ACCRAC AWARD WINNING PAPER TRUNK NEUROMUSCULAR RESPONSES TO A SINGLE WHOLE-BODY VIBRATION SESSION IN PATIENTS WITH CHRONIC LOW BACK PAIN:ACROSS-SECTIONAL STUDY Jean-Alexandre Boucher, DC, a Jacques Abboud, BSc, b Jean-Daniel Dubois, MSc, a Elise Legault, BSc, b Martin Descarreaux, DC, PhD, c and Yves Henchoz, PhD d,e ABSTRACT Objective: Whole-body vibration (WBV) exercise is progressively adopted as an alternative therapeutic modality for enhancing muscle force and muscle activity via neurogenic potentiation. So far, possible changes in the recruitment patterns of the trunk musculature after WBV remain undetermined. The main objective of this study was to evaluate the short-term effects of a single WBV session on trunk neuromuscular responses in patients with chronic low back pain (cLBP) and healthy participants. Methods: Twenty patients with cLBP and 21 healthy participants performed 10 trunk flexion-extensions before and after a single WBV session consisting of five 1-minute vibration sets. Surface electromyography (EMG) of erector spinae at L2-L3 and L4-L5 and lumbopelvic kinematic variables were collected during the trials. Data were analyzed using 2-way mixed analysis of variance models. Results: The WBV session led to increased lumbar EMG activity during the flexion and extension phases but yielded no change in the quiet standing and fully flexed phases. Kinematic data showed a decreased contribution to the movement of the lumbar region in the second extension quartile. These effects were not different between patients with cLBP and healthy participants. Conclusions: Increased lumbar EMG activity after a single WBV session most probably results from potentiation effects of WBV on lumbar muscles reflex responses. Decreased EMG activity in full trunk flexion, usually observed in healthy individuals, was still present after WBV, suggesting that the ability of the spine stabilizing mechanisms to transfer the extension torque from muscles to passive structures was not affected. (J Manipulative Physiol Ther 2013;36:564-571) Key Indexing Terms: Vibration; Low Back Pain; Electromyography; Kinematics C hronic low back pain (cLBP) represents a major health care problem and a leading cause of dis- ability in modern society. It is a highly incapaci- tating disorder linked with substantial use of health care resources as a result of medical consultations, investiga- tions, and prescriptions. Nonspecific low back pain (LBP), defined as pain with no identifiable cause, accounts for approximately 90% of cases. 1 Besides pain sensation, deficits in proprioception, 2 muscular atrophy, 3 changes in postural control, 4 and altered muscle recruitment pat- terns 5,6 have all been observed in patients with cLBP. Back muscle recruitment patterns in patients with LBP have often been investigated using trunk flexion-extension tasks. 7 In healthy participants, myoelectric silence or re- duced activity of the low back extensor musculature is usually observed during full trunk flexion. For instance, persistence of activity in the paraspinal muscles during full a PhD student, Département de Psychologie, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada. b MSc student, Département des Sciences de l’Activité Physique, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada. c Professor, Département de Chiropratique, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada. d Postdoctoral fellow, Département de Chiropratique, Univer- sité du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada. e Postdoctoral fellow, Service de Rhumatologie, Centre Hospi- talier Universitaire Vaudois, Lausanne, Switzerland. Submit requests for reprints to: Martin Descarreaux, DC, PhD, Professor, Département de Chiropratique, 3613 Pavillon de Chiro- pratique, Université du Québec à Trois-Rivières, Trois-Rivières, QC Canada G9A 5H7 (e-mail: martin.descarreaux@uqtr.ca). Paper submitted March 19, 2013; in revised form September 2, 2013; accepted September 3, 2013. 0161-4754/$36.00 Copyright © 2013 by National University of Health Sciences. http://dx.doi.org/10.1016/j.jmpt.2013.09.001 564