Physical activity values in two- to seven-year-old children measured by accelerometer over five consecutive 24-hour days.

Introduction: interpretation of accelerometer-derived physical activity in preschool children is confounded by differences in cut-off points.

Aim: the purpose of this study was to analyze physical activity in 2-to-7-year-old children to establish reference values for daily activity.

Methods: observational study in children aged 2-7 years, without chronic diseases and whose parents provided informed consent. The main variable was physical activity, measured continuously over 120 hours (three workdays and two weekend days) by accelerometer. Secondary variables were weight status (body mass index [BMI] Z-score) and gender. The relationship between the main variable and secondary variables was determined through the t-test, ANOVA and the Pearson correlation coefficient. A multivariate model was used to obtain the standard deviation (SD) of all possible combinations of values, constructing percentiles of normality (x ± SD and x ± 2·SD).

Results: one hundred and thirty-six children (35% of municipality children) were included in the study (54.4% of them were girls). Their weight status distribution was: 25 underweight (18.4%), 54 normal weight (39.7%), 12 risk of overweight (8.8%), 22 overweight (16.2%) and 23 obese (16.8%). The median age was 5.7 years and the mean physical activity was 592 counts/minute. The boys undertook more physical activity (p = 0.031) and the underweight and normal-weight children undertook more physical activity than the overweight and obese children (p = 0.012). There were no significant differences according to age. The multivariate analysis showed significant differences (p < 0.001) according to gender and weight status. In boys, physical activity decreased as weight status increased. In contrast, the girls in the extreme BMI groups obtained higher levels of physical activity.

Conclusion: overweight and obese preschool children had lower levels of physical activity than normal weight children. Physical activity levels were higher in boys.