Within- and between-day reliability of trunk mechanical behaviors estimated using position-controlled perturbations

Brad D. Hendershot, Babak Bazrgari, Maury A. Nussbaum, Michael L. Madigan

Research output: Contribution to journalArticlepeer-review

12 Scopus citations


Recent applications of position-controlled perturbation techniques to the human trunk have allowed separate estimation of intrinsic and reflexive trunk mechanical behaviors. These mechanical behaviors play an important role in spinal stability and have been associated with low back pain risk, yet the reliability of these measures remains unknown. Therefore, the objective of the current study was to assess within- and between-day reliability of several measures of trunk mechanical behaviors obtained from position-controlled trunk perturbations. A secondary objective was to assess if different harness designs, used to connect a participant to the perturbing device, influenced reliability. Data were analyzed from baseline measurements obtained from two previously published studies, and a third unpublished study. The total combined subject pool included 33 healthy young adults (17 M, 16 F). Relative and absolute reliability was quantified using intraclass correlation coefficients (ICCs) and standard errors of measurement (SEM), respectively. Within-day ICCs of intrinsic trunk stiffness (0.84-0.90) and effective mass (0.91-95) were excellent, and were generally higher than ICCs for reflex gain (0.55-0.85), maximum reflex force (0.65-0.85), and timing of maximum reflex force (0.48-0.86). Within-day ICCs (0.48-0.95) were consistently superior to between-day values (0.19-0.72). Improvements in harness design increased both within- and between-day reliability and reduced SEMs for most measures.

Original languageEnglish
Pages (from-to)2019-2022
Number of pages4
JournalJournal of Biomechanics
Issue number11
StatePublished - Jul 26 2012

Bibliographical note

Funding Information:
This work was supported by an award ( R01OH008504 ) from the Centers for Disease Control and Prevention (CDC) . Its contents are solely the responsibility of the authors and do not necessarily represent the official views of the CDC.


  • Position perturbation
  • Reflex
  • Reliability
  • Stiffness
  • Trunk

ASJC Scopus subject areas

  • Biophysics
  • Orthopedics and Sports Medicine
  • Biomedical Engineering
  • Rehabilitation


Dive into the research topics of 'Within- and between-day reliability of trunk mechanical behaviors estimated using position-controlled perturbations'. Together they form a unique fingerprint.

Cite this