title: Concurrent validity and reliability of a novel wireless inertial measurement system to assess trunk movement.
abstract: BACKGROUND
  Assessment of movement dysfunctions commonly comprises trunk range of motion (ROM), movement or control impairment (MCI), repetitive movements (RM), and reposition error (RE). Inertial measurement unit (IMU)-systems could be used to quantify these movement dysfunctions in clinical settings. The aim of this study was to evaluate a novel IMU-system when assessing movement dysfunctions in terms of concurrent validity and reliability.
  
  
  METHODS
  The concurrent validity of the IMU-system was tested against an optoelectronic system with 22 participants. The reliability of 14 movement dysfunction tests were analysed using generalizability theory and coefficient of variation, measuring 24 participants in seven trials on two days.
  
  
  RESULTS
  The IMU-system provided valid estimates of trunk movement in the primary movement direction when compared to the optoelectronic system. Reliability varied across tests and variables. On average, ROM and RM were more reliable, compared to MCI and RE tests.
  
  
  CONCLUSIONS
  When compared to the optoelectronic system, the IMU-system is valid for estimates of trunk movement in the primary movement direction. Four ROM, two MCI, one RM, and one RE test were identified as reliable and should be studied further for inter-subject comparisons and monitoring changes after an intervention.
authors.affiliation: Zurich University of Applied Sciences, Department of Health, Institute of Physiotherapy, Technikumstrasse 71, 8400 Winterthur, Switzerland; University of Tampere, School of Medicine, Kalevantie 4, FI-33014 University of Tampere, Finland. Electronic address: christoph.bauer@zhaw.ch.
authors.forename: C M
authors.initials: CM
authors.lastname: Bauer
authors.affiliation: Zurich University of Applied Sciences, Department of Health, Institute of Physiotherapy, Technikumstrasse 71, 8400 Winterthur, Switzerland.
authors.forename: F M
authors.initials: FM
authors.lastname: Rast
authors.affiliation: Zurich University of Applied Sciences, Department of Health, Institute of Physiotherapy, Technikumstrasse 71, 8400 Winterthur, Switzerland.
authors.forename: M J
authors.initials: MJ
authors.lastname: Ernst
authors.affiliation: Zurich University of Applied Sciences, Department of Health, Institute of Physiotherapy, Technikumstrasse 71, 8400 Winterthur, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Kool
authors.affiliation: Zurich University of Applied Sciences, Department of Health, Institute of Physiotherapy, Technikumstrasse 71, 8400 Winterthur, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: Oetiker
authors.affiliation: University of Eastern Finland, Department of Applied Physics, University of Eastern Finland, P.O. Box 1627, 70211 Kuopio, Finland. Electronic address: saara.rissanen@uef.fi.
authors.forename: S M
authors.initials: SM
authors.lastname: Rissanen
authors.affiliation: UKK Institute for Health Promotion Research, Kaupinpuistonkatu 1, 33500 Tampere, Finland. Electronic address: jaana.h.suni@uta.fi.
authors.forename: J H
authors.initials: JH
authors.lastname: Suni
authors.affiliation: University of Tampere, School of Medicine, Kalevantie 4, FI-33014 University of Tampere, Finland; Tampere University Hospital, Department of Physical and Rehabilitation Medicine, Tampere University Hospital, P.O. Box 2000, 33521 Tampere, Finland. Electronic address: markku.kankaanpaa@pshp.fi.
authors.forename: M
authors.initials: M
authors.lastname: Kankaanpää
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D008297:Male; D009068:Movement; D018482:Muscle, Skeletal / Q000502:physiology; D009213:Myography / Q000379:methods; D060726:Torso / Q000502:physiology*; D059015:Wireless Technology
keywords: Biomechanical phenomena; Generalizability-theory; Movement disorders; Reproducibility of results