HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when Rapid Responses are posted Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Shirley, D. Articles by Ellis, E. Search for Related Content PubMed PubMed Citation Articles by Shirley, D. Articles by Ellis, E. Related Collections Anatomy and Physiology: Musculoskeletal System Injuries and Conditions: Low Back Social Bookmarking                      What's this?

The Relationship Between Submaximal Activity of the Lumbar Extensor Muscles and Lumbar Posteroanterior Stiffnesss

D Shirley, PT, GradDipManipTh, is Lecturer, School of Physiotherapy, Faculty of Health Sciences, The University of Sydney, East Street, POB 170, Lidcombe, New South Wales, Australia 2141 (d.shirley{at}cchs.usyd.edu.au).
M Lee, MBiomedE, is Lecturer, School of Exercise and Sports Science, Faculty of Health Sciences, The University of Sydney
E Ellis, PhD, PT, is Senior Lecturer, School of Physiotherapy, Faculty of Health Sciences, The University of Sydney

Address all correspondence to Ms Shirley

Background and Purpose. Some patients with low back pain are thought to have increased lumbar posteroanterior (PA) stiffness. Increased activity of the lumbar extensors could contribute to this stiffness. This activity may be seen when a PA force is applied and is thought to represent much less force than occurs with a maximal voluntary contraction (MVC). Although MVCs of the lumbar extensors are known to increase lumbar PA stiffness, the effect of small amounts of voluntary contraction is not known. In this study, the effect of varying amounts of voluntary isometric muscle activity of the lumbar extensors on lumbar PA stiffness was examined. Subjects. Twenty subjects without low back pain, aged 26 to 45 years (=34, SD=5.6), participated in the study. Methods. Subjects were asked to perform an isometric MVC of their lumbar extensor muscles with their pelvis fixed by exerting a force against a steel plate located over their T4 spinous process. They were then asked to perform contractions generating force equivalent to 0%, 10%, 30%, 50%, and 100% of that obtained with an MVC. Posteroanterior stiffness at L4 was measured during these contractions. Results. A Friedman one-way analysis of variance for repeated measures demonstrated a difference in PA stiffness among all levels of muscle activity. Conclusion and Discussion. Voluntary contraction of the lumbar extensor muscles will result in an increase in lumbar PA stiffness even at low levels of activity.

Key Words: Lumbar spine • Lumbar stiffness • Muscle activation • Physical therapy

CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?

This article has been cited by other articles:

				D Shirley, P. W. Hodges, A. E. M. Eriksson, and S. C. Gandevia Spinal stiffness changes throughout the respiratory cycle J Appl Physiol, October 1, 2003; 95(4): 1467 - 1475. [Abstract] [Full Text] [PDF]