A Methodological Model for Collecting High-Quality Data on Physical Activity in Developing Settings—The Experience of the 1993 Pelotas (Brazil) Birth Cohort Study

Abstract

Background:Prospective studies on physical activity (PA), diet, and body composition in adolescents are lacking, particularly outside high-income countries.Goals:To describe the methods used to assess these variables in the 1993 Pelotas (Brazil) Birth Cohort and to discuss the fieldwork challenges faced and alternatives to overcome them.Methods:In 2006–07 a subsample of the 1993 Pelotas cohort was revisited. PA was estimated using questionnaires, a combined heart-rate and motion sensor (Acti-Heart), and the ActiGraph GT1M accelerometer. Diet was investigated by questionnaire. Total body water was determined by stable isotopes. Thirty individuals had their total energy expenditure assessed by doubly labeled water. All data were collected at participants’ home.Results:The logistics of the fieldwork and the difficulties in undertaking the study and alternatives to overcome them are presented. Preliminary analyses show that 511 individuals were traced (response rate = 90.0%). Compliance of both adolescents and their families for the motion sensors and body-composition measurements was excellent.Conclusions:The authors conclude that it is feasible to carry out high-quality studies on PA in developing countries. They hope the article will be useful to other researchers interested in carrying out similar studies.

Intensidade e duração dos esforços físicos em aulas de Educação Física

“…The categories moderate, vigorous and very vigorous were grouped to compose the outcome "moderate to vigorous physical activities (MVPA)". 21 The total time spent in MVPA was recorded for each class.…”

Prospective Associations Between Physical Activity Level and Body Composition in Adolescence: 1993 Pelotas (Brazil) Birth Cohort

“…A detailed description of the measurement procedure is available elsewhere. 16 In brief, children ingested a fixed dose (2.2 g) of deuterium diluted in water, and saliva samples were taken before and 4 to 5 hours after dose administration. Isotope enrichment of the dose solution and saliva samples was determined in duplicate by isotope-ratio mass spectrometry (Delta XP; ThermoFisher Scientific, Waltham, MA) at UCL Institute of Child Health, London, UK.…”

“…Data were collected at the participants' homes, except for the postdose saliva sample, which on some occasions had to be collected in their schools or elsewhere, depending on where the subjects were at the time when collection had to take place. 16 …”

Objectively measured physical activity and body composition indices in Brazilian adolescents

“…Data collection was carried out from August 2006 to January 2007. A detailed description of the cohort, its design, methods and measurements taken at each follow-up until 2004 is available elsewhere 15 and another recent publication has focused on the methodological aspects of the present follow-up 16 . In brief, all 5249 newborns delivered in Pelotas' hospitals in 1993 constitute the cohort and sub-samples of the cohort were reexamined at age one, three and six months and at one and four years.…”

“…A detailed description of physical activity assessment is available elsewhere 16 . Free-living physical activity was assessed with the Actigraph accelerometer (model GT1M, Actigraph Inc, Fl, US) for 5 consecutive days (Wednesday to Monday).…”