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MULTIFIDUS MORPHOLOGY, FATIGABILITY AND ACTIVATION IN PERSONS WITH CHRONIC UNILATERAL LOW BACK PAIN
by
George J. Beneck
__________________________________________________________________
A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of the
Requirements for the Degree
DOCTOR OF PHILOSOPHY
(BIOKINESIOLOGY)
August 2010
Copyright 2010 George J. Beneck
Object Description
| Title | Multifidus morphology, fatigability and activation in persons with chronic unilateral low back pain |
| Author | Beneck, George J. |
| Author email | gbeneck@csulb.edu; beneck@usc.edu |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Biokinesiology |
| School | School of Dentistry |
| Date defended/completed | 2010-06-10 |
| Date submitted | 2010 |
| Restricted until | Unrestricted |
| Date published | 2010-08-10 |
| Advisor (committee chair) |
Kulig, Kornelia Powers, Christopher M. |
| Advisor (committee member) |
Baker, Lucinda L. Gordon, James Colletti, Patrick M. |
| Abstract | Recent research suggests that chronic low back pain may be due to altered neuromuscular control of the lumbar spine. The purpose of this dissertation was to examine the morphology, fatigability, and activation of the lumbar multifidus in healthy persons and persons with chronic low back pain. To accomplish this objective, three studies were undertaken.; The purpose of study #1 was to determine whether persons with chronic unilateral low back pain have diminished multifidus muscle volume. Volume was diminished by 18.1% only at L5-S1 region with no differences between the painful and nonpainful sides. The results indicate considerable localized, bilateral multifidus atrophy in persons with chronic unilateral low back pain despite low disability and similar activity levels to the matched control subjects.; The purpose of study #2 was to determine whether the lumbar extensors, particularly the deep fibers of multifidus, are more fatigable in persons with chronic low back pain. Normalized median frequency slopes were not different between groups or muscles. The results of this study do not support the hypothesis that the deep fibers of multifidus are more fatigable in persons with chronic low back pain.; The purpose of study #3 was to determine whether the activation of the lumbar extensors was delayed in persons with chronic low back pain and whether the delay was greatest in the deep fibers of multifidus. EMG recordings of the lumbar extensors were conducted during a sudden load release perturbation to the trunk. The activation of the extensors following the load release was not significantly different between groups. Feedforward activation of the deep multifidus among subjects with chronic low back pain was found in fewer subjects and fewer trials. There were no group differences in feedforward activation of the superficial multifidus.; A common finding across studies #1 and #3 was evidence of selective impairment of the deep fibers of multifidus. This finding was not supported by study #2. Since the lumbar extensors are a highly redundant system, load sharing by the other lumbar extensors could explain the lack of differences in fatigability. Alternatively, retained activity level, despite chronic low back pain, preserved the lumbar extensors from physiological fatigability. The findings from studies #1 and #3 suggest that muscle impairment in persons with chronic low back pain may be predominately in the deep fibers of multifidus. |
| Keyword | multifidus; low back pain; morphology; fatigability; activation |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m3371 |
| Rights | Beneck, George J. |
| Repository name | Libraries, University of Southern California |
| Repository address | Los Angeles, California |
| Repository email | http://www.usc.edu/isd/libraries/services/ask_a_librarian/email/ |
| Filename | etd-Beneck-3998 |
| Archival file | uscthesesreloadpub_Volume48/etd-Beneck-3998.pdf |
Description
| Title | Page 1 |
| Full text | MULTIFIDUS MORPHOLOGY, FATIGABILITY AND ACTIVATION IN PERSONS WITH CHRONIC UNILATERAL LOW BACK PAIN by George J. Beneck __________________________________________________________________ A Dissertation Presented to the FACULTY OF THE USC GRADUATE SCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of the Requirements for the Degree DOCTOR OF PHILOSOPHY (BIOKINESIOLOGY) August 2010 Copyright 2010 George J. Beneck |
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