Delayed abdominal muscle onsets and self-report measures of pain and disability in chronic low back pain☆
Received 8 May 2009; received in revised form 5 August 2009; accepted 28 September 2009. published online 23 October 2009. Corrected Proof
Abstract
Objective
The objective of this study was the measure the onset time of the transverse abdominis (TA) muscle during rapid unilateral shoulder movements in individuals with chronic low back pain (LBP), and to evaluate the relationship between latency times and self-report measures of pain and disability.
Design
Descriptive cross-sectional study.
Setting
University laboratory.
Participants
Eighty individuals with chronic LBP of a non-specific origin (males n=44, females n=36).
Main outcome measures
Responses of the right and left surface TA/internal obliques were measured using surface electromyography (EMG) during rapid unilateral shoulder flexion, abduction, and extension. Pain intensity was measured using a visual analog scale (VAS), and disability with the Oswestry disability index (ODI).
Results
Seventy-five percent of individuals were identified as lacking feedforward activation. A significant side×direction main effect was identified, with the ipsilateral latency more delayed in flexion and abduction (F(2316)=58.2, p<0.001). Individuals without feedforward activation had lower ODI scores (23.2±6.9% vs 31.0±9.2%, mean difference 7.8%, 95% CI 3.9 to 11.6%, p<0.001). Regression analysis found that 17% of the variance in VAS scores for the entire sample (n=80) were explained by the latency times measured. This relationship was stronger when the sample was separated into individuals who did (n=20), and did not (n=60) have feedforward activation.
Conclusion
Deep abdominal muscle onsets during rapid limb movement were significantly associated with self-rated pain scores. Seventy-five percent of individuals with chronic non-specific LBP exhibited delayed activation. No evidence has been provided in this study to support, or refute the use of specific localized deep abdominal contractions for exercise rehabilitation programs.
aDepartment of Sport and Exercise Science, University of Auckland, Tamaki Campus, Private Bag 92019, Auckland, New Zealand
bFaculty of Health Sciences, University of Ontario, Institute of Technology, 2000 Simcoe St. North, Oshawa, Ontario, Canada L1H 7K4
Corresponding author. Tel.: +649 373 7599x82378.
☆ We certify that no party having a direct interest in the results of the research supporting this article has or will confer a benefit on us or on any organization with which we are associated AND, if applicable, we certify that all financial and material support for this research (eg, NIH or NHS grants) and work are clearly identified in the title page of the manuscript.
ABSTRACT
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