Longitudinal association between moderate to vigorous physical activity and lipid profile indicators in adolescents.

The objective of this study was to examine the association between time engaged in moderate (MPA), vigorous (VPA), and moderate-to-vigorous (MVPA) physical activity (PA) and indicators of lipid profile in adolescents. This longitudinal study with a four-year follow-up, and three collection points (2014, 2015 and 2017) analyzed the data of 136 adolescents (10-13 years old; 53.7% girls), in João Pessoa, Brazil. The time in MPA, VPA and MVPA times was measured by accelerometers. The lipid profile indicators analyzed were total cholesterol (TC), low-density (LDL-C) and high-density lipoproteins cholesterol (HDL-C), triglycerides (TG), non-HDL-C, TC/HDL-C and TG/HDL-c ratios. There was an inverse association between MPA time and TC values (ß = -0.560; 95%CI: -1.116; -0.004); VPA and LDL-C (ß = -0.962; 95%CI: -1.678; -0.246) and non-HDL-C (ß = -0.955; 95%CI: -1.708; -0.201); and MVPA and TC (ß = -0.436; 95%CI: -0.816; -0.055), TG (ß = -0.415; 95%CI: -0.712; -0.118), LDL-C (ß = -0.460; 95%CI: -0.823; -0.096), non-HDL-C (ß = -0.522; 95%CI: -0.908; -0.136) and TC/HDL-C (ß = -0.472; 95%CI: -0.889; -0.055). Adolescents more engaged in PA, especially in MVPA, exhibited better levels of TC, TG, LDL-C, non-HDL-C and TC/HDL-C; and AFV exerted a greater influence on LDL-c and non-HDL-c levels.HighlightsThis study is one of the first observational longitudinal studies to analyze the association between different PA intensities, measured by accelerometer, and lipid profile indicators, with a 4-year follow-up and 3 collection points in adolescents from a low-to-middle income country;Adolescents engaged in PA, especially MVPA intensity, obtained better TC, TG, LDL-c, non-HDL-C and TC/HDL-C levels;VPA was more strongly associated with LDL-C and non-HDL-C levels compared to MVPA.

Barriers and facilitators of domain-specific physical activity: a systematic review of reviews.

BACKGROUND: Knowing what facilitates and hinders physical activity behaviour across domains (leisure, travel, work or education, and household) is central for the development of actions for more active lifestyles. Thus, the aim of this systematic review of reviews was to summarize the evidence on barriers and facilitators of domain-specific physical activity. METHODS: We included systematic reviews with or without meta-analysis that investigated the association between modifiable barriers and facilitators and levels of domain-specific physical activity. Reviews published until September 2020 were retrieved from PubMed, ISI Web of Science, Scopus, Regional Library of Medicine (BIREME), and PsycNET, and from the reference list of selected articles. Each review was screened by two independent reviewers for eligibility. Data extracted from selected papers included methodological aspects (number of primary studies, study designs, and age groups); physical activity domains and barriers and facilitators investigated; and direction of association. For each pair of barrier/facilitator and domain-specific physical activity, we recorded the number of positive, negative, and null associations reported across reviews. Quality assessment of each systematic review was performed using the AMSTAR-2 tool. RESULTS: Forty-four systematic reviews were selected. The evidence base was largest for leisure-time followed by travel-related physical activity. A very small number of reviews included physical activity in work, educational and domestic settings. Across all physical activity domains, factors related to the built environment were more abundant in the reviews than intra and interpersonal factors. Very consistent positive associations were observed between a range of intrapersonal factors and leisure-time physical activity, as well as moderately consistent evidence of positive association for general social support and support from family members. Evidence of moderate consistency was found for the positive association between transport-related physical activity and positive beliefs about consequences, walkability, and existence of facilities that support active travel. Evidence on barriers and facilitators for physical activity at work, educational, and domestic settings was limited in volume and consistency. CONCLUSIONS: Efforts and resources are required to diversify and strength the evidence base on barriers and facilitators of domain-specific physical activity, as it is still limited and biased towards the leisure domain and built environment factors. TRIAL REGISTRATION: PROSPERO CRD42020209710.

Barreiras e facilitadores para a prática de atividade física em diferentes domínios no Brasil: uma revisão sistemática / Barriers and facilitators for physical activity domains in Brazil: a systematic review

Resumo O objetivo foi revisar sistematicamente as evidências científicas sobre as barreiras e os facilitadores para a prática de atividade física (AF) na população brasileira, considerando os diferentes domínios (lazer, deslocamento, trabalho/estudo e tarefas domésticas). A busca foi conduzida nas bases de dados MEDLINE/PubMed, ISI Web of Science, Scopus, BIREME/LILACS e APA PsycNET, considerando o período de 2010 a 2020. Posteriormente, foi incluída a busca na Revista Brasileira de Atividade Física e Saúde. O processo de seleção consistiu na leitura de títulos e resumos, seguida de textos na íntegra. A avaliação foi realizada por pares e, mediante discrepância, um terceiro revisor era consultado. O domínio do lazer e as barreiras e os facilitadores ambientais foram os mais investigados nos 78 artigos incluídos. Houve consistência nas associações positivas de seis diferentes facilitadores pessoais e sociais para o lazer e um fator ambiental para o deslocamento. Encontrou-se um número reduzido de investigações sobre os domínios de trabalho/estudo e tarefas domésticas, sendo importante o incentivo a futuras investigações acerca das barreiras e dos facilitadores pessoais e sociais relacionados à AF de deslocamento.

Abstract This study aimed to systematically review scientific evidence on the barriers and facilitators of physical activity (PA) among the Brazilian population, considering different domains (leisure, travel, work/study, and household). The search was conducted in the MEDLINE/PubMed, ISI Web of Science, SCOPUS, BIREME/LILACS, and APA PsycNET databases and was limited to papers published between 2010 and 2020. A manual search of the Brazilian Journal of Physical Activity & Health was also conducted. The selection process consisted of screening titles and abstracts, followed by the analysis of full texts. Each paper was assessed by two independent reviewers, and when discrepancies arose, a third reviewer was consulted. Leisure, environmental barriers and facilitators were the most investigated domains in the 78 included studies. There was consistency in the positive associations between six different intrapersonal and social facilitators for leisure PA and one environmental factor for travel. There have been a small number of investigations on the work/study and household domains, and future investigations on intrapersonal and social barriers and facilitators in the travel domain are important.

Barriers and facilitators for physical activity domains in Brazil: a systematic review. / Barreiras e facilitadores para a prática de atividade física em diferentes domínios no Brasil: uma revisão sistemática.

This study aimed to systematically review scientific evidence on the barriers and facilitators of physical activity (PA) among the Brazilian population, considering different domains (leisure, travel, work/study, and household). The search was conducted in the MEDLINE/PubMed, ISI Web of Science, SCOPUS, BIREME/LILACS, and APA PsycNET databases and was limited to papers published between 2010 and 2020. A manual search of the Brazilian Journal of Physical Activity & Health was also conducted. The selection process consisted of screening titles and abstracts, followed by the analysis of full texts. Each paper was assessed by two independent reviewers, and when discrepancies arose, a third reviewer was consulted. Leisure, environmental barriers and facilitators were the most investigated domains in the 78 included studies. There was consistency in the positive associations between six different intrapersonal and social facilitators for leisure PA and one environmental factor for travel. There have been a small number of investigations on the work/study and household domains, and future investigations on intrapersonal and social barriers and facilitators in the travel domain are important.

O objetivo foi revisar sistematicamente as evidências científicas sobre as barreiras e os facilitadores para a prática de atividade física (AF) na população brasileira, considerando os diferentes domínios (lazer, deslocamento, trabalho/estudo e tarefas domésticas). A busca foi conduzida nas bases de dados MEDLINE/PubMed, ISI Web of Science, Scopus, BIREME/LILACS e APA PsycNET, considerando o período de 2010 a 2020. Posteriormente, foi incluída a busca na Revista Brasileira de Atividade Física e Saúde. O processo de seleção consistiu na leitura de títulos e resumos, seguida de textos na íntegra. A avaliação foi realizada por pares e, mediante discrepância, um terceiro revisor era consultado. O domínio do lazer e as barreiras e os facilitadores ambientais foram os mais investigados nos 78 artigos incluídos. Houve consistência nas associações positivas de seis diferentes facilitadores pessoais e sociais para o lazer e um fator ambiental para o deslocamento. Encontrou-se um número reduzido de investigações sobre os domínios de trabalho/estudo e tarefas domésticas, sendo importante o incentivo a futuras investigações acerca das barreiras e dos facilitadores pessoais e sociais relacionados à AF de deslocamento.

[Reproducibility, validity and internal consistency of the environment scale for physical activity of adolescents]. / Reprodutibilidade, validade e consistência interna da escala de ambiente para a atividade física em adolescentes.

The objective was to analyze the reproducibility, validity and internal consistency of the environment scale for the physical activity in adolescents. Reproducibility study with 171 adolescents (59.5% female); and validity and internal consistency with 1.353 adolescents (53.1% female). The scale contained 25 items in three domains: places of practice (PP - 14 items); urban security (US - six items) and; in transit (TS - five items). Kappa PABAK and Spearman correlation (rho) were used to assess reproducibility, exploratory factor analysis (EFA) and confirmatory (CFA) for validity, the combined reliability index (CRI) for internal consistency. The reproducibility of the scores was PP - rho = 0.76; US - rho = 0.78 and; TS - rho = 0.66. Three factors were identified in the EFA: PP (eight items, factorial loads from 0.36 to 0.67); US (four items, factorial loads from 0.60 to 0.78) e; TS (four items, factorial loads from 0.35 to 0.64). The CFA confirmed the model with three factors and with levels recommended for the fit quality indicators of the model. The internal consistency was satisfactory for PP (CRI = 0.85), US (CRI = 0.90) and TS (CRI = 0.79). The environment scale for the practice of physical activity showed adequate levels of reproducibility, construct validity and internal consistency.

Objetivou-se analisar a reprodutibilidade, validade e consistência interna da escala de ambiente para a atividade física em adolescentes. A análise de reprodutibilidade foi feita com 171 adolescentes (59,5% do sexo feminino), e as de validade e consistência interna compreenderam 1.353 adolescentes (53,1% do sexo feminino). A escala continha 25 itens, em três domínios: locais de prática (LP - 14 itens); segurança urbana (SU - seis itens) e; no trânsito (ST - cinco itens). O Kappa PABAK e a correlação de Spearman (rho) foram utilizados para avaliar a reprodutibilidade; a análise fatorial exploratória (AFE) e confirmatória (AFC) para a validade; e o índice de fidedignidade combinada (IFC) para avaliar a consistência interna. A reprodutibilidade dos escores foi de: LP - rho = 0,76; SU - rho = 0,78 e; ST - rho = 0,66. Foram identificados três fatores na AFE: LP (oito itens, cargas fatoriais de 0,36 a 0,67); SU (quatro itens, cargas fatoriais de 0,60 a 0,78) e; ST (quatro itens, cargas fatoriais de 0,35 a 0,64). A AFC confirmou o modelo com três fatores e com níveis recomendados para os indicadores de qualidade de ajuste do modelo. A consistência interna foi satisfatória para LP (IFC = 0,85), SU (IFC = 0,90) e ST (IFC = 0,79). A escala de ambiente para a prática de atividade física apresentou níveis adequados de reprodutibilidade, validade de construto e consistência interna.

Reprodutibilidade, validade e consistência interna da escala de ambiente para a atividade física em adolescentes / Reproducibility, validity and internal consistency of the environment scale for physical activity of adolescents

Resumo Objetivou-se analisar a reprodutibilidade, validade e consistência interna da escala de ambiente para a atividade física em adolescentes. A análise de reprodutibilidade foi feita com 171 adolescentes (59,5% do sexo feminino), e as de validade e consistência interna compreenderam 1.353 adolescentes (53,1% do sexo feminino). A escala continha 25 itens, em três domínios: locais de prática (LP - 14 itens); segurança urbana (SU - seis itens) e; no trânsito (ST - cinco itens). O Kappa PABAK e a correlação de Spearman (rho) foram utilizados para avaliar a reprodutibilidade; a análise fatorial exploratória (AFE) e confirmatória (AFC) para a validade; e o índice de fidedignidade combinada (IFC) para avaliar a consistência interna. A reprodutibilidade dos escores foi de: LP - rho = 0,76; SU - rho = 0,78 e; ST - rho = 0,66. Foram identificados três fatores na AFE: LP (oito itens, cargas fatoriais de 0,36 a 0,67); SU (quatro itens, cargas fatoriais de 0,60 a 0,78) e; ST (quatro itens, cargas fatoriais de 0,35 a 0,64). A AFC confirmou o modelo com três fatores e com níveis recomendados para os indicadores de qualidade de ajuste do modelo. A consistência interna foi satisfatória para LP (IFC = 0,85), SU (IFC = 0,90) e ST (IFC = 0,79). A escala de ambiente para a prática de atividade física apresentou níveis adequados de reprodutibilidade, validade de construto e consistência interna.

Abstract The objective was to analyze the reproducibility, validity and internal consistency of the environment scale for the physical activity in adolescents. Reproducibility study with 171 adolescents (59.5% female); and validity and internal consistency with 1.353 adolescents (53.1% female). The scale contained 25 items in three domains: places of practice (PP - 14 items); urban security (US - six items) and; in transit (TS - five items). Kappa PABAK and Spearman correlation (rho) were used to assess reproducibility, exploratory factor analysis (EFA) and confirmatory (CFA) for validity, the combined reliability index (CRI) for internal consistency. The reproducibility of the scores was PP - rho = 0.76; US - rho = 0.78 and; TS - rho = 0.66. Three factors were identified in the EFA: PP (eight items, factorial loads from 0.36 to 0.67); US (four items, factorial loads from 0.60 to 0.78) e; TS (four items, factorial loads from 0.35 to 0.64). The CFA confirmed the model with three factors and with levels recommended for the fit quality indicators of the model. The internal consistency was satisfactory for PP (CRI = 0.85), US (CRI = 0.90) and TS (CRI = 0.79). The environment scale for the practice of physical activity showed adequate levels of reproducibility, construct validity and internal consistency.

Muscle endurance of Brazilian children and adolescents: a systematic review of the literature / Resistência muscular de crianças e adolescentes brasileiros: uma revisão sistemática da literatura

ABSTRACT Muscle endurance (ME) is considered to be an important indicator of health-related fitness in childhood and adolescence. The present study aimed to identify and summarize the evidence on the prevalence of adequate ME in Brazilian children and adolescents (6 to 18 years old). A systematic search of studies published from 2009 to 2019 was performed in six databases (LILACS; SciELO; SportDiscus; Medline/PubMed; Web of Science; Scopus). We found 16,168 articles, 20 of which met the eligibility criteria and were included in this review for data extraction and assessment of their risk of bias. Among the 23,805 children and adolescents participating in the studies, 43.5% of the total (43.7% of boys and 41.0% of girls) had adequate abdominal ME. Different test batteries were reported, the main ones being PROESP/BR®, FITNESSGRAM®, and AAHPERD®. Most studies were carried out in the South (50.0%) and Southeast (20.0%) regions of Brazil. Regarding the distribution of studies by geographic region and human development index (HDI), there were no disparities in ME between studies conducted in regions with a lower HDI (43.1% for the Northeast and 32.2% for the North) and those with a higher HDI (46.8% for the South and 33.1% for the Southeast). We conclude that less than half of Brazilian children and adolescents of both genders have an abdominal ME adequate for health, with ​​slightly lower values among females.

RESUMO A resistência muscular (RM) tem sido considerada um importante indicador da aptidão relacionada a saúde na infância e adolescência. O estudo teve como objetivo identificar e sumarizar as evidências sobre a prevalência de RM adequada em crianças e adolescentes (6 a 18 anos) no Brasil. Foi realizada uma busca sistemática em seis bases de dados (LILACS; Scielo; SportDiscus; Medline/Pubmed; Web of Science; Scopus), de estudos publicados no período de 2009 a 2019. Foram encontrados 16.168 artigos, sendo que 20 estudos preencheram os critérios de elegibilidade e foram incluídos na presente revisão para extração dos dados e avaliação quanto o seu risco de viés. Entre as 23.805 crianças e adolescentes participantes nos estudos, 43,5% do total (43,7% dos meninos e 41,0% das meninas) apresentaram RM abdominal adequada. Diferentes baterias de testes foram identificadas, sendo as principais PROESP/BR®, FITNESSGRAM® e AAHPERD®. A maioria dos estudos foram realizados de na região Sul (50,0%) e Sudeste (20,0%) do Brasil. Em relação as distribuições dos estudos pelas regiões geográficas e índices de desenvolvimento humano (IDH), não houveram disparidades na RM entre os estudos nas regiões com menores IDH (Nordeste 43,1% e Norte 32,2%) e as de maiores IDH (Sul 46,8% e Sudeste 33,1%). Conclui-se que menos da metade das crianças e adolescentes brasileiras de ambos os sexos possuem uma RM abdominal adequada para a saúde, com valores ligeiramente inferiores no sexo feminino.

Breaks in Sedentary Time and Cardiometabolic Markers in Adolescents. / Breaks no Tempo em Comportamento Sedentário e Marcadores Cardiometabólicos em Adolescentes.

BACKGROUND: The interruption of the time spent in sedentary behavior (breaks) has been associated with better levels of cardiometabolic indicators in the adult population, but in adolescents, further investigations are still needed to confirm these findings. OBJECTIVES: To analyze the association of the number of breaks per day in sedentary behaviors with cardiometabolic markers and whether it was moderated by nutritional status and excessive time on sedentary behavior in adolescents. METHODS: This is a cross-sectional study of 537 adolescents (52.3% girls), aged between 10 and 14 years, enrolled in public schools in the city of João Pessoa, Paraíba state, Brazil. The number of daily breaks (>100 counts/minutes) in sedentary time was measured by Actigraph GT3X+ accelerometers. The following cardiometabolic markers were analyzed: systolic and diastolic blood pressure (mmHg), fasting blood glucose levels, total cholesterol, triglycerides, HDL-c, LDL-c (all in mg/dL) and body mass index (BMI) (kg/m2). Linear regression was used to analyze the association between the number of breaks and cardiometabolic markers and whether this association was moderated by nutritional status and excessive time in sedentary behavior. The significance level of p<0.05 was adopted for all analyses. RESULTS: The number of daily breaks was negatively associated with BMI (boys - ß = -0.083; 95%CI: -0.132; -0.034 and girls - ß = -0.115; 95%CI: -0.169; -0.061), but not with the remaining cardiometabolic markers. The number of breaks per day was negatively associated with BMI (ß = -0.069; 95% CI: -0.102; -0.035), but not with the other cardiometabolic markers and this association was not moderated by the adolescents' nutritional status (p=0.221), or by excessive time in sedentary behavior (p=0.176). CONCLUSIONS: Including breaks in sedentary time seems to contribute to lower BMI values in adolescents.

FUNDAMENTO: Interrupções no tempo despendido em comportamento sedentário (breaks) têm sido associadas a melhores níveis de indicadores cardiometabólicos na população adulta. No entanto, em adolescentes, os achados sobre essa associação ainda são conflitantes. OBJETIVOS: Analisar a associação do número de breaks por dia em comportamento sedentário com marcadores cardiometabólicos e avaliar se ela é moderada pelo estado nutricional e o tempo excessivo em comportamento sedentário em adolescentes. MÉTODOS: Estudo transversal com 537 adolescentes (52,3% do sexo feminino), de 10 a 14 anos de idade, de escolas públicas de João Pessoa (PB). O número diário de breaks em comportamento sedentário (>100 counts/minutos) foi mensurado por meio de acelerômetros (Actigraph GT3X+). Os marcadores cardiometabólicos analisados foram: pressão arterial sistólica e diastólica (mmHg), glicose de jejum, colesterol total, triglicerídeos, HDL-c, LDL-c (todos em mg/dL) e índice de massa corporal (IMC) (kg/m2). Utilizou-se a regressão linear para analisar a associação do número de breaks com marcadores cardiometabólicos e avaliar se ela é moderada pelo estado nutricional e o tempo excessivo em comportamento sedentário. O nível de significância de p<0,05 foi adotado para todas as análises. RESULTADOS: O número de breaks por dia se associou negativamente ao IMC (ß = −0,069; IC95%: −0,102; −0,035), mas não aos demais marcadores cardiometabólicos, e essa associação não foi moderada pelo estado nutricional dos adolescentes (p=0,221) e nem pelo tempo excessivo em comportamento sedentário (p=0,176). CONCLUSÃO: A inclusão de breaks no tempo em comportamento sedentário parece contribuir para valores mais baixos do IMC em adolescentes.

Reliability, validity and internal consistency of social support and self-efficacy scales for physical activity in adolescents with 10 to 14 years of age.

OBJECTIVE: To analyze the reliability, validity and internal consistency of the physical activity social support (SSS) and self-efficacy (SES) scales among adolescents aged 10-14 years. METHODS: The reliability study included 171 adolescents (mean age=12.3±1.0 years, 59.6% female) and validity and consistency study with 1,107 (mean age=12.0±1.0 years, 52.7% female). The SSS had 15 items and the SES eight items. Reliability was determined by Spearman's correlation analysis (rho) and validity and internal consistency by factor analysis (exploratory - EFA and confirmatory - CFA) and the composite reliability (CR), respectively. RESULTS: The reliability of SSS (father: rho=0.80; p<0.001 | mother: rho=0.76; p<0.001 | friends: rho=0.75; p<0.001) and SES (rho=0.72; p<0.001) were considered high. In the EFA, three factors were identified for the SSS (father, mother and friends - five items each) and one factor for SES (five items), confirmed in the CFA. Quality parameters of adjustment in the final models were satisfactory for SSS (chi-square=240.5 [p<0.001]; root mean square residual - RMR=0.05; root mean square error of approximation - RMSEA=0.04 [90%CI 0.04-0.05]; goodness of fit index - GFI=0.97; adjusted goodness of fit index - AGFI=0.96 and comparative fit index - CFI=0.97) and SES (chi-square=5.4 [p=0.07]; RMR=0.01; RMSEA=0.04 [90%CI 0.00-0.08]; GFI=0.99; AGFI=0.99 and CFI=0.97). Internal consistency was considered satisfactory for SSS (CR: father=0.79, mother=0.77, friends=0.78) and low for SES (CR=0.38). CONCLUSIONS: The scales showed satisfactory levels of reliability and of construct validity. However, only the SSS showed adequate levels of internal consistency.

Breaks no tempo em comportamento sedentário e marcadores cardiometabólicos em adolescentes / Breaks in sedentary time and cardiometabolic markers in adolescents

Resumo Fundamento: Interrupções no tempo despendido em comportamento sedentário (breaks) têm sido associadas a melhores níveis de indicadores cardiometabólicos na população adulta. No entanto, em adolescentes, os achados sobre essa associação ainda são conflitantes. Objetivos: Analisar a associação do número de breaks por dia em comportamento sedentário com marcadores cardiometabólicos e avaliar se ela é moderada pelo estado nutricional e o tempo excessivo em comportamento sedentário em adolescentes. Métodos: Estudo transversal com 537 adolescentes (52,3% do sexo feminino), de 10 a 14 anos de idade, de escolas públicas de João Pessoa (PB). O número diário de breaks em comportamento sedentário (>100 counts/minutos) foi mensurado por meio de acelerômetros (Actigraph GT3X+). Os marcadores cardiometabólicos analisados foram: pressão arterial sistólica e diastólica (mmHg), glicose de jejum, colesterol total, triglicerídeos, HDL-c, LDL-c (todos em mg/dL) e índice de massa corporal (IMC) (kg/m2). Utilizou-se a regressão linear para analisar a associação do número de breaks com marcadores cardiometabólicos e avaliar se ela é moderada pelo estado nutricional e o tempo excessivo em comportamento sedentário. O nível de significância de p<0,05 foi adotado para todas as análises. Resultados: O número de breaks por dia se associou negativamente ao IMC (ß = −0,069; IC95%: −0,102; −0,035), mas não aos demais marcadores cardiometabólicos, e essa associação não foi moderada pelo estado nutricional dos adolescentes (p=0,221) e nem pelo tempo excessivo em comportamento sedentário (p=0,176). Conclusão: A inclusão de breaks no tempo em comportamento sedentário parece contribuir para valores mais baixos do IMC em adolescentes.

Abstract Background: The interruption of the time spent in sedentary behavior (breaks) has been associated with better levels of cardiometabolic indicators in the adult population, but in adolescents, further investigations are still needed to confirm these findings. Objectives: To analyze the association of the number of breaks per day in sedentary behaviors with cardiometabolic markers and whether it was moderated by nutritional status and excessive time on sedentary behavior in adolescents. Methods: This is a cross-sectional study of 537 adolescents (52.3% girls), aged between 10 and 14 years, enrolled in public schools in the city of João Pessoa, Paraíba state, Brazil. The number of daily breaks (>100 counts/minutes) in sedentary time was measured by Actigraph GT3X+ accelerometers. The following cardiometabolic markers were analyzed: systolic and diastolic blood pressure (mmHg), fasting blood glucose levels, total cholesterol, triglycerides, HDL-c, LDL-c (all in mg/dL) and body mass index (BMI) (kg/m2). Linear regression was used to analyze the association between the number of breaks and cardiometabolic markers and whether this association was moderated by nutritional status and excessive time in sedentary behavior. The significance level of p<0.05 was adopted for all analyses. Results: The number of daily breaks was negatively associated with BMI (boys - ß = −0.083; 95%CI: −0.132; −0.034 and girls - ß = −0.115; 95%CI: −0.169; −0.061), but not with the remaining cardiometabolic markers. The number of breaks per day was negatively associated with BMI (ß = −0.069; 95% CI: −0.102; −0.035), but not with the other cardiometabolic markers and this association was not moderated by the adolescents' nutritional status (p=0.221), or by excessive time in sedentary behavior (p=0.176). Conclusions: Including breaks in sedentary time seems to contribute to lower BMI values in adolescents.

Validade e clareza dos conceitos e terminologias do Guia de Atividade Física para a População Brasileira / Validity and Clarity of the Concepts and Terminologies of the Physical Activity Guidelines for the Brazilian Population

Nosso objetivo foi avaliar a validade e a clareza dos conceitos e terminologias adotados na elaboração do Guia de Atividade Física para a População Brasileira (Guia). O Grupo de Trabalho Domínios da Atividade Física (GT Domínios) conduziu a avaliação da validade e da clareza dos conceitos e terminologias relacionados a atividade física (AF), comportamento sedentário, domínios (tempo livre, deslocamento, trabalho ou estudo e tarefas domésticas) e intensidades da AF (leve, moderada e vigorosa), em três etapas: 1- Proposição dos conceitos; 2- Escuta com pesquisadores (dois momen-tos); 3- Consulta pública. Os conceitos propostos pelo GT Domínios foram baseados em guias in-ternacionais, artigos científicos, relatórios nacionais e conhecimentos técnico-científicos-acadêmicos dos integrantes do GT Domínios, discutidos em reuniões (etapa 1). Na escuta com pesquisadores (etapa 2) foram testadas a validade e a clareza dos conceitos em dois momentos. Participaram 70 e 40 pesquisadores vinculados aos outros GT do Guia no primeiro e segundo momentos, respectiva-mente. Em ambas as escutas, todos os conceitos apresentaram índice de concordância para validade e clareza igual ou superior a 80%. As sugestões convergentes indicadas na etapa 2 foram incluídas e novas versões dos conceitos foram disponibilizadas para a terceira etapa (consulta pública) realizada pelo Ministério da Saúde. Foram realizadas 14 sugestões relacionadas aos conceitos que foram aceitas e incorporadas ao texto do Guia, quando pertinentes. Conclui-se que os conceitos e terminologias relacionados a AF propostos pelo GT Domínios para compor o Guia, após a avaliação de pesquisa-dores especialistas e da população consultada, são válidos e claros

We evaluated the validity and clarity of the concepts and terminologies adopted to develop the Physical Activity Guidelines for the Brazilian Population (Guidelines). The Physical Activity Domains Working Group (Domains WG) assessed the validity and clarity of the following concepts: physical activity, seden-tary behavior, PA domains (free time, commuting, work or study, and domestic tasks) and intensities (light, moderate and vigorous). The concepts were evaluated in three stages: 1- Concept proposition; 2- Expert consultation (two steps); 3- Public consultation. The concepts proposed by the Domains WG were based on international guidelines, scientific articles, official documents from the Ministry of Health, and techni-cal-scientific-academic knowledge of the Domains WG members, discussed in a series of meetings (stage 1). In the second stage (expert consultation), validity and clarity of the concepts were tested on two occasions. Seventy and forty researchers working in the other Guidelines WGs contributed to first and second steps, respectively. In both occasions, validity and clarity agreement were equal to or greater than 80% for all concepts. Suggestions provided in step 2 were adopted, and new versions of the concepts were made available for the third step, a public consultation carried out by the Ministry of Health. Fourteen suggestions related to the concepts were made and, when relevant, included in the Guidelines. According to the assessment and suggestions by experts and members of the public, the concepts and terminologies proposed by the Domains WG for the Guidelines are valid and clear

Is the association between sociodemographic variables and physical activity levels in adolescents mediated by social support and self-efficacy? / A associação entre variáveis sociodemográficas e níveis de atividade física emadolescentes é mediada por apoio social e autoeficácia?

Abstract Objective Analyze whether the association between sociodemographic variables and physical activity levels is mediated by psychosocial factors. Methods This is a cross-sectional epidemiological study of public and private high school students in João Pessoa, Paraíba state, Brazil. A total of 2540 adolescents (57.0% female) were analyzed (16.4 ± 1.2 years). Physical activity was estimated using a questionnaire, self-efficacy, and parents' and friends' social support by scales, all previously validated. Results The association between sex and the physical activity level of adolescents was partially mediated by the social support of parents (β = 0.79; p < 0.001) and friends (β = 2.96; p < 0.001), and the association between age and physical activity level was partially mediated by parents' social support (β = 0.78; p < 0.001). The associations between sex and age and physical activity levels of adolescents were mediated by the social support of parents and friends. Conclusions Differences in physical activity levels between adolescent females and males and between younger and older adolescents may be partially explained by differences in social support provided by parents and friends. Implementation strategies to increase the social support of parents and friends may help reduce the differences in physical activity levels between these subgroups of adolescents.

Resumo Objetivo Analisar se a associação entre variáveis sociodemográficas e níveis de atividade física é mediada por fatores psicossociais. Métodos Este é um estudo epidemiológico transversal com estudantes do ensino médio de escolas públicas e privadas de João Pessoa, Paraíba, Brasil. Foram analisados 2.540 adolescentes (57,0% do sexo feminino) (16,4 ± 1,2 anos). A atividade física foi estimada por meio de questionário, autoeficácia e apoio social dos pais e amigos através de escalas, todas previamente validadas. Resultados A associação entre sexo e o nível de atividade física dos adolescentes foi parcialmente mediada pelo apoio social dos pais (β = 0,79; p < 0,001) e dos amigos (β = 2,96; p < 0,001) e a associação entre idade e nível de atividade física foi parcialmente mediada pelo apoio social dos pais (β = 0,78; p < 0,001). A associação entre sexo e idade e níveis de atividade física dos adolescentes foi mediada pelo apoio social de pais e amigos. Conclusões As diferenças nos níveis de atividade física entre adolescentes do sexo feminino e masculino e entre adolescentes mais jovens e mais velhos podem ser parcialmente explicadas pelas diferenças no apoio social fornecido pelos pais e amigos. A implantação de estratégias para aumentar o apoio social de pais e amigos pode ajudar a reduzir as diferenças nos níveis de atividade física entre esses subgrupos de adolescentes.

Is the association between sociodemographic variables and physical activity levels in adolescents mediated by social support and self-efficacy?

OBJECTIVE: Analyze whether the association between sociodemographic variables and physical activity levels is mediated by psychosocial factors. METHODS: This is a cross-sectional epidemiological study of public and private high school students in João Pessoa, Paraíba state, Brazil. A total of 2540 adolescents (57.0% female) were analyzed (16.4±1.2 years). Physical activity was estimated using a questionnaire, self-efficacy, and parents' and friends' social support by scales, all previously validated. RESULTS: The association between sex and the physical activity level of adolescents was partially mediated by the social support of parents (ß=0.79; p<0.001) and friends (ß=2.96; p<0.001), and the association between age and physical activity level was partially mediated by parents' social support (ß=0.78; p<0.001). The associations between sex and age and physical activity levels of adolescents were mediated by the social support of parents and friends. CONCLUSIONS: Differences in physical activity levels between adolescent females and males and between younger and older adolescents may be partially explained by differences in social support provided by parents and friends. Implementation strategies to increase the social support of parents and friends may help reduce the differences in physical activity levels between these subgroups of adolescents.

Attendance in Physical Education classes and associated factors among high school students / Participação nas aulas de Educação Física e fatores associados em estudantes do ensino médio

This study examined the prevalence of attendance in Physical Education (PE) classes and associated factors among high school students. A cross-sectional study performed with 2,874 public and private high school students (57.9% girls, mean age of 16.45 years; SD = 1.22) from João Pessoa, Paraíba, Brazil. Attendance in PE classes was measured by the question: 'How many PE classes do you attend during a normal week? The factors measured were: attitude, self-efficacy, risks and benefits related to physical activity (PA), perceived health, PA level, sedentary behavior and nutritional status. Binary logistic regression was used. It was observed that 41.9% attended two or more PE classes per week, with higher prevalence rates in public school students than private school counterparts (56.6% vs. 6.6%; p < 0.001). Higher attendance in PE classes was observed in male and younger students from both school systems. It was also observed in students who did not work, were members of the highest economic class and whose parents had higher schooling levels in public schools, and from 1st and 2nd grades of high school education in private institutions. Attending two or more PE classes per week is positively associated with a more favorable attitude to engaging in PA as well as its level, in both school systems, and with positive health perception among public students. In conclusion, attendance in PE classes was low, particularly in private schools. Attending two or more PE classes per week was associated with positive aspects of PA and health in the students under study

O presente estudo determinou a prevalência de participação nas aulas de Educação Física (EF) e analisou fatores associados em estudantes do ensino médio. Estudo transversal com 2.874 estudantes do ensino médio das redes pública e privada (57,9% feminino, média de idade = 16,45 anos; DP = 1,22) de João Pessoa, Paraíba, Brasil. A participação nas aulas foi mensurada pela pergunta: 'Durante uma semana normal, em quantas aulas de EF você participa?'. Os fatores mensurados foram: atitude, autoeficácia, riscos e benefícios relacionados à prática de atividade física (AF), percepção de saúde, nível de AF, comportamento sedentário e estado nutricional. Foi utilizada regressão logística binária. Observou-se que 41,9% dos estudantes parti-cipavam de duas aulas ou mais de EF por semana, sendo maior nas escolas públicas comparado às privadas (56,6% vs. 6,6%; p < 0,001). Uma maior participação nas aulas foi identificada nos estudantes do sexo masculino e mais jovens de ambas redes de ensino, nos estudantes da rede pública que não trabalhavam, de classe econômica mais alta e com maior escolarização dos pais, e naqueles da rede privada das 1ª e 2ª séries do ensino médio. Participar de duas ou mais aulas de EF por semana foi positiva e significativamente associada com atitude mais favorável à prática e ao nível de AF dos estudantes; e com percepção positiva de saúde nos estudantes da rede pública. A participação nas aulas de EF foi baixa, particularmente na rede privada. Participar de duas ou mais aulas de EF por semana se associou a aspectos positivos em relação à AF e à saúde dos estudantes

Os fatores sociodemográficos moderam a associação da prática de atividade física dos pais e amigos com o nível de atividade física dos adolescentes? / Sociodemographic factors moderate the association of the physical activity practice of parents and friends with the level of physical activity of adolescents?

O objetivo deste estudo foi analisar se os fatores sociodemográficos moderam a associação da prática de atividade física dos pais e dos amigos com o nível de atividade física dos adolescentes. Trata-se de um estudo epidemiológico transversal, realizado com 2.859 adolescentes (57,8% sexo feminino) de 14 a 19 anos de idade do município de João Pessoa, Paraíba. O nível de atividade física dos adolescentes e a prática de atividade física dos pais e dos amigos foram mensurados por questionários. A prevalência de adolescentes fisicamente ativos foi de 50,2% (IC95%: 47,3-53,1), sendo mais elevada no sexo masculino (66,3%; IC95%: 63,7-69,0) comparada ao feminino (38,4%; IC95%: 36,1-40,8). Os resultados da regressão logística binária demostraram que há associação entre a prática de ativida-de física dos pais e dos amigos e o nível de atividade física dos adolescentes (p < 0,001). No entanto, essa associação é moderada por fatores sociodemográficos (sexo e classe econômica). A magnitude da medida de associação entre a prática de atividade física dos amigos e a dos adolescentes foi mais elevada nos adolescentes do sexo masculino (OR = 5,02; IC95%: 2,73-9,26 vs. feminino OR = 2,21; IC95%: 1,55-3,14) e de classe econômica A/B (OR = 3,90; IC95%: 2,39-6,39 vs. classe C/D/E: OR = 2,27; IC95%: 1,53-3,37). A prática de atividade física da mãe se associou de forma significativa e positiva com o nível de atividade física nos adolescentes de classe econômica A/B (OR = 1,87; IC95%: 1,32-2,62). Conclui-se que os fatores sociodemográficos moderam a associação da prática de atividade física dos amigos e da mãe com o nível de atividade física dos adolescentes. A magnitude da associação entre essas variáveis variou com o sexo e a classe econômica dos adolescentes.

The objective of this study was to analyze if the sociodemographic factors moderate the association of physical activity practice of parents and friends, and the level of physical activity among adolescents. It was an cross sectional epidemiological study with 2,859 adolescents (57.8% female) 14-19 years old of the city of João Pessoa, Paraíba. The level of physical activity among adolescents and the physical activity of parents and friends were measured by questionnaires. The prevalence of physically active adolescents was 50.2% (95%CI: 47.3-53.1), being higher in males (66.3%; 95%CI: 63.7-69.0) compared to female (38.4%; 95%CI: 36.1-40.8). The results of binary logistic regression analysis showed that there is an association between physical activity of parents and friends and the level of physical activity among adolescents (p < 0.001). However, this association is moderated by sociodemographic factors (sex and economic class). The magnitude of the measure of the association between the practice of physical activity of friends and adolescents was higher in male (OR = 5.02; 95%CI: 2.73-9.26 vs. female OR = 2.21; 95%CI: 1.55-3.14) and A/B economic class adolescents (OR = 3.90; 95%CI: 2.39-6.39 vs. class C/D/E: OR = 2.27; 95%CI: 1.53-3.37). The physical activity of the mother was associated significantly and positively with the level of physical activity in adolescents of A/B economic class (OR = 1.87; 95%CI: 1.32-2.62). We conclude that sociodemographic factors moderate the association of physical activity from friends and from the mother with the level of adolescents physical activity. The magnitude of the association between these variables varied with sex and economic class of adolescents.

Padrões de comportamento sedentário em adolescentes de um município da região Nordeste do Brasil / Patterns of sedentary behavior in adolescents from a municipality in Northeastern Brazil

O objetivo desse estudo foi descrever os padrões de comportamento sedentário de adolescentes. Trata-se de um estudo transversal com 656 adolescentes (10 ­ 14 anos de idade) de escolas públicas de João Pessoa, Paraíba. O comportamento sedentário foi mensurado por acelerômetro Actigraph GT3X+ (≤ 100 counts/min). Os padrões de comportamento sedentário foram definidos pelo tempo médio (na semana; em dias de meio e final de semana; dentro e fora do horário escolar), número de bouts e breaks diários, e tempo excessivo sedentário (> 8 horas/dia). Os adolescentes permaneceram em média 444,63 min/dia em comportamento sedentário, sendo mais elevado nos dias de meio de semana (448,73 min/dia) comparado aos do final de semana (434,38 min/dia; p = 0,004) e no horário escolar (164,32 min/dia) comparado ao fora da escola (142,21 min/dia; p < 0,001). Apresentaram em média, 96,19 breaks por dia de comportamento sedentário, sendo 98,6% desses em intervalos de curta duração (< 20 minutos). Verificou-se que 30,2% (IC95%: 26,7-33,7) dos adolescentes passavam > 8 horas/dia em comportamento sedentário. No geral, os do sexo feminino e mais jovens (10 ­ 11 anos) apresentaram maior número médio de breaks por dia. Os adolescentes mais velhos (12 ­ 14 anos) apresentaram maior número de bouts longos e os do sexo masculino e classe econômica média-baixa maior número de breaks longos. A exposição dos adolescentes aos comportamentos sedentários foi alta, principalmente nos dias do meio de semana e no horário escolar. A maioria dos bouts e breaks no comportamento sedentário foi realizada em períodos de curta duração, com variações de exposição conforme as características sociodemográficas dos adolescentes

The aim of this study was to describe the patterns of sedentary behavior of adolescents. It is a cross-sectional study with 656 adolescents (10 to 14 years old) from public schools in João Pessoa, Paraíba. Sedentary be-havior was measured by Actigraph GT3X+ accelerometer (≤ 100 counts/minute). Sedentary behavior pat-terns were defined by the average time (in the week; middle and weekend days; in-school and out-of-school), number of bouts and breaks per day and excessive sedentary time (> 8 hours/day). Adolescents remained on average 444.63 minutes/day in sedentary behavior, being higher on mid-week days (448.73 min/day) com-pared to weekend days (434.38 min/day; p = 0.004) and during the time in school (164.32 min/day) com-pared to the time outside of school (142.21 min/day; p < 0.001). They showed on average 96.19 breaks per day of sedentary behavior, being 98.6% of these in short intervals (< 20 minutes). It was verified that 30.2% (95%CI: 26.7-33.7) of the adolescents spent > 8 hours/day in sedentary behavior. Overall, those females and the youngest (10 ­ 11 years old) had the highest average number of breaks per day. The older adolescents (12 ­ 14 years old) had a greater number of long duration bouts and the males and middle-lower economic class adolescents had more long-term breaks. We conclude that exposure to sedentary behaviors was high, especially on mid-week days and during school time. Most bouts and breaks in sedentary behavior were performed by short periods with variations of exposure according adolescents sociodemographic characteristics

[Standards of physical activity practices in adolescents in a city of Northeastern Brazil]. / Padrões de prática de atividade física em adolescentes de um município da região Nordeste do Brasil.

The scope of this study was to describe the standards of physical activity practices and analyze its variations as sociodemographic characteristics of adolescents in a city of Northeastern Brazil. The sample consisted of 2,350 adolescents in the city of João Pessoa in the Brazilian State of Paraíba. The prevalence of physical activity was determined and the practice scores (minutes/week) calculated: general and types (sports, exercise, active commuting and recreational activities). Multiple linear regression was used to estimate the relative contribution of the types of practice for the general score of physical activity. The physical activities most practiced were active commuting (55.2%) and sports (52.7%). The activities that presented the greatest explanatory capacity for the overall score of practice were: sports (38.1%) and exercises (21.8%). The explanatory capacity of sports was increased in all subgroups, except in female patients. The practice of exercise contributes to the major changes in the general score in female adolescents from private schools. Recreational activities and active commuting had the largest contribution for the female gender. Sports and exercise were the activities that contributed the most to explain the changes in the general practice score.

O objetivo do presente estudo foi descrever os padrões de prática de atividade física e analisar suas variações conforme as características sociodemográficas de adolescentes de um município da região nordeste do Brasil. A amostra foi de 2.350 adolescentes do município de João Pessoa (PB). Foram determinadas as prevalências de atividade física e calculados os escores de prática (minutos/semana): geral e por tipos (esportes, exercícios físicos, deslocamento ativo e atividades recreativas). A regressão linear foi utilizada para estimar a contribuição relativa dos tipos de prática para o escore geral de atividade física. As atividades mais praticadas foram: deslocamentos (55,2%) e esportes (52,7%). As atividades que apresentaram maior capacidade explicativa para o escore geral de prática foram: esportes (38,1%) e exercícios físicos (21,8%). A capacidade explicativa dos esportes foi elevada em todos os subgrupos, exceto no sexo feminino. A prática de exercícios físicos contribuiu para as maiores variações no escore geral nos adolescentes do sexo feminino e de escolas privadas. As atividades recreativas e o deslocamento ativo tiveram a maior contribuição para o sexo feminino. Esportes e exercícios foram as atividades que mais contribuíram para explicar as variações no escore geral de prática.

Padrões de prática de atividade física em adolescentes de um município da região Nordeste do Brasil / Standards of physical activity practices in adolescents in a city of Northeastern Brazil

Resumo O objetivo do presente estudo foi descrever os padrões de prática de atividade física e analisar suas variações conforme as características sociodemográficas de adolescentes de um município da região nordeste do Brasil. A amostra foi de 2.350 adolescentes do município de João Pessoa (PB). Foram determinadas as prevalências de atividade física e calculados os escores de prática (minutos/semana): geral e por tipos (esportes, exercícios físicos, deslocamento ativo e atividades recreativas). A regressão linear foi utilizada para estimar a contribuição relativa dos tipos de prática para o escore geral de atividade física. As atividades mais praticadas foram: deslocamentos (55,2%) e esportes (52,7%). As atividades que apresentaram maior capacidade explicativa para o escore geral de prática foram: esportes (38,1%) e exercícios físicos (21,8%). A capacidade explicativa dos esportes foi elevada em todos os subgrupos, exceto no sexo feminino. A prática de exercícios físicos contribuiu para as maiores variações no escore geral nos adolescentes do sexo feminino e de escolas privadas. As atividades recreativas e o deslocamento ativo tiveram a maior contribuição para o sexo feminino. Esportes e exercícios foram as atividades que mais contribuíram para explicar as variações no escore geral de prática.

Abstract The scope of this study was to describe the standards of physical activity practices and analyze its variations as sociodemographic characteristics of adolescents in a city of Northeastern Brazil. The sample consisted of 2,350 adolescents in the city of João Pessoa in the Brazilian State of Paraíba. The prevalence of physical activity was determined and the practice scores (minutes/week) calculated: general and types (sports, exercise, active commuting and recreational activities). Multiple linear regression was used to estimate the relative contribution of the types of practice for the general score of physical activity. The physical activities most practiced were active commuting (55.2%) and sports (52.7%). The activities that presented the greatest explanatory capacity for the overall score of practice were: sports (38.1%) and exercises (21.8%). The explanatory capacity of sports was increased in all subgroups, except in female patients. The practice of exercise contributes to the major changes in the general score in female adolescents from private schools. Recreational activities and active commuting had the largest contribution for the female gender. Sports and exercise were the activities that contributed the most to explain the changes in the general practice score.

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.

Perceived neighborhood environmental characteristics and different types of physical activity among Brazilian adolescents.

Little is known about the association between environmental characteristics and types of physical activity in adolescents in a Latin American context. The aim of this study was to examine the association between perceived neighborhood environmental characteristics and different types of physical activity in 2,874 adolescents from Joao Pessoa, Paraiba State, Northeastern Brazil. The types of activity measured by questionnaire (≥10 min/day) included sports, physical exercises, active commuting and recreational activities. Neighborhood characteristics were measured by a 15-item scale. Multilevel analyses showed that adolescents who reported "having places they liked to go to" (OR = 1.41; 95%CI: 1.10-1.79) and "places with opportunities to practice" (OR = 1.29; 95%CI: 1.01-1.65) were more likely to play sports. "Seeing interesting things while walking" (OR = 1.24; 95%CI: 1.01-1.53) and "Seeing other adolescents engaged in physical activity" (OR = 1.47; 95%CI: 1,05-2,06) were associated with exercises. "Seeing other adolescents engaged in physical activity" (OR = 1.47; 95%CI: 1.18-1.82), "the neighborhood is not violent" (OR = 1.29; 95%CI: 1.04-1.60) and "having places they like to go to" (OR = 1.59; 95%CI: 1.13-2.25) were positively associated and "places with opportunities to practice" (OR = 0.79; 95%CI: 0.63-0.98) inversely related to active commuting. "Seeing other adolescents engaged in physical activities" (OR = 1.31; 95%CI: 1.05-1.63) and "seeing interesting things while walking" (OR = 1.26; 95%CI: 1.02-1.56) were associated with recreational activities. Neighborhood environmental characteristics associated with the physical activity vary with the type of practices adopted by adolescents.