Introduction: Lumbar spine stability programs have been advocated to prevent and
rehabilitate low back injury. Specifically, abdominal ‘drawing in’ has been used to train
motor control deficits in individuals with low back pain. This technique requires
differential activity within deep and superficial lumbar multifidus fibres, yet the ability of
these fibres to act differentially has not been extensively examined. Deep fibres are
hypothesized to act as spinal stabilizers while superficial fibres are hypothesized to act as
global movers of the trunk.
Objective: To investigate differential excitation of deep and superficial lumbar multifidus
fibres during segmental indentation loads to the lumbar spine.
Methods: Posterior-anterior indentation loads were applied to individual lumbar spinous
processes of prone participants at three different velocities and three different indentation
displacements. Indentations consisted of an initial downward displacement that was
subsequently held for 500 milliseconds. Intramuscular electromyography (EMG) of deep
and superficial lumbar multifidus fibres at L3, L4 and L5 was recorded. EMG was
quantified by “average” root mean square (RMS), peak RMS of a sliding RMS window
and time-to-peak RMS over the indentation phase and 500 millisecond hold phase.
Results: Increased indentation displacement at the slowest velocity resulted in increased
“average” RMS of only the L5 superficial multifidus fibres. Increased indentation
velocity produced differential effects in deep and superficial multifidus fibres. “Average”
RMS and peak RIVIS significantly increased with increasing indentation velocity in most
deep fibre recording sites, yet superficial fibre excitation did not significantly increase. In
most EMG recording sites, the time-to-peak RMS increased with increasing indentation
displacement and decreased with increasing indentation velocity.
Conclusion: Differential excitation of superficial and deep multifidus fibres was found
with increasing indentation velocity; however, the result was opposite to that
hypothesized. This result is clinically relevant because it suggests deep multifidus fibre
excitation may increase in response to increased perturbation magnitude, possibly to
restore vertebral body position. Differential excitation effects may also be related to
different mechanical stimuli experienced by deep and superficial fibres due to vertebral
body movement during indentation loads.
11
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU./2856 |
| Date | 11 1900 |
| Creators | Apperley, Scott |
| Publisher | University of British Columbia |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | 4453277 bytes, application/pdf |
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