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.

The aim of this study was to examine the longitudinal influences of early life social and biological indicators on objectively measured physical activity. All newborns in 2004 in the city of Pelotas, Southern Brazil were enrolled in a birth cohort study. At the age of 6 years, a follow-up visit included objective assessment of overall physical activity (summarized in milli-g, 1 mg = 0.001 g) by tri-axial wrist worn accelerometry. The associations between early life exposures, such as type of delivery, parity, birth weight, preterm delivery, maternal physical activity, socioeconomic position, and overall physical activity were examined. Valid accelerometry data were obtained from 2604 children (78.2% of the eligible individuals). Girls were less active than boys (β = − 8.65 mg; 95% CI − 10.0; − 7.30). Higher socioeconomic position was related to lower activity levels (β = − 9.69 mg. 95% CI − 12.45; − 6.93) and a similar association was found with maternal schooling. No associations were found with birthweight, type of delivery or preterm delivery. This study provides evidence for the role of some social factors in explaining children's physical activity behaviors, and minimizes the influence of some early life biological factors at determining physical activity levels.

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.Physical inactivity is responsible for chronic diseases, premature mortality 1 and substantial economic burdens 2 . With one in three adults and four in five adolescents worldwide failing to achieve the recommended levels of physical activity 3 and no signs of improvement at the population level 4 , the pandemic of physical inactivity is one of the biggest challenges to global health. Sedentary behaviour, on the other hand, is a distinct class of waking behavior in a sitting, reclining, or lying posture with an energy expenditure ≤1.5 Metabolic Equivalents 5 . Increasing evidence suggests that prolonged sedentary time may elevate the risk of chronic diseases and mortality in adults and the combination of prolonged sitting time and low levels of physical activity may be particularly detrimental to health 6 .Understanding the causes of physical inactivity and prolonged sedentary time is essential for developing interventions to improve public health. Hence, many studies have been conducted to understand why some people are more active than others. It is generally understood that physical activity and sedentary behaviour are jointly influenced by a range of individual, interpersonal, environmental and policy factors across different stages in life 7,8 . However, one consistently understudied area is whether and how prenatal, birth and early life factors influence open Scientific RepoRtS | (2020) 10:786 | https://doi.org/10.1038/s41598-019-57070-xwww.nature.com/scientificreports www.nature.com/scientificreports/ these behaviours 9,10 . The Developmental Origins of Health and Disease Theory, based on Barker's hypothesis 11 , emphasises the im...

Policymakers rely on information for describing and monitoring levels of physical activity among the population. However, in Uruguay there is no research presenting physical activity practices nationwide. The present study aims to describe the leisure time physical activity levels and their unequal distribution among Uruguayan adults. Data from the 2014 Uruguayan National Health Survey (n = 3543 adults aged > 15 years) were analysed. Physical activity was measured by questionnaire, with participants reporting the number of days and time spent doing physical activity during leisure time in a typical week. Only 25.1% of the participants met the international recommendations for physical activity. Males were twice as active as females in early adulthood in terms of time. The absolute socioeconomic gap between the poorest and wealthiest income quintiles was around 20 percentage points, and participants with the highest physical activity levels were within the wealthiest and highest-educational levels. A low proportion of the population met the proxy of the international recommendations for physical activity. Important socioeconomic inequalities have been found in physical activity practices and must be considered in public health interventions.

BackgroundPhysical exercise interventions have been extensively advocated for the treatment of obesity; however, clinical trials evaluating the effectiveness of exercise interventions on weight control show controversial results. Compensatory mechanisms through a decrease in energy expenditure and/or an increase in caloric consumption is a possible explanation. Several physiological mechanisms involved in the energy balance could explain compensatory mechanisms, but the influences of physical exercise on these adjustments are still unclear. Therefore, the present trial aims to evaluate the effects of exercise on non-exercise physical activity energy expenditure, energy intake and appetite sensations among active overweight/obese adults, as well as, to investigate hormonal changes associated with physical exercise.MethodsThis study is a randomized controlled trial with parallel, three-group experimental arms. Eighty-one overweight/obese adults will be randomly allocated (1:1:1 ratio) to a vigorous exercise group, moderate exercise group or control group. The trial will be conducted at a military institution and the intervention groups will be submitted to exercise sessions in the evening, three times a week for 65 min, during a 2-week period. The primary outcome will be total spontaneous physical activity energy expenditure during a 2-week period. Secondary outcomes will be caloric intake, appetite sensations and laboratorial biomarkers. Intention-to-treat analysis will be performed using linear mixed-effects models to evaluate the effect of treatment-by-time interaction on primary and secondary outcomes. Data analysis will be performed using SAS 9.3 and statistical significance will be set at p < 0.05.DiscussionThe results of the present study will help to understand the effect of physical exercise training on subsequent non-exercise physical activity, appetite and energy intake as well as understand the physiological mechanisms underlying a possible compensatory phenomenon, supporting the development of more effective interventions for prevention and treatment of obesity.Trial registrationPhysical Exercise and Energy Balance trial registry, trial registration number: NCT 03138187. Registered on 30 April 2017.Electronic supplementary materialThe online version of this article (10.1186/s13063-018-2445-6) contains supplementary material, which is available to authorized users.