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.
|Number of pages||9|
|State||Published - Jul 2013|
Bibliographical noteFunding Information:
This work was supported by award R01-OH008504 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. The authors thank Mr. Waldron and Mr. Vest for their assembly and maintenance of the testing apparatus. The authors dedicate this work to Dr. Kevin P. Granata, whose original ideas formed the foundation for the current investigation.
- Creep deformation
- Low back pain
- Trunk flexion
ASJC Scopus subject areas
- Human Factors and Ergonomics
- Physical Therapy, Sports Therapy and Rehabilitation
- Safety, Risk, Reliability and Quality
- Engineering (miscellaneous)