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Session: Poster session I
Session starts: Thursday 24 January, 15:00

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Paul van Drunen (Delft University of Technology)
Yorick Koumans (Delft University of Technology)
Riender Happee (Delft University of Technology)

Abstract:
Low-back pain (LBP) is a common disorder, which affects 40-60% of the adult population annually in Western Europe and North America [1]. Motor control deficits (e.g., delayed reflex responses and increased co-contraction) have been suggested as potential cause and/or effect of a-specific chronic low-back pain and its recurrent behaviour [2, 3]. In a previous study, motor control identification was achieved for low-back stabilization [4]. However, preload biased the results due to the reduced involvement of the abdominal muscles. In this study, six healthy subjects were seated on a movable platform while restrained at the pelvis. Upper body sway was evoked by moving the platform in the sagittal plane, while low-back & trunk kinematics and back & abdominal muscle activity were recorded. Subjects were asked to perform a relax task or a stay upright task. Two perturbations types were applied: anterior-posterior horizontal translations and swing-like rotations around the virtual rotation point in the lumbar spine. For the stay upright task, we hypothesized a modulation in the neuromuscular control due to perturbation type; the intrinsic contributions are dominant during the translational perturbations, while reflexes contribute more during the swing-like perturbations. During the relax task, no big differences are expected for both perturbations. Coherences were high for the EMG measurements of both the back and abdominal muscles, indicating involvement of both muscle groups. In the translational task, increased co-contraction levels were found for the stay upright task leading to a decreased compliance. In future studies, this method will be applied to determine the neuromuscular control of LBP-patients, so potential modulations in reflexive and intrinsic contributions could be identified. “This research is supported by the Dutch Technology Foundation STW, which is the applied science division of NWO, and the Technology Programme of the Ministry of Economic Affairs.” See www.neurosipe.nl - Project 10732: QDISC REFERENCES [1] P. L. Loney and P. W. Stratford, “The Prevalence of Low Back Pain in Adults: A Methodological Review of the Literature”, Phys.Ther., Vol. 79, pp. 384-396, (1999). [2] J. Cholewicki, A. P. D. Simons and A. Radebold, “Effects of external trunk loads on lumbar spine stability”, J.Biomech., Vol. 33, pp. 1377-1385, (2000). [3] A. Radebold, J. Cholewicki, G. K. Polzhofer and H. S. Greene, “Impaired Postural Control of the Lumbar Spine Is Associated With Delayed Muscle Response Times in Patients With Chronic Idiopathic Low Back Pain”, Spine, Vol. 26, pp. 724-730, (2001). [4] P. van Drunen, E. Maaswinkel, F.C.T. van der Helm, J.H. van Dieën and R. Happee, “Identifying Intrinsic and Reflexive Contributions to Low-Back Stabilization”, Under Review in J.Biomech.