title: Development and validation of energy expenditure prediction models based on GT3X accelerometer data in 5- to 9-year-old children.
abstract: BACKGROUND
  Accelerometry has been established as an objective method that can be used to assess physical activity behavior in large groups. The purpose of the current study was to provide a validated equation to translate accelerometer counts of the triaxial GT3X into energy expenditure in young children.
  
  
  METHODS
  Thirty-two children aged 5-9 years performed locomotor and play activities that are typical for their age group. Children wore a GT3X accelerometer and their energy expenditure was measured with indirect calorimetry. Twenty-one children were randomly selected to serve as development group. A cubic 2-regression model involving separate equations for locomotor and play activities was developed on the basis of model fit. It was then validated using data of the remaining children and compared with a linear 2-regression model and a linear 1-regression model.
  
  
  RESULTS
  All 3 regression models produced strong correlations between predicted and measured MET values. Agreement was acceptable for the cubic model and good for both linear regression approaches.
  
  
  CONCLUSIONS
  The current linear 1-regression model provides valid estimates of energy expenditure for ActiGraph GT3X data for 5- to 9-year-old children and shows equal or better predictive validity than a cubic or a linear 2-regression model.
authors.affiliation: Monitoring and Evaluation Branch, Swiss Federal Institute of Sport Magglingen, Magglingen, Switzerland.
authors.forename: Gerda
authors.initials: G
authors.lastname: Jimmy
authors.forename: Roland
authors.initials: R
authors.lastname: Seiler
authors.forename: Urs
authors.initials: U
authors.lastname: Maeder
mesh_terms: D061725:Accelerometry / Q000706:statistics & numerical data*; D000465:Algorithms; D002153:Calorimetry, Indirect; D002648:Child; D002675:Child, Preschool; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008962:Models, Theoretical; D009043:Motor Activity; D011237:Predictive Value of Tests; D015203:Reproducibility of Results