title: Controlled and free-living evaluation of objective measures of sedentary and active behaviors.
abstract: BACKGROUND
  Emerging interest in the health impacts of sedentary behaviors has driven the exploration of objective instrumentation capable of capturing these behaviors. The purpose was to compare (under laboratory conditions) outputs from ActiGraph (AG), Intelligent Device for Energy Expenditure and Physical Activity (IDEEA), and activPAL Professional (AP) against direct observation (DO) in sedentary, standing, and active behaviors; and assess convergent validity of instrument outputs under free-living conditions.
  
  
  METHODS
  Participants (13 males/16 females; 28.9 ± 6.2 years) wore instruments concurrently during laboratory and free-living studies. AG cutpoints of ≤50, <100, and ≤259 counts/minute were used to determine time in sedentary behaviors. Laboratory data were evaluated using mean percent error. Free-living data were analyzed using dependent t tests and RM ANOVA.
  
  
  RESULTS
  AP precisely measured all identified DO behaviors under laboratory conditions; IDEEA precisely identified sitting and standing. For the free-living study, there was no difference in sedentary time detected by AP and IDEEA but a significant difference was observed in standing time. No difference was apparent between AP and AG259 in sit/lie/stand or ambulatory activity time.
  
  
  CONCLUSIONS
  In a laboratory setting, the utility of all instruments to classify activities into behavioral categories was confirmed. This may enhance research on sedentary behaviors and health-related outcomes.
authors.affiliation: Dept of Human Movement Sciences, University of Wisconsin-Milwaukee, WI, USA.
authors.forename: Teresa L
authors.initials: TL
authors.lastname: Hart
authors.forename: James J
authors.initials: JJ
authors.lastname: McClain
authors.forename: Catrine
authors.initials: C
authors.lastname: Tudor-Locke
mesh_terms: D056044:Actigraphy / Q000295:instrumentation*; D000203:Activities of Daily Living; D000328:Adult; D001519:Behavior / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D057185:Sedentary Behavior; D016138:Walking; D055815:Young Adult