Citation

Vette AH, Masani K, Wu N, Popovic MR. Med. Eng. Phys. 2014; 36(1): 102-109.

Affiliation

Department of Mechanical Engineering, University of Alberta, 4-9 Mechanical Engineering Building, Edmonton, Alberta T6G 2G8, Canada; Glenrose Rehabilitation Hospital, 10230 111 Avenue NW, Edmonton, Alberta T5G 0B7, Canada.

Copyright

(Copyright © 2014, Institute of Physics and Engineering in Medicine, Publisher Elsevier Publishing)

DOI

10.1016/j.medengphy.2013.10.005

PMID

24246838

Abstract

Trunk instability during sitting is a major problem following neuromuscular injuries such as stroke and spinal cord injury. In order to develop new strategies for alleviating this problem, a better understanding of the intrinsic contributions of the healthy trunk to sitting control is needed. As such, this study set out to propose and validate a novel methodology for determining multidirectional trunk stiffness during sitting using randomized transient perturbations. Fifteen healthy individuals sitting naturally on a custom-made seat were randomly perturbed in eight horizontal directions. Trunk stiffness and damping were quantified using force and trunk kinematics in combination with translational and torsional models of a mass-spring-damper system. The results indicate that stiffness and damping of the healthy trunk are roughly symmetrical between the two body sides. Moreover, both quantities are smallest in the anterior and largest in the lateral directions. In conclusion, a novel protocol for identifying intrinsic trunk stiffness and damping has been developed, eliminating anticipation effects with respect to perturbation timing and direction. Subsequent studies will use these findings as a reference not only for quantifying trunk stiffness and damping in individuals with various neuromuscular disorders, but also for assessing whether neuroprostheses could increase upper body stiffness and, hence, stability.

Language: en