title: Trunk muscle reflexes are elicited by small continuous perturbations in healthy subjects and patients with low-back pain.
abstract: Low-back pain (LBP) has been recognized as the leading cause of disability worldwide. Lumbar instability has been considered as an important mechanism of LBP and one potential contributor to lumbar stability is trunk muscle reflex activity. However, due to the differences in experimental paradigms used to quantify trunk mechanics and trunk reflexes it remains unclear as to what extent the reflex pathway contributes to overall lumbar stability. The goal of this work was to determine to what extent reflexes of various trunk muscles were elicited by the small continuous perturbations normally used to quantify trunk mechanics. Electromyographic (EMG) activity was measured bilaterally from 3 trunk extensor muscles and 3 trunk flexor muscles at four epochs: 25-50ms, 50-75ms, 75-100ms and 100-125ms following each perturbation. Reflex activity was seen in all muscles as 34 of the 48 muscle-epoch combinations showed a significant reflex response to either perturbations in the forward or backward direction. However, the reflex EMG activity did not correlate with mechanical estimates of the reflex response. Thus, even though reflexes are indeed elicited by the small perturbations used to quantify trunk mechanics, their exact contribution to overall lumbar stability remains unknown.
authors.affiliation: School of Rehabilitation, University of Montreal, C.P. 6128, succursale Centre-ville, Montreal, Qc H3C 3J7, Canada; Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Montreal Rehabilitation Institute, 6300 Avenue de Darlington, Montreal, Qc H3S 2J4, Canada. Electronic address: daniel.ludvig@mail.mcgill.ca.
authors.forename: Daniel
authors.initials: D
authors.lastname: Ludvig
authors.affiliation: Occupational Health and Safety Research Institute Robert-Sauvé, 505 Boulevard de Maisonneuve O, Montréal, Qc H3A 3C2, Canada; Centre for Interdisciplinary Research in Rehabilitation of Greater Montreal (CRIR), Montreal Rehabilitation Institute, 6300 Avenue de Darlington, Montreal, Qc H3S 2J4, Canada.
authors.forename: Christian
authors.initials: C
authors.lastname: Larivière
mesh_terms: D000009:Abdominal Muscles / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D000368:Aged; D064131:Back Muscles / Q000502:physiology*; D004576:Electromyography / Q000379:methods*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D017116:Low Back Pain / Q000175:diagnosis / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000502:physiology; D012018:Reflex / Q000502:physiology*; D060726:Torso / Q000502:physiology*; D055815:Young Adult
keywords: EMG; Perturbations; Reflex; Stiffness; Trunk