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Activator Methods International Ltd.
2950 N. Seventh Street, Suite 200
Phoenix, AZ 85014
ofc 602-224-0220
fax 602-224-0230
toll free 1-800-598-0224
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Subject: Neurophysiological Research |
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| Title: Mechanical Force Spinal Manipulation Increases Trunk Muscle Strength Assessed by Electromyography: A Comparative Clinical Trial |
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| Reference: Tony S. Keller, Ph.D., Christopher J. Colloca, D.C. : in press. |
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Abstract: Objective: The objective of this study was to determine if mechanical force, manually-assisted (MFMA) spinal manipulative therapy (SMT) affects paraspinal muscle strength assessed using surface electromyography (sEMG).
Design & Setting: This study is a prospective clinical trial comparing sEMG output in an active treatment group and two control groups in an outpatient chiropractic clinic, Phoenix, AZ, USA.
Subjects: Forty low back pain (LBP) subjects participated in the study. Twenty LBP patients (9 females and 11 males with a mean age of 35 years and 51 years, respectively) and twenty age and gender matched sham-SMT/control LBP patients (10 females and 10 males with a mean age of 40 years and 52 years, respectively) were assessed.
Methods: Twenty consecutive LBP patients (SMT treatment group) performed maximum voluntary contraction (MVC) isometric trunk extensions while lying prone on a treatment table. Surface, linear enveloped sEMG was recorded from the erector spinae musculature at L3 and L5 during the trunk extension procedure. Subjects were then assessed using the Activator Methods Chiropractic Technique (AMCT) protocol, during which time they were treated using MFMA SMT. The MFMA SMT treatment was followed by a dynamic stiffness and algometry assessment, after which a second or post MVC isometric trunk extension and sEMG assessment was performed. Another twenty consecutive LBP subjects were assigned to one of two control groups, a sham-SMT group, and a control group. The sham-SMT group underwent the same experimental protocol with the exception that the subjects received a sham-MFMA SMT and dynamic stiffness assessment. The control group received no SMT treatment, stiffness assessment, or algometry assessment intervention. Within group analysis of MVC sEMG output (pre-SMT vs. post-SMT sEMG output) and across group analysis of MVC sEMG output ratio (post-SMT sEMG/pre-SMT sEMG output) during MVC was performed using a paired observations t-test (POTT) and a robust analysis of variance (RANOVA), respectively.
Main Outcome Measures: Surface, linear enveloped electromyographic recordings during isometric maximum voluntary contraction (MVC) trunk extension were used as the primary outcome measure.
Results: Nineteen of the 20 patients in the SMT treatment group showed a positive increase in sEMG output during MVC (range –9.7% to 66.8%) following the active MFMA SMT treatment and stiffness assessment. The SMT treatment group showed a significant (POTT, P<0.001) increase in erector spinae muscle sEMG output (21% increase compared to pre-SMT levels) during MVC isometric trunk extension trials. There were no significant changes in pre vs. post-SMT MVC sEMG output for the sham-SMT (5.8% increase) or control (3.9% increase) groups. Moreover, the sEMG output ratio of the SMT treatment group was significantly greater (RANOVA, P=0.05) than either the sham-SMT or control groups.
Conclusions: The results of this preliminary clinical trial demonstrated that MFMA SMT results in a significant increase in sEMG erector spinae isometric MVC muscle output. These findings indicate that altered muscle function may be a potential short-term therapeutic effect of MFMA SMT, and forms the basis for a randomized, controlled clinical trial to further investigate acute and long-term changes in low back function.
Support for this study was from the National Institute of Chiropractic Research. |
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