Gender Gap for Accelerometry-Based Physical Activity Across Different Age Groups in 5 Brazilian Cohort Studies.

OBJECTIVES: This study aims to evaluate the gender inequalities in accelerometer-based physical activity (PA) across different age groups using data from 5 Pelotas (Brazil) cohorts. METHODS: The data come from 4 birth cohort studies, covering all live births in the urban area of Pelotas for each respective year (1982, 1993, 2004, and 2015), and the Como vai? cohort study focusing on 60 years and above. Raw accelerometry data were collected on the nondominant wrist using GENEActive/ActiGraph devices and processed with the GGIR package. Overall PA was calculated at ages 1, 2, 4, 6, 11, 15, 18, 23, 30, and 60+ years, while moderate to vigorous PA was calculated from 6 years onward. Absolute (difference) and relative (ratio) gender inequalities were calculated and intersectionality between gender and wealth was also evaluated. RESULTS: The sample sizes per cohort ranged from 965 to 3462 participants. The mean absolute gender gap was 19.3 minutes (95% confidence interval, 12.7-25.9), with the widest gap at 18 years (32.9 min; 95% confidence interval, 30.1-35.7) for moderate to vigorous PA. The highest relative inequality was found in older adults (ratio 2.0; 95% confidence interval, 1.92-2.08). Our intersectionality results showed that the poorest men being the most active group, accumulating around 60 minutes more moderate to vigorous PA per day compared with the wealthiest women at age 18. CONCLUSIONS: Men were more physically active than women in all ages evaluated. PA gender inequalities start at an early age and intensify in transition periods of life. Relative inequalities were marked among older adults.

Independent, Stratified, and Joint Associations of Sedentary Time and Physical Activity With Cardiovascular Disease: A Systematic Review.

BACKGROUND: Recent statistics highlight cardiovascular diseases (CVD) as a major global cause of death. This review examines the methodological approaches and the main results of independent, stratified, and joint association of sedentary time (ST) and physical activity (PA) on CVD outcomes. METHODS: We searched PubMed, Embase, Web of Science, and Scopus for prospective cohorts that examined the independent, stratified, or joint associations of ST and PA with CVD outcomes. Independent associations were defined as analyses mutually adjusted for PA and ST. Stratified associations were considered when there was a reference group in each stratum of PA or ST, and joint associations were defined by a single reference group for all other combined categories of ST and PA levels. RESULTS: Of 45 articles, 69% explored independent association of ST or PA on CVD outcomes, while 31% using a stratified/joint approach. Most studies used self-reports for ST and PA and focused on CVD mortality. Mutually adjusted analyses identified ST positively and PA inversely associated to CVD outcomes. Stratified studies showed higher ST's pronounced impact on CVD for lower PA levels. High PA mitigated but did not eliminate ST's negative impact. Joint analyses revealed highest CVD risk in those with both high ST and low PA, and elevated risk in various intermediate combinations. CONCLUSIONS: Employing independent, stratified, and joint association approaches can yield distinct and complementary public health messages aimed at promoting cardiovascular health. Recommendations should aim to not only to encourage boosting PA levels, but also, concurrently decrease ST.

Device-measured sedentary time and intensity-specific physical activity in relation to all-cause and cardiovascular disease mortality: the UK Biobank cohort study.

BACKGROUND AND AIMS: Understanding the amounts of intensity-specific movement needed to attenuate the association between sedentary time and mortality may help to inform personalized prescription and behavioral counselling. Herein, we examined the joint associations of sedentary time and intensity-specific physical activity with all-cause and cardiovascular disease (CVD) mortality. METHODS: Prospective cohort study including 73,729 adults from the UK Biobank who wore an Axivity AX3 accelerometer on their dominant wrist for at least 3 days, being one a weekend day, between June 2013 and December 2015. We considered the median tertile values of sedentary time and physical activity in each intensity band to determine the amount of physical activity needed to attenuate the association between sedentary time and mortality. RESULTS: During a median of 6.9 years of follow-up (628,807 person-years), we documented 1521 deaths, including 388 from CVD. Physical activity of any intensity attenuated the detrimental association of sedentary time with mortality. Overall, at least a median of 6 min/day of vigorous physical activity, 30 min/day of MVPA, 64 min/day of moderate physical activity, or 163 min/day of light physical activity (mutually-adjusted for other intensities) attenuated the association between sedentary time and mortality. High sedentary time was associated with higher risk of CVD mortality only among participants with low MVPA (HR 1.96; 95% CI 1.23 to 3.14). CONCLUSIONS: Different amounts of each physical activity intensity may attenuate the association between high sedentary time and mortality.

Is rest-activity rhythm prospectively associated with all-cause mortality in older people regardless of sleep and physical activity level? The 'Como Vai?' Cohort study.

OBJECTIVE: This study aims to test the association of rest-activity rhythm (intradaily variability and interdaily stability) with all-cause mortality in an older adult cohort in Brazil. It also assesses whether the amount of time spent at each intensity level (i.e., physical activity and nocturnal sleep) interferes with this association. METHODS: This cohort study started in 2014 with older adults (≥60 years). We investigated deaths from all causes that occurred until April 2017. Rest-activity rhythm variables were obtained using accelerometry at baseline. Intradaily variability indicates higher rhythm fragmentation, while interdaily stability indicates higher rhythm stability. Cox proportional-hazard models were used to test the associations controlling for confounders. RESULTS: Among the 1451 older adults interviewed in 2014, 965 presented valid accelerometry data. During the follow-up period, 80 individuals died. After adjusting the analysis for sociodemographic, smoking, morbidity score, and number of medicines, an increase of one standard deviation in interdaily stability decreased 26% the risk of death. The adjustment for total sleep time and inactivity did not change this association. On the other hand, the association was no longer significant after adjusting for overall physical activity and moderate to vigorous physical activity. CONCLUSION: Rest-activity rhythm pattern was not associated with mortality when physical activity was considered, possibly because this pattern could be driven by regular exercise. Promoting physical activity remains a relevant strategy to improve population health.

Profile of leisure-time physical activity and sedentary behavior in adults in Brazil: a nationwide survey, 2019.

OBJECTIVES: to estimate the prevalence of leisure-time physical activity and sedentary behavior in adults in Brazil. METHODS: this was a cross-sectional, population-based study carried out in a sample of 88,531 Brazilians, using data from the 2019 National Health Survey; leisure-time physical activity (overall and aerobic exercise) was measured according to the World Health Organization guidelines; the weighted prevalence and respective 95% confidence intervals (95%CI) of physical activity, physical inactivity and sedentary behavior were estimated. RESULTS: according to the selected sample, 26.4% (95%CI 25.9;27.1) of Brazilian adults were physically active, 14.0% (95%CI 13.5;14.4) were insufficiently physically active and 59.5% (95%CI 58.8;60.2) were physically inactive; sedentary behavior ≥ 6 hours was reported by 30.1% (95%CI 29.5;30.8) of the population; only 8.6% (95%CI 8.2;8.9) met the recommendations for muscle-strengthening activities. CONCLUSION: most Brazilian adults were physically inactive and did not meet international recommendations for leisure-time physical activity and reduction in sedentary behavior.

Trajectories of Device-Measured Physical Activity During Early Childhood and Its Determinants: Findings From the 2015 Pelotas (Brazil) Birth Cohort Study.

BACKGROUND: The objective was to describe trajectories of physical activity (PA) measured by accelerometry during early childhood and to test associations with sociodemographic, gestational, maternal, and perinatal determinants. METHODS: Data from 1798 children from the 2015 Pelotas (Brazil) Birth Cohort were analyzed. PA was measured with wrist accelerometers at 1, 2, and 4 years. PA trajectories were estimated using group-based trajectory modeling, and associations with determinants were tested using Poisson regression with robust variance. RESULTS: Two trajectories were identified: Moderate and high PA, both showing a linear increase in PA in the first years but differing in volume. Girls (prevalence ratio [PR]: 0.91; 95% confidence interval [CI], 0.88-0.94), highly educated mothers (PR: 0.93; 95% CI, 0.88-0.97), and high birth weight children (PR: 0.91; 95% CI, 0.85-0.97) showed less probability of high PA trajectory. Birth order ≥3 (PR: 1.06; 95% CI, 1.01-1.11) was associated with higher likelihood of high PA trajectory. CONCLUSIONS: Children showed an increase in PA during the first years, with 2 trajectories that differ in PA levels. Female sex, high maternal schooling, and high birth weight reduced the probability of having a high PA trajectory, while higher birth order increased this probability. These characteristics should be considered when planning PA interventions for children in early childhood.

Bi-directional associations between physical activity and growth indicators of pre-school aged children.

Physical activity for young children provides a wealth of benefits for health and development. However, little is known about the inter-relationship of physical activity and growth indicators. The aim of this study was to test the bi-directional associations of physical activity and growth indicators in children under five years of age. This prospective study included 1,575 children with data on physical activity and growth indicators at ages 12, 24 and 48 months. Accelerometers were used to measure physical activity. Z-scores for length/height-for-age, weight-for-length/height, weight-for-age and body mass index (BMI)-for-age were calculated. Bi-directional associations between physical activity and growth indicators were evaluated using cross-lagged panels based on Generalized Estimating Equations and cross-lagged structural equation models. Physical activity was consistently associated with lower weight-related growth indicators: BMI-for-age: ß=-0.12; Weight-for-age: ß=-0.11; Weight-for-length/height: ß=-0.12. Higher BMI-for-age indicated lower physical activity (ß=-0.06). When the exposure was lagged, the association of physical activity on weight-related growth indicators remained, but weight-related growth indicators showed a negative association on physical activity. A bi-directional association between physical activity and weight-related growth indicators was observed. The magnitude of associations were stronger when physical activity was modelled as exposure. These results reinforce the importance of physical activity since early years.

Perfil de atividade física no tempo livre e tempo sedentário em adultos no Brasil: inquérito nacional, 2019 / Profile of leisure-time physical activity and sedentary behavior in adults in Brazil: a nationwide survey, 2019 / Perfil de la actividad física en el tiempo libre y sedentario em adultos en Brasil: encuesta nacional, 2019

Objetivos: estimar a prevalência de atividade física no tempo livre e comportamento sedentário em adultos no Brasil. Métodos: estudo seccional, populacional, na amostra de 88.531 brasileiros da Pesquisa Nacional de Saúde de 2019; a atividade física (geral e modalidades aeróbias) no tempo livre foi mensurada conforme as diretrizes da Organização Mundial da Saúde; estimaram-se as prevalências ponderadas, e respectivos intervalos de confiança de 95% (IC95%), de atividade física, inatividade física e tempo sedentário. Resultados: a partir da amostra selecionada, 26,4% (IC95% 25,9;27,1) dos adultos brasileiros eram fisicamente ativos, 14,0% (IC95% 13,5;14,4) eram insuficientemente ativos e 59,5% (IC95% 58,8;60,2) eram inativos; o tempo sedentário ≥ 6 horas foi relatado por 30,1% (IC95% 29,5;30,8) da população; apenas 8,6% (IC95% 8,2;8,9) atenderam às recomendações de atividade física para fortalecimento muscular. Conclusão: a maioria dos brasileiros adultos era inativa e não atendeu às recomendações internacionais de atividade física no tempo livre e restrição de tempo sedentário.

Objectives: to estimate the prevalence of leisure-time physical activity and sedentary behavior in adults in Brazil. Methods: this was a cross-sectional, population-based study carried out in a sample of 88,531 Brazilians, using data from the 2019 National Health Survey; leisure-time physical activity (overall and aerobic exercise) was measured according to the World Health Organization guidelines; the weighted prevalence and respective 95% confidence intervals (95%CI) of physical activity, physical inactivity and sedentary behavior were estimated. Results: according to the selected sample, 26.4% (95%CI 25.9;27.1) of Brazilian adults were physically active, 14.0% (95%CI 13.5;14.4) were insufficiently physically active and 59.5% (95%CI 58.8;60.2) were physically inactive; sedentary behavior ≥ 6 hours was reported by 30.1% (95%CI 29.5;30.8) of the population; only 8.6% (95%CI 8.2;8.9) met the recommendations for muscle-strengthening activities. Conclusion: most Brazilian adults were physically inactive and did not meet international recommendations for leisure-time physical activity and reduction in sedentary behavior.

Objetivos: estimar la prevalencia de actividad física en el tiempo libre y comportamiento sedentario de adultos en Brasil. Métodos: estudio seccional, poblacional, de la muestra de la Encuesta Nacional de Salud de 2019 a partir de lo cual, se estimó la prevalencia ponderada (porcentaje e intervalo de confianza del 95%) de actividad física (general y aeróbica), la inactividad física y el comportamiento sedentario. Resultados: según la muestra elegida, 26,4% (IC95% 25,9;27,1) son físicamente activos, 59,5% (IC95% 58,8;60,2) son inactivos, 14,0% (IC95% 13,5;14,4) son insuficientemente activos y 30,1% (IC95% 29,5;30,8) pasan ≥6 horas sedentarios en su tiempo libre; sólo el 8,6% (IC95% 8,2;8,9) de los adultos cumple con las recomendaciones de actividad física para fortalecimiento muscular. Conclusión: la mayoría de los adultos brasileños son inactivos, no cumplen con las recomendaciones internacionales de actividad física en el tiempo libre y la restricción del tiempo sedentario.

Objective and Self-Reported Physical Activity and Risk of Falling Among Community-Dwelling Older Adults From Southern Brazil.

This study evaluated prospective associations between self-reported and objectively measured physical activity (PA) and risk of falls among older adults. A cohort study started in 2014 with 1,451 community-dwelling older adults living in Pelotas, Brazil. Leisure-time PA was obtained by the International Physical Activity Questionnaire and 7-day raw accelerometer data evaluated for total, light PA, and moderate to vigorous PA. In 2016-2017, participants recorded their falls in the previous 12 months. Around 23% of the 1,161 participants followed-up in 2016-2017 experienced a fall in the last 12 months. Participants who did not spend any time in self-reported leisure-time PA at baseline had on average 34% higher risk of falls, and individuals in the lowest tertile for moderate to vigorous PA had on average 51% higher risk of falls compared to those in the highest tertile. Low levels of self-reported and objectively measured moderate to vigorous PA were related to higher risk of falling among Brazilian older adults.

Educational performance and conduct problem trajectories from childhood to adolescence: Observational and genetic associations in a Brazilian birth cohort.

Background: Educational difficulties are an important potential influence on both the onset and course of children's conduct problems. This study evaluated the association between school failure and children's conduct problems in Brazil, a context with high rates of both conditions, using both observational and genetic approaches. Methods: Prospective, population-based, birth cohort study in Pelotas city, Brazil. Parents reported on conduct problems four times between ages 4-15 years, and group-based trajectory analysis was used to classify 3469 children into trajectories of childhood-limited, early-onset persistent, adolescence-onset, or low conduct problems. School failure was measured as having repeated a school grade up to age 11, and a polygenic risk score (PRS) predicting educational attainment was calculated. Multinomial adjusted regression models were used to estimate the association between school failure (observational measure and the PRS) and conduct problem trajectories. To consider possible variation in effects of school failure by social context, interactions were tested with family income and school environment (using both observational and PRS methods). Results: Children repeating a school grade had increased odds of being on to childhood-limited (OR: 1.57; 95% CI 1.21; 2.03), adolescence-onset (OR: 1.96; 95% CI 1.39; 2.75), or early-onset persistent trajectory (OR: 2.99; 95% CI 1.85; 4.83), compared to the low conduct problem trajectory. School failure also predicted increased risk for early-onset persistent problems versus the childhood-limited problems (OR: 1.91; 95% CI 1.17; 3.09). Using a genetic PRS approach, similar findings were observed. Associations varied according to the school environment: school failure had larger effects on children in better school environments. Conclusion: School performance, whether measured in terms of repeating school grades or genetic susceptibility, was consistently associated with trajectories of child conduct problems into mid-adolescence. We also found a larger association for children in better school environments.

Changes in Physical Activity and Sedentary Patterns on Cardiometabolic Outcomes in the Transition to Adolescence: International Children's Accelerometry Database 2.0.

OBJECTIVE: To examine the associations of changes in physical activity and sedentary patterns with changes in cardiometabolic outcomes from childhood to adolescence. STUDY DESIGN: Youth from the International Children's Accelerometry Database (n = 1088; 55% girls), aged 8-13 years and followed for ∼4 years, were used in this analysis. Hip-mounted accelerometers were used and all physical activity intensities were expressed as the % of total wear-time. Sedentary time was separated into time spent in bouts <10 minutes and ≥10 minutes. A composite z score for cardiometabolic risk (CMR score) was computed by summing the standardized values for systolic and diastolic blood pressure, triglycerides (TG), low-density lipoprotein cholesterol (LDL-c), and the inverse high-density lipoprotein cholesterol. Multivariate analyses were performed using adjusted linear regression models. RESULTS: Increase in sedentary time was unfavorably associated with changes in CMR score (ß = 0.021; CI 0.004-0.037), TG (ß = 0.003; CI 0.001-0.005), and diastolic blood pressure (ß = 0.068; CI 0.009-0.128). Decrease in moderate-to-vigorous physical activity was unfavorably associated with changes in LDL-c (ß = -0.009; CI -0.017 to -0.001) and TG (ß = -0.007; CI -0.013 to -0.001). Increase in ≥10 minutes sedentary time was unfavorably associated with changes in CMR score (ß = 0.017; CI 0.004-0.030), LDL-c (ß = 0.003; CI 0.000-0.005), and TG (ß = 0.003; CI 0.000-0.004). Decrease in light-intensity physical activity was unfavorably associated with changes in CMR score (ß = -0.020; CI = -0.040 to 0.000). CONCLUSIONS: More physical activity and less prolonged sedentary time are beneficial for cardiometabolic health in youth transitioning to adolescence.

Objectively Measured Physical Activity and Polypharmacy Among Brazilian Community-Dwelling Older Adults.

BACKGROUND: Previous observations regarding association between physical activity (PA) and use of medicines among older adults are derived from self-reported PA. This study aimed to evaluate the association between objectively measured PA and polypharmacy among older adults with multimorbidity in Southern Brazil. METHODS: This study included 875 noninstitutionalized older people, aged ≥60 years. Prescribed medicines used in the 15 days prior to the interview, socioeconomic data, and the presence of comorbidities were self-reported. Accelerometers were used to evaluate PA following the interview. RESULTS: Prevalence of polypharmacy (≥5 medicines) was 38.3% (95% confidence interval, 35.0-41.5); those belonging to the lowest tertile of PA used more medicines. The authors observed a significant inverse association for polypharmacy between men belonging to the second and third tertiles of PA for objectively measured overall PA and light PA compared with the most inactive tertile. For women, the association between PA and polypharmacy was significant for overall, light, and moderate to vigorous PA only in the third tertile. CONCLUSIONS: Overall, light and moderate to vigorous PA were inversely associated to polypharmacy and differed by gender. Promotion of PA in older adults may be an effective intervention to reduce the number of medicines used independent of the number of comorbidities.

Number of days required to estimate physical activity constructs objectively measured in different age groups: Findings from three Brazilian (Pelotas) population-based birth cohorts.

PURPOSE: The present study aims to estimate the minimum number of accelerometer measurement days needed to estimate habitual physical activity (PA) among 6- (2010), 18- (2011) and 30- (2012) year-old participants, belonging to three population-based Brazilian birth cohorts. METHOD: PA was assessed by triaxial wrist-worn GENEActiv accelerometers and the present analysis is restricted to participants with at least 6 consecutive days of measurement. Accelerometer raw data were analyzed with R-package GGIR. Description of PA measures (overall PA, moderate-to-vigorous PA (MVPA), light PA (LPA)) on weekdays and weekend days were conducted, and statistical differences were tested with chi-squared and Kruskal-Wallis tests. Spearman Brown Formulae was applied to test reliability of different number of days of accelerometer use. RESULTS: Differences between week and weekend days regarding LPA, MVPA and overall PA, were only observed among 30-year-olds. Higher levels of MVPA (p = 0.006) and overall PA (p<0.001) were identified on weekdays. For overall PA, to achieve a reliability coefficient >0.70, two and three days of measurement were needed in adults and children, respectively. For LPA, a reliability coefficient >0.70 was achieved with five days in 6-year-old children, three days in 18-year-old young adults, and four days in 30-year-old adults. Considering MVPA, four days would be necessary to represent a week of measurement among all cohort groups. CONCLUSION: Our results show that four and five measurement days are needed to estimate all habitual PA constructs, for children and adults, respectively. Also, among 30-year-old adults, it is important to make efforts towards weekend days measurement.

Prenatal and birth predictors of objectively measured physical activity and sedentary time in three population-based birth cohorts in Brazil.

Physical inactivity is a global pandemic with no signs of improvement. Prolonged sitting time is an emerging risk factor that exacerbates the health consequences of physical inactivity. Both behaviours are influenced by various individual and environmental factors but it remains unknown whether early-life exposures "program" these behaviours in later life. The current evidence is limited by a small number of studies which were primarily conducted in high-income countries, and a narrow range of early-life variables examined. Using data from three population-based Brazilian birth cohorts (analytical samples: n = 2740 for 1982 cohort, aged 30 years; n = 3592 for 1993 cohort, aged 18; n = 2603 for 2004 cohort, aged 6), we show that being female and higher family socioeconomic status at birth are strong and consistent predictors of lower physical activity and higher sedentary time from childhood to adulthood. Meanwhile, higher birth weight and lower birth order may also predict lower physical activity and higher sedentary time. Our findings are distinct from evidence from high-income countries, suggesting the importance of broader socioeconomic context in determining individual's activity patterns through the life- course. Such evidence is essential for understanding the biological etiology and socioeconomic context of physical activity and sedentary behaviour at an early stage in life.

Objectively Measured Physical Activity Reduces the Risk of Mortality among Brazilian Older Adults.

OBJECTIVES: Use of objectively measured physical activity (PA) in older adults to assess relationship between PA and risk of all-causes mortality is scarce. This study evaluated the associations of PA based on accelerometry and a questionnaire with the risk of mortality among older adults from a city in Southern Brazil. DESIGN: A cohort study. SETTING: Urban area of Pelotas, Southern Brazil. PARTICIPANTS: A representative sample of older adults (≥60 y) from Pelotas, enrolled in 2014. MEASUREMENTS: Overall physical activity (mg), light physical activity (LPA), and moderate to vigorous physical activity (MVPA) were estimated by raw accelerometer data. The International Physical Activity Questionnaire estimated leisure time and commuting PA. Hazard ratios (excluding deaths in the first 6 mo) stratified by sex were estimated by Cox regression analysis considering adjustment for confounders. RESULTS: From the 1451 older adults interviewed in 2014, 145 died (10%) after a follow-up of an average 2.6 years. Men and women in the highest tertile of overall PA had on average a 77% and 92% lower risk of mortality than their less active counterparts (95% confidence interval [CI] = .06-.84 and 95% CI = .01-.65, respectively). The highest tertile of LPA was also related to a lower risk of mortality in individuals of both sexes (74% and 91% lower risk among men and women, respectively). MVPA statistically reduced the risk of mortality only among women (hazard ratio [HR] = .30 and HR = .07 in the second and third tertiles). Self-reported leisure-time PA was statistically associated with a lower risk of mortality only among men. Women in the highest tertiles of commuting PA showed a lower risk of mortality than those in the reference group. CONCLUSION: Accelerometry-based PA was associated with a lower risk of mortality among Brazilian older adults. Older individuals should practice any type of PA. J Am Geriatr Soc 68:137-146, 2019.

How many days are needed to estimate wrist-worn accelerometry-assessed physical activity during the second trimester in pregnancy?

BACKGROUND: Objective methods to measure physical activity (PA) can lead to better cross-cultural comparisons, monitoring temporal PA trends, and measuring the effect of interventions. However, when applying this technology in field-work, the accelerometer data processing is prone to methodological issues. One of the most challenging issues relates to standardizing total wear time to provide reliable data across participants. It is generally accepted that at least 4 complete days of accelerometer wear represent a week for adults. It is not known if this same assumption holds true for pregnant women. AIM: We assessed the optimal number of days needed to obtain reliable estimates of overall PA and moderate-to-vigorous physical activity (MVPA) during the 2nd trimester in pregnancy using a raw triaxial wrist-worn accelerometer. METHODS: Cross-sectional analyses were carried out in the antenatal wave of the 2015 Pelotas (Brazil) Birth Cohort Study. Participants wore the wrist ActiGraph wGT3X-BT accelerometer for seven consecutive days. The daily average acceleration, which indicated overall PA, was measured as milli-g (mg), and time spent in MVPA (minutes/day) was analyzed in 5-minute bouts. ANOVA and Kruskal-Wallis tests were used to compare variability across days of the week. Bland-Altman plots and the Spearman-Brown Prophecy Formula were applied to determine the reliability coefficient associated with one to seven days of measurement. RESULTS: Among 2,082 pregnant women who wore the accelerometer for seven complete days, overall and MVPA were lower on Sundays compared to other days of the week. Reliability of > = 0.80 to evaluate overall PA was reached with at least three monitoring days, whereas seven days were needed to estimate reliable measures of MVPA. CONCLUSIONS: Our findings indicate that obtaining one week of accelerometry in adults is appropriate for pregnant women, particularly to obtain differences on weekend days and reliably estimate overall PA and MVPA.

Associations of physical activity and sedentary time with body composition in Brazilian young adults.

The findings of studies on the association between physical activity and adiposity are not consistent, and most are cross-sectional and used only self-reported measures. The aims of this study were to evaluate: 1) independent and combined cross-sectional associations of objectively-measured physical activity and sedentary time with body composition outcomes at 30 years, and 2) prospective associations of changes in self-reported physical activity from 23 to 30 years with the same outcomes in participants from the 1982 Pelotas (Brazil) Birth Cohort. Body mass index, waist circumference, visceral abdominal fat, fat mass index, and android/gynoid fat ratio were the outcomes. 3,206 participants were analysed. In cross-sectional analyses, higher objectively-measured moderate-to-vigorous physical activity was associated with lower body mass index (ß = 0.017, 95%CI: -0.026; -0.009), waist circumference (ß = -0.043, 95%CI: -0.061; -0.025), visceral abdominal fat (ß = -0.006, 95%CI: -0.009; -0.003), and fat mass index (ß = -0.015, 95%CI: -0.021; -0.009), independent of sedentary time. Sedentary time was independently associated only with higher fat mass index (ß = 0.003, 95%CI: 0.001; 0.005). In longitudinal analyses, using self-reported measure, adiposity was lower among those who were consistently active or who became active. Adiposity was similar among the "became inactive" and "consistently inactive" subjects. Our findings suggest metabolic benefits from engagement in physical activity throughout young adulthood, with stronger associations on concurrent levels.

Are consumption of dairy products and physical activity independently related to bone mineral density of 6-year-old children? Longitudinal and cross-sectional analyses in a birth cohort from Brazil.

OBJECTIVE: To evaluate cross-sectional and longitudinal associations of consumption of dairy products and physical activity (PA) with bone mineral density (BMD). DESIGN: Cohort study with children from the 2004 Pelotas (Brazil) Birth Cohort. SETTING: Pelotas, a medium-sized Brazilian city. SUBJECTS: The study started in 2004 and mothers/children were interviewed/measured periodically from birth to age 6 years. PA was measured by maternal proxy at 4 and 6 years and by accelerometry at 6 years. Consumption of dairy products was measured using 24 h food recall (at 4 years) and FFQ (at 6 years). Total-body and lumbar-spine BMD (g/cm2) were measured by dual-energy X-ray absorptiometry. RESULTS: At 6 years, BMD was measured in 3444 children and 2636 children provided data on objectively measured PA by accelerometry. Consumption of dairy products at 4 years was associated with higher lumbar-spine BMD at 6 years in boys, while current consumption was positively associated with BMD in both sexes (P < 0·001). PA assessed by maternal report at 4 and 6 years of age was associated with higher BMD at 6 years in boys. PA assessed by accelerometry was positively related to total-body and lumbar-spine BMD in boys and lumbar-spine BMD in girls. We did not find evidence for an interaction between PA and consumption of dairy products on BMD. CONCLUSIONS: We observed positive and independent longitudinal and cross-sectional associations between consumption of dairy products and PA with BMD in the total body and at the lumbar spine in young children.

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

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

Socioeconomic position and sedentary behavior in Brazilian adolescents: A life-course approach.

Socioeconomic position (SEP) is a potential correlate of sedentary behavior in adolescents. The aim of this study was to examine the associations between SEP and self-reported and objective measures of sedentary behavior in adolescents, using a life-course approach. Data from the 1993 Pelotas (Brazil) Birth Cohort Study were analyzed (N=5249). Cross-sectional and longitudinal associations between multiple SEP indicators (maternal education, family income, SEP composite, cumulative family income) at birth, 11, 15 and 18years, and five sedentary behavior outcomes (≥4h/day screen time; ≥4h/day TV; ≥2h/day computer; ≥2h/day video game; ≥12.7h/day objectively measured sedentary time) at 11, 15 and 18years, were examined. In cross-sectional analyses, higher SEP was positively associated with more screen time at ages 11 and 15years. There was a consistent and positive association between higher SEP with time spent using a computer, and with sedentary time assessed through accelerometry. SEP at birth had a positive and direct effect on screen, computer and total sedentary time at 18years. Participants in the highest cumulative income group had higher odds of high sedentary behavior in screen (OR: 2.40; 95% CI: 1.50-3.54), computer (OR: 7.35; 95% CI: 4.19-12.89) and total sedentary time (OR: 5.40; 95% CI: 3.53-10.35), respectively, compared with their counterparts with lower cumulative income. Our findings showed that SEP is an early determinant of sedentary behavior in adolescents.