Categorisation of Children??s Physical Activity Levels Using Accelerometry

Abstract

0211 Previous work using accelerometers has produced cut-points to categorise different intensities of activity in adults and children (Freedson, 1998; Puyau, 2002; Reilly, 2003). Further research is required to investigate if the accelerometer output for a given activity level is Influenced by the age of the child and thus necessitate the development of age-specific cut-points for categorisation purposes. PURPOSE: To determine the Influence of a child's age on accelerometry output for a given level of activity as defined by the Children's Physical Activity Form (CPAF, O'Hara, 1989), as sedentary, light, moderate and vigorous activities. METHODS: 37, 3–4yrs old, 43, 5–8 yrs old and 32, 9–10 yrs old children took part in age-specific physical activity classes, incorporating sedentary, light, moderate and vigorous activities. Activity was monitored simultaneously by direct observation using CPAF and also CSA accelerometers. Accelerometer output was calculated as counts per minute (cpm) and a corresponding CPAF score (60 = sedentary; 120 = light; 180 = moderate; 240 = vigorous) was produced for every minute of the class. Only those minutes consisting exclusively of a single activity category were analysed. One-way ANOVA and Tukey's pairwise comparisons were performed on each activity level across the three age-groups. RESULTS: The table shows that in sedentary and moderate activity, there is no significant difference in accelerometer cpm between age-groups. There is a significant difference† in cpm between the 5–8 age-group and the other two groups in light activity. In the vigorous activity intensity category, a significant difference‡ in cpm was found between 9–10yrs and the other age-groups. CONCLUSIONS: These data suggest that children's age may Influence physical activity categorisation when physical activity is measured using accelerometry.Table