title: Capturing the pattern of physical activity and sedentary behavior: exposure variation analysis of accelerometer data.
abstract: BACKGROUND
  Capturing the complex time pattern of physical activity (PA) and sedentary behavior (SB) using accelerometry remains a challenge. Research from occupational health suggests exposure variation analysis (EVA) could provide a meaningful tool. This paper (1) explains the application of EVA to accelerometer data, (2) demonstrates how EVA thresholds and derivatives could be chosen and used to examine adherence to PA and SB guidelines, and (3) explores the validity of EVA outputs.
  
  
  METHODS
  EVA outputs are compared with accelerometer data from 4 individuals (Study 1a and 1b) and 3 occupational groups (Study 2): seated workstation office workers (n = 8), standing workstation office workers (n = 8), and teachers (n = 8).
  
  
  RESULTS
  Line graphs and related EVA graphs highlight the use of EVA derivatives for examining compliance with guidelines. EVA derivatives of occupational groups confirm no difference in bouts of activity but clear differences as expected in extended bouts of SB and brief bursts of activity, thus providing evidence of construct validity.
  
  
  CONCLUSIONS
  EVA offers a unique and comprehensive generic method that is able, for the first time, to capture the time pattern (both frequency and intensity) of PA and SB, which can be tailored for both occupational and public health research.
authors: School of Physiotherapy and Exercise Science, Curtin University, Perth, Western Australia, Australia.
authors: Leon
authors: L
authors: Straker
authors: Amity
authors: A
authors: Campbell
authors: Svend Erik
authors: SE
authors: Mathiassen
authors: Rebecca Anne
authors: RA
authors: Abbott
authors: Sharon
authors: S
authors: Parry
authors: Paul
authors: P
authors: Davey
mesh_terms: D061725:Accelerometry / Q000706:statistics & numerical data*; D000704:Analysis of Variance; D005260:Female; D006306:Health Surveys; D006801:Humans; D018670:Monitoring, Ambulatory; D009043:Motor Activity; D015999:Multivariate Analysis; D015203:Reproducibility of Results; D012107:Research Design; D057185:Sedentary Behavior