Johan Lefevre

Reliability and Validity of the Flemish Physical Activity Computerized Questionnaire in Adults

The purpose of this study was to investigate the test-retest reliability and concurrent validity of the Flemish Physical Activity Computerized Questionnaire (FPACQ) in employed/unemployed and retired people. The FPACQ was developed to assess detailed information on several dimensions of physical activity and sedentary behavior over a usual week. A triaxial accelerometer, the RT3 Triaxial Research Tracker (RT3), in combination with a written 7-day activity record, was used as the objective criterion measure. In employed/unemployed people, 2-week test-retest reliability for several activity variables calculated from the FPACQ was good to excellent with intraclass correlations (ICCs) ranging from .67 to .99. In retired people ICCs were lower but, except for time spent eating, still fair to excellent, ranging from .57 to .96. Except for time spent in leisure time activities for men and the average energy expenditure related to sports participation in women, correlations between the RT3 and the FPACQ generally supported the relative validity of the FPACQ for employed/unemployed people (r ranging from .37 to .88). Values for retired people were somewhat lower (r ranging from .15 to .85), but most variables still reached at least moderate correlations. Concerning absolute validity, the FPACQ generally overestimated physical activity and underestimated sedentary behavior compared to the RT3. From this study, it can be concluded that the FPACQ is a reliable and reasonably valid questionnaire for assessing different dimensions of physical activity and sedentary behavior.

Age at menarche in Flemish girls: current status and secular change in the 20th century

The age at menarche in a national sample of 4894 Flemish schoolgirls was surveyed in 1979-1980. The probit estimate of the mean age at menarche was 13.20 +/- 0.02 years (SD = 1.25 years). This estimate falls well within the range of reported ages at menarche for girls in northwestern Europe, but is slightly later than those for French-speaking girls in Belgium and in France. Status quo secular data for the 20th century indicate a decline in estimated mean ages at menarche of Flemish girls from about 14.3 years before World War II to 13.6 and 13.2 years, respectively, among girls born just before and during the war. Subsequently, mean ages at menarche of Flemish girls are fairly stable between 13.0 and 13.2 years. These secular changes are of the same magnitude as those observed in other European countries.

O tracking da atividade física: Um estudo em adolescentes do sexo masculino

The purpose of this study is to analyze the tracking of physical activity in adolescent males with a quasi-simplex model formulated in the structural covariance modeling paradigm. Data was taken from the Leuven growth study in which 588 adolescent males ‐ with ages varying from 12.76 to 17.73 ‐ had been followed during 6 years. Physical activity was evaluated by a validated questionnaire. The physical activity indicator was the amount of time spent in formal sport activity regardless of the amount of hours spent in physical education. Data was analyzed through an autoregressive quasi-simplex model that allows analysis of different tracking formulation. Vigorous methods to estimate maximum likelihood were employed. The results were: high stability of physical activity year-by-year; moderate tracking in the adolescence; and low values of intra-individual instability in the differences that occurred among the studied individuals in each point in time.