Empirical validation of an instrument to measure habitual physical activity in youth from Maputo, Mozambique

To develop a questionnaire to assess habitual physical activity in Mozambic an children and youth, a study with school youth of Maputo was done. The st udy included the assessment of usual activities, development of the questio nnaire, and testing its validity and reliability. The questionnaire was ini tially based on anecdotal observations of the usual activities of this popu lation, then a sample of 20 children was observed during 24 h and interview ed the day before with a model that asked the subjects about the time spent ; in each activity. Fifteen days later the same students were interviewed w ith title questionnaire in order to test its validity. After another 15 day s, the reliability of the questionnaire was tested. To score the questionna ire, estimation of metabolic equivalents (METS) of the socioculturally spec ific activities was done. This was based on published tables and heart rate monitoring of the children performing the activities listed on the questio nnaire. Intraclass correlations between time observed and time reported ran ged form 0.06-0.80, demonstrating limited capacity of the children to repor t time. However, percentage of agreement between the observations and the q uestionnaire concerning activity levels was 83%. It was concluded that the questionnaire may be a useful instrument for assessing the patterns of phys ical activity of African youth and for classifying groups according to leve ls of activity. However, it has limited utility for estimating energy expen diture. (C) 2000 Wiley-Liss, Inc.