title: Validation of the TracmorD triaxial accelerometer to assess physical activity in preschool children.
abstract: OBJECTIVE
  To assess validity evidence of TracmorD to determine energy used for physical activity in 3-4-year-old children.
  
  
  METHODS
  Participants were randomly selected from GECKO Drenthe cohort (n = 30, age 3.4 ± 0.3 years). Total energy expenditure (TEE) was measured using the doubly labeled water method. Sleeping metabolic rate (SMR) was measured by indirect calorimetry (Deltatrac). TEE and SMR were used to calculate physical activity level (PAL) and activity energy expenditure (AEE). Physical activity was monitored using a DirectLife triaxial accelerometer, TracmorD with activity counts per minute (ACM) and activity counts per day (ACD) as outcome measures.
  
  
  RESULTS
  The best predictor for PAL was ACM with gender and weight, the best predictor for AEE was ACM alone (backward regression, R(2) = 0.50, P = 0.010 and R2 = 0.31, P = 0.011, respectively). With ACD, the prediction model for PAL included ACD, height, gender, and sleep duration (R2 = 0.48, P = 0.033), the prediction model for AEE included ACD, gender and sleep duration (R2 = 0.39, P = 0.042). The accelerometer was worn for 5 days, but 3 days did not give a different estimated PAL.
  
  
  CONCLUSIONS
  TracmorD provides moderate-to-strong validity evidence that supports its use to evaluate energy used for physical activity in 3-4-year-old children.
authors.affiliation: Department of Epidemiology, University of Groningen, UMCG, Groningen, The Netherlands.
authors.forename: Anna
authors.initials: A
authors.lastname: Sijtsma
authors.forename: Henk
authors.initials: H
authors.lastname: Schierbeek
authors.forename: Annelies H C
authors.initials: AH
authors.lastname: Goris
authors.forename: Koen F M
authors.initials: KF
authors.lastname: Joosten
authors.forename: Imke
authors.initials: I
authors.lastname: van Kessel
authors.forename: Eva
authors.initials: E
authors.lastname: Corpeleijn
authors.forename: Pieter J J
authors.initials: PJ
authors.lastname: Sauer
mesh_terms: D061725:Accelerometry / Q000295:instrumentation / Q000379:methods; D056044:Actigraphy / Q000295:instrumentation / Q000379:methods*; D001481:Basal Metabolism; D001827:Body Height; D001835:Body Weight; D002153:Calorimetry, Indirect; D002675:Child, Preschool; D015331:Cohort Studies; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D063766:Pediatric Obesity / Q000209:etiology; D005082:Physical Exertion; D012737:Sex Factors; D012890:Sleep