title: Physical activity levels in three Brazilian birth cohorts as assessed with raw triaxial wrist accelerometry.
abstract: BACKGROUND
  Data on objectively measured physical activity are lacking in low- and middle-income countries. The aim of this study was to describe objectively measured overall physical activity and time spent in moderate-to-vigorous physical activity (MVPA) in individuals from the Pelotas (Brazil) birth cohorts, according to weight status, socioeconomic status (SES) and sex.
  
  
  METHODS
  All children born in 1982, 1993 and 2004 in hospitals in the city of Pelotas, Brazil, constitute the sampling frame; of these 99% agreed to participate. The most recent follow-ups were conducted between 2010 and 2013. In total, 8974 individuals provided valid data derived from raw triaxial wrist accelerometry. The average acceleration is presented in milli-g (1 mg = 0.001g), and time (min/d) spent in MVPA (>100 mg) is presented in 5- and 10-min bouts.
  
  
  RESULTS
  Mean acceleration in the 1982 (mean age 30.2 years), 1993 (mean age 18.4 years) and 2004 (mean age 6.7 years) cohorts was 35 mg, 39 mg and 60 mg, respectively. Time spent in MVPA was 26 [95% confidence interval (CI) 25; 27], 43 (95% CI 42; 44) and 45 (95% CI 43; 46) min/d in the three cohorts, respectively, using 10-min bouts. Mean MVPA was on average 42% higher when using 5-min bouts. Males were more active than females and physical activity was inversely associated with age of the cohort and SES. Normal-weight individuals were more active than underweight, overweight and obese participants.
  
  
  CONCLUSIONS
  Overall physical activity and time spent in MVPA differed by cohort (age), sex, weight status and SES. Higher levels of activity in low SES groups may be explained by incidental physical activity.
authors.affiliation: Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil, Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, Postgraduate Program in Public Health, Federal University of Rio Grande, Rio Grande, Brazil and Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil, Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, Postgraduate Program in Public Health, Federal University of Rio Grande, Rio Grande, Brazil and Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway inacio_cms@yahoo.com.br.
authors.forename: Inácio Cm
authors.initials: IC
authors.lastname: da Silva
authors.affiliation: Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil, Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, Postgraduate Program in Public Health, Federal University of Rio Grande, Rio Grande, Brazil and Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil, Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, Postgraduate Program in Public Health, Federal University of Rio Grande, Rio Grande, Brazil and Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: Vincent T
authors.initials: VT
authors.lastname: van Hees
authors.affiliation: Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil, Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, Postgraduate Program in Public Health, Federal University of Rio Grande, Rio Grande, Brazil and Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: Virgílio V
authors.initials: VV
authors.lastname: Ramires
authors.affiliation: Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil, Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, Postgraduate Program in Public Health, Federal University of Rio Grande, Rio Grande, Brazil and Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: Alan G
authors.initials: AG
authors.lastname: Knuth
authors.affiliation: Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil, Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, Postgraduate Program in Public Health, Federal University of Rio Grande, Rio Grande, Brazil and Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: Renata M
authors.initials: RM
authors.lastname: Bielemann
authors.affiliation: Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil, Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, Postgraduate Program in Public Health, Federal University of Rio Grande, Rio Grande, Brazil and Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil, Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, Postgraduate Program in Public Health, Federal University of Rio Grande, Rio Grande, Brazil and Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: Ulf
authors.initials: U
authors.lastname: Ekelund
authors.affiliation: Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil, Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, Postgraduate Program in Public Health, Federal University of Rio Grande, Rio Grande, Brazil and Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: Soren
authors.initials: S
authors.lastname: Brage
authors.affiliation: Postgraduate Program in Epidemiology, Federal University of Pelotas, Pelotas, Brazil, Medical Research Council Epidemiology Unit, University of Cambridge, Cambridge, UK, Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne, UK, Postgraduate Program in Public Health, Federal University of Rio Grande, Rio Grande, Brazil and Department of Sport Medicine, Norwegian School of Sport Sciences, Oslo, Norway.
authors.forename: Pedro C
authors.initials: PC
authors.lastname: Hallal
mesh_terms: D061725:Accelerometry; D000293:Adolescent; D000328:Adult; D001938:Brazil / Q000453:epidemiology; D002648:Child; D015331:Cohort Studies; D015444:Exercise; D005260:Female; D006801:Humans; D007182:Income / Q000706:statistics & numerical data*; D008297:Male; D009043:Motor Activity; D009765:Obesity / Q000453:epidemiology*; D050177:Overweight / Q000453:epidemiology; D012923:Social Class; D013851:Thinness / Q000453:epidemiology*
keywords: Activity monitor; cohort studies; motor activity; movement