title: Validity of Activity Monitor Step Detection Is Related to Movement Patterns.
abstract: BACKGROUND
  There is a need to examine step-counting accuracy of activity monitors during different types of movements. The purpose of this study was to compare activity monitor and manually counted steps during treadmill and simulated free-living activities and to compare the activity monitor steps to the StepWatch (SW) in a natural setting.
  
  
  METHODS
  Fifteen participants performed laboratory-based treadmill (2.4, 4.8, 7.2 and 9.7 km/h) and simulated free-living activities (eg, cleaning room) while wearing an activPAL, Omron HJ720-ITC, Yamax Digi- Walker SW-200, 2 ActiGraph GT3Xs (1 in "low-frequency extension" [AGLFE] and 1 in "normal-frequency" mode), an ActiGraph 7164, and a SW. Participants also wore monitors for 1-day in their free-living environment. Linear mixed models identified differences between activity monitor steps and the criterion in the laboratory/free-living settings.
  
  
  RESULTS
  Most monitors performed poorly during treadmill walking at 2.4 km/h. Cleaning a room had the largest errors of all simulated free-living activities. The accuracy was highest for forward/rhythmic movements for all monitors. In the free-living environment, the AGLFE had the largest discrepancy with the SW.
  
  
  CONCLUSIONS
  This study highlights the need to verify step-counting accuracy of activity monitors with activities that include different movement types/directions. This is important to understand the origin of errors in step-counting during free-living conditions.
authors.affiliation: Dept of Kinesiology, University of Massachusetts, Amherst, MA.
authors.forename: Amanda
authors.initials: A
authors.lastname: Hickey
authors.forename: Dinesh
authors.initials: D
authors.lastname: John
authors.forename: Jeffer E
authors.initials: JE
authors.lastname: Sasaki
authors.forename: Marianna
authors.initials: M
authors.lastname: Mavilia
authors.forename: Patty
authors.initials: P
authors.lastname: Freedson
mesh_terms: D056044:Actigraphy / Q000295:instrumentation*; D004777:Environment; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory; D015203:Reproducibility of Results; D012924:Social Conditions; D016138:Walking