title: Reproducibility of a triaxial seismic accelerometer (DynaPort).
abstract: OBJECTIVE
  To examine the reproducibility of a triaxial seismic accelerometer under controlled conditions and real-life conditions.
  
  
  METHODS
  Instrumental reproducibility was examined using a shaker device. The accelerometers (DynaPort MiniMod; McRoberts B.V., The Hague, The Netherlands) were shaken at four frequencies (0.8, 2.1, 3.6, and 4.6 Hz) in x- and y-directions. The magnitude of acceleration ranged from 0 to 1.277g. Additionally, reproducibility under real-life conditions was examined in 55 adolescents (12-17 yr), with the accelerometer attached to the lower back. Each subject walked four short walking trials on level ground at preferred speed. To make this setting meet real-life conditions, we detached and reattached the accelerometer between trials 2 and 3. Detachment of accelerometer between trials 2 and 3 was done by either the same researcher or different researchers (four in total). Intra- and interobserver reproducibility were calculated.
  
  
  RESULTS
  Intra- and interinstrumental intraclass correlation coefficients (ICC) were 0.99 for both x- and y-directions. The intrainstrumental coefficients of variance (CoV) were lower than 1.13%. The interinstrumental CoV were lower than 1.37%. Intraobserver ICC was 0.97, and interobserver ICC was 0.88.
  
  
  CONCLUSIONS
  The reproducibility of the accelerometer is high under the controlled conditions of a shaker device and in walking at preferred speed.
authors.affiliation: Faculty of Human Movement Sciences, VU University, Amsterdam, The Netherlands.
authors.forename: Vincent T
authors.initials: VT
authors.lastname: Van Hees
authors.forename: Sander M
authors.initials: SM
authors.lastname: Slootmaker
authors.forename: Gert
authors.initials: G
authors.lastname: De Groot
authors.forename: Willem
authors.initials: W
authors.lastname: Van Mechelen
authors.forename: Rob C
authors.initials: RC
authors.lastname: Van Lummel
mesh_terms: D000054:Acceleration; D000293:Adolescent; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D016138:Walking