MVPA, especially MVPA in inactive status, and excessive ST were risk factors for AIS. Additionally, the joint effects of insufficient MVPA and excessive ST probably increase the risk of AIS.

Behavioural risk patterns in adolescents with excess weight participating in the PRALIMAP-INÈS trial

OBJECTIVE

To investigate clustering of risk behaviours in adolescents with excess weight.

DESIGN

Cross-sectional analysis of baseline data from the PRALIMAP-INÈS trial. Information on food frequency consumption (fruit, vegetables, sugary products and beverages), physical activity, sedentary behaviour (week and weekend days), smoking and alcohol consumption (current frequency and intoxication episodes) and socio-demographic data was collected using self-reported questionnaires. Behavioural risk factors were entered as categorical variables in a two-step clustering procedure: multiple correspondence analysis followed by hierarchical clustering. Associations between cluster membership and socio-demographic variables were investigated using multivariable multinomial logistic regression.

SETTING

French PRALIMAP-INÈS trial.

PARTICIPANTS

Adolescents with excess weight.

RESULTS

A total of 1391 participants (13-18 years old, 58·2 % female) were included in the analysis, which resulted in the identification of four groups of participants, including, respectively, 543 (39·0 %), 373 (26·8 %), 246 (17·7 %) and 229 (16·5 %) participants. Clusters 1 and 4 showed associations of rather healthy behaviours (high physical activity and low consumption of sugary products; high consumption of fruit and vegetables, respectively), while clusters 2 and 3 showed associations of rather unhealthy behaviours (high sedentary behaviour and low consumption of fruit and vegetables; smoking and alcohol consumption, respectively). Both social status and family structure were associated with cluster membership.

CONCLUSIONS

Risk behaviour patterns in adolescents with excess weight were clustered in both healthier and less healthy ways, with a complex interplay with socio-demographic factors.

Validity and Reliability of Questionnaires That Assess Barriers and Facilitators of Sedentary Behavior in the Pediatric Population: A Systematic Review

We systematically reviewed the literature about the validity and reliability of barriers and facilitators of sedentary behavior questionnaires for children and adolescents, considering accelerometers as the reference method. We included studies that assessed the agreement between the barriers and facilitators of sedentary behavior through a questionnaire and an objective measure (e.g., accelerometry). We searched four electronic databases (MEDLINE/PubMed, CINAHL, Web of Science, and SCOPUS): these databases were searched for records from inception to 5 March 2021, and updated to November 2022. The search strategy used the following descriptors: children and adolescents; barriers or facilitators; questionnaires; accelerometers; and validation or reliability coefficient. Studies identified in the search were selected independently by two reviewers. The inclusion criteria were: (i) population of children and adolescents, (ii) original studies, (iii) subjective and objective measurement methods, (iv) studies that report validity or reliability, and (v) population without specific diseases. Seven studies were eligible for our review. The main exclusion reasons were studies that did not report validity or reliability coefficients (56.6%) and non-original studies (14.5%). The participants' ages in the primary studies ranged from 2 to 18 years. Cronbach's alpha coefficient was the most reported reliability assessment among the eligible articles, while Pearson and Spearman's coefficients were prevalent for validity. The reliability of self-report questionnaires for assessing sedentary behavior ranged from r = 0.3 to 1.0. The validity of the accelerometers ranged from r = -0.1 to 0.9. Family environment was the main factor associated with sedentary behavior. Our findings suggest that questionnaires assessing the barriers and facilitators of sedentary behavior are weak to moderate. PROSPERO Registration (CRD42021233945).

Changes in the body composition of boys aged 11-18 years due to COVID-19 measures in the Czech Republic

BACKGROUND

The lockdown measures related to coronavirus disease 2019 (COVID) impacted the health of adolescents by reducing physical activity (PA). The physical changes in response to decreases in PA can be measured with full body composition analysis. The aim of this study was to evaluate the effects of long-term PA restrictions on body fat (BF), fat-free mass (FFM) and skeletal muscle mass (SMM) in adolescents.

METHODS

A total of 1669 boys (before PA restriction (G1): 998; after PA restrictions ended (G2): 671; between the ages of 11 and 18 were included. The measured parameters were body mass (BM), visceral fat area (VFA), BF, FFM and SMM. The whole-body composition was evaluated using bioelectrical impedance analysis (BIA).

RESULTS

Compared to G1, G2 exhibited an increase in BF between 1.2 and 5.1%. This difference was significant in boys aged 13 to 18 years (p < 0.05). VFA increased between 5.3 and 20.5 cm²; this increase was significant in boys aged 13 to 18 years (p < 0.05). SMM decreased between 2.6 and 3.8%, and this decrease was significant in all age groups (p < 0.05). Changes in body composition were not accompanied by any significant changes in BM.

CONCLUSIONS

COVID-19 restrictions reduced PA, resulting in a significant decrease in SMM. This decrease may impact boys' ability to engage in sufficiently varied PA, which may lead to a further decline in PA and subsequent medical consequences in adulthood.

Sedentary patterns and cardiometabolic risk factors in Mexican children and adolescents: analysis of longitudinal data

BACKGROUND

Sedentary behavior is a modifiable risk factor for cardiometabolic health; however, the assessment of total sedentary time may not capture youth's highly active and interrupted activity patterns. This study examined the associations between sedentary activity patterns and cardiometabolic risk factors among Mexican youth, who have a disproportionate burden of metabolic diseases, using a repeated measure design out of a longitudinal data.

METHODS

570 subjects in the Early Life Exposure in Mexico to ENvironmental Toxicants (ELEMENT) birth cohort, who were followed up to three-time points during adolescence, were included. Bout duration, and frequency and percentages of waking time spent in specific intensities of activity, were quantified using ActiGraph wGT3X-BT wrist accelerometers. Self-reported questionnaires were used to query the usual duration of different sedentary behaviors. Outcomes were fasting lipid profile, markers for glucose homeostasis, anthropometry, and blood pressure. Associations were modeled using linear mixed-effects models, and isotemporal substitution approach was additionally used to assess the effect of replacing objectively assessed sedentary activity with other activity intensities, adjusting for potential confounders.

RESULTS

Each hour of self-reported screen-based time was positively associated with diastolic blood pressure (mm Hg) [β = 0.30, 95% confidence interval (95% CI) = 0.10, 0.51], and an hour of other sedentary time was associated with log serum glucose (mg/dL) [β = 0.01, 95% CI = 0.004, 0.017]. Substitution models showed that replacing 5% of sedentary time with moderate to vigorous physical activity (MVPA) was associated with lower waist circumference (cm) [β = - 1.35, 95% CI = - 1.91, - 0.79] and log serum triglycerides (mg/dL) [β = - 0.11, 95% CI = - 0.18, - 0.03]. Substituting one uninterrupted sedentary bout with light activity was associated with lower insulin (μIU/mL) [β = - 0.06, 95% CI = - 0.10, - 0.02].

CONCLUSIONS

Sedentary time was associated with cardiometabolic risk factors in Mexican youth in a context-specific manner. Replacing sedentary time with higher intensities was associated with improvements in some cardiometabolic markers.

A 4-Yr Mixed Longitudinal Study of Health Behaviors and Fat Mass Accrual during Adolescence and Early Adulthood

PURPOSE

Physical activity (PA), sedentary time (SED), and energy intake (EI) are associated with fat mass accrual in children and youth. Previous studies relied primarily on cross-sectional designs and proxy measures of body composition such as body mass index. We aimed to prospectively investigate associations between PA, SED, EI, and total body fat mass accrual using dual-energy x-ray absorptiometry.

METHODS

This analysis of the mixed longitudinal Healthy Bones III Study included data from 312 participants (138 boys age 9 to 21 yr at baseline). For each participant, we acquired a maximum of four annual total body dual-energy x-ray absorptiometry scans from which we determined fat mass (in kilograms; n = 748 observations). We assessed total PA, moderate-to-vigorous PA (MVPA) and SED with accelerometers (ActiGraph GT1M) and measured EI via 24-h dietary recall. We fit sex-specific multilevel models adjusting for maturity (years from age at peak height velocity (APHV)), weight status, ethnicity, total PA, MVPA, SED, and EI.

RESULTS

Boys and girls demonstrated divergent trajectories of fat mass accrual; rate of fat mass accrual in girls was four times greater than boys at APHV and increased across adolescence, whereas boys' fat mass plateaued after APHV. In boys, within-person change in MVPA negatively predicted fat mass independent of SED; each annual increase in MVPA of 6 min·d -1 was associated with a 0.21-kg lower fat mass. In girls, between-person average MVPA negatively predicted fat mass accrual independent of SED; greater MVPA of 4 min·d -1 across adolescence was associated with a 0.31-kg lower fat mass.

CONCLUSIONS

MVPA demonstrates an independent and negative effect on fat mass in boys and girls. Given different trajectories of fat mass accrual and movement behaviors between boys and girls, PA interventions aimed at preventing obesity in youth may benefit from a sex and gendered approach.

Recreational Soccer Training Effects on Pediatric Populations Physical Fitness and Health: A Systematic Review

This systematic review analyzed the effects of recreational soccer programs on physical fitness and health-related outcomes in youth populations. Studies were sought in the following databases: (i) PubMed, (ii) Scopus, (iii) SPORTDiscus, and (iv) Web of Science. The eligibility criteria included (1) population: youth (<18 years old) populations with no restrictions on sex or health condition; (2) intervention: exposure to a recreational soccer training program of at least four weeks duration; (3) comparator: a passive or active control group not exposed to a recreational soccer training program; (4) outcomes: physical fitness (e.g., aerobic, strength, speed, and change-of-direction) or health-related measures (e.g., body composition, blood pressure, heart rate variability, and biomarkers); (5) study design: a randomized parallel group design. The search was conducted on 6 September 2022 with no restrictions as to date or language. The risk of bias was assessed using the PEDro scale for randomized controlled studies. From a pool of 37,235 potentially relevant articles, 17 were eligible for inclusion in this review. Most of the experimental studies revealed the beneficial effects of recreational soccer for improving aerobic fitness and its benefits in terms of blood pressure and heart-rate markers. However, body composition was not significantly improved by recreational soccer. The main results revealed that recreational soccer training programs that are implemented twice a week could improve the generality of physical fitness parameters and beneficially impact cardiovascular health and biomarkers. Thus, recreational soccer meets the conditions for being included in the physical education curriculum as a good strategy for the benefit of the general health of children and young people.

Esports players, got muscle? Competitive video game players' physical activity, body fat, bone mineral content, and muscle mass in comparison to matched controls

BACKGROUND

Esports players, like traditional athletes, practice for long hours and, thus, are vulnerable to the negative health effects of prolonged sitting. There is a lack of research on the physical activity and the health ramifications of prolonged sitting by competitive players. The purpose of this study was to investigate activity levels, body mass index (BMI), and body composition in collegiate esports players as compared to age-matched controls.

METHODS

Twenty-four male collegiate esports players and non-esports players between 18 and 25 years of age signed a written consent to participate. Physical activity was examined using daily activity (step count) with a wrist-worn activity tracker. A questionnaire assessing physical activity was also administered. Secondary outcomes included body-fat percentage, lean-body mass, BMI, and bone mineral content measured using dual X-ray absorptiometry.

RESULTS

The step count in the esports players was significantly lower than the age-matched controls (6040.2 ± 3028.6 vs. 12843.8 ± 5661.1; p = 0.004). Esports players exhibited greater body-fat percentage (p = 0.05), less lean body mass (p = 0.003), and less bone mineral content (p = 0.03), despite no difference in BMI between the esports and non-esports players.

CONCLUSION

As compared to non-esports players, collegiate esports players were significantly less active and had a higher body-fat percentage, with lower lean body mass and bone mineral content. The BMIs showed no difference between the 2 groups. Esports athletes displayed significantly less activity and poor body composition, which are all correlated with potential health issues and risk of injury. BMI did not capture this difference and should not be considered as an accurate measure of health in competitive esports players.

School and non-school day screen time profiles and their differences in health and educational indicators in adolescents

Sedentary behavior and screen-based devices in particular have been negatively associated with a wide range of health and educational indicators. However, few have examined these relationships separately for school days and non-school days, and none have used a person-centered approach. This study aimed to identify school and non-school day screen time profiles, as well as examine possible differences in health indicators (physical fitness, fatness, physical activity, sleep duration, and Mediterranean diet) and academic performance. This study involved the participation of 1573 Spanish adolescents aged 12-16 years (54.73% girls). Academic performance was measured through grades in Mathematics, Language, English, and Physical Education. Physical fitness was measured through a battery of tests (cardiorespiratory fitness was measured using the 20 m shuttle run test, and muscular strength with both handgrip and standing long jump tests), while fatness (skinfold thicknesses) was assessed with calipers. Finally, physical activity, screen time, sleep duration, and adherence to the Mediterranean diet were measured using self-reported questionnaires. Hierarchical cluster analyses based on square Euclidian distances and Ward's method were performed based on daily minutes of screen time recorded on school and non-school days. We identified four clusters labeled and described as: (1) "High-high": highest screen time on school and non-school days; (2) "High-low": high screen time on school days and low screen time on non-school days; (3) "Low-high": low screen time on school days and high screen time on non-school days; (4) "Low-low": lowest screen time on school and non-school days. Adolescents who belonged to the "High-high" profile had worse health-related behaviors (i.e., physical activity, sleep duration, and adherence to Mediterranean diet) and academic performance than most other profiles, while adolescents who belonged to "Low-low" profile showed the opposite pattern. Adolescents in the "Low-high" profile had a higher sleep duration on school days and better academic performance than those in the "High-low" profile. No differences in body fat, cardiorespiratory fitness, and muscular strength were found between the four different profiles. The results suggest that adolescents who accumulated a large amount of screen time on school and non-school days reported worse health-related behaviors and academic performance. Moreover, adolescents who had high screen time on school days reported only a short sleep duration on school days and worse academic performance than on non-school days. Conducting interventions to reduce screen time in these four profiles, particularly in the groups of students with more screen time on school days, becomes essential to improving adolescents' healthy lifestyles and academic performance.

Association of daily and time-segmented physical activity and sedentary behaviour with mental health of school children and adolescents from rural Northeastern Ontario, Canada

Physical activity (PA) and sedentary behaviour (SED) have been linked to the mental health of children and adolescents, yet the timing of behaviours may play a role in this relationship and clarifying this could inform interventions. We explored cross-sectional associations of PA and SED in varying time segments throughout the school day with the mental health of school-aged children and adolescents from rural Northeastern Ontario, Canada. A total of 161 students (56% female, M = 10.3 years old) wore accelerometers for 8 days (7 nights) and completed a self-report survey (parent reported for children younger than 11). Mental health was measured using the Strengths and Difficulties Questionnaire. Accelerometer-measured SED, light PA (LPA), and moderate and vigorous PA (MVPA) were estimated in the time-segments before school (06:00–08:44), school time (08:45–15:04), after school (15:05–16:59), and evenings (17:00–21:59). Associations were tested with multilevel linear regressions while adjusting for confounding factors. Students spent 72.6 min in MVPA, 209.0 min in LPA, and 621.0 min in SED per day. Daily SED was associated with less conduct problems (β = −0.27, p &lt; 0.05). Evening LPA was inversely associated with hyperactivity (β = −1.45, p &lt; 0.05), while SED was associated with hyperactivity and with peer problems before school (β = 1.70 and β = 1.01, respectively, p &lt; 0.05), and during school (β = −0.83 and β = −0.57, respectively, p &lt; 0.05). No associations were observed for MVPA, emotional symptoms, or prosocial behaviour. In conclusion, displacing SED with LPA in some specific periods of the day may benefit the mental health of students; taking this into account could strengthen interventions.

The Family Level Assessment of Screen Use-Mobile Approach: Development of an Approach to Measure Children's Mobile Device Use

BACKGROUND

There is a strong association between increased mobile device use and worse dietary habits, worse sleep outcomes, and poor academic performance in children. Self-report or parent-proxy report of children's screen time has been the most common method of measuring screen time, which may be imprecise or biased.

OBJECTIVE

The objective of this study was to assess the feasibility of measuring the screen time of children on mobile devices using the Family Level Assessment of Screen Use (FLASH)-mobile approach, an innovative method that leverages the existing features of the Android platform.

METHODS

This pilot study consisted of 2 laboratory-based observational feasibility studies and 2 home-based feasibility studies in the United States. A total of 48 parent-child dyads consisting of a parent and child aged 6 to 11 years participated in the pilot study. The children had to have their own or shared Android device. The laboratory-based studies included a standardized series of tasks while using the mobile device or watching television, which were video recorded. Video recordings were coded by staff for a gold standard comparison. The home-based studies instructed the parent-child dyads to use their mobile device as they typically use it over 3 days. Parents received a copy of the use logs at the end of the study and completed an exit interview in which they were asked to review their logs and share their perceptions and suggestions for the improvement of the FLASH-mobile approach.

RESULTS

The final version of the FLASH-mobile approach resulted in user identification compliance rates of >90% for smartphones and >80% for tablets. For laboratory-based studies, a mean agreement of 73.6% (SD 16.15%) was achieved compared with the gold standard (human coding of video recordings) in capturing the target child's mobile use. Qualitative feedback from parents and children revealed that parents found the FLASH-mobile approach useful for tracking how much time their child spends using the mobile device as well as tracking the apps they used. Some parents revealed concerns over privacy and provided suggestions for improving the FLASH-mobile approach.

CONCLUSIONS

The FLASH-mobile approach offers an important new research approach to measure children's use of mobile devices more accurately across several days, even when the child shares the device with other family members. With additional enhancement and validation studies, this approach can significantly advance the measurement of mobile device use among young children.

Energy intakes, macronutrient intakes and the percentages of energy from macronutrients with adolescent BMI: results from a 5-year cohort study in Ho Chi Minh City, Vietnam

BACKGROUND

Adolescence is a period of life when dietary patterns and nutrient intakes may greatly influence adult fatness. This study assesses the tracking of energy and nutrient intakes of Ho Chi Minh City adolescents over 5 years. It explores the possible relationships between energy and the percentage of energy from macronutrients with BMI.

METHODS

Height, weight, time spent on physical activity, screen time and dietary intakes were collected annually between 2004 and 2009 among 752 junior high school students with a mean age of 11·87 years at baseline. The tracking was investigated using correlation coefficients and weighted kappa statistics (k) for repeated measurements. Mixed effect models were used to investigate the association between energy intakes and percentage energy from macronutrients with BMI.

RESULTS

There were increases in the mean BMI annually, but greater in boys than in girls. Correlation coefficients (0·2 < r < 0·4) between participants' intakes at baseline and 5-year follow-up suggest moderate tracking. Extended kappa values were lowest for energy from carbohydrate (CHO) in both girls and boys (k = 0·18 & 0·24, respectively), and highest for protein in girls (k = 0·47) and fat in boys (k = 0·48). The multilevel models showed the following variables significantly correlated with BMI: CHO, fat, percentage of energy from CHO, fat, time spent for moderate to vigorous physical activity, screen time, age and sex.

CONCLUSIONS

The poor to fair tracking observed in this cohort suggests that individual dietary patterns exhibited in the first year are unlikely to predict energy and nutrient intakes in the fifth year.

Childhood Obesity: Position Statement of Polish Society of Pediatrics, Polish Society for Pediatric Obesity, Polish Society of Pediatric Endocrinology and Diabetes, the College of Family Physicians in Poland and Polish Association for Study on Obesity

Childhood obesity is one of the most important problems of public health. Searching was conducted by using PubMed/MEDLINE, Cochrane Library, Science Direct, MEDLINE, and EBSCO databases, from January 2022 to June 2022, for English language meta-analyses, systematic reviews, randomized clinical trials, and observational studies from all over the world. Five main topics were defined in a consensus join statement of the Polish Society of Pediatrics, Polish Society for Pediatric Obesity, Polish Society of Pediatric Endocrinology and Diabetes and Polish Association for the Study on Obesity: (1) definition, causes, consequences of obesity; (2) treatment of obesity; (3) obesity prevention; (4) the role of primary care in the prevention of obesity; (5) Recommendations for general practitioners, parents, teachers, and regional authorities. The statement outlines the role of diet, physical activity in the prevention and treatment of overweight and obesity, and gives appropriate recommendations for interventions by schools, parents, and primary health care. A multisite approach to weight control in children is recommended, taking into account the age, the severity of obesity, and the presence of obesity-related diseases. Combined interventions consisting of dietary modification, physical activity, behavioral therapy, and education are effective in improving metabolic and anthropometric indices. More actions are needed to strengthen the role of primary care in the effective prevention and treatment of obesity because a comprehensive, multi-component intervention appears to yield the best results.

Physical Activity Patterns Among Adolescents in Latin America and the Caribbean Region

Background

Physical activity implies different patterns, but studies focused on physical inactivity and sedentary behaviors. This study aimed to estimate the prevalence of different physical activity patterns among adolescents in Latin America and the Caribbean region (LAC).

Methods

Pooled analysis of the most updated data of the Global School-based Student Health surveys. Age-standardized prevalence of four outcomes was estimated using information of last 7 days: physical inactivity (0 days of at least 60min/day), insufficient physical activity (<5 days of at least 60min/day), commuting physical activity (≥5 days of walking or biking to school), and sedentary behavior (≥3 hours/day of sitting time).

Results

A total of 132,071 records (33 countries) was analyzed, mean age 14.6 years, 51.2% girls. Pooled age-standardized prevalence of physical inactivity was 22.3%, greater among females (25.4%) than males (19.1%); insufficient physical activity was present in 67.7%, greater in females (73.6%) than males (61.5%); commuting physical activity was seen in 43.7%, similar between females (43.3%) and males (44.1%); and sedentary behavior was present in 43.4%, greater among females (45.4%) than males (41.3%).

Conclusions

In LAC, almost two thirds of adolescents are insufficiently physically active, ≥40% are sedentary, and ≥20% are physically inactive, more frequent among girls than boys.

CHAP-child: an open source method for estimating sit-to-stand transitions and sedentary bout patterns from hip accelerometers among children

BACKGROUND

Hip-worn accelerometer cut-points have poor validity for assessing children's sedentary time, which may partly explain the equivocal health associations shown in prior research. Improved processing/classification methods for these monitors would enrich the evidence base and inform the development of more effective public health guidelines. The present study aimed to develop and evaluate a novel computational method (CHAP-child) for classifying sedentary time from hip-worn accelerometer data.

METHODS

Participants were 278, 8-11-year-olds recruited from nine primary schools in Melbourne, Australia with differing socioeconomic status. Participants concurrently wore a thigh-worn activPAL (ground truth) and hip-worn ActiGraph (test measure) during up to 4 seasonal assessment periods, each lasting up to 8 days. activPAL data were used to train and evaluate the CHAP-child deep learning model to classify each 10-s epoch of raw ActiGraph acceleration data as sitting or non-sitting, creating comparable information from the two monitors. CHAP-child was evaluated alongside the current practice 100 counts per minute (cpm) method for hip-worn ActiGraph monitors. Performance was tested for each 10-s epoch and for participant-season level sedentary time and bout variables (e.g., mean bout duration).

RESULTS

Across participant-seasons, CHAP-child correctly classified each epoch as sitting or non-sitting relative to activPAL, with mean balanced accuracy of 87.6% (SD = 5.3%). Sit-to-stand transitions were correctly classified with mean sensitivity of 76.3% (SD = 8.3). For most participant-season level variables, CHAP-child estimates were within ± 11% (mean absolute percent error [MAPE]) of activPAL, and correlations between CHAP-child and activPAL were generally very large (> 0.80). For the current practice 100 cpm method, most MAPEs were greater than ± 30% and most correlations were small or moderate (≤ 0.60) relative to activPAL.

CONCLUSIONS

There was strong support for the concurrent validity of the CHAP-child classification method, which allows researchers to derive activPAL-equivalent measures of sedentary time, sit-to-stand transitions, and sedentary bout patterns from hip-worn triaxial ActiGraph data. Applying CHAP-child to existing datasets may provide greater insights into the potential impacts and influences of sedentary time in children.

Causal assessment in evidence synthesis: A methodological review of reviews

In fields (such as population health) where randomised trials are often lacking, systematic reviews (SRs) can harness diversity in study design, settings and populations to assess the evidence for a putative causal relationship. SRs may incorporate causal assessment approaches (CAAs), sometimes called 'causal reviews', but there is currently no consensus on how these should be conducted. We conducted a methodological review of self-identifying 'causal reviews' within the field of population health to establish: (1) which CAAs are used; (2) differences in how CAAs are implemented; (3) how methods were modified to incorporate causal assessment in SRs. Three databases were searched and two independent reviewers selected reviews for inclusion. Data were extracted using a standardised form and summarised using tabulation and narratively. Fifty-three reviews incorporated CAAs: 46/53 applied Bradford Hill (BH) viewpoints/criteria, with the remainder taking alternative approaches: Medical Research Council guidance on natural experiments (2/53, 3.8%); realist reviews (2/53, 3.8%); horizontal SRs (1/53, 1.9%); 'sign test' of causal mechanisms (1/53, 1.9%); and a causal cascade model (1/53, 1.9%). Though most SRs incorporated BH, there was variation in application and transparency. There was considerable overlap across the CAAs, with a trade-off between breadth (BH viewpoints considered a greater range of causal characteristics) and depth (many alternative CAAs focused on one viewpoint). Improved transparency in the implementation of CAA in SRs in needed to ensure their validity and allow robust assessments of causality within evidence synthesis.

Relations between physical activity, sedentary time, and body fat from childhood to adolescence: Do they differ by sex?

BACKGROUND

Efforts to reveal the direction of influence between physical activity (PA), sedentary time (ST) and body fat in youth have produced inconsistent results, possibly due to a lack of adjustment for confounders and other factors. Sex-specific associations have rarely been studied.

METHODS

A sample from two Norwegian birth cohorts (n = 809) were followed biennially over five waves from the age of 6-14 years. Physical activity and ST were recorded by accelerometers, and body fat was assessed by bioelectrical impedance measurements.

RESULTS

By applying a dynamic panel model (DPM) that adjusts for all time-invariant confounding factors, it was found that among boys, increased fat mass index (FMI) at ages 8, 10 and 12 years predicted decreased PA two years later (8-10 years: B = -0.67, (95% CI: -1.1, -0.24); 10-12 years: B = -0.33, (95% CI: -0.61, -0.05); 12-14 years: B = -0.29, (95% CI: -0.52, -0.06)). Regarding the opposite direction of influence, more PA at age 12 forecasted reduced FMI at age 14 (B = -0.16, (95% CI: -0.24, -0.07)), whereas increased FMI predicted increased ST across all time points in boys only (6-8 years: B = 0.23, (95% CI:0.02.43); 8-10 years: B = 0.23, (95% CI:.08.39); 10-12 years: B = 0.13, (95% CI:.03.23); 12-14 years: B = 0.17, (95% CI:.07, 26)). The revealed relationships were significantly stronger in boys compared to the (absent) relations in girls. Sensitivity analyses examining moderate to vigorous PA (MVPA) rather than total PA were in accordance with the main findings.

CONCLUSIONS

In boys, increased FMI predicted reduced PA and increased ST two years later from childhood to adolescence. The opposite direction of influence was evident from only ages 12-14. There were no prospective relationships between FMI and PA or ST among girls.

Trends in Obesity and Obesity-Related Risk Factors among Adolescents in Korea from 2009 to 2019

This study was conducted to identify the trends in obesity prevalence among adolescents and changes in the risk factors related to obesity. The study analyzed secondary data obtained from Korean Youth Risk Behavior Web-based Surveys conducted from 2009 to 2019. The Korean Youth Risk Behavior Web-based Survey is an annual survey of a nationwide representative sample of enrolled students aged 13–18 years in middle and high schools in Korea. Linear and trend analyses showed that the prevalence of obesity increased by 0.47% on average annually; this increase was statistically significant. Healthy food intake decreased significantly, but the prevalence of unhealthy food intake and the prevalence of skipping breakfast increased significantly. Vigorous-intensity physical activity, physical activity for over 60 min a day, and muscle-strengthening exercise for more than 3 days a week increased significantly, but so did the adolescents’ sedentary time. Therefore, health care providers and public policymakers need to actively manage adolescent obesity, which has been continuously increasing since 2009. In addition, long-term trends in obesity-related risk factors such as physical activity and dietary behaviors need to be considered in the development of obesity management strategies.

Screen time and health issues in Chinese school-aged children and adolescents: a systematic review and meta-analysis

Backgrounds

Many literature reviews summarized relationships between screen time and child health, but they only included a few studies conducted in Chinese children and adolescents. The potential influence of screen time may vary by social context. The current systematic review and meta-analysis aimed to evaluate relationships between screen time and health issues among Chinese school-aged children and adolescents.

Methods

Peer-reviewed articles written in Chinese and English were retrieved from CNKI, Wanfang, PubMed, Embase, and Web of Science from inception to June 2020. The Downs & Black checklist was applied to assess study quality. Meta analyses used random effect models and mixed effects model to calculate pooled adjusted odds ratios and 95% confidence intervals. Heterogeneity, sensitivity, and publication bias were assessed using Q and I² statistics, “one-study removed” analysis, the funnel plot, trim and fill analysis, and classical fail-safe N, respectively.

Results

In total, we identified 252 articles reporting 268 studies with unique samples. These studies investigated relationships between screen time and health issues of adiposity, myopia, psycho-behavioral problems, poor academic performance, cardiometabolic disease risks, sleep disorder, poor physical fitness, musculoskeletal injury, sub-health, and miscellaneous issues of height and pubertal growth, injury, sick leave, and respiratory symptoms. Proportions of studies reporting positive relationships with screen time were lowest in adiposity (50.6%) and higher in myopia (59.2%) and psycho-behavioral problems (81.8%). Other health issues were examined in 10 or less studies, all of which had more than half showing positive relationships. The pooled odds ratio from 19 studies comparing health risks with the screen time cutoff of 2 hours per day was 1.40 (95% CI: 1.31 to 1.50, I² = 85.9%). The pooled effect size was 1.29 (95% CI: 1.20 to 1.39) after trimming 7 studies for publication bias adjustments.

Conclusions

Findings exclusively generated from Chinese school-aged children and adolescents resonate those mainly from western countries. Evidence suggests that higher levels of screen time are related with greater risks of various health issues, although the relationships appear to be weak and intertwined with other confounding factors. Future studies need to investigate health-specific dose effects and mechanisms of screen time.

Supplementary information

The online version contains supplementary material available at 10.1186/s12889-022-13155-3.

Physical Education on the Beach: An Alternative Way to Improve Primary School Children's Skill- and Health-Related Outcomes during the COVID-19 Pandemic

The COVID-19 restrictions could preclude children from participating in physical education (PE) interventions. This study aimed to evaluate the efficacy of a PE intervention conducted on the beach on children’s skill- and health-related outcomes, as a possible alternative PE intervention that could be also applied during the COVID-19 pandemic. The study involved 106 primary school children, randomly assigned to the traditional indoor (TI) intervention or to the experimental outdoor (EO) intervention. The intervention period lasted 4 months and consisted of two 1-h sessions per week. Intervention was conducted just before the beginning of the COVID-19 pandemic. Children’s anthropometric parameters (height, weight, BMI, body fat percentage, and abdominal circumference), fitness parameter (VO_2peak), health parameters (resting heart rate, and systolic and diastolic blood pressure), gross motor coordination, and physical activity level were assessed before and after intervention. Both groups significantly improved fitness and motor coordination but worsened some anthropometric parameters (weight, abdominal circumference) after the intervention period. The EO group showed a higher increase of gross motor coordination than the TI group. Results of this study demonstrated that children benefited from a well-structured PE intervention conducted in the natural environment of the beach improving physical fitness and gross motor coordination. Therefore, planning outdoor PE interventions could be an alternative and safe way to encourage and implement physical activity at school during the particular period of COVID-19 pandemic.

The effect of TV viewing on children's obesity risk and mental well-being: Evidence from the UK digital switchover

We examine the effect of screen-based activities on obesity and mental well-being for children, using a large survey dataset representative of the UK population and an event study model that exploits exogenous variation in the entry date of the digital television transition in the UK. The digital transition increased the number of available free television channels from 5 to 40, leading to a rise in television viewing time. Our results show that receiving access to digital television signal considerably increases the mental health total difficulties score among children, and that this impact grows over time. We also find suggestive evidence that the digital transition could have increased BMI for children. Underlying the net effects appear to be decreases in participation in social and physical activities.

Binge Watching during COVID-19: Associations with Stress and Body Weight

Binge watching is becoming increasingly common and may impact energy balance and body weight. The COVID-19 pandemic has created conditions conducive to binge watching and increased stress. We investigated relationships between COVID-related stress and binge watching behaviors, and potential variation in this relationship by body weight. Adults (n = 466) completed a cross-sectional online survey assessing binge watching behaviors during and before the pandemic, COVID-related stress, and body weight. Participants reported an increase in binge watching frequency from before to during the pandemic (F1,401 = 99.970, p < 0.001), with rates of high binge watching ("3-4 times per week" to "3 or more times per day") increasing from 14.6% to 33.0%. Binge watching episode duration increased from 3.26 ± 1.89 h to 3.92 ± 2.08 h (p < 0.001). The increase in binge watching frequency was greatest in individuals with obesity and high stress (F 4,401 = 4.098, p = 0.003). Participants reporting high stress reported higher frequency of eating while binge watching, as well as higher levels of negative emotional triggers, consequences to binge watching, and lack of control over binge watching (all p < 0.001). Our results show that binge watching increased during the pandemic, with greater increases among individuals reporting higher COVID-related stress, especially those with obesity, and concomitant effects on eating, and highlight a need for interventions to minimize the obesogenic impact of binge watching during the pandemic.

Physical Activity Among Preadolescents Modifies the Long-Term Association Between Sedentary Time Spent Using Digital Media and the Increased Risk of Being Overweight

BACKGROUND

This study aimed to examine whether sedentary digital media use in preadolescence increases the risk of being overweight 3 years later, and whether this association differs based on preadolescents' leisure-time physical activity (LTPA) levels.

METHODS

The authors conducted a 3-year follow-up study among 4661 participants with a mean (SD) age of 11 (1) years at baseline and 14 (1) years at follow-up. A web-based questionnaire assessed sedentary digital media use and LTPA. The authors categorized baseline LTPA duration into 3 levels: 0 to 5 (low), 6 to 8 (moderate), and ≥9 (high) hours per week. In addition, the authors categorized adolescents as normal weight or overweight/obese at follow-up.

RESULTS

Greater amounts of sedentary digital media use at baseline associated with an increased risk of being overweight 3 years later even after adjusting for confounders. This only held for preadolescents with low baseline LTPA (OR = 1.14; 95% confidence interval, 1.05-1.24), but not among those with moderate (OR = 1.02; 0.91-1.15) or high (OR = 0.96; 0.85-1.08) LTPA.

CONCLUSIONS

Preadolescent LTPA modified the long-term association between sedentary digital media use and being overweight; specifically, 6 hours per week or more of LTPA mitigated the increased risk of being overweight associated with higher amounts of digital media use.

Age-related change in sedentary behavior during childhood and adolescence: A systematic review and meta-analysis

Sedentary behaviors are highly prevalent in youth and may be associated with markers of physical and mental health. This systematic review and meta-analysis aimed to quantify the age-related change in sedentary behavior during childhood and adolescence. Ten electronic databases were searched. Inclusion criteria specified longitudinal observational studies or control group from an intervention; participants aged ≥5 and ≤18 years; a quantitative estimate of the duration of SB; and English language, peer-reviewed publication. Meta-analyses summarized weighted mean differences (WMD) in device-assessed sedentary time and questionnaire-assessed screen-behaviors over 1-, 2-, 3-, or more than 4-year follow-up. Effect modification was explored using meta-regression. Eighty-five studies met inclusion criteria. Device-assessed sedentary time increased by (WMD 95% confidence interval [CI]) 27.9 (23.2, 32.7), 61.0 (50.7, 71.4), 63.7 (53.3, 74.0), and 140.7 (105.1, 176.4) min/day over 1-, 2-, 3-, and more than 4-year follow-up. We observed no effect modification by gender, baseline age, study location, attrition, or quality. Questionnaire-assessed time spent playing video games, computer use, and a composite measure of sedentary behavior increased over follow-up duration. Evidence is consistent in showing an age-related increase in various forms of sedentary behavior; evidence pertaining to variability across socio-demographic subgroups and contemporary sedentary behaviors are avenues for future research.

Better health indicators of FitSpirit participants meeting 24-h movement guidelines for Canadian children and youth

This study aims to determine the proportion of girls who meet the recommendations for moderate-to-vigorous physical activity (MVPA), screen time and sleep duration among FitSpirit participants and evaluate the associations of these recommendations with perceived health-related quality of life (QOL), perceived health, physical activity (PA), self-efficacy and body mass index. Cross-sectional analyses of FitSpirit data were performed. All variables were collected through an online questionnaire. The proportion of girls meeting all recommendations was 2.2%, while 72.5% met either one or two and 25.4% met none. A greater percentage of girls with ≥3 years in FitSpirit met MVPA and sleep recommendations combined when compared with fewer years (12.9% vs. 1.7% with 1 year; vs. 10.1% with 2 years; p < 0.05). Meeting the combinations of MVPA and screen time (β = 0.19, 95% CI = 0.40, 1.68), MVPA and sleep (β = 0.20, 95% CI = 0.27, 1.04) and all three combined (β = 0.17, 95% CI = 0.33, 1.71) was the most significant predictors of better perceived QOL. Respecting MVPA recommendations predicted a better perceived health (β = 0.18, 95% CI = 0.18, 0.87) while girls who slept as recommended had a better PA-related self-efficacy (β = 0.23, 95% CI = 0.51, 2.11). Not meeting any recommendation was associated with inferior PA-related self-efficacy (β = -0.32, 95% CI = -3.03, -1.21). Lastly, meeting MVPA and sleep recommendations was significantly associated with lower body mass index z-scores (β = -0.14, 95% CI = -1.16, -0.11). There was a small percentage of girls following all of the recommendations. Furthermore, meeting individual and combined recommendations was associated with better perceived QOL and health, PA self-efficacy as well as healthier body mass index z-score.

Criterion-Related Validity of Field-Based Fitness Tests in Adults: A Systematic Review

We comprehensively assessed the criterion-related validity of existing field-based fitness tests used to indicate adult health (19–64 years, with no known pathologies). The medical electronic databases MEDLINE (via PubMed) and Web of Science (all databases) were screened for studies published up to July 2020. Each original study’s methodological quality was classified as high, low and very low, according to the number of participants, the description of the study population, statistical analysis and systematic reviews which were appraised via the AMSTAR rating scale. Three evidence levels were constructed (strong, moderate and limited evidence) according to the number of studies and the consistency of the findings. We identified 101 original studies (50 of high quality) and five systematic reviews examining the criterion-related validity of field-based fitness tests in adults. Strong evidence indicated that the 20 m shuttle run, 1.5-mile, 12 min run/walk, YMCA step, 2 km walk and 6 min walk test are valid for estimating cardiorespiratory fitness; the handgrip strength test is valid for assessing hand maximal isometric strength; and the Biering–Sørensen test to evaluate the endurance strength of hip and back muscles; however, the sit-and reach test, and its different versions, and the toe-to-touch test are not valid for assessing hamstring and lower back flexibility. We found moderate evidence supporting that the 20 m square shuttle run test is a valid test for estimating cardiorespiratory fitness. Other field-based fitness tests presented limited evidence, mainly due to few studies. We developed an evidence-based proposal of the most valid field-based fitness tests in healthy adults aged 19–64 years old.

Is knowledge of screen time guidelines associated with stages of behavior change for television viewing among adolescents?

It is unknown whether knowledge of guidelines for television (TV) viewing translate into behavior change for TV time among adolescents. The purpose of the present study is to verify whether knowledge of TV recommendations (spending <2 hr/day watching TV) is associated with the stages of behavior change related to TV viewing among adolescents. Schoolchildren (11-16 years) from six schools were recruited. Their knowledge of TV guidelines (correct [<2 hr/day], overestimated [<1 hr/day or never watch TV], underestimated [<3hr/day or watch TV whenever they wanted], and do not know [response option]) and stages of behavior change related to TV (precontemplation, contemplation, preparation, action, and maintenance) were assessed by a questionnaire. Multinomial logistic regression was used to test the association between knowledge and stages of behavior change. A total of 792 adolescents (53% girls) participated, of whom 45% were in the precontemplation stage, while 35% underestimated and 18% did not know the TV guidelines. Those who overestimated the guidelines had higher odds of being in the maintenance stage than did those who knew the recommendations correctly (odds ratio [OR] 2.06), while those who underestimated the guidelines had lower odds of being in the maintenance (OR 0.22) and any other stage compared to those who were aware of the recommendations (the precontemplation stage was the reference). Underestimating the guidelines was associated with being in the precontemplation stage, while overestimating them was associated with the maintenance stage. Interventions should test whether increasing knowledge can help shifting those in the precontemplation and contemplation toward action and maintenance.

Physical activity behaviours in adolescence: current evidence and opportunities for intervention

Young people aged 10-24 years constitute 24% of the world's population; investing in their health could yield a triple benefit-eg, today, into adulthood, and for the next generation. However, in physical activity research, this life stage is poorly understood, with the evidence dominated by research in younger adolescents (aged 10-14 years), school settings, and high-income countries. Globally, 80% of adolescents are insufficiently active, and many adolescents engage in 2 h or more daily recreational screen time. In this Series paper, we present the most up-to-date global evidence on adolescent physical activity and discuss directions for identifying potential solutions to enhance physical activity in the adolescent population. Adolescent physical inactivity probably contributes to key global health problems, including cardiometabolic and mental health disorders, but the evidence is methodologically weak. Evidence-based solutions focus on three key components of the adolescent physical activity system: supportive schools, the social and digital environment, and multipurpose urban environments. Despite an increasing volume of research focused on adolescents, there are still important knowledge gaps, and efforts to improve adolescent physical activity surveillance, research, intervention implementation, and policy development are urgently needed.

A 3-year longitudinal study of the association of physical activity and sedentary behaviours with childhood obesity in China: The childhood obesity study in China mega-cities

OBJECTIVES

Examine school children's physical activity (PA) and sedentary behaviours (SB) during 2015 to 2017 in China, and study their associations with children's weight status and relevant gender differences.

METHODS

This open cohort study included students from five major cities (Beijing, Shanghai, Xi'an, Nanjing, and Chengdu) across China. Data were collected from students in 2015, 2016, and 2017 (n = 5535) and from their parents and school personnel. Children's weight, height, and waist circumference were measured. SB and PA factors were evaluated using questionnaires. Mixed-effects models examined the relationship between weight status and PA-/SB-associated factors using this longitudinal data.

RESULTS

These children had high rates of obesity (12.4%, 95% CI 11.6%-13.3%) and central obesity (28.1%, 95% CI 26.9%-29.3%) during 2015 to 2017. Boys were more likely to have obesity than girls (16.5% vs 8.4%, respectively) as well as centrally obesity (36.3% vs 19.8%, respectively) and spent more time in screen viewing than girls (hours/week ± SD: 2015, 1.8 ± 2.5 vs 1.5 ± 2.0; 2016, 2.0 ± 2.4 vs 1.8 ± 2.5; 2017, 1.7 ± 2.3 vs 1.4 ± 2.1 hours/week). Those who walked <5 minutes on their average daily walk to school were more likely to have obesity (OR: 1.96, 95% CI 1.03-3.73) than those who spent ≥15 minutes on walking to school. When stratified by gender, this higher risk was only observed in girls (OR: 3.01, 95% CI 1.09-8.35). Children who spent more time in screen viewing were more likely to have obesity (OR: 1.13, 95% CI 1.06-1.21) and have central obesity (OR: 1.05, 95% CI 1.02-1.09). The association for obesity was consistent in boys and girls (boys, OR: 1.15, 95% CI 1.05-1.25; girls, OR: 1.12, 95% CI 1.00-1.24).

CONCLUSIONS

More screen time and less walking time were risk factors for developing obesity in urban Chinese children. The associations varied by gender.