Surface EMG Validation and Reliability Studies
Questions & Answers
1. For what uses or conditions has SEMG been shown to be reliable and valid?
Electrical potentials are produced when muscle tissue contracts.
These potentials may be measured and recorded by inserting
wire or needle electrodes in the muscle tissue, or by placing surface
electrodes on the skin overlying the muscle(s) being evaluated.
Surface electrodes measure the activity of groups of muscles working together.
Paraspinal sEMG is a physiological measurement, not a “stand alone” diagnostic procedure for a
specific disease or condition. It may be used when a quantitative assessment of paraspinal muscle
activity id desired. By analogy, consider other physiological measurements used in clinical practice. An
oral thermometer will tell the clinician if a fever is present, and whether the clinical status of the patient
is improving. It is useful screening tool, and helps the clinician evaluate response to treatment.
However, by itself, it cannot be used to diagnose the condition causing the fever. Similarly, sEMG is
useful in evaluating alterations in paraspinal muscle activity that are of interest to the chiropractor, such
as those associated with vertebral subluxation.
Paraspinal SEMG scans, taken in concert with other examination
findings, may be helpful in determining the following:
1. Asymmetrical contraction
2. Areas of muscle splinting
3. Severity of the condition
4. Aberrant recruitment patterns
5. Dysponesis
6. Responses to dysafferentation
7. Response to chiropractic adjustment
The U.S. Food and Drug Administration has accepted the following indications for use:
1. To measure bilateral differences in surface EMG along the spine
2. To measure surface EMG along the spine during functional tasks.
Reliability is a measure of the ability to reproduce a measurement, which is expressed as a coefficient
ranging from 0.00 to 1.00. Perfect reliability results in a coefficient of 1.00, while chance agreement
would be 0.0. As an example, Hass and Panzer (Haas M, Panzer DM. Palpatory diagnosis of
subluxation. In: Gatterman M, ed. Foundations of Chiropractic Subluxation. St. Louis, MO: Mosby,
1995.) noted that the inter-examiner reliability of palpation for muscle tension is poor, with coefficients
ranging from 0.07 to 0.20. Surface EMG, in contrast, demonstrates excellent reliability.
2. What are accepted protocols for the use of SEMG?
Protocols and normative data for paraspinal EMG scanning have been published in the refereed
literature. Hand held electrodes are applied to the skin of the patient overlying the spine at 15 paired
sites. EMG signals are measured in microvolts (10-6 volts). A computer analyzes these signals, and
compares
them to a normative data base.
See: Kent C, Gentempo P. Protocols and normative data for paraspinal EMG
scanning in chiropractic practice. Journal of Chiropractic Research and Clinical Investigation 1990;
6(3):64.
Kent C, Gentempo P. Normative data for paraspinal surface electromyographic
scanning using a 25-500 Hz bandpass. Journal of Vertebral Suubluxation Reaearch 1996; 1(1):43.
3. What is the evidence that SEMG can be used to reliably obtain data in a clinical setting?
Studies, by researchers from 3 colleges and universities confirm reliability of one sEMG widely used in
chiropractic practice, the Insight SEMG:
1. The largest and most recent is collaborative study by researchers from the Florida Atlantic University
College of Biomedical Science and Life University found that the Insight(tm) surface EMG technology
demonstrated excellent reliabilty.
"This study revealed excellent inter-examiner and intra-examiner reliability of static paraspinal
surface electromyography in a large number of subjects."
McCoy, M., Blanks, R., Campbell, I., Stone, P., Fedorchuk, C., George, I., Jastremski, N., Butaric,L.
Inter-examiner and Intra-examiner Reliability of Static Paraspinal Surface Electromyography.
Presentation. 2006 International Research and Philosophy Conference. Sherman College of Straight
Chiropractic. Spartanburg, SC. November 3-5, 2006.
McCoy, M., Blanks, R., Campbell, I., Stone, P., Fedorchuk, C., George, I., Jastremski, N., Butaric,L.
Inter-examiner and Intra-examiner Reliability of Static Paraspinal Surface Electromyography.
Proceedings of the 2006 International Research and Philosophy Conference. Sherman College of
Straight Chiropractic. Spartanburg, SC. November 3-5, 2006. J. Vertebral Subluxation Res. November
27, 2006
McCoy, M., Blanks, R., Campbell, I., Stone, P., Fedorchuk, C., George, I., Jastremski, N., Butaric,L.
Inter-examiner and Intra-examiner Reliability of Static Paraspinal Surface Electromyography. Poster
Presentation. Association of Chiropractic Colleges Research Agenda Conference. March 15-18, 2007.
McCoy, M., Blanks, R., Campbell, I., Stone, P., Fedorchuk, C., George, I., Jastremski, N., Butaric,L.
Inter-examiner and Intra-examiner Reliability of Static Paraspinal Surface Electromyography.
Proceedings of the Association of Chiropractic Colleges Research Agenda Conference. March 15-18,
2007. Journal of Chiropractic Education. Spring 2007.
2. A second study was the basis of a dissertation by Hazel Faulkner, D.C., for an M.Sc. degree from the
Institute or Medicine, Health and Social Care, University of Portsmouth.
“These results show that those subjects who have received recent and regular chiropractic adjustment
have excellent reliability.”
Faulkner HC: Test-retest reliability of sEMG paraspinal scans: A comparative study. Institute of
Medicine, Health and Social Care. University of Portsmouth. M.Sc. dissertation. August 2006.
4. What is the evidence that indicates which layers of muscle are read by SEMG?
A general rule is that the larger and more superficial a muscle is, the greater it’s contribution to the
sEMG signal. In chiropractic applications, the objective is to measure the activity of groups of muscles
working together, not to isolate individual muscles.
The muscles contributing to the sEMG recordings at the various regions may be summarized as follows:
 CERVICAL
Upper Trapezius
Splenius Capitis
Spinalis Cervicis
Semispinalis Cervicis
 UPPER THORACIC
Middle Trapezius
Longissimus
Semispinalis Cervicis
Splenius Cervicis
Multifidus
 LOWER THORACIC
Longissimus
Multifidus
Latissimus Dorsi
Serratus Posterior
 LUMBAR
Iliocostalis Lumborum
Multifidus
Reference: Cram JR, Kasman GS, Holtz J: Introduction to Surface Electromyography. Gaithersburg, MD.
Aspen Publishers, Inc. 1998. Pages 132-135.
5. What is the evidence that it is a valid measure of muscle activity associated with tissue the subluxation
complex?
Paraspinal muscle dysfunction is generally accepted as a clinical manifestation of vertebral subluxation.
Traditional chiropractic analysis includes examination of the paraspinal tissues for taut and tender
muscle fibres. See: Janse J, Houser RH, Wells BF: Chiropractic Principles and Technic, Chicago, 1947,
National College of Chiropractic (reprinted 1978) and Schafer RC: Basic Chiropractic Procedural
Manual, Arlington, Va, 1984, American Chiropractic Association.
D.D. Palmer expressed the relationship between tone and the dynamics of health and disease as follows:
“Life is an expression of tone. tone is the normal degree of nerve tension. Tone is expressed in function
by normal elasticity, strength, and excitability . . . the cause of disease is any variation in tone.” (Palmer
DD: The Chiropractor’s Adjuster. DPortland, OR. Portland Printing House. 1910).
Contemporary textbooks from major medical publishers address the association of sEMG assessment of
paraspinal muscle activity and vertebral subluxation.
“Surface EMG provides objective, quantitative data concerning the changes in paraspinal muscle
function that accompany vertebral subluxation...studies support the construct validity of paraspinal
SEMG as an outcome assessment for chiropractic adjustment. “ (Masarsky CS, Todres-Masarsky M
(eds): Somatovisceral Aspects of Chiropractic. An Evidence-Based Approach. Philadelphia, PA.
Churchill Livingstone. 2001. Pages 91 and 93.)
Eriksen reviews several studies where sEMG was used as an outcome assessment for subluxation
complex . See: Eriksen K:Upper Cervical Subluxation Complex. Baltimore, MD. Lippincott Williams
& Wilkins. 2004. Pages 215-220. Examples of sEMG changes are featured in Appendix G of this text.
473-G through 477-G.
“The preponderance of evidence clearly supports the use of sEMG in the evaluation of the muscular
component of the vertebral subluxation complex.”
(Eriksen K, Rochester RP: Orthospinology Procedures. An Evidence-Based Approach to Spinal Care.
Baltimore, MD. Lippincott Williams & Wilkins. 2007. Page 128).
6. What is the evidence that it is of use in monitoring a patient’s response to care?
A study was conducted at the New Zealand College of Chiropractic. It examined both reliability and
pre/post sEMG changes.
“Under the conditions of this study, using the Insight…
Subluxation Station, it is concluded that sEMG is an objective
measure of change which can be used as an assessment of patient
progress.”
Kelly S, Boone WR: The clinical application of surface electromyography as an objective measure of
change in the chiropractic assessment of patient progress: a pilot study. Journal of Vertebral
Subluxation Research 1998;2(4):1-7.
Regarding clinical validity, paraspinal surface EMG has been shown, in controlled studies, to be
responsive to chiropractic adjustments and spinal manipulation. Shambaugh (Shambaugh P. Changes in
electrical activity in muscles resulting from chiropractic adjustment: a pilot study. JMPT 1987;
10(6):300) conducted a controlled study where surface electrodes were used to record paraspinal EMG
activity pre- and post-chiropractic adjustment. Shambaugh concluded, “Results of this study show that
significant changes in muscle electrical activity occur as a consequence of adjusting.”
In the osteopathic literature, Ellestad et al (Ellestad S, Nagle R, Boesler D, Kilmore M.
Electromyographic and skin resistance responses to osteopathic manipulative treatment for low-back
pain. JAOA 1988; 88(8):991.) conducted a controlled study which found that paraspinal EMG activity
decreased in patients following osteopathic manipulation. Such changes were not observed in controls in
either study.
These studies support the construct validity of paraspinal SEMG as an outcome assessment for
chiropractic adjustment.