Sedentary behavior in Brazilian children and adolescents: a systematic review

Association between sedentary behavior, diet and nutritional status in adolescents: baseline results from the LONCAAFS Study

The aim of the present study was to analyze the relationship between time spent engaged in sedentary behaviors, type of diet, and overweight in adolescents. A cross-sectional study using data from the Longitudinal Study on Sedentary Behavior, Physical Activity, Eating Habits, and Health of Adolescents - LONCAAFS Study. A total of 1,438 adolescents (10 to 14 years old) from public schools in the city of João Pessoa, Brazil, participated in the study. To evaluate the combined effects of excessive time in sedentary behavior and consumption from two food groups: Convenience and Prudent on overweight, we performed multiple logistic regression analyses, adjusted for energy, level of physical activity, sex, and age. Excessive time in sedentary behavior increased the chance of adolescents being overweight by 37% (OR = 1.37; 95%CI: 1.04-1.80). This chance increased to 43% when the adolescents were simultaneously engaged in excessive sedentary behavior and had high consumption of the Convenience food group (OR = 1.43; 95%CI: 1.05-1.94) and increased to 39% on those who engaged in excessive sedentary behavior and had low consumption of foods from the Prudent (OR = 1.39; 95%CI: 1.04-1.84). Excessive sedentary behavior is associated with being overweight and the chance increases with the consumption of convenient foods.

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.

Is more prolonged sun exposure associated with healthier life habits and obesity indicators in Portuguese children?

OBJECTIVES

Sun exposure seems to have an indirect effect on the development of obesity through vitamin D synthesis in the skin, the primary source of this vitamin. The present study aimed to investigate associations among sun exposure time, obesity indicators, and lifestyle habits in children.

METHODS

A total of 4755 children (3-10 years; 49.86% boys) from the north, center and south-central Portugal were included in the present study. During 2016/2017 children's sun exposure time, screen time, time devoted to the practice of physical activity and active play were collected through standard questionnaires answered by parents. Statistical analyses were conducted to investigate differences among sun exposure time according to the sex, age, obesity indicators and lifestyle habits.

RESULTS

Linear regression analysis showed that sun exposure time presented a negative association with Body Mass Index (β = -0.09, 95% CI: -0.18; -0.003; p = .042), body fat % (β = -0.31, 95%; CI: -0.54; -0.07; p = .010), computer time (β = -0.08, 95% CI: -0.12; - 0.05; p < .0001) and a positive association with active play time (β = 0.22, 95% CI: 0.17; 0.27; p < .0001) and total time of physical activity practice (β = 10.01, 95% CI: 4.52; 15.20; p < .0001).

CONCLUSIONS

The results reinforce the need for future guidance on the ideal sun exposure time, especially in children, who are at risk for vitamin D deficiency. Standardization of criteria for classifying optimal sun exposure time in this age group, considering the parameters that affect vitamin D status, such as age and seasonality, should be considered when planning future guidelines.

The genetic predisposition increases the chances of schoolchildren maintaining higher adiposity levels after three years

BACKGROUND

The behavior of anthropometrics and the relationship with genetic factors through a long-term perspective should be better explored. This study aims to verify the odds of maintaining the nutritional status classification after three years, according to the rs9939609 polymorphism (FTO gene).

METHODS

It was a retrospective longitudinal study with 355 schoolchildren (7-17 years). Body mass index, body-fat percentage (BF%), and waist circumference (WC) were measured at baseline and follow-up. The FTO gene was evaluated from blood collection and genotyping performed by real-time polymerase chain reaction. Odds ratios and 95% confidence intervals were calculated.

RESULTS

For those homozygous with the A allele, the odds of being at less favorable classification at follow-up were 2.29 (1.24; 4.22) and 4.05 (2.08; 7.86) times higher than expected for BF% and WC, respectively, whereas the odds of being in the more favorable classification at follow-up were 0.34 (0.12; 0.93) and 0.11 (0.01; 0.78) for BF% and WC, respectively. The odds of being at less favorable classification were higher for AA carriers with less favorable classification at baseline for BF% and WC compared to AT and TT carriers.

CONCLUSIONS

Schoolchildren with a genetic predisposition to obesity and unfavorable anthropometric profile at baseline had more chances of maintaining their nutritional status after three years of follow-up.

Effects of a Physical Exercise Program and Health Advice on Sedentary Behavior of Adolescents

Sedentary behavior (SB) is a risk factor for chronic non-communicable diseases. This study aimed to assess the effects of an extracurricular physical exercise program and health advice on SB in adolescents. This was a non-randomized experimental study involving 19 adolescents divided into an intervention group (IG) and a control group (CG), aged 13-16 years from a public school in a Brazilian municipality. SB was measured using self-reports and accelerometers. The intervention included physical exercise and health advice. Repeated measures analysis of variance with a significance level of α = 5% was used. There was a time*group interaction for the subscapular fold ((pre IG = 16.30 mm vs. CG = 13.44 mm, post IG = 14.00 mm vs. CG = 15.89 mm) p = 0.001), and VO2MAX ((pre IG = 32.75 mL/kg/min vs. CG = 30.66 mL/kg/min, post IG = 35.76 mL/kg/min vs. CG = 29.28 mL/kg/min) p = 0.008). The accelerometer showed significant differences between groups in the total SB ((pre IG = 647.49 min/day vs. CG = 535.24 min/day, post IG = 614.02 min/day vs. CG = 586.97 min/day) p = 0.045), with a significant decrease in the IG. In conclusion, an extracurricular physical exercise program and health advice was effective in reducing SB in adolescents.

Screen time and low back pain in children and adolescents: a systematic review of Brazilian studies

OBJECTIVE

To identify and summarize the possible associations between screen time and low back pain in children and adolescents.

DATA SOURCE

Systematic searches were performed in five electronic databases (Lilacs, Scielo, Scopus, PubMed and Web of Science) on 01/25/2021, complemented by manual searches in reference lists and on Google Scholar, looking for original scientific articles that included Brazilian observational studies; whose samples had children and/or adolescents aged between 6 and 19 years, without specific clinical conditions, and that presented analyses of associations between indicators of screen time and nonspecific low back pain, based on regression models.

DATA SYNTHESIS

Nine cross-sectional studies whose samples had adolescents were included. Of the 18 analyses identified, nine reported risk relationships between the variables of interest. More specifically, risk associations were found in two studies that evaluated adolescents exposed to at least three hours using cell phone or tablet, and watching television per day. Also, instruments, cut-off points adopted, and screen equipment evaluated were diverse.

CONCLUSIONS

Even though most of the risk associations were borderline from the statistical point of view, we found a higher frequency of risk associations between screen time and non-specific low back pain in adolescents exposed to screen time for at least three hours a day. In addition, further longitudinal studies with samples composed of children should be conducted across the country.

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).

Association between Pulmonary Function and Body Composition in Children and Adolescents with and without Obesity

Lung function in children and adolescents with obesity must consider the coexistence of two complex and related phenomena: obesity and growth. The assessment of body composition can identify changes in respiratory dynamics arising, exclusively or jointly, from adiposity and lean body mass. This study aimed to compare pulmonary function and the dysanapsis indices of children and adolescents without asthma, with and without obesity, considering body composition, pubertal development, and physical activity practice. We performed a cross-sectional study with 69 participants, 41 (59.42%) of whom have obesity. All participants carried out spirometry and the assessment of, respectively, body composition by dual-energy X-ray absorptiometry, vital signs, pubertal development, and physical activity practice. In our data, the group with obesity had higher values of forced vital capacity (FVC) and lower values of the ratio between forced expiratory volume in one second and FVC (FEV₁/FVC). Analyzing the entire sample, we found a positive correlation between FVC and a negative correlation between FEV₁/FVC with fat mass markers. At the same time, inspiratory capacity, expiratory reserve volume, and peak expiratory flow were correlated with lean body mass markers. In addition, participants with obesity presented a lower dysanapsis index. In conclusion, children and adolescents with obesity showed increased FVC and reduced FEV₁/FVC. Our findings are possibly related to the increase in fat mass, not to lean body mass. We hypothesize that these findings are associated with the dysanaptic growth pattern, which is higher in obesity, evidenced by the reduction of the dysanapsis index.

Relationship of Objectively Measured Physical Activity, Sedentary Behavior and Sleep Time with Cardiovascular and Mtabolic Outcomes in Adolescents (A Pilot Study): ABCD Growth Study

STUDY OBJECTIVE

Different behaviors are considered important factors that may influence a healthy lifestyle. Given this fact, we aim to analyze the relationship between moderate-vigorous physical activity (MVPA), sleep time, and sedentary time, with cardiometabolic outcomes in adolescents.

METHODS

Cross-sectional study, with 152 eutrophic and healthy adolescents. The behavioral variables were collected objectively and the arterial thickness was measured through ultrasound. Blood variables (LDL, TG, HDL, glucose, and insulin) were collected in a private laboratory. To analyze the data, the Student t test and Kruskal-Wallis test were used to compare the groups. All analyses adopted p < 0.05.

RESULTS

Girls who demonstrated better combined behaviors, presented significant results for TG (p = 0.045), BP (p = 0.016), and cardiovascular score (p = 0.049) when compared to their peers. Furthermore, the practice of physical activity combined with sufficient sleep time was associated with lower values of arterial thickening (p = 0.017).

CONCLUSIONS

In view of the results presented, it is possible to state that the aggregation of behaviors was more consistent in females and that the practice of physical activity and adequate sleep time can reflect on cardiovascular health.

Impact of sports participation on cardiovascular health markers of children and adolescents: Systematic review and meta-analysis

BACKGROUND

Cardiovascular diseases have a high prevalence in adults and their development begins in the first decades of life. On the other hand, sports participation in childhood and adolescence provides benefits which can delay the onset of these diseases.

AIM

To synthesize the available literature on the impact of sports participation on cardiovascular outcomes in children and adolescents.

METHODS

This systematic review was conducted on studies of children and adolescents (aged 8-18 years) who regularly practiced a sport and had reported cardiovascular outcomes (blood pressure and intima-media thickness) recorded. The Medline/PubMed, SciELO, Reference Citation Analysis (https://www.referencecitationanalysis.com/) and Bireme databases were searched.

RESULTS

In total, 3314 publications for blood pressure and 122 publications for intima-media thickness were identified in the databases. After exclusions (e.g., duplicate articles, animal studies and those that did not meet the inclusion criteria), four publications for blood pressure (449 adolescents) and two publications for intima-media thickness were included (402 adolescents). For blood pressure, all publications were longitudinal in design (follow-up ranging from 12 wk to 12 mo) and involved adolescents aged from 8 years to 18 years of age. For intima-media thickness, both publications were longitudinal in design and involved adolescents aged from 11 years to 18 years of age.

CONCLUSION

Sports participation seems to promote benefits to cardiovascular structure and function in adolescents. However, studies with adolescents are scarce and further research is needed to understand this phenomenon.

The influence of sedentary behaviour on mental health among children and adolescents: A systematic review and meta-analysis of longitudinal studies

BACKGROUND

Systematic reviews that have examined associations between sedentary behaviour (SB) and mental health among children and adolescents are mainly based on cross-sectional investigations. There is a lack of evidence for a prospective relationship between SB and mental health in children and adolescents. This systematic review synthesized longitudinal studies that examined prospective associations between SB and mental health among children and adolescents.

METHODS

We conducted computer searches for English language literature from electronic databases of PubMed, Embase, PsycInfo and Google scholar, and manually screened the references of existing relevant studies to select studies for the synthesis. We included observational longitudinal studies that assessed the association between SB and mental health among children and adolescents. This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

In total, 58 longitudinal studies met the inclusion criteria and were synthesized in the review. We found that higher SB among children and adolescents was associated with increased depression, anxiety and other mental health problems later in life. A dose-response association between SB and mental health was observed, suggesting that children and adolescents who spend more time on SB may have a higher risk of developing poorer mental health later.

CONCLUSIONS

The findings in the present study suggest that intervention programs targeting reducing SB may benefit to the prevention of poor mental health among children and adolescents. Future intervention studies especially randomized controlled trials are needed to elucidate a causal relationship between SB and mental health among children and adolescents.

What are the characteristics that influence the sitting time in university students?

Abstract The objective was to estimate the relationship between sociodemographic characteristics, link with the university, behavioral, biological, and self-rated related to health, with time sitting in university students at federal institutions in the state of Bahia, Brazil. This cross-sectional study was carried out with university students from six institutions (Federal University “Recôncavo da Bahia”, Federal University of “Bahia”, Federal University of “Oeste da Bahia”, University of International Integration of Afro-Brazilian Lusophony, Federal University of “Vale do São Francisco” and Federal University of “Sul da Bahia”) in the state from Bahia in 2019. Time sitting in hours per day was investigated and relation sociodemographic, link with the university, behavioral, biological, self-rated of stress and health variables. Path analysis was used to apply multivariate linear regression. The significance status was 5%. A total of 1,217 university students participated of the study. The final model accounts for 6% of sitting time. Self-rated health as positive (β: -0.117; p: <0.001), increasing age (β: -0.115; p: <0.001) and physical activity practice (β: -0.113; p: <0.001) contributed to the decrease in sitting time. The increase in the amount of inadequate eating habits (β: 0.063; p: 0.032) favored the increase in sitting time. The adjustment indices were satisfactory. Concluded that self-rated health as positive, advancing age and physical activities practice were determinants of reduced sitting time, on the other hand, irregular eating behaviors favored sedentary behavior.

Abdominal obesity-related risk factors in children from public schools of Barbacena, Minas Gerais, Brazil

OBJECTIVE

To evaluate the sociodemographic and lifestyle factors associated with abdominal obesity in children from public schools in Barbacena, state of Minas Gerais, Brazil.

METHODS

This is a cross-sectional study conducted on 326 students aged 7 to 9 years from public schools in the urban area of the city. Anthropometric data included body weight, height, body mass index according to age, waist circumference, and waist-to-height ratio. Food consumption was evaluated using the Previous Day Food Questionnaire. Abdominal obesity was assessed based on waist circumference and waist-to-height ratio. The bivariate and multivariate analyses were performed by logistic regression, estimating the crude and adjusted odds ratio (OR), with 95% confidence interval.

RESULTS

The prevalence of overweight was 30.7%; whereas the prevalence of abdominal obesity was 9.2 and 12.6% according to waist circumference and waist-to-height ratio, respectively. Boys (OR 2.76; 95%CI 1.22-6.25) and children from central schools (OR 2.73; 95%CI 1.08-6.80) presented an increased chance of abdominal obesity according to waist circumference. Abdominal obesity according to waist-to-height ratio was associated with the central location of the schools (OR 2.18; 95%CI 1.02-4.63) and the habit of skipping supper (OR 2.01; 95%CI 1.00-4.09).

CONCLUSIONS

The findings showed that being a boy, studying in a central school, and skipping supper were the main risk factors associated with abdominal obesity.

The genetic predisposition to obesity has no influence on waist circumference when screen time and sleep duration are adequate in children and adolescents

The aim of the present study was to verify whether the amount of sleep duration, screen time, and physical activity moderate the relationship between FTO rs9939609 polymorphism and waist circumference (WC) in children and adolescents. This is a cross-sectional study conducted with 1338 children and adolescents, aged between 6 and 17 years. Lifestyle habits were assessed through self-reported questionnaire. WC was measured on the narrowest part of the trunk between the last rib and the iliac crest. FTO rs9939609 polymorphism was genotyped by real time polymerase chain reaction. The PROCESS macro for the SPSS was used for moderation analyses, through multiple linear regression models. Results indicated significant interactions were found between sleep duration and screen time X FTO rs9939609, showing that these lifestyle behaviours are moderators in the relationship between a genetic predisposition for obesity and higher WC. For physical activity, there was no significant interaction. Therefore, sleeping more than 564 min a day (i.e. 9.4 h) and spending no more than 233 min in front of screen may counteract the genetic predisposition to obesity in children and adolescents.

Use of latent class analysis as a method of assessing the physical activity level, sedentary behavior and nutritional habit in the adolescents' lifestyle: A scoping review

BACKGROUND

Currently, adolescents' lifestyle is commonly characterized by physical inactivity, sedentary behavior, and inappropriate eating habits in general. A person-oriented approach as Latent Class Analysis (LCA) can offer more insight than a variable-centered approach when investigating lifestyle practices, habits, and behaviors of adolescent population.

OBJECTIVE

The aim of the present study was to assess which variables are mostly used to represent the physical activity level, sedentary behavior SB) and nutritional habit in the adolescents' lifestyle in studies that used the LCA.

DESIGN

Scoping review.

METHODS

The study was a performed in accordance with the proposed criteria for systematic reviews and meta-analyses-Preferred Reporting Items for Systematic Reviews and Meta-Analyses and registered in PROSPERO (CRD42018108444). The original articles were searched in MEDLINE/PubMed, Scopus, ScienceDirect, Web of Science, PsycINFO, and SPORTdiscus. The Quality Assessment Tool analyzed the risk of bias of the included studies.

RESULTS

30 original articles were selected. The physical activity level (28 studies), SB and nutritional habits (18 studies) were the most common variable used to evaluate the adolescent's lifestyle by LCA model. Specifically, physical inactivity and high SB were the manifest variables with higher frequency in the negative latent classes (LCs) in adolescent girls. On the other hand, physical exercises and sports were activities more commonly labeled as positive LCs.

CONCLUSIONS

The LCA models of the most of selected studies showed that physical inactivity, high SB were the most common in the LCs with negative characteristics of the adolescents' lifestyle. Better understanding the results of analyzes of clusters of multivariate behaviors such as the LCA can help to create more effective strategies that can make the lifestyle of adolescents healthier.

Students' Physical Activity Profiles According to Children's Age and Parental Educational Level

The aim of this study was to identify different profiles of physical activity (PA) behaviors according to the school student’s age stage and their parents’ or guardians education level. Seven hundred twenty-seven students and parents of different educational stages were invited to take part in this study. The participants included, Preschool (1 to 5 years old), Primary School (6 to 11 years old), Secondary School (12 to 15 years old), and High School (16 to 18 years old). A questionnaire to assess the educational level of parents (low, intermediate, and high) and their child’s PA level and sedentary behaviors across various age stages was administered. The results showed a number of different physical activity profiles for preschool (4), primary (6), secondary (7) and high school (2) students. Primary and secondary school children’s behavioral profiles were reported to differ significantly between both physical activity levels and sedentary behaviors, while preschool students’ behavioral profiles only differed between sedentary behaviors. Higher parental education was most prevalent in clusters with significantly higher levels of PA in primary and secondary students, while there were equivocal trends for parental education level influencing behavioral profiles of high school students. These findings suggest there is some association between the behavioral profiles of student’s physical activity and sedentary behavior, and parental education level, most noticeably during the early to middle age stages.

Overweight in Rural Quilombola and Non-quilombola Adolescents From the Northeast of Brazil

Introduction: Overweight is an emerging problem among children and adolescents that leads to the development of several morbidities and health risks. Overweight occurs differently in different populations, especially in vulnerable groups like the rural and quilombola communities (an African-descendant population). This study aimed to estimate the prevalence of overweight and to investigate the possible associated factors in rural adolescents living in both quilombola and non-quilombola communities in Northeast Brazil.

Methods: This study is a population-based cross-sectional study with a household approach carried out in 2015 with 390 adolescents (age 10–19 years) living in rural quilombola and non-quilombola communities. The nutritional status was gauged using z-scores calculated for body mass index (BMI) and varies with gender and age. Prevalence ratios (PRs) and 95% confidence intervals (95% CIs) were used to establish associations between the results and explained variables. The multivariate analysis followed a model with a hierarchical entry of covariables controlled by gender and age.

Results: The study showed that 18.5% of rural adolescents were overweight, of which 17.9% were quilombolas and 19.0% were non-quilombolas. A significant difference in overweight between the samples was not found. In the multivariate-adjusted model, age ≥16 years (PR: 0.51; 95% CI: 0.28–0.95), the habit of having regular breakfast (PR: 0.58; 95% CI: 0.35–0.98), and process of attending school (PR: 0.35; 95% CI: 0.17–0.71) were associated with a lower prevalence of overweight. Stationary screen time, in contrast, was associated with a higher prevalence (PR: 1.61; 95% CI: 1.05–2.46). The process of attending school was associated with a lower prevalence of overweight (PR: 0.26; 95% CI: 0.09–0.69), even for the quilombolas.

Conclusions: A low prevalence of overweight was identified in rural adolescents. Overweight was significantly associated with the habit of having regular breakfast, older age, stationary screen time, and the process of attending school. The results reveal that school is a potential space for health promotion interventions, specifically in the most vulnerable rural regions, such as the quilombola communities. Besides, the study emphasizes the importance of adopting a healthy lifestyle early in life, including cultivating the habit of having regular breakfast and reducing stationary screen time.

Combination of sleep duration, TV time and body mass index is associated with cardiometabolic risk moderated by age in youth

OBJECTIVES

The combination of sleep duration, television (TV) time and body mass index (BMI) may be related to the alteration of cardiometabolic risk. However, there are few studies that use these variables grouped, and showing the moderating role of age. This study aimed to verify if the combination of sleep duration, TV time and BMI is associated with cardiometabolic risk and the moderating role of age in this relationship in youth.

METHODS

Cross-sectional study conducted with 1411 adolescents (611 male), aged 10-17 years. Sleep duration, TV time and BMI were assessed and grouped into eight categories. Cardiometabolic risk was assessed by a continuous metabolic risk score, including the following variables: low HDL-cholesterol, elevated triglycerides, dysglycemia, high systolic blood pressure, high waist circumference and low cardiorespiratory fitness. Generalized linear models were used to test moderation of age in the relationship between the eight categories of sleep duration/television time/BMI with cardiometabolic risk.

RESULTS

Cardiometabolic risk factor showed association with all overweight or obesity independent of sleep time and TV time. Age moderated the relationship between sleep duration/television time/BMI with cardiometabolic risk. This association was stronger in younger adolescents (11 and 13 years), indicating that individuals with inadequate sleep, prolonged TV time and overweight/obesity present higher cardiometabolic risk values when compared to 15-year-old adolescents.

CONCLUSION

Overweight/obesity, independently of sleep duration and TV time, is the main risk factor for cardiometabolic disorders in adolescence. When moderated by age, younger adolescents that presented the combination of risk factors had higher cardiometabolic risk.

Physical activity level in overweight adolescents at school: a systematic review

Abstract – The objective of this systematic review was to identify the association between overweight/obesity and level of physical activity in Brazilian children and adolescents in the school setting. For search strategy, the main reference databases (PubMed, LILACS, SciELO, SPORTDiscus, Web of Science, ERIC) were used. Baseline searches resulted in 3,265 potentially relevant titles (2,775 titles after removal of duplicate studies); 21 studies met all inclusion criteria and were included for analysis. Studies were carried out from 2007 to 2019; 47.6% of them were conducted in Southern Brazil, and only one study had nationwide approach. Prevalence from 5.4% to 21% was identified for overweight, 3.5% to 16.9% for obesity and 11.8% to 40.1% for overweight + obesity. According to results, 64.3% of overweight, 69.8% of obese and 37.7% of young overweight people were considered insufficiently active. The non-standardization of instruments to assess levels of physical activity and the lack of information regarding other Brazilian regions were classified as important limitations. The results reinforce the increase in the prevalence of overweight in Brazilian children and adolescents, and the high prevalence of physical inactivity among them. For every ten overweight children/adolescents, six are reported to be insufficiently active.

A Network Perspective on the Relationship between Screen Time, Executive Function, and Fundamental Motor Skills among Preschoolers

The present study aimed to analyze the dynamic and nonlinear association between screen time, executive function (EF), and fundamental motor skills (FMS) in preschoolers, considering sex and body mass index (BMI) from a network perspective. Forty-two preschoolers (24 boys, 3.91 ± 0.77 years old) provided screen time, EF, FMS, and BMI data. EF was measured using the Go/No Go task, and accuracy of Go (sustain attention), reaction time of Go, and accuracy of No Go (inhibitory control) were considered. Relationships between screen time, EF, FMS, sex, and BMI were explored using a network analysis. The emerged network highlights that screen time is intensely associated with the other variables in the network, while the accuracy of Go has the greater connectivity with other nodes in the network (2.27), being the most sensitive to potential intervention changes. Moreover, sex (1.74), screen time (0.93), and accuracy of Go (0.71) showed the greatest closeness. This study showed that in the emerged network, independent of sex, screen exposure affects the accuracy on Go task, and these components affect the variables in the network, as motor abilities and tasks involved in inhibitory control.

Sedentary Behaviors of a School Population in Brazil and Related Factors

Background. Overweight and obesity arise from a complex range of genetic, environmental, behavioral, educational, and socioeconomic factors. The present study explored the sedentary practices and some life habits related to health among children from the school population of Uruguaiana (Rio Grande do Sul, Brazil). Methods: A cross-sectional descriptive study was conducted to characterize the life habits of the school boys and girls from fourth grade (9-10 years old). Results: A total of 470 fourth-grade boys and girls (9-10 years old) participated in the study. As regards the variables linked to habits, 24% of the boys and girls answered they had not had breakfast the day they completed the questionnaire and 51.8% stated they did not have breakfast any given day of the week. Regarding sedentary habits, 25.3% of children watched TV or played video games five or more hours a day and 9% rarely played sports with their parents or caregivers. Statistical significance was recorded between "number of hours watching TV and playing video games" and "playing sports with parents or caregivers" (p < 0.05). Conclusions: Association between the times spent watching TV or playing video games and the practice of physical exercise in the family proves once again the importance of the family in education for the health of children. The school provides direct access to schoolchildren and their parents to launch numerous health education programs.

Relationship between sleep duration and TV time with cardiometabolic risk in adolescents

Objective

To verify the association between sleep duration and television time with cardiometabolic risk and the moderating role of age, gender, and skin color/ethnicity in this relationship among adolescents.

Methods

Cross-sectional study with 1411 adolescents (800 girls) aged 10 to 17 years. Television time, sleep duration, age, gender, and skin color/ethnicity were obtained by self-reported questionnaire. Cardiometabolic risk was evaluated using the continuous metabolic risk score, by the sum of the standard z-score values for each risk factor: high-density lipoprotein cholesterol, triglycerides, glycemia, cardiorespiratory fitness, systolic blood pressure, and waist circumference. Generalized linear regression models were used.

Results

There was an association between television time and cardiometabolic risk (β, 0.002; 95% CI, 0.001; 0.003). Short sleep duration (β, 0.422; 95% CI, 0.012; 0.833) was positively associated with cardiometabolic risk. Additionally, age moderated the relationship between television time and cardiometabolic risk (β, − 0.009; 95% CI, − 0.002; − 0.001), suggesting that this relationship was stronger at ages 11 and 13 years (β, 0.004; 95% CI, 0.001; 0.006) compared to 13 to 15 years (β, 0.002; 95% CI, 0.001; 0.004). No association was found in older adolescents (β, 0.001; 95% CI, − 0.002; 0.002).

Conclusions

Television time and sleep duration are associated with cardiometabolic risk; adolescents with short sleep have higher cardiometabolic risk. In addition, age plays a moderating role in the relationship between TV time and cardiometabolic risk, indicating that in younger adolescents the relationship is stronger compared to older ones.

Are neighborhood characteristics associated with sedentary behavior in adolescents? A systematic review

Sedentary behavior (SB) has emerged as a potential risk factor for chronic diseases. SB includes activities requiring low energy expenditure (≤1.5 metabolic equivalents) performed in a sitting or reclining posture. Our study aimed to gather evidence on the association between SB outcomes in adolescents (10-19 years) and neighborhood characteristics. This systematic review (PROSPERO registration number: CRD42018076877) examined studies indexed in PubMed Central®, LILACS, ScienceDirect, and SPORTDiscus databases. Sixteen articles were included. Insecurity during daytime hours, crime incidence, physical and social disorders, a higher neighborhood socioeconomic level, and time spent with peers were associated with higher levels of SB. Traffic, availability of a favorable environment for physical activity, and higher residential density were associated with lower levels of SB. Despite great variability in the SB cutoff points and methodology used for evaluating SB and neighborhood characteristics among studies, the evidence suggests that adolescent SB might be influenced by neighborhood characteristics.

Latin American interventions in children and adolescents' sedentary behavior: a systematic review

OBJECTIVE To identify and evaluate the effects of community-based interventions on the sedentary behavior (SB) of Latin American children and adolescents. METHODS A systematic review on community-based trials to reduce and/or control SB in Latin American countries (Prospero: CRD42017072157). Five databases (PubMed, Web of Science, Scopus, SciELO and Lilacs) and a reference lists were searched. RESULTS Ten intervention studies met the eligibility criteria and composed the descriptive synthesis. These studies were conducted in Brazil (n=5), Mexico (n=3), Ecuador (n=1) and Colombia (n=1). Most interventions were implemented in schools (n=8) by educational components, such as meetings, lessons, and seminars, on health-related subjects (n=6). Only two studies adopted specific strategies to reduce/control SB; others focused on increasing physical activity and/or improving diet. Only one study used an accelerometer to measure SB. Seven studies investigated recreational screen time. Eight studies showed statistically significant effects on SB reduction (80%). CONCLUSIONS Latin America community-based interventions reduced children and adolescents' SB. Further studies should: define SB as a primary outcome and implement strategies to reduce such behaviour; focus in different SBs and settings, other than recreational screen time or at-home sitting time; and use objective tools together with questionnaires to measure sedentary behaviour in.

Influence of the Parental Educational Level on Physical Activity in Schoolchildren

The factors influencing physical activity participation in children are varied, although there is evidence that the educational level of parents may be one important factor. The aim of this study is to analyze the influence of parental education on the level of physical activity and the sedentary behavior of their children. The parents of 727 students, separated based on school group (preschool: n = 179; primary: n = 284; secondary: n = 230; high: n = 34), were invited to complete a series of questionnaires assessing their educational level (low, intermediate, and high) and their child’s level of physical activity and sedentary behavior. Primary school students with high- and intermediate-educated parents were found to engage in significantly more physical activity per week and spent more time engaged in homework than children with lower-educated parents. Secondary school students with higher-educated parents were found to spend significantly less time engaged in sedentary behavior than children with lower- or intermediate-educated parents, and high schoolers with higher-educated parents engaged in less tablet time than children with lower-educated parents. Multiple linear regression demonstrated that greater physical activity was precipitated by certain sedentary behaviors in children with more educated parents, such as total time watching TV (primary school), doing homework (secondary school), and total time using a tablet/similar (high school), which increased total time engaged in physical activity. These findings suggest that more educated parents may implement structured time for their children to engage in a balance of physical activity and sedentary behaviors.

National Adolescent School-based Health Survey - PeNSE 2015: Sedentary behavior and its correlates

OBJECTIVE

To investigate the association between sedentary behavior (SB) and sociodemographic, social support, behavioral, and health variables among Brazilian adolescents.

METHODS

The 2015 National Adolescent School-based Health Survey (PeNSE) was a cross-sectional study consisting of 102,072 Brazilian ninth-graders (mainly aged 13-15 years). SB was defined as the time (in hours) watching television, using a computer, playing video games, talking to friends, or doing other activities in a sitting position. For analysis purposes, SB was categorized into different cut-offs as per the sample distribution quartiles: >2 versus <2 (25th percentile); >4 versus <4 (50th 26 percentile) and >6 versus <6 (75th 27 percentile). We employed Poisson univariate and multivariate regression analyses with robust variance and hierarchical entry of variables for each cut-off point.

RESULTS

The prevalence rates of each SB cut-off point were 68.15% (CI: 67.44-68.86), 44.15% (CI: 43.40-44.90) and 24.97% (CI:24.37-25.57) for >2, >4 and >6 hours, respectively. The following characteristics were positively and significantly associated with each SB cut-off point in the final models: females, current employment, higher household economic status and higher maternal schooling, lower levels of parents checking homework, tobacco and alcohol use, soft drink and fruit consumption, and regular, poor or very poor self-assessed health status. Conversely, students who self-declared brown were less likely to be classified as a SB cut-off point. Significant associations with age, report of close friends, and physical activity varied by different SB cut-off points.

CONCLUSION

Understanding the SB correlates in their different dimensions contributes to the identification of subgroups of adolescents with higher SB prevalence, which is crucial in the development and improvement of public policies. The demographic and behavioral characterization of these groups can guide the development of future intervention strategies, considering the school and family contexts of these adolescents.

Reliability and validity of a sedentary behavior questionnaire for South American pediatric population: SAYCARE study

Background

Multicenter studies from Europe and the United States have developed specifically standardized questionnaires for assessing and comparing sedentary behavior, but they cannot be directly applied for South American countries. The aim of this study was to assess the reliability and validity of the South American Youth Cardiovascular and Environmental (SAYCARE) sedentary behavior questionnaire.

Methods

Children and adolescents from seven South American cities were involved in the test-retest reliability (children: n = 55; adolescents: n = 106) and concurrent validity (children: n = 93; adolescents: n = 94) studies. The SAYCARE sedentary behavior questionnaire was administered twice with two-week interval and the behaviors were parent-reported for children and self-reported for adolescents. Questions included time spent watching television, using a computer, playing console games, passive playing (only in children) and studying (only in adolescents) over the past week. Accelerometer was used for at least 3 days, including at least one weekend day. We compared values of sedentary time, using accelerometers, by quartiles of reported sedentary behavior time and their sum.

Results

The reliability of sedentary behavior time was moderate for children (rho ≥0.45 and k ≥ 0.40) and adolescents (rho ≥0.30). Comparisons between the questionnaire and accelerometer showed a low overall agreement, with the questionnaire systematically underreporting sedentary time in children (at least, − 332.6 ± 138.5 min/day) and adolescents (at least, − 399.7 ± 105.0 min/day).

Conclusion

The SAYCARE sedentary behavior questionnaire has acceptable reliability in children and adolescents. However, the findings of current study indicate that SAYCARE questionnaire is not surrogate of total sedentary time.

OVERWEIGHT IN ADOLESCENTS: FOOD INSECURITY AND MULTIFACTORIALITY IN SEMIARID REGIONS OF PERNAMBUCO

Objective:

To investigate context of overweight adolescents from the semiarid and rural areas of Pernambuco, considering the multifactorial nature of the determinants of being overweight, and the food and nutritional insecurity conditions of the region.

Methods:

A population based cross-sectional study was conducted from September to October 2015. The nutritional status of adolescents was assessed by body mass index (BMI) and classified by the BMI/Age indicator, according to sex. To analyze the factors associated with being overweight, the variables were grouped into: socioeconomic, demographic, environmental, lifestyle, psychological, biological and food and nutritional security. Poisson regression was used to verify the association between being overweight and independent variables.

Results:

The prevalence of excessive weight found was 20.1%, namely: 13.4% overweight and 6.7% obese. After adjusting for the confounding variables, the variables: occupancy situation (rented house), alcohol consumption, food security and light food insecurity, body perception (overweight and obese) and age range (10 to 14 years), were associated with being overweight. High food and nutritional insecurity was identified in 80.4% of the population. The moderate and severe forms were more frequent, and precarious social conditions were still prevalent in the region.

Conclusions:

The prevalence of being overweight was high, exceeding the expected for a population with better living conditions. The determinants of being overweight were: alcohol consumption, occupancy situation, self-perceived weight, age and food security/mild food insecurity.

SYSTEMATIC REVIEW OF PHYSICAL ACTIVITY AND SEDENTARY BEHAVIOR INDICATORS IN SOUTH-AMERICAN PRESCHOOL CHILDREN

Objective:

To summarize indicators and describe in detail the methods used to physical activity and sedentary behavior measurement in South American preschool children.

Data source:

In 2017, we searched for articles on researches carried out in South American countries, which presented physical activity and/or sedentary behavior indicators in children aged two to six years. These searches were conducted in Spanish, English, and Portuguese in four electronic databases (LILACS, PubMed, SciELO, and Web of Science), Google Scholar, and in reference lists.

Data summary:

Out of 416 articles initially assessed, 13 composed the descriptive summary. Samples from Argentina, Brazil, and Chile were included. Three articles provided accelerometer-based estimates of moderate physical activity: 32, 70.1, and 71.3 minutes per day. The mean total sedentary behavior was 468.3 and 562.9 minutes per day and, considering the cut-off point of 2 hours per day of screen time, we found the following prevalence rates: 39.4, 40.3, and 100%. The studies adopted a wide number of instruments and strategies to evaluate those behaviors.

Conclusions:

Although the summary has pointed to high exposure to sedentary behavior in preschool children, with particular focus on screen time, it is essential to broaden the discussion and approximate the methods used to assess physical activity and sedentary behavior, making the evidence more comparable and strong, so as to elaborate preventive strategies and actions.

Effects of the Girls on the Move randomized trial on adiposity and aerobic performance (secondary outcomes) in low-income adolescent girls

BACKGROUND

Limited, mixed evidence exists regarding the effectiveness of physical activity interventions on adiposity and aerobic performance in adolescent underrepresented populations.

OBJECTIVE

To examine effects of Girls on the Move on body mass index z-scores (BMI-z), percent (%) body fat, and aerobic performance in fifth- to eighth-grade underrepresented girls.

METHODS

A group randomized trial, involving 12 intervention and 12 control schools in low-income areas, was conducted. Participants (n = 1519) were low-active girls. The 17-week intervention included (a) a physical activity club, (b) two motivational interviewing sessions, and (c) one Internet-based session. BMI-z was determined from measured height and weight; % body fat was assessed using bioelectric impedance. Aerobic performance was assessed using a shuttle run. Demographics, physical activity (accelerometer), and pubertal development were assessed. Linear mixed models, adjusting for baseline, were used to examine group differences in postintervention.

RESULTS

No significant between-group differences in BMI-z existed at postintervention, but % body fat increased less among intervention than control group girls (M_change = 0.43% vs 0.73%). Aerobic performance decreased less in intervention vs control (M_change = -0.39 vs -0.57).

CONCLUSIONS

Although the intervention positively impacted % body fat and aerobic performance in underrepresented girls, more research is necessary to determine optimal implementation for yielding greater effects.

EXERGAMES IN ADOLESCENTS: ASSOCIATED FACTORS AND POSSIBLE REDUCTION IN SEDENTARY TIME

OBJECTIVE

To describe the use of exergames, associated factors and to quantify the time attributed to the use of exergames within the time spent on video games in a sample of adolescents from Curitiba, Paraná, Brazil.

METHODS

This was a cross-sectional study that evaluated frequency and weekly volume of physical activities using the Physical Activity Questionnaire for Adolescents. Weekly frequency and daily time of use of exergames and videogames were self-reported. Mann-Whitney and Kruskal Wallis tests were used to compare the time spent playing exergames, and Poisson regression was used to test the associations (p<0.05).

RESULTS

495 adolescents were interviewed (51.3% girls), predominantly aged between 12 and 13 years (41.3%), under/normal weight (60.4%), medium socioeconomic status (39.8 %) and from public schools (69.3%). Most of the participants did not have video games in their bedroom (74.3%) and did not reach recommended levels of physical activity (55.5%). One in five adolescents used exergames (16.4%). Age (RP: 0.54; 95%CI 0.30-0.97, p=0.039) and having a console in the bedroom (RP: 1.89; 95%CI 1.27- 2.81, p=0.002) were associated with exergame use. Male sex (X_: 195.0; AIQ: 486.3; p=0.024) practice of leisure time physical activity (X_: 160.0; AIQ: 350.0; p=0.048) were associated with weekly volume of exergame use.

CONCLUSIONS

Overall, less than two out of ten adolescents used exergames, and the use was higher among young adolescents and those who had a console in their bedrooms. Volume of use was higher among boys and those performing more than five hours of leisure time physical activity per week. In addition, a considerable part of the time devoted to the use of video games, was in fact, destined to the use of exergames.

Prevalence of excessive screen time and TV viewing among Brazilian adolescents: a systematic review and meta-analysis

PURPOSE

To evaluate the prevalence of excessive screen-based behaviors among Brazilian adolescents through a systematic review with meta-analysis.

DATA SOURCE

Systematic review and meta-analysis were recorded in the International Prospective Register of Ongoing Systematic Reviews (PROSPERO-CRD 2017 CRD42017074432). This review included observational studies (cohort or cross-sectional) that evaluated the prevalence of excessive screen time (i.e. combinations involving different screen-based behaviors) or TV viewing (≥2h/day or >2h/day in front of screen) through indirect or direct methods in adolescents aged between 10 and 19 years. The research strategy included the following databases: MEDLINE, LILACS, SciELO and ADOLEC. The search strategy included terms for "screen time", "Brazil", and "prevalence". Random effect models were used to estimate the prevalence of excessive screen time in different categories.

DATA SUMMARY

Twenty-eight out of 775 studies identified in the search met the inclusion criteria. The prevalence of excessive screen time and TV viewing was 70.9% (95% CI: 65.5-76.1) and 58.8% (95% CI: 49.4-68.0), respectively. There was no difference between sexes in both analyses. The majority of studies included showed a low risk of bias.

CONCLUSIONS

The prevalence of excessive screen time and TV viewing was high among Brazilian adolescents. Intervention are needed to reduce the excessive screen time among adolescents.

Stability and bidirectional relationship between physical activity and sedentary behaviours in Brazilian adolescents: Longitudinal findings from a school cohort study

Purpose

We investigated the stability, correlations and bidirectional relationship of light physical activities (PA), moderate and vigorous PA (MVPA), television viewing (TV) and video game/computer use (VG) in Brazilian adolescents.

Methods

Adolescent Nutritional Assessment Longitudinal Study-ELANA is a middle school cohort study conducted in Rio de Janeiro-Brazil in 2010–2012. Self-reported data on PA (International Physical Activity Questionnaire- IPAQ) and screen activities were obtained from 810 adolescents (mean ages of 10.9 years old (SD 0.78) for girls; 11 years old (SD 0.85) for boys) to perform autoregressive cross-lagged structural equation models in two time points for PA and three time points for screen activities.

Results

There was no significant stability of light PA and MVPA for boys and girls. Moderate stability of screen activities were found for both genders, with a significant coefficient of TV for boys (T1-T2:0.29; T2-T3:0.27 p<0.001); and VG for boys (T1-T2:0.33; T2-T3:0.35 p<0.001) and girls (T1-T2: 0.26; T2-T3:0.37 p<0.01). Significant lagged effects were obtained only among girls: light PA had effect on VG (-0.10 p<0.01), as well as in the opposite direction of TV on light PA (-0.03 p<0.01) and TV on MVPA (-0.11 p<0.01).

Conclusion

The light PA, MVPA and screen activities (among girls) did not demonstrate stability over time. A warning scenario was suggested by the stability of high amounts of screen activities among boys over time. Screen activities had bidirectional association with light PA and MVPA among girls over time.

Associations between TV viewing, sitting time, physical activity and insomnia among 100,839 Brazilian adolescents

Our aim was to examine the relationship between insomnia and levels of physical activity (PA) and time spent sitting and TV viewing among Brazilian adolescents. Data from the Brazilian Scholar Health Survey, a nationally representative survey of 9th grade adolescents [mean: 14.28 years (range: 11-18 years)] conducted in 2015 (n = 100,839) were used. Self-reported insomnia, TV viewing, sitting time and total PA (adapted International PA Questionnaire) were collected. Chronological age, race, type of city (capital or interior) country region, goodies ingestion and ultra-processed foods ingestion were covariates. Logistic regression analyses were conducted to assess the associations. A higher sitting time and TV viewing (≥8 h/day) was associated with a higher risk of insomnia among boys [sitting time: OR = 2.39 (95%CI = 1.88-3.04); TV:OR = 2.49(95%CI = 1.92-3.22) and girls [sitting time: OR = 2.17(95%CI = 1.84-2.57; TV:OR = 1.72(95%CI = 1.44-2.04)]. More than 4 h of sitting time per day was associated with higher risk of insomnia in adolescents who comply [boys: OR = 1.43(95%CI = 1.19-1.73); girls: OR = 1.66(95%CI = 1.41-1.94)] and who do not comply with the 300 min/week of physical activity recommendation [boys = OR = 1.35(95%CI = 1.13-1.60); girls: OR = 1.38(95%CI = 1.20-1.57)]. Our data suggest that higher levels of TV viewing or sitting are associated with sleep difficulties in this large cohort of adolescents, irrespective of their physical activity behavior.

Prevalence and correlates of screen time among Brazilian adolescents: findings from a country-wide survey

The purpose of this study was to evaluate the distribution, prevalence, and correlates of excessive screen time (>2 h/day) among Brazilian adolescents. The Study of Cardiovascular Risks in Adolescents (ERICA) is a national, school-based, cross-sectional multicenter study. Information about time spent in front of screens was assessed by questionnaire. Poisson regression models were used to examine the associations between following correlates (region, sex, age, skin color, income, Internet access, and number of TVs at home) and excessive screen time. A total of 66 706 Brazilian adolescents (aged 12–17 years) were included. The overall mean time in front of screens was 3.25 h/day (95% confidence interval (95%CI): 3.20–3.31) and the prevalence of excessive screen time was 57.3% (95%CI: 55.9–58.6). Moreover, excessive screen time also differs across Brazilian regions, being higher in Southeast and South, respectively. In adjusted models stratified by region, the socioeconomic status was associated with excessive screen time in North, Northeast, and Midwest. In all regions, having a computer with Internet access was associated with higher prevalence of excessive screen time. In conclusion, prevalence of excessive screen time in Brazilian adolescents is high. It presents regional variations and facility for Internet access.

Physical activity but not sedentary time is associated with vitamin D status in adolescents: study of cardiovascular risk in adolescents (ERICA)

BACKGROUND/OBJECTIVES

The association between active lifestyle components and vitamin D status in adolescents remains relatively unexplored. We aimed to investigate independent and joint associations of moderate-to-vigorous physical activity (MVPA) and screen time with serum 25-hydroxyvitamin D [25(OH)D] concentrations in adolescents.

METHODS

This multicenter cross-sectional study involved 1152 Brazilian adolescents (age 12-17 years). Serum 25(OH)D was measured in a single laboratory and categorized as ≤20, 21-29, or ≥30 ng/mL. Demographic and lifestyle characteristics were assessed by self-reports. Ordered logistic regression was used to investigate potential associations of being physically active (MVPA ≥ 300 min/week) and excessive screen time (>2 h/day) with serum 25(OH)D concentrations.

RESULTS

The prevalence of higher serum 25(OH)D concentrations (≥30 ng/mL) was 36.4%. In adjusted models, being physically active was associated with higher serum 25(OH)D concentrations only in boys [proportional odds ratio (POR) = 2.04, 95% CI 1.42-2.93], while excessive screen time was not associated with serum 25(OH)D. Adolescents who were physically active and limited their screen time had higher odds of a higher serum 25(OH)D concentration, but the association was significant only for boys (POR = 2.11, 95% CI 1.19-3.74).

CONCLUSIONS

MVPA may play an important role in increasing serum 25(OH)D concentrations in adolescence, especially for boys, regardless of screen time.

Temporal Trends of Physical Activity and Sedentary Behavior Simultaneity in Brazilian Students

OBJECTIVE

To evaluate trends in physical activity and sedentary behavior simultaneity among Brazilian students from 2009 to 2015 and its association with independent variables.

METHODS

This study presents a panel of 3 cross-sectional studies carried out in 2009, 2012, and 2015 (Pesquisa Nacional de Saúde do Escolar-PeNSE). The population was comprised of ninth-grade public and private schools students from Brazilian capitals. Physical activity and sedentary behavior variables were combined to create the outcome of simultaneity of these risk factors.

RESULTS

A large proportion of students were simultaneously inactive and sedentary in the 3 surveys. However, it was possible to observe a downward trend (2009: 56.4%; 95% confidence interval, 55.7-57.1; 2012: 53.7%; 95% confidence interval, 53.0-54.4; 2015: 51.9%; 95% confidence interval, 51.2-52.7). In 2015, estimates of physical inactivity and sedentary behavior simultaneity were greater than 48% for 20 out of 27 of the Brazilian states. Significant declining trends were observed among mideast residents, females, nonwhite, and those attending private schools. Only around 5%-7% of the adolescents were both active and nonsedentary in the 3 surveys.

CONCLUSION

Despite of a slight decreasing trend in the proportion of Brazilian students simultaneously inactive and sedentary throughout the period, the prevalence remained elevated across the surveys.

Factor Structure of Responses to the Portuguese Version of Questions About Screen Time-Based Sedentary Behavior Among Adolescents

BACKGROUND

This study aimed to examine the factor structure of responses to the Portuguese version of questions related to screen time-based sedentary behavior among adolescents.

METHODS

This cross-sectional study with a sample of 1083 adolescents aged 14-19 years was conducted in Brazil. The sample was randomly divided into 2 groups for an exploratory factor analysis and for a confirmatory factor analysis. Screen time was investigated by a Portuguese version of questions about time sitting in front of television, computer, and video games on weekdays and weekends.

RESULTS

Scree plots showed 2 factors with eigenvalues above 1. One factor was formed by items about television and computer use, and the other factor was formed by items about video game use. The exploratory factor analysis with 2 factors resulted in factor loadings above .60. A second model with 1 factor was estimated and resulted in factor loadings above .55. A confirmatory factor analysis was estimated based on the 2-factor exploratory factor analysis and goodness-of-fit statistics were adequate. Confirmatory factor analysis with 1 factor had goodness-of-fit statistics adequate.

CONCLUSIONS

The Portuguese language version of self-report screen time had 2 possible factor solutions, and items demonstrated good factor structure with reasonable reliability making it suitable for use in the future studies.

Prevalence of excessive body fat among adolescents of a south Brazilian metropolitan region and State capital, associated risk factors, and consequences

BACKGROUND

The prevalence of overweight/obesity has become a major concern for public health in developing countries. Risk factors need to be well documented so that these countries develop public policies to fight the problem. Thus, the objective of this study is to determine the prevalence of excess fat among adolescents of a South Brazilian State Capital associated with risk factors and their consequences.

METHODS

This study was conducted between 2014 and 2016 with adolescents aged 11-18 years. The following body composition measurements were collected: body mass, height, waist circumference, fat mass and bone mineral density (this latter through dual energy X-ray absorptiometry). Biochemical data as glucose, total cholesterol, and triglycerides were also collected. Finally, socioeconomic questionnaires were applied, as well as questionnaires regarding: the education level of guardians, active transportation, time spent with sedentary activities and physical activities. Odds ratios and chi-square test were applied in statistical analysis.

RESULTS

Data from 675 adolescents, from which 70% were males, were analyzed. The mean age was 14.7 ± 1.8 years. The prevalence of excess fat was 18.2% in boys and 92.1% in girls. As for sedentary lifestyle and physical inactivity, having one of these factors increased the risk of being overweight by 7.9 times for boys and 3.0 times for girls. In boys, there was a significant association between excess fat and waist circumference (p = 0.000; OR = 13.5; CI = 7.0-25.9), physical activity level (p = 0.000; OR = 4.0; CI = 2.5-6.5), triglycerides (p = 0.019; OR = 2.2; CI = 1.1-4.2) and total cholesterol (p = 0.000; OR = 2.6; CI = 1.6-4.5). In girls, there was an association between having excess fat and an increase in total cholesterol (p = 0.000; OR = 8.0; CI = 2.6-24.4).

CONCLUSIONS

The high prevalence of excess fat was greater than what was described by some studies conducted in developed countries. This reality demonstrates the need to implement public policies that can directly promote the reduction of sedentary habits and reinforce the importance of adopting an active lifestyle.

Screen-based sedentary behavior during adolescence and pulmonary function in a birth cohort

Background

Adolescents spend many hours in sitting activities as television viewing, video game playing and computer use. The relationship between sedentary behavior and respiratory health remains poorly elucidated. To date there have been no studies evaluating the relationship between sedentary behavior and pulmonary function in young populations. The purpose of this study is to examine the association between the trajectory of screen-based sedentary behavior from 11 to 18 years and pulmonary function at 18 years in a Brazilian birth cohort.

Methods

Data from a longitudinal prospective study conducted among the participants of the 1993 Pelotas (Brazil) Birth Cohort. Time spent on television, video games, and computers during a weekday was self-reported at ages 11, 15 and 18 years. For each age, sedentary behavior was defined as the sum of time spent on these screen-based activities. To evaluate the sedentary behavior trajectory during adolescence group-based trajectory modeling was used. Outcome variables were three pulmonary function parameters: forced expiratory volume in one second (FEV₁), forced vital capacity (FVC), and peak expiratory flow (PEF), evaluated by spirometry, at 18 years expressed as z-scores. Crude and adjusted linear regressions, stratified by sex, were performed.

Results

The three-group trajectory of sedentary behavior was the best fitting model. The trajectory groups were: always high (representing 38.8% of the individuals), always moderate (54.1%), and always low (7.1%). In the adjusted analyses, boys in the always-low group for sedentary behavior had higher FVC at 18 years (β = 0.177; 95% CI:0.027;0.327; p = 0.021) than boys in the always-high group. There were no differences for other pulmonary function parameters in boys. No significant association was found for girls.

Conclusion

The trajectory of screen-based sedentary behavior throughout adolescence was not consistent associated with pulmonary function at 18 years.

Electronic supplementary material

The online version of this article (doi:10.1186/s12966-017-0536-5) contains supplementary material, which is available to authorized users.