Predictive Validity and Classification Accuracy of ActiGraph Energy Expenditure Equations and Cut-Points in Young Children

Xanne Janssen,Søren Brage,John J Reilly,Trina Hinkley,Ulf Ekelund,Marijka Batterham,Dylan P Cliff,Anthony D Okely,Rachel A Jones,Reury Fp Bacurau

doi:10.1371/journal.pone.0079124

Abstract

ObjectivesEvaluate the predictive validity of ActiGraph energy expenditure equations and the classification accuracy of physical activity intensity cut-points in preschoolers.MethodsForty children aged 4–6 years (5.3±1.0 years) completed a ∼150-min room calorimeter protocol involving age-appropriate sedentary, light and moderate-to vigorous-intensity physical activities. Children wore an ActiGraph GT3X on the right mid-axillary line of the hip. Energy expenditure measured by room calorimetry and physical activity intensity classified using direct observation were the criterion methods. Energy expenditure was predicted using Pate and Puyau equations. Physical activity intensity was classified using Evenson, Sirard, Van Cauwenberghe, Pate, Puyau, and Reilly, ActiGraph cut-points.ResultsThe Pate equation significantly overestimated VO2 during sedentary behaviors, light physical activities and total VO2 (P<0.001). No difference was found between measured and predicted VO2 during moderate-to vigorous-intensity physical activities (P = 0.072). The Puyau equation significantly underestimated activity energy expenditure during moderate-to vigorous-intensity physical activities, light-intensity physical activities and total activity energy expenditure (P<0.0125). However, no overestimation of activity energy expenditure during sedentary behavior was found. The Evenson cut-point demonstrated significantly higher accuracy for classifying sedentary behaviors and light-intensity physical activities than others. Classification accuracy for moderate-to vigorous-intensity physical activities was significantly higher for Pate than others.ConclusionAvailable ActiGraph equations do not provide accurate estimates of energy expenditure across physical activity intensities in preschoolers. Cut-points of ≤25counts⋅15 s−1 and ≥420 counts⋅15 s−1 for classifying sedentary behaviors and moderate-to vigorous-intensity physical activities, respectively, are recommended.

Highlights

Measuring young children’s physical activity (PA) and sedentary behavior (SB) objectively is important to improve all aspects of PArelated research in this age group
Accelerometry has become the method of choice to objectively assess children’s free-living habitual PA and SB and the ActiGraph accelerometer is the most widely used in young children [1,2,3]
Because direct observation systems such as Children’s Activity Rating Scale (CARS) rely on subjective classification and use general category descriptions to assign levels to activities based on the apparent intensity of the activity, it is possible that misclassification may occur for some individuals. To overcome this potential limitation and confirm findings for PA intensity classification based on direct observation, we developed an additional criterion measure including both direct observation and EE measured by the room calorimeter

Summary

Introduction

Measuring young children’s physical activity (PA) and sedentary behavior (SB) objectively is important to improve all aspects of PArelated research in this age group. Several equations [4,5] and cut-points [4,5,6,7,8,9] have been developed to predict energy expenditure (EE) and classify PA intensity or SB from ActiGraph accelerometer output counts per time unit. The accuracy of these equations for predicting EE over the range of PA intensities is, unclear. There are differences in the age ranges examined, and activities included in the validation protocols vary from using only ambulatory activities (walking and running) [4] to including free-living activities (e.g. arts and crafts and stair walking) [5,6,7,8,9]

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