title: Identifying intrinsic and reflexive contributions to low-back stabilization.
abstract: Motor control deficits have been suggested as potential cause and/or effect of a-specific chronic low-back pain and its recurrent behavior. Therefore, the goal of this study is to identify motor control in low-back stabilization by simultaneously quantifying the intrinsic and reflexive contributions. Upper body sway was evoked using continuous force perturbations at the trunk, while subjects performed a resist or relax task. Frequency response functions (FRFs) and coherences of the admittance (kinematics) and reflexes (sEMG) were obtained. In comparison with the relax task, the resist task resulted in a 61% decrease in admittance and a 73% increase in reflex gain below 1.1Hz. Intrinsic and reflexive contributions were captured by a physiologically-based, neuromuscular model, including proprioceptive feedback from muscle spindles (position and velocity) and Golgi tendon organs (force). This model described on average 90% of the variance in kinematics and 39% of the variance in sEMG, while resulting parameter values were consistent over subjects.
authors.affiliation: BioMechanical Engineering Department, Faculty of Mechanical Engineering, Delft University of Technology, Mekelweg 4, 2628 CD Delft, The Netherlands. P.vanDrunen@TUDelft.nl
authors.forename: P
authors.initials: P
authors.lastname: van Drunen
authors.forename: E
authors.initials: E
authors.lastname: Maaswinkel
authors.forename: F C T
authors.initials: FC
authors.lastname: van der Helm
authors.forename: J H
authors.initials: JH
authors.lastname: van Dieën
authors.forename: R
authors.initials: R
authors.lastname: Happee
mesh_terms: D000328:Adult; D001415:Back / Q000502:physiology*; D001696:Biomechanical Phenomena; D004576:Electromyography / Q000379:methods; D006801:Humans; D017116:Low Back Pain / Q000503:physiopathology; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology; D011187:Posture / Q000502:physiology; D012026:Reflex, Stretch / Q000502:physiology*