Disturbance and recovery of trunk mechanical and neuromuscular behaviors following repeated static trunk flexion: Influences of duration and duty cycle on creep-induced effects

Khoirul Muslim, Babak Bazrgari, Brad Hendershot, Nima Toosizadeh, Maury A. Nussbaum, Michael L. Madigan

Research output: Contribution to journalArticlepeer-review

18 Scopus citations

Abstract

Occupations involving frequent trunk flexion are associated with a higher incidence of low back pain. To investigate the effects of repeated static flexion on trunk behaviors, 12 participants completed six combinations of three static flexion durations (1, 2, and 4 min), and two flexion duty cycles (33% and 50%). Trunk mechanical and neuromuscular behaviors were obtained pre- and post-exposure and during recovery using sudden perturbations. A longer duration of static flexion and a higher duty cycle increased the magnitude of decrements in intrinsic stiffness. Increasing duty cycle caused larger decreases in reflexive muscle responses, and females had substantially larger decreases in reflexive responses following exposure. Patterns of recovery for intrinsic trunk stiffness and reflexive responses were consistent across conditions and genders, and none of these measures returned to pre-exposure values after 20 min of recovery. Reflexive responses may not provide a compensatory mechanism to offset decreases in intrinsic trunk stiffness following repetitive static trunk flexion. A prolonged recovery duration may lead to trunk instability and a higher risk of low back injury.

Original languageEnglish (US)
Pages (from-to)643-651
Number of pages9
JournalApplied Ergonomics
Volume44
Issue number4
DOIs
StatePublished - Jul 2013
Externally publishedYes

Keywords

  • Biomechanics
  • Creep deformation
  • Gender
  • Low back pain
  • Reflex
  • Stiffness
  • Trunk flexion

ASJC Scopus subject areas

  • Human Factors and Ergonomics
  • Physical Therapy, Sports Therapy and Rehabilitation
  • Safety, Risk, Reliability and Quality
  • Engineering (miscellaneous)

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