Identifying intrinsic and reflexive contributions to low-back stabilization

• Published in: Journal of biomechanics 2013-05, Vol.46 (8), p.1440-1446
• Main Authors: van Drunen, P, Maaswinkel, E, van der Helm, F.C.T, van Dieën, J.H, Happee, R
• Format: Article
• Language: English
• Subjects: Admittance; Adult; Back - physiology; Biomechanical Phenomena; Electrical impedance; Electromyography - methods; Experiments; Feedback; Golgi tendon organ; Humans; Low Back Pain - physiopathology; Lumbar Spine; Mathematical models; Middle Aged; Motors; Muscle spindles; Muscle, Skeletal - physiology; Physical Medicine and Rehabilitation; Postural control; Posture - physiology; Reflex, Stretch - physiology; Resists; Stabilization; Studies; System identification; Tasks; Variance
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2013.03.007

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 1.1 Hz. 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.