Comparison of physical activity using questionnaire and accelerometer in 4^th grade children

The purpose of this study was to assess physical activity using questionnaires and an accelerometer in 4^th grade children (aged 9-10 years) and compare differences between the methods of evaluation. Fourth elementary school children were selected (total = 221), including 106 boys and 115 girls. The participants were investigated on their anthropometry and physical activity. The questionnaire was used to evaluate exercise time and the accelerometer was used to measure moderate-to-vigorous physical activity (MVPA). During weekdays and weekdays, the exercise time was significantly higher than MVPA for girls. For boys, the exercise time was significantly higher than MVPA only on the weekends. As a result of Bland-Altman analysis, for both boys and girls in weekday and weekends, mean of questionnaire and accelerometer was associated with difference of questionnaire and accelerometer (Boys in weekday, r = 0.777, p < 0.001; Boys in weekends, r = 0.964, p < 0.001; Girls in weekday, r = 0.731, p < 0.001; Girls in weekends, r = 0.937, p < 0.001). In conclusion, our results suggested that a questionnaire-based evaluation of exercise time shows significant difference compared with accelerometer-based measurement of MVPA. In addition, exercise time of questionnaire-based evaluation was higher than MVPA of accelerometer-based measurement for both boys and girls on all days.