title: Ability of the actiwatch accelerometer to predict free-living energy expenditure in young children.
abstract: OBJECTIVE
  To determine whether activity counts obtained with the Actiwatch monitor are associated with total expenditure and body composition in young children.
  
  
  METHODS
  Actiwatch activity monitors were tested in 29 children 4 to 6 years old under field conditions over eight days. Total energy expenditure (TEE) was assessed with the doubly labeled water (DLW) technique. Correlation analyses were used to identify variables related to energy expenditure and percentage body fat. Multiple linear regression analyses were used to examine the variance in TEE and percentage body fat explained by activity counts after adjusting for relevant covariates.
  
  
  RESULTS
  Both average total daily activity counts (658,816 +/- 201,657) and the pattern of activity were highly variable among subjects. TEE was significantly related to lean body mass (r = 0.45) and age (r = 0.48; p < 0.05 for both). Activity counts alone were not associated with TEE. In multiple linear regression analyses, TEE was independently associated with only lean body mass. Percentage fat mass was independently associated with body weight, being a girl, and being white, but not with average total activity counts.
  
  
  CONCLUSIONS
  Activity counts obtained with the Actiwatch under free-living conditions do not reflect TEE in 4- to 6-year-old children and are not correlated with percentage fat mass. Therefore, average total activity counts obtained with the Actiwatch may be of limited value in identifying children at risk for becoming obese.
authors.affiliation: Nutrition Research Medical Unit, Pediatric Hospital, National Medical Center Siglo XXI, Mexican Institute of Social Security, Mexico City, Mexico.
authors.forename: Mardya
authors.initials: M
authors.lastname: Lopez-Alarcon
authors.forename: Jaime
authors.initials: J
authors.lastname: Merrifield
authors.forename: David A
authors.initials: DA
authors.lastname: Fields
authors.forename: Tena
authors.initials: T
authors.lastname: Hilario-Hailey
authors.forename: Frank A
authors.initials: FA
authors.lastname: Franklin
authors.forename: Richard M
authors.initials: RM
authors.lastname: Shewchuk
authors.forename: Robert A
authors.initials: RA
authors.lastname: Oster
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Gower
mesh_terms: D000273:Adipose Tissue; D001741:Black or African American; D001823:Body Composition; D002648:Child; D002675:Child, Preschool; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D009043:Motor Activity; D044465:White People