Global prevalence and gender inequalities in at least 60 min of self-reported moderate-to-vigorous physical activity 1 or more days per week: An analysis with 707,616 adolescents.

BACKGROUND: Guidelines recommend that adolescents should accumulate an average of 60 min per day of moderate-to-vigorous physical activity (MVPA). However, using only this cut-off could hide important information. For instance, from a population-level point of view, increasing physical activity for those with no or low physical activity could provide more health benefits than increasing physical activity for those with intermediate levels. Also, including a more sensitive cut-point of ≥1 day per week could be an additional strategy for identifying those with low access/opportunities for physical activity practice. Thus, the current study aims to estimate the prevalence of ≥60 min of MVPA ≥1 days per week among adolescents globally, and to describe any relevant gender inequalities. METHODS: We used representative datasets from 146 countries/territories collected between 2003 and 2019. MVPA was self-reported. Participants were grouped into younger (≤14 years old) and older (>14 years old) adolescents. Crude Poisson regression models were used to identify the relative differences in ≥60 min of MVPA ≥1 days per week between boys and girls, and random-effects meta-analysis models were used to identify the pooled estimates. Analyses were stratified by country and region. RESULTS: Approximately 80% of both younger and older adolescents reported ≥60 min of MVPA ≥1 days per week. This prevalence was ≥94% in Europe and Central Asia and North America, while the estimates for the other regions were <77%. The prevalence of ≥60 min of MVPA ≥1 days per week was higher among boys than girls, with the largest differences occurring among the oldest adolescents (PR≤14y: 1.04 (95% confidence interval (95%CI): 1.03‒1.04) vs. PR>14y: 1.09 (95%CI: 1.08‒1.10)). CONCLUSION: Approximately 8 out of 10 adolescents reported accumulating ≥60 min of MVPA ≥1 day per week, with notable differences between regions. Gender differences were observed in several countries, especially among the oldest adolescents. Priorities for physical activity promotion among adolescents should include increasing access/opportunities for physical activity among those who do not achieve ≥60 min of MVPA ≥1 days per week and reducing gender inequalities.

Effects of two years of physically active lessons on cognitive indicators in children.

Our purpose was to evaluate the effect of physically active lessons (PAL) on the cognitive performance of children during two years of follow-up. Four classes (second grade of elementary school) were divided into two intervention classes (n = 34) and two control classes (n = 27). Evaluations were performed before the intervention (M1), after 3 (M2) and 9 (M3) months in the 1st year, and 14 (M4) and 18 (M5) months in the 2nd year. The intervention was based on PAL integrated with the curricular components, which stimulated the children to stand or move in the classroom. Cognitive performance was evaluated using three computerized tests for response inhibition, selective attention, and cognitive flexibility. The children in the intervention classes presented improved cognitive performance in the execution of all tasks along the two years follow-up, in both correct answers and time reactions, with exception of correct answers of visual search. For the intervention classes, in most of the tasks, the mean differences confidence interval of 95% did not include the 0 on the two last moments of evaluation, and in all cases, the mean differences of them between M1 versus M5 were significantly different with high values of effect size (cohen -d > 1). PAL promotes modest improvements in diverse cognitive functions in children.

Two-Year Effectiveness of a Controlled Trial With Physically Active Lessons on Behavioral Indicators of School Children.

Purpose: In this study, we evaluated the effectiveness of two years of an intervention with physically active lessons on indicators of sedentary behavior and physical activity measured objectively in elementary school children. Methods: A controlled clinical trial with cluster sampling was carried out in 2018 and 2019, with four classes of children in the 2nd year of elementary school. The intervention group classes received dynamic activities linked to the pedagogical content (n = 34) for 2 years. The indicators of sedentary behavior and physical activities were evaluated using ActivPal and ActiGraph GT3X accelerometers during the school shift. Crude and adjusted models of Generalized Estimation Equations with Bonferroni's post hoc were used to identify the differences between the groups (three evaluations in 2018 and two evaluations in 2019). Results: There was a reduction in stationary behavior (p = .01) and an increase in light physical activity (p = .044) during the two years. In the first year there were reductions in standing time (p = .044) and number of transitions (p ≤ .001), and an increase in walking time (p = .017). However, in the second year, the mean differences in percentage points were smaller than in the first year. No differences were found for sitting time as well as for moderate and vigorous physical activity. We observed a large effect size for all variables. Conclusions: The introduction of physically active lessons in the classroom reduced time in stationary behavior and increased time in light physical activity. However, the effects on behavior observed in the first year were not maintained in the second year of intervention.

Multimorbidity is associated with TV-viewing, but not with other types of screen-based behaviors in Brazilian adults.

BACKGROUND: The presence of multimorbidity increases the risk of mortality, and identifying correlates of multimorbidity can direct interventions by targeting specific modifiable correlates. Here we aimed to investigate the association between two types of screen-based behaviors and multimorbidity. METHODS: We used data from 87,678 Brazilian adults from the National Health Survey (2019). Multimorbidity (presence of two or more chronic conditions among 12 possibilities), TV-viewing, and time on other types of screens (computer, tablet, or cell phone), were self-reported. Crude and adjusted binary and multinominal logistic regression models were performed stratified by sex, age group, and the number of chronic conditions. RESULTS: Considering adjusted values, 2 h/day as a reference, and reporting values in odds ratio (OR) and prevalence ratio (PR) with 95% confidence intervals (95%CI), multimorbidity presented associations with TV-viewing in general [from OR (95%CI) 1.10 (1.03-1.18) in 2 to < 3 h/d, to OR (95%CI) 1.57 (1.40-1.76) in ≥ 6 h/d], except in 2 to < 3 h/d time category for male and 35 to 49 years, and all time categories for 18 to 34 years. In addition, TV-viewing was associated with an increasing number of chronic conditions, all greater in ≥ 6 h/d [2 conditions - PR (95%CI) 1.24 (1.08-1.43); 3 conditions - PR (95%CI) 1.74 (1.45-2.08); 4 or more conditions - PR (95%CI) 2.29 (1.93-2.73)], except in 2 conditions on 2 to < 3 h/d. Other types of screen-based behaviors were only associated with multimorbidity among males [≥ 6 h/d: OR (95%CI) 1.22 (1.01-1.48)] and older individuals (65 years) in some time categories [3 to < 6 h/d: OR (95%CI) 1.98 (1.42-2.77) and ≥ 6 h/d: OR (95%CI) 1.73 (1.06-2.84)]. CONCLUSION: Intervention strategies for reducing screen time in Brazilian adults should focus mainly on TV-viewing, which seems to be associated with more harmful conditions than time on other types of screen-based behaviors.

The moderating effect of physical activity on the association between screen-based behaviors and chronic diseases.

We analyzed the associations of screen-based behaviors with obesity, hypertension, and diabetes, and the moderation of different physical activity (PA) domains in these associations. We used data from the 2019 Brazilian National Health Survey, including data from 80,940 adults (mean age of 32.6 years). TV viewing, other screens (PC, tablet, and cell phone), PA domains (leisure-time, occupational, and transport) were collected via interview. Logistic regression models were used. There was a dose-response association of higher TV viewing with diabetes. Within the groups with medium and higher time spent on other screens, those with < 150 min/week in leisure-time PA increased the odds for obesity [1-2.9 h/day: OR = 1.18 (1.01, 1.39)] and hypertension [1-2.9 h/day: OR = 1.29 (1.08, 1.53); ≥ 6 h/day: OR = 1.47 (1.03, 2.09)]. Likewise, among the participants who spent ≥ 6 h/day of TV viewing, those with < 150 min/week of occupational PA presented higher odds for hypertension [OR = 1.61 (1.03, 2.53)]. In the group with higher use of other screens, < 150 min per week of occupational PA was associated with lower odds for obesity [1-2.9 h/day: OR = 0.81 (0.68, 0.97)] and hypertension [≥ 6 h/day: OR = 0.65 (0.44, 0.98)]. In conclusion, the associations of other screens with obesity and hypertension were strongest among those without leisure-time PA, while the moderator role of occupational PA was not clear.

Prevalence and sociodemographic correlates of physical activity and sitting time among South American adolescents: a harmonized analysis of nationally representative cross-sectional surveys.

BACKGROUND: To identify the prevalence and sociodemographic correlates of different domains of physical activity (PA) and higher sitting time among South American adolescents. METHODS: Data from national surveys of 11 South American countries were analyzed, and comprised information on 166,901 adolescents. PA (≥ 60 min/day of moderate-vigorous PA), physical education classes (PEC) (≥ 3 classes/wk), active commuting to school (≥ 1 d/wk), and higher sitting time (≥ 3 h/d) were self-reported. Sociodemographic correlates, such as gender, age, and food security status were explored using a random effect meta-analysis for logistic parameters. RESULTS: Recommended PA ranged between 7.5% (Brazil) and 19.0% (Suriname). Peru (2.2%) and Guyana (43.1%) presented the lowest prevalence of PEC and active commuting to school, respectively. Higher sitting time was less prevalent in Bolivia (24.6%) and more prevalent in Argentina (55.6%). Compared to girls, boys were more prone to reach recommendations for PA [OR = 1.94(1.65;2.28)]; to reach ≥ 3 PEC [OR = 1.17(1.04;1.33)] and to be active in commuting to school [(OR = 1.14(1.06;1.23)], but less prone to higher sitting time [OR = 0.89(0.82;0.96)]. Older adolescents had less odds of reach PA guidelines [OR = 0.86(0.77; 0.97)] and accumulated higher sitting time [OR = 1.27(1.14;1.41)]. Adolescents with food insecurity reported more PEC [OR = 1.12(1.04;1.21)] and active commuting to school [OR = 1.12(1.02;1.22)] but had less higher sitting time than their food security pairs [OR = 0.89(0.81;0.98)]. CONCLUSIONS: Few adolescents reach the PA recommendation. Actions aiming the promotion of PA and the reduction of sitting time must consider girls and older adolescents as target groups, as well as the specifics of each country.

Time trends and inequalities of physical activity domains and sitting time in South America.

Background: We aimed to investigate time trends and inequalities of different physical activity (PA) domains and sitting time (ST) in adults from South American countries. Methods: We included cross-sectional data of nationally representative surveys on adults (n = 597 843) from nine South American countries (Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Peru, Uruguay, and Venezuela), with data collection time frames ranging from 2005 to 2020. Data on different PA domains (leisure-time, transport, and occupational) and ST were assessed through questionnaires. Trends according to education level (quintiles), gender (m/w), and age group (18-34 years, 35-49 years, 50-64 years) were estimated for the harmonized indicators of nonzero PA in the different domains, ≥150 min/week of total PA and ≥8 hours/d of ST. Results: Chile (2009/2010 = 78.9% vs 2016/2017 = 70.5%), and Peru (2009/2010 = 78.6% vs 2011 = 69.6%) reduced total PA, while Brazil (2013 = 57.3% vs 2019 = 67.0%) and Uruguay (2006 = 69.4% vs 2013 = 79.4%) increased, and Argentina and Venezuela maintained. There was an increasing trend for ST in Argentina, Peru, and Uruguay. Leisure-time PA increased in most countries (6/8 countries). Transport PA was relatively stable, while occupational PA presented mixed findings. Education inequalities increased over time for total and leisure-time PA, while age and gender inequalities were relatively constant. Conclusions: Future South American countries' efforts may be warranted to promote PA and reduce ST in adults, while addressing inequalities when implementing actions.

Measurement of physical activity and sedentary behavior in national health surveys, South America.

Objectives: To characterize how physical activity and sedentary behavior have been measured in national health surveys in South American countries. Methods: An extensive search was made for national health surveys from all 12 South American countries through health websites, national statistical offices, and contact with researchers and policy-makers. The following eligibility criteria were used to select surveys: conducted in a South American country; used a nationally representative sample ≥ 18 years; coordinated by the public, private or mixed private-public sector; and assessed physical activity and/or sedentary behavior. Data were extracted on general information about the surveys, specific details about the physical activity and sedentary behavior assessment, and additional questions related to activity behavior. Results: In total, 36 surveys were included, two of which were multicountry surveys; all surveys assessed physical activity and 27 assessed sedentary behavior. Most surveys (23/36; 64%) were based on previously validated international questionnaires, but 13 (57%) of these deviated from the reference tools, introducing changes and adaptations. Sedentary behavior was assessed mostly through questions on screen time and/or daily sitting time in the same physical activity questionnaires. No survey used device-based measures to generate data on these behaviors. Conclusions: Differences between instruments used and modifications limit the comparability of data across countries. This highlights the importance of standardizing assessment within South America for physical activity and sedentary behavior sections in national surveys, with the broader aim of contributing to establishing a standardized strategy for the surveillance of physical activity and sedentary behavior in South America.

Association of public physical activity facilities and participation in community programs with leisure-time physical activity: does the association differ according to educational level and income?

BACKGROUND: Our aim was to analyze the association of the presence of public physical activity (PA) facilities and participation in public PA programs with leisure-time PA, with an emphasis on the moderating role of educational level and income. METHODS: We used data of 88,531 adults (46,869 women), with a mean age of 47.2 ± 17.1y, from the 2019 Brazilian National Health Survey. Leisure-time PA (dichotomized considering 150 min/week), the presence of a public PA facility near the household (yes or no), participation in public PA programs (yes or no), educational level (divided into quintiles) and per capita income (divided into quintiles) were all self-reported through interviews. Adjusted logistic regression models were used for the analyses. RESULTS: The presence of public PA facilities near the household and the participation in public PA programs were associated with higher leisure-time PA among all quintiles of income and educational level. However, multiplicative interactions revealed that participating in PA programs [Quintile (Q)1: OR: 13.99; 95%CI: 6.89-28.38 vs. Q5: OR: 3.48; 95%CI: 2.41-5.01] and the presence of public PA facilities near the household (Q1: OR: 3.07; 95%CI: 2.35-4.01 vs. Q5: OR: 1.38; 95%CI: 1.22-1.55) were more associated with higher odds of being active in the leisure-time among the lowest quintile of educational level. CONCLUSIONS: The presence of public PA facilities and participation in public PA programs are environmental correlates that may be relevant for designing effective public health interventions to reduce social inequalities in leisure-time PA among adults in low-income areas.

Does stressful workplace characteristics moderate or confound the association between occupational physical activity and elevated depressive symptoms? A large study including 36,442 adults.

BACKGROUND: We tested whether stressful workplace characteristics confound or moderate the association between occupational physical activity and depressive symptoms. METHOD: We used data of 36,442 employed adults (16,992 women), with a mean age of 39.3 ± 12.6y, from the 2013 Brazilian National Health Survey. Depressive symptoms were assessed through the Patient Health Questionnaire-9 (cut-point: ≥10). Occupational physical activity was self-reported and classified using the cut-point of 150 min/week and the highest quintile. Ten stressful workplace characteristics (e.g. exposure to stress, noise, violence) were also self-reported dichotomously. Logistic regression models were used considering the adjustment for potential confounders. RESULTS: Most of the stressful workplace characteristics were associated with elevated depressive symptoms (8/10 characteristics) and higher occupational physical activity (9/10 characteristics). Although there were no interactions in combined associations, we found that the association between occupational physical activity and depressive symptoms consistently reduced after adjusting for the cluster of positive screening for at least two stressful workplace characteristics in men [highest quintile: ORunadjusted: 1.63 (95%CI 1.22-2.17) vs ORadjusted: 1.36 (1.08-1.91); ≥150 min/week: ORunadjusted: 1.43 (1.09-1.88) vs ORadjusted: 1.25 (0.95-1.64)], and women [highest quintile: ORunadjusted: 2.15 1.73-2.66) vs ORadjusted: 1.83 (1.47-2.29); ≥150 min/week: ORunadjusted: 2.11 (1.68-2.65) vs ORadjusted: 1.80 (1.42-2.27)]. LIMITATIONS: The cross-sectional design limits the causal inference. CONCLUSIONS: Stressful workplace characteristics did not moderate, but acted as confounders in the association between occupational physical activity and elevated depressive symptoms and should be considered in future studies.

Measurement of physical activity and sedentary behavior in national health surveys, South America / Medición de la actividad física y del sedentarismo en encuestas nacionales de salud en América del Sur / Mensuração de atividade física e comportamento sedentário em pesquisas nacionais de saúde, América do Sul

ABSTRACT Objectives. To characterize how physical activity and sedentary behavior have been measured in national health surveys in South American countries. Methods. An extensive search was made for national health surveys from all 12 South American countries through health websites, national statistical offices, and contact with researchers and policy-makers. The following eligibility criteria were used to select surveys: conducted in a South American country; used a nationally representative sample ≥ 18 years; coordinated by the public, private or mixed private-public sector; and assessed physical activity and/or sedentary behavior. Data were extracted on general information about the surveys, specific details about the physical activity and sedentary behavior assessment, and additional questions related to activity behavior. Results. In total, 36 surveys were included, two of which were multicountry surveys; all surveys assessed physical activity and 27 assessed sedentary behavior. Most surveys (23/36; 64%) were based on previously validated international questionnaires, but 13 (57%) of these deviated from the reference tools, introducing changes and adaptations. Sedentary behavior was assessed mostly through questions on screen time and/or daily sitting time in the same physical activity questionnaires. No survey used device-based measures to generate data on these behaviors. Conclusions. Differences between instruments used and modifications limit the comparability of data across countries. This highlights the importance of standardizing assessment within South America for physical activity and sedentary behavior sections in national surveys, with the broader aim of contributing to establishing a standardized strategy for the surveillance of physical activity and sedentary behavior in South America.

RESUMEN Objetivos. Describir cómo se han medido la actividad física y el sedentarismo en las encuestas nacionales de salud en los países de América del Sur. Métodos. Se llevó a cabo una extensa búsqueda de encuestas nacionales de salud de los doce países sudamericanos en sitios web de salud, oficinas nacionales de estadística y mediante el contacto con investigadores y responsables de formular políticas. Para escoger las encuestas se emplearon los siguientes criterios de selección: realizada en un país sudamericano; muestra representativa a nivel nacional de ≥ 18 años; coordinada por el sector público, el sector privado o mixto público-privado; y evaluación de la actividad física o el sedentarismo. Se extrajeron datos como información general de las encuestas, detalles específicos de la evaluación de la actividad física y el sedentarismo, y otras preguntas relacionadas con la actividad física. Resultados. En total, se incluyeron 36 encuestas, dos de las cuales se realizaron en varios países. Todas las encuestas evaluaron la actividad física; 27, el sedentarismo. La mayoría de las encuestas (23/36; 64%) se basaron en cuestionarios internacionales anteriormente validados, de los cuales 13 (57%) se desviaron de las herramientas de referencia al tener cambios y adaptaciones. El sedentarismo se evaluó principalmente en los mismos cuestionarios de actividad física mediante preguntas sobre el tiempo invertido delante de pantallas o el tiempo diario sentado. Ninguna encuesta aplicó medidas basadas en dispositivos para obtener datos sobre estos comportamientos. Conclusiones. Las diferencias entre los instrumentos empleados y las modificaciones limitan la comparabilidad de los datos en todos los países. Esto pone de relieve la importancia de estandarizar la evaluación en América del Sur de las secciones dedicadas a la actividad física y al sedentarismo en las encuestas nacionales, con el objetivo general de contribuir a la creación de una estrategia estandarizada para la vigilancia de la actividad física y el sedentarismo en América del Sur.

RESUMO Objetivos. Caracterizar como a atividade física e o comportamento sedentário têm sido medidos em pesquisas nacionais de saúde em países sul-americanos. Métodos. Foi realizada uma busca extensa de pesquisas nacionais de saúde de todos os 12 países sul-americanos em sites de saúde e órgãos nacionais de estatística, e pelo contato com pesquisadores e formuladores de políticas. Foram usados os seguintes critérios de elegibilidade para selecionar as pesquisas: conduzida em um país sul-americano; que tenha usado uma amostra nacionalmente representativa ≥ 18 anos; coordenada pelo setor público, privado ou público-privado; e que tenha avaliado a atividade física e/ou o comportamento sedentário. Os dados extraídos eram sobre informações gerais das pesquisas, detalhes específicos sobre a avaliação da atividade física e do comportamento sedentário e questões adicionais relacionadas ao comportamento na atividade. Resultados. Ao todo, 36 pesquisas foram incluídas, duas das quais foram conduzidas em vários países. Todas as pesquisas avaliaram a atividade física e 27 avaliaram o comportamento sedentário. A maioria das pesquisas (23/36; 64%) baseou-se em questionários internacionais previamente validados e 13 (57%) delas se desviaram das ferramentas de referência, introduzindo mudanças e adaptações. O comportamento sedentário foi avaliado principalmente por meio de perguntas sobre tempo de tela e/ou tempo diário sentado nos mesmos questionários sobre atividade física. Nenhuma pesquisa utilizou medições realizadas por dispositivos para gerar dados sobre esses comportamentos. Conclusões. As diferenças entre os instrumentos usados e as modificações limitam a comparabilidade dos dados entre os países, o que destaca a importância de padronizar a avaliação na América do Sul para as seções de atividade física e comportamento sedentário em pesquisas nacionais, com o objetivo mais amplo de contribuir para o estabelecimento de uma estratégia padronizada para a vigilância da atividade física e do comportamento sedentário na América do Sul.

Correlates of screen-based behaviors among adults from the 2019 Brazilian National Health Survey.

We aimed to investigate correlates of TV viewing and other types of screen-based behaviors in a nationally representative sample of Brazilian adults. In the 2019 Brazilian National Health Survey (including 88,509 adults), TV viewing time and other types of screen behaviors (computer, tablet, and cellphone use) were self-reported and different geographical, sociodemographic, behavioral, and health status factors were investigated as potential correlates. Multinomial logistic regression models were used for the main analyses. Living in capital cities, urban areas, being unemployed, high consumption of soft drinks, obesity, and elevated depressive symptoms were each associated with more TV viewing and more time using other types of screens. There were differential associations between TV viewing and the use of other types of screen across age and socioeconomic variables. For instance, younger adults have a more diverse portfolio of screen time than older adults. To conclude, levels of screen-based behaviors vary by geographical, sociodemographic, behavioral, and health status characteristics. Interventions should focus on high-risk population groups and may benefit from targeting specific sedentary behaviors of interest.

Time Trends and Sociodemographic Inequalities in Physical Activity and Sedentary Behaviors Among Brazilian Adults: National Surveys from 2003 to 2019.

BACKGROUND: The authors analyzed time trends and sociodemographic inequalities in different physical activity and sedentary behavior domains between 2003 and 2019. METHODS: A secondary analysis of data from 5 cross-sectional Brazilian epidemiological surveys (World Health Survey-2003, National Household Sample Survey-2008/2015, and Brazilian Health Survey-2013/2019) conducted among a nationally representative sample of Brazilian adults. The authors used data on different domains of physical activity (leisure, commute, total transport, and total physical activity) and sedentary behavior (TV viewing and other types of screens) that were available in the different surveys. Gender, age group, country region, ethnicity, type of area and city, and quintiles of income and educational achievement were used as sociodemographic correlates. RESULTS: The prevalence of leisure-time physical activity increased over time (2008: 7.0% vs 2019: 26.5%). There was also an increased trend of social inequality in leisure-time physical activity. A trend of reduction was observed for active commuting (2008: 35.0% vs 2019: 21.8%), while total transport physical activity was stable (2013: 49.5% vs 2019: 49.6%). Directions of findings were opposite for sedentary behavior, with reduced trend for >3 hours per day of TV viewing (2008: 34.8% vs 2019: 21.8%) and increased trend for >3 hours per day of other types of screen time (2008: 6.4% vs 2019: 22.2%). CONCLUSION: A positive trend exists in leisure-time physical activity, but there was also an increase in social inequalities for physical activity in Brazil.

Effects of Physically Active Lessons on Movement Behaviors, Cognitive, and Academic Performance in Elementary Schoolchildren: ERGUER/Aracaju Project.

BACKGROUND: To evaluate the effects of the introduction of physically active lessons on movement behaviors, cognitive, and academic performance in schoolchildren. METHODS: This was a cluster-controlled trial. A total of 61 students from the second year of elementary school in a public school in Brazil made up 2 intervention classes (n = 34) with the introduction of physically active lessons and 2 control classes (n = 27). Sedentary behavior, physical activity, cognitive, and academic performance were evaluated in 3 moments, which were compared using models of generalized estimating equations. RESULTS: The intervention was effective for reducing the standing time between the baseline and 3 months while increasing the walking time between baseline and 3 months and baseline and 9 months. There was a reduction in time in stationary activities and increased time in light physical activities between all moments. The intervention group increased their performance in the go/no go test, showing a smaller number of errors between the baseline and 3 months and baseline and 9 months, and a reduction in the test time between baseline and 3 months. No impact on students' academic performance was observed. CONCLUSION: Physically active lessons improve movement behaviors and cognitive functions among elementary schoolchildren.

Associations of sedentary behaviors and physical activity with social isolation in 100,839 school students: The Brazilian Scholar Health Survey.

OBJECTIVE: To examine the relationship between physical activity, sedentary behaviors, and social isolation in a representative sample of Brazilian adolescents. METHOD: Cross sectional analyses using data from the Brazilian Scholar Health Survey conducted in 2015. The sample included 100,839 adolescents (mean age: 14.3 y, 51.4% Female) from 3040 schools. Information about social isolation (number of close friends and perceived loneliness), physical activity (International Physical Activity Questionnaire) and sedentary behaviors (total sitting time and TV viewing) were self-reported. Chronological age, race and type of city (state capital or other) were co-variables. Logistic regression models were used to analyze the data (results are presented as odds ratios (OR) with 95% confidence intervals). RESULTS: Physical activity was associated with lower odds of both social isolation indicators in boys, and with lower likelihood of having few friends in girls. Greater sitting time was associated with higher likelihood of social isolation, as was low (<1 h/d) [boys: OR: 1.54 (95% CI: 1.33 to 1.77); girls: OR: 1.31 (95% CI: 1.17 to 1.48] and high TV viewing (≥8 h/d) [boys: OR: 1.75 (95% CI: 1.47 to 2.09)]; girls: OR: 1.58 (95% CI: 1.37 to 1.82)]. More than 300 min/week of physical activity was sufficient to eliminate the association of high TV viewing and high sitting time with markers of social isolation in boys. CONCLUSION: Physical activity is associated with a lower prevalence of social isolation, especially among boys. Both high and low amounts of TV viewing increase the likelihood of social isolation. Physical activity reduced the association between TV viewing and sitting with social isolation among boys.