Clusters of 24-hour movement behavior and diet and their relationship with health indicators among youth: a systematic review.

Movement-related behaviors (physical activity [PA], sedentary behavior [SB], and sleep) and diet interact with each other and play important roles in health indicators in youth. This systematic review aimed to investigate how PA, SB, sleep, and diet cluster in youth by biological sex; and to examine which cluster are associated with health indicators. This study was registered in PROSPERO (number: CRD42018094826). Five electronic databases were assessed. Eligibility criteria allowed studies that included youth (aged 19 years and younger), and only the four behaviors {PA, SB, sleep, and diet (ultra-processed foods [UPF]; fruits and vegetables [FV])} analyzed by applying data-based cluster procedures. From 12,719 articles screened; 23 were included. Of these, four investigated children, and ten identified clusters by biological sex. Sixty-six mixed cluster were identified including, 34 in mixed-sex samples, 10 in boys and 11 in girls. The most frequent clusters in mixed-sex samples were "High SB UPF Low Sleep", "Low PA High SB Satisfactory Sleep", and "High PA". The main difference in profiles according to sex was that girls' clusters were characterized by high sleep duration, whereas boys' clusters by high PA. There were a few associations found between cluster types and health indicators, highlighting that youth assigned to cluster types with low PA exhibited higher adiposity. In conclusion, the youth presented a range of clusters of behaviors, typically exhibiting at least one unhealthy behavior. Similar patterns were observed in both sexes with the biggest difference in time of sleep for girls and PA for boys. These findings underscore the importance of intervention strategies targeting multiple behaviors simultaneously to enhance health risk profiles and indicators in children and adolescents.

Association of sleep timing and sleep variability with health-related outcomes in a sample of Brazilian adolescents.

OBJECTIVES: This cross-sectional study aimed to examine the relationships of sleep timing and sleep variability with depressive symptoms, health-related quality of life (HRQoL), daytime sleepiness, and body mass index (BMI) in adolescents. METHODS: Adolescents from three schools (n = 571, 56% female, 16.3 ± 1.0 years) had their sleep examined by actigraphy, their anthropometrics assessed, and answered a survey. Sleep timing was examined by combining groups of median-dichotomized onset and wakeup times (early onset and early wakeup; early onset and late wakeup; later onset and early wakeup; later onset and later wakeup); sleep variability was based on within-participant standard deviations of onset and wakeup; and sleep duration as the length of time between onset and wakeup. The sleep variables were separated for weekdays and weekend. Mixed linear models were fitted to compare each sleep variable with health-related outcomes. RESULTS: Higher values of daytime sleepiness were observed in adolescents from the late-early and late-late timing group during the week. Greater sleep midpoint and wakeup variability on weekdays were related with higher daytime sleepiness. Adolescents in the late-late and early-late groups showed higher daytime sleepiness. Increased of all sleep variability variables was related with greater daytime sleepiness. Higher depressive symptoms scores were found among adolescents in the late-early subgroup and with the increase of sleep variability. Participants with greater sleep onset variability and sleep midpoint variability reported less HRQoL. CONCLUSIONS: Not only sleep duration, but sleep timing and variability also relate to health outcomes, and should be addressed by policies and interventions among adolescents.

Independent and joint associations of cardiorespiratory fitness and weight status with health-related quality of life among Brazilian adolescents.

PURPOSE: To investigate the independent and joint associations of cardiorespiratory fitness and body mass index (BMI) with five dimensions of Health-Related Quality of Life (HRQoL) in a cross-sectional sample of Brazilian adolescents. METHODS: 619 Brazilian schoolchildren answered a survey, BMI categories (healthy weight and overweight/obesity) were assessed by their weight and height, and they participated in a 20-m shuttle run test. HRQoL was measured using the KIDSCREEN-27 across five dimensions: Physical Well-Being, Psychological Well-Being, Autonomy and Parent Relation, Peers and Social Support, and School Environment. Sex, age, maternal education, physical activity level, and habitual sedentary behaviour were assessed and used as adjusting variables. Cardiorespiratory fitness was categorized in tertiles and independent and joint associations were tested using mixed-effects linear regressions. RESULTS: Higher levels of cardiorespiratory fitness were favourably associated with the physical well-being, psychological well-being, and peer and social support dimensions of HRQoL. Adolescents with overweight/obesity presented higher scores on peer and social support dimensions when compared to healthy-weight adolescents. Independent of the adolescents' BMI categories, better cardiorespiratory fitness was positively associated with physical and psychological well-being when compared with the category of overweight/obesity and low cardiorespiratory fitness. In addition, adolescents with overweight/obesity combined with intermediate cardiorespiratory fitness or high cardiorespiratory fitness had higher scores on the peer and social support dimension. CONCLUSION: Cardiorespiratory fitness is a strong correlate of HRQoL across most of the dimensions measured, while BMI was a correlate of one dimension of HRQoL. Future studies should evaluate these relationships prospectively and experimentally.

A higher energy-adjusted Dietary Inflammatory Index is positively associated with total and visceral body fat in young male adults.

BACKGROUND: The energy-adjusted Dietary Inflammatory Index (E-DII™) has been associated with a high body mass index and markers of chronic diseases. Also, pro-inflammatory diets with a high E-DII have been positively associated with metabolic disturbances such as glucose intolerance and type II diabetes mellitus. However, it is unclear whether E-DII scores are positively associated with body fat percentage and visceral fat per se. This cross-sectional study aimed to evaluate whether the E-DII is associated with body fat content and metabolic health indicators in lean and obese young men. METHODS: The present study was conducted on 59 participants, without comorbidities, not using tobacco, medication and nutritional supplements. Dietary data were obtained by 3-day food records to calculate E-DII scores based on 28 food parameters. Body composition was assessed by dual X-ray absorptiometry (DXA). Blood samples were taken to measure fasting glucose, insulin, triacylglycerols, total cholesterol, and low- and high-density lipoprotein cholesterol. An oral glucose tolerance test also was performed. Associations were determined by mixed-effects linear regression. RESULTS: E-DII scores ranged from -3.48 to +3.10. Energy intake was similar across E-DII tertiles. After adjusting for covariates, the highest E-DII tertile was associated with increased body fat, visceral adipose tissue and waist circumference. There was no association between E-DII scores and glycaemic parameters. CONCLUSIONS: In young participants, a dietary pattern with a higher E-DII (i.e., pro-inflammatory) score was associated with high body fat and markers of central adiposity assessed by DXA, regardless of body mass.

School schedule affects sleep, but not physical activity, screen time and diet behaviors.

BACKGROUND: Behavioral changes during adolescence are affected by biological and social aspects. However, environment aspects, which are beyond adolescents' control, also contribute to behavior adoption, and school may have a significant impact in these behaviors. This cross-sectional study aims to investigate how lifestyle behaviors are associated with the school shift attended by high school students. METHODS: The sample comprised 635 high school students (51.2% girls, 16.33 ± 1.0 years old) from Southern Brazil. Physical activities of different intensities (light and moderate-to-vigorous), sedentary behaviors, and sleep (duration, efficiency, and timing) were measured using accelerometers. Engagement in sport and non-sport activities, screen time indicators, and diet were self-reported. Linear models were fitted to compare each lifestyle behavior between the two school shifts. RESULTS: Students attending the afternoon shift slept (ß = 01:29 95%CI 01:13; 01:46) and woke up later (ß = 01.41 95%CI 01:27; 01:54), and had a longer sleep duration (ß = 00:12 95%CI 0:02; 00:21) than those attending the morning shift. However, the sleep efficiency of those in the afternoon shift was lower than their peers in the morning shift (ß = -1.89 95%CI -3.01; -0.77). CONCLUSIONS: School schedule was associated with sleep behaviors of adolescents, but not with other lifestyle behaviors.

Psychosocial correlates of objectively measured in-school and out-of-school physical activity among Brazilian adolescents.

Physical activity is influenced by an interplay of time and setting, thus, the role of psychosocial factors on behavior is expected to vary across the day. This cross-sectional study identified the psychosocial correlates of time spent in physical activity during in-school (i.e., 08:00-11:59) and out-of-school (i.e., 12:00-22:00) time segments. The sample consisted of adolescents (7th to 9th grade) of two public schools in Florianópolis, Brazil. Accelerometer measured light-intensity (LPA) and moderate-to-vigorous-intensity physical activity (MVPA) were estimated. Psychosocial correlates of physical activity (i.e., outcome expectations, attitude, self-efficacy, support from parents, and support from peers) were self-reported. Linear mixed models were applied and interaction effects of gender and age were also analyzed. From a total of 194 participants, 138 and 112 provided in-school and out-of-school valid data, respectively. Outcome expectations were associated with out-of-school MVPA (ß = 0.18; p = .006). Age interaction effects were observed for the associations between outcome expectations and out-of-school LPA (ß = 0.21; p = .009) and between self-efficacy and out-of-school MVPA (ß = 0.19; p = .009). In conclusion, psychosocial correlates were positively associated with out-of-school physical activity and the effects varied according to age. No psychosocial correlates were identified for LPA and MVPA performed during schooltime.

Clustering of 24-h movement behaviors associated with cardiorespiratory fitness among adolescents: a latent class analysis.

This study aimed to examine the clustering of 24-h movement behaviors (moderate to vigorous physical activity, screen time, and sleep duration) and their association with cardiorespiratory fitness among adolescents. We evaluated 561 adolescents (52.1% girls; mean age, 13.0 ± 1.0 years) from Florianópolis, Brazil. A 20-m shuttle run was used to assess cardiorespiratory fitness, while a questionnaire was used to measure 24-h movement behaviors. A latent class analysis was performed to identify the clustering of 24-h movement behaviors, while linear Bayesian mixed-effect regression models were applied to identify their association with cardiorespiratory fitness. Two classes were identified: unhealthy (10.4%), characterized as a high probability of practicing less than 300 min/week of moderate to vigorous physical activity, spending more than 4 h/day in front of screens, and sleeping less than 8 h/day; and healthy (89.6%), characterized by a high probability of practicing more than 420 min/week of moderate to vigorous physical activity, spending less than 2 h/day in front of screens, and sleeping 8-10 h/day. Adolescents in the healthy class had a higher cardiorespiratory fitness level than those in the unhealthy class. Most adolescents were grouped in the healthy class and had higher cardiorespiratory fitness levels than those in the unhealthy class. These results suggest that families and professionals should work toward creating healthier lifestyles for adolescents by increasing opportunities to practice moderate to vigorous physical activity, reduce screen time, and favor healthy sleep to increase their cardiorespiratory fitness levels. What is Known: • Moderate to vigorous physical activity, screen time, and sleep duration are positively, negatively, and inconsistently associated with cardiorespiratory fitness, respectively, when analyzed separately. • Little is known about the clustering of 24-h movement behaviors and how they are associated with cardiorespiratory fitness levels in adolescents. What is New: • The 24-h movement behaviors clustered into almost opposite classes among adolescents (healthy and unhealthy classes). • Adolescents in the healthy class had greater cardiorespiratory fitness levels than those in the unhealthy class.

Association between physical activity, screen time activities, diet patterns and daytime sleepiness in a sample of Brazilian adolescents.

OBJECTIVE: To examine the association between physical activity, screen time, eating habits and daytime sleepiness among Brazilian adolescents. METHODS: Adolescents from three high schools (n = 876, 49.8% female, 16.4 ± 1.2 years) participated in this cross-sectional survey. Variables related to lifestyle behaviors (ie, physical activity, screen time, eating habits, sleep duration) were collected through an online questionnaire. Daytime sleepiness was assessed using the Pediatric Daytime Sleepiness Scale (PDSS). Excessive daytime sleepiness was defined as a PDSS score ≥20. RESULTS: The average PDSS score was 18.9 (SD ± 4.8) points and 46.8% of adolescents were classified as having excessive daytime sleepiness. Physical activity was inversely associated with PDSS score (ß = -0.29, 95% CI -0.47; -0.11). Consuming processed foods frequently (ß = 1.16, 95% CI 0.85; 1.47) and using social media (ß = 0.22, 95% CI 0.14; 0.30) were positively associated with PDSS score. Similar findings were observed for the odds of excessive daytime sleepiness. Physical activity was inversely associated (OR = 0.91, 95% CI 0.84; 0.99), while frequent consumption of processed foods (OR = 1.55, 95% CI 1.33; 1.82) and using social media (OR = 1.13, 95% CI 1.02; 1.24) were positively associated with excessive daytime sleepiness. CONCLUSIONS: Lower physical activity level, a higher consumption processed foods, and higher social media use were associated with daytime sleepiness in this sample of Brazilian adolescents.

Association between muscle strength and risk factors for metabolic syndrome in children and adolescents: a systematic review.

The aim of this systematic review was to identify and summarize evidence for the association between muscle strength (MS) and metabolic syndrome (MetS), and MS and combinations of risk factors for MetS in children and adolescents. Five databases (Medline/PubMed, EBSCO, Scielo, Scopus, and Web of Knowledge) were searched up to November 2019 with complementary reference list searches. Inclusion criteria were studies that investigated the relationship between MS and MetS or MS and combinations of risk factors for MetS in children and adolescents (≤19 years of age). Risk of bias was assessed using standard procedures. From the total of 15,599 articles initially identified, 13 articles were included, representing 11,641 children and adolescents. Higher MS values were associated with lower risk for MetS or combinations of risk factors for MetS (n=11/13 studies). Of the total of included studies, about 23.1% (03/13) were longitudinal and all included studies were classified as having a moderate risk of bias. This review provides preliminary evidence for a beneficial relationship between MS and MetS among children and adolescents. Additionally, although the body of evidence points to the beneficial relationship between higher MS and lower risk for combination of factors for MetS in children and adolescents, this relationship is inconclusive.

Prevalence and sociodemographic factors associated with meeting the 24-hour movement guidelines in a sample of Brazilian adolescents.

BACKGROUND: The present cross-sectional study aimed to determine the proportion of adolescents meeting the 24-hour movement guidelines, and investigate sociodemographic factors associated with meeting them. METHODS: Self-reported (average daily volume of MVPA, sleep duration, and time watching videos and playing videogames) and accelerometer-measured (MVPA and sleep duration) 24-hour movement behaviors were classified according to recommendations, and sex, age, socioeconomic status (SES), family structure, parental education, and number of people in the household were tested as correlates of meeting recommendations using multilevel logistic regressions. RESULTS: The proportion of adolescents (n = 867, mean age: 16.4 years, 50.3% girls) meeting the MVPA, ST, and sleep duration guidelines was of 25%, 28%, and 41%, respectively, for self-reported data. From accelerometer data (n = 688), 7.1% met MVPA and 31.7% met sleep duration recommendations. Adherence to all three recommendations was 3% with self-report and 0.2% with accelerometer data. Boys were more likely to meet MVPA, but not ST and sleep-duration recommendations. A positive relationship was observed between age and meeting the ST recommendation. CONCLUSIONS: Adherence to the sleep duration recommendation was higher than to the screen-time and MVPA recommendations and few in this sample of Brazilian adolescents achieved the 24-hour guidelines. Efforts are needed to improve 24-hour movement behaviors.

Patterns of Objectively and Self-Reported Sedentary Behavior in Children and Adolescents Living With Human Immunodeficiency Virus: The PositHIVe Health Study.

PURPOSE: Sedentary behavior (SB) has been shown to be associated with unhealthy outcomes in children, and it is not clear whether children living with human immunodeficiency virus (HIV) engage in different patterns of SB compared with healthy children. This cross-sectional study aimed to compare patterns of SB between children living with HIV and a healthy control group. METHODS: A group of children with HIV and a paired control group wore accelerometers for 1 week and answered a questionnaire with items related to television viewing habits and computer usage. Accelerometer-derived and self-reported SB were compared between children living with HIV and controls and between treatment-based and viral load subgroups. RESULTS: A total of 130 children (of which 53% are girls with a mean age of 12.1 y) participated in the study with 65 in each group. Children in the control group exhibited significantly more objectively measured SB daily when compared with the HIV group (515 vs 490 min/d, respectively), but no differences were found between the treatment-based and viral load subgroups. Children with HIV watched more television on weekdays, compared with the control group (P < .05). No other differences were found in comparisons of self-reported SB between the control and HIV and the treatment-based or viral load subgroups. CONCLUSION: Children living with HIV spend less time being sedentary than those in the healthy control group. Future studies are important for clarifying the causes and consequences of these differences.

Clustering of screen time behaviours in adolescents and its association with waist circumference and cardiorespiratory fitness.

OBJECTIVES: To identify the association of clusters of screen time (ST) behaviours with waist circumference (WC) and cardiorespiratory fitness (CRF) among adolescents. DESIGN: Cross-sectional study of 574 adolescents (53% girls, 13 years), conducted in 2017. METHODS: Waist circumference was measured, a shuttle run was performed to assess CRF, and a questionnaire was applied. Sex, age, socioeconomic status was reported, and daily duration of ST indicators for television viewing, computer use, videogame playing, and cellphone use, in weekdays and weekend days. Latent class analysis was performed to identify typologies of ST behaviours. Mixed-effects linear regressions were used to test the association of ST clusters with WC and CRF. RESULTS: Participants' WC was 66.9±8cm and CRF was 39.5±4mlO2/kg/min. Four clusters were identified: "Low ST" (25%); "High ST" (20%); "Gamers" (17%); and "High cellphone" (39%). No significant associations were found between ST clusters and WC. Maximum oxygen uptake was higher in those in the "Low ST" cluster compared to the other clusters. No significant interactions for sex were observed. CONCLUSIONS: Typologies of ST behaviours do not seem to be related to WC; however, those in the Low ST cluster had higher CRF compared to their peers in the other clusters, suggesting that total ST may be more important for CRF than specific indicators.

Sociodemographic, biological, and psychosocial correlates of light- and moderate-to-vigorous-intensity physical activity during school time, recesses, and physical education classes.

BACKGROUND: Identifying factors associated with physical activity (PA) is useful in planning interventions and policies. The aim of this study was to identify sociodemographic, biological, and psychosocial factors associated with PA performed in school settings. METHODS: Data collected for the present study included gender, age, socioeconomic status, body fat percentage, aerobic fitness, self-efficacy, attitudes, peer and parental support, and perception of school environment. Dependent variables were light-intensity PA (LPA) and moderate-to-vigorous-intensity PA (MVPA) performed during school time, recesses, and physical education (PE) classes. Multiple regression analyses were performed. RESULTS: Participating adolescents (n = 567, 53% female, 12.9 ± 5.3 years) spent 5% of school time in MVPA and 27% in LPA, 15% of recesses in MVPA and 44% in LPA, and 16% of PE classes in MVPA and 41% in LPA. Boys engaged in more MVPA in all categories. Age was inversely related with MVPA and LPA in all periods, whereas body fat percentage was inversely related with MVPA in school time and PE classes. Attitude was inversely related with MVPA in all periods and with LPA in recesses. Considering PA to be good and enjoyable was positively associated with MVPA in school time. CONCLUSION: Adolescents spent little time in PA during school. Future interventions should implement enjoyable activities at school.

Superiority of Interferon Gamma Assay Over Tuberculin Skin Test for Latent Tuberculosis in Inflammatory Bowel Disease Patients in Brazil.

BACKGROUND AND AIMS: To compare tuberculin skin test (TST) and interferon gamma release assay (IGRA) in the screening of LTBI among patients with inflammatory bowel disease (IBD) in an endemic area for tuberculosis, to evaluate the need for repeating tests during anti-TNFα, therapy, and to check whether the results may be affected by immunosuppression. METHODS: A cross-sectional study of 110 IBD patients and 64 controls was conducted in Rio de Janeiro, Brazil. The TST was administered after the Quantiferon(®)-TB Gold In-tube test was performed. RESULTS: TST and IGRA agreement was poor regarding diagnosis (kappa: control = 0.318; UC = 0.202; and CD = - 0.093), anti-TNFα therapy (kappa: with anti-TNFα = 0.150; w/o anti-TNFα = - 0.123), and immunosuppressive therapy (IST) (kappa: with IS = - 0.088; w/o IS = 0.146). Indeterminate IGRA was reported in four CD patients on IST. Follow-up tests after anti-TNFα identified conversion in 8.62% using TST and 20.0% using IGRA. Considering IGRA as a criterion standard, TST showed low sensitivity (19.05%) and positive predictive value (PPV) (21.05%). LTBI detection remarkably improved when IGRA was added to TST (sensitivity of 80.95% and PPV of 53.13%). Results were particularly relevant among CD patients where rates started from zero to reach sensitivity and PPV of more than 60%. CONCLUSION: IGRA alone was more effective to detect LTBI than TST alone and had an overall remarkable added value as an add-on sequential test, particularly in CD patients. While cost-effectiveness of these strategies remains to be evaluated, IGRA appears to be justified in CD prior to and during anti-TNFα therapy, where tuberculosis is endemic.

Patterns of risk behaviors in Brazilian older adults: A latent class analysis.

AIM: The aim of the present study was to describe the clustering of diet, physical activity, television viewing, and tobacco and alcohol use among Brazilian older adults (aged ≥60 years). METHODS: We carried out a secondary analysis of the Brazilian National Health Survey of 2013. Brazilian older adults (n = 11 177) reported their consumption of fruit and vegetables, leisure physical activity, television viewing, tobacco smoking, and alcohol intake. Latent class analysis was used to identify behavior patterns. RESULTS: Three classes of behaviors were identified. The "Healthy" class (34.8%) had the highest probability of meeting recommendations for physical activity, and fruit and vegetable consumption; the "Poor diet and PA" class (46.5%) presented low probabilities of meeting recommendations for physical activity and alcohol consumption; and the "Smoking and binge drinking" class (18.7%) had the highest probability of smoking and binge drinking. CONCLUSIONS: Three behavioral patterns were identified in the Brazilian older population. Even in the "Healthy" class, less than half of the older adults were considered physically active, suggesting that there is no completely healthy profile. Nevertheless, physical activity and fruit and vegetable consumption behaviors clustered, as did smoking and binge drinking. Geriatr Gerontol Int 2019; 19: 245-248.

Pattern of Sedentary Behavior in Different Periods of School Time of Brazilian Adolescents.

BACKGROUND: Sedentary behavior (SB) is related to unhealthy outcomes and is performed in many contexts, including school. The aim of this study was to identify sociodemographic, biological, and psychosocial correlates of SB performed at school in a sample of adolescents. METHODS: Adolescents provided information regarding sex, age, socioeconomic status, and psychosocial variables related to physical activity (self-efficacy, attitudes, perception of school environment, peer and parental support). Body fat was estimated using skinfolds, and maximum aerobic capacity with a 20 m shuttle run. Adolescents wore accelerometers and SB performed during class time, physical education (PE) classes, and recesses was estimated. RESULTS: Adolescents (N = 567, 53% female, 12.9 ± 5.3 years old) spent 67% of class time, 41% of PE classes, and 41% of recesses in SB. Girls spent more time in SB, and age was negatively associated with SB. Body fat was positively associated with SB in class time and PE classes. Peer support for physical activity was negatively associated with SB in class time, whereas attitudes related to physical activity were negatively associated with SB during PE classes and recesses. CONCLUSION: Adolescents spend long periods in SB at school, even during opportunities to be active like PE classes and recesses.

Sedentary behavior during school-time: Sociodemographic, weight status, physical education class, and school performance correlates in Brazilian schoolchildren.

OBJECTIVES: To investigate whether sedentary behavior during school-time is associated with gender, age, mother's education, having physical education classes, weight status, and academic performance. DESIGN: Cross-sectional study. METHODS: A sample of 571 children (7-12 years old) from five elementary schools in Florianopolis, South Brazil had their height and weight measured, and wore accelerometers during class time. Teachers completed a form to evaluate children's reading and writing skills. Parents provided sociodemographic and educational information. Data was analyzed using multilevel linear regression analyses. RESULTS: Children spent an average of 132min in sedentary behavior during school-time (64% of total school-time). Girls (137.5min), obese children (138.1min), older children (144.2min), and those who did not have physical education classes (140.2min) spent more time engaged in sedentary activities than their peers. Academic performance and mother's education were not associated with sedentary behaviors. CONCLUSIONS: Children spent most of their school-time in sedentary activities, with girls, older students, and obese students being even more sedentary than their peers. Physical education classes were a protective factor against excessive sedentary behavior in school. Interventions for reducing sedentary behavior during school-time could employ additional strategies to benefit the at risk groups. In addition, encouraging student's participation in physical education classes could minimize the time spent in sedentary behavior during school hours.

Trends in screen time on week and weekend days in a representative sample of Southern Brazil students.

BACKGROUND: Economic and technological improvements can help increase screen time use among adolescents, but evidence in developing countries is scarce. The aim of this study was to examine changes in TV watching and computer/video game use patterns on week and weekend days after a decade (2001 and 2011), among students in Santa Catarina, southern Brazil. METHODS: A comparative analysis of two cross-sectional surveys that included 5 028 and 6 529 students in 2001 and 2011, respectively, aged 15-19 years. The screen time use indicators were self-reported. 95% Confidence intervals were used to compare the prevalence rates. All analyses were separated by gender. RESULTS: After a decade, there was a significant increase in computer/video game use. Inversely, a significant reduction in TV watching was observed, with a similar magnitude to the change in computer/video game use. The worst trends were identified on weekend days. CONCLUSIONS: The decrease in TV watching after a decade appears to be compensated by the increase in computer/video game use, both in boys and girls. Interventions are needed to reduce the negative impact of technological improvements in the lifestyles of young people, especially on weekend days.

Longitudinal and cross-sectional changes in active commuting to school among Brazilian schoolchildren.

OBJECTIVE: The objective of the study is to evaluate cross-sectional and longitudinal changes in children's commuting to school in a representative sample of a Brazilian city. METHODS: Two school-based studies were carried out in 2002 (n=2936; 7-10 years old) and 2007 (n=1232; 7-15 years old) in Florianopolis, Brazil. Cross-sectional data were collected from children aged 7 to 10 years in 2002 and 2007. Longitudinal analyses were performed with data from 733 children participating in both surveys. Children self-reported their mode of transportation to school using a validated illustrated questionnaire. Changes were tested with chi square statistics and McNemar's test. RESULTS: Cross-sectional data showed a 17% decline in active commuting; a decrease from 49% in 2002 to 41% in 2007. On the other hand, active commuting among the 733 children increased as they entered adolescence 5 years later, rising from 40% to 49%. CONCLUSION: Active commuting to school decreased in Brazilian children aged 7-10 years over a five year period; whereas, it increased among children entering adolescence. Policies should focus on safety and environmental determinants to increase active commuting.

Factors associated with active commuting to school and to work among Brazilian adolescents.

BACKGROUND: Active commuting has decreased substantially in recent decades and has been more frequent in specific demographic and socioeconomic profiles. The objective of this study was to describe the prevalence of active trips and the possible associations with demographic and socioeconomic variables. METHODS: A questionnaire on lifestyle and risk behavior was administered to a sample population of 5028 adolescents, ages 15 to 19 years, attending public high schools in the state of Santa Catarina, Brazil. Logistic regressions (odds ratio--OR; 95% confidence interval) were used to test associations. RESULTS: Active commuting to school was reported for 56.7% of students, and active commuting to work was reported for 70.0%. The likelihood of commuting passively was greater among girls (school: OR = 1.27; 1.10-1.45), older adolescents (school: OR = 1.17; 1.02-1.33; work: OR = 1.49; 1.22-1.82), those who lived in rural areas (school: OR = 12.1; 9.91-14.8), those who spent more time in commuting (school: OR = 2.33; 2.01-2.69; work: OR = 4.35; 3.52-5.38), and those from high-income families (school: OR = 1.40; 1.21-1.62; work: OR = 1.69; 1.37-2.08). CONCLUSIONS: The proportion of students taking active trips was higher when going to work than to school. All indicators were associated with the mode of commuting, except gender and place of residence for commuting to work.