Metabolic Thresholds and Validated Accelerometer Cutoff Points for the Actigraph GT1M in Young Children Based on Measurements of Locomotion and Play Activities

Abstract

The purpose of the current study was to determine metabolic thresholds and subsequent activity intensity cutoff points for the ActiGraph GT1M with various epochs spanning from 5 to 60 sec in young children. Twenty-two children, aged 4 to 9 years, performed 10 different activities including locomotion and play activities. Energy expenditure was measured with indirect calorimetry. Thresholds and cutoff points were determined through receiver operating characteristic curves. The lower metabolic threshold was 6.19 kcal·kg⁻¹·h⁻¹ for moderate and 9.28 kcal·kg⁻¹·h⁻¹ for vigorous intensity. The cutoff points for the GT1M accelerometer appear to be lower than those for the previous model (7164). For 5-sec epochs, a cutoff point of 143 counts resulted for moderate intensity and of 208 counts for vigorous intensity activity. Whether short or long epochs were chosen when collecting data to determine cutoff points, does not appear to have an influence on the resulting cutoff values. Similarly, comparable results are seen when analyses are based on locomotion only as opposed to a wide range of activities including children's play.

Keywords:

• accelerometry
• cutoff points
• metabolic thresholds
• ActiGraph
• physical activity assessment