Please use this identifier to cite or link to this item: http://hdl.handle.net/2123/3539

Title: Systematic nonlinear relations between displacement amplitude and joint mechanics at the human wrist
Authors: Halaki, Mark
O’Dwyer, Nicholas
Cathers, Ian
Discipline of Exercise and Sport Science
Faculty of Health Sciences
Keywords: Wrist
Amplitude
Joint mechanics
Stiffness
Damping
Issue Date: 2006
Publisher: Elsevier
Citation: M.Halaki , N.O’Dwyer , I.Cathers (2006) Systematic nonlinear relations between displacement amplitude and joint mechanics at the human wrist. Journal of Biomechanics, Volume 39, Issue 12, Pages 2171 - 2182. The original publication is available at http://www.elsevier.com/locate/jbiomech.
Abstract: This study quantified the systematic effects on wrist joint mechanics of changes in amplitude of displacement ranging from within the region of short range stiffness (0.2% of resting muscle length) up to 3% of resting muscle length. The joint mechanics were modelled using a second order system from which estimates of joint stiffness, viscosity, inertia, natural resonant frequency and damping ratio were obtained. With increasing amplitude of displacement, the stiffness decreased by 31%, the viscosity decreased by 73%, the damping ratio decreased by 71% and the resonant frequency decreased from 10.5 Hz to 7.3 Hz. The patterns of change in joint mechanics with displacement amplitude were nonlinear but systematic and were well described by power relationships with high R2 values. These relationships provide normative data for the adult population and may be used in the modelling of human movement, in the study of neurological disorders and in robotics where human movement is simulated. The observed patterns of high initial stiffness and viscosity, decreasing progressively as displacement amplitude increases, may provide a good compromise between postural stability and liveliness of voluntary movement.
URI: http://hdl.handle.net/2123/3539
ISSN: 0021-9290
Department/Unit/Centre: Discipline of Exercise and Sport Science
Faculty of Health Sciences
Appears in Collections:Research Papers and Publications. Discipline of Exercise and Sport Science

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