Integrating Test Findings With Standing Neutral Static SEMG

By David Marcarian

One of the most time-proven decisions in chiropractic is the use of weight-bearing postures during X-ray examinations. There is little dispute that chiropractors can learn much more about structure and function from a standing film than one performed in a non-weight-bearing position.

The same logic applies to the static surface EMG evaluation. When you want more information about reactions to load, gravity and resulting compensations, you choose weight-bearing testing.
I recently met with a group of doctors to discuss the merits of standing SEMG testing in contrast with seated evaluations. The doctors were using seated testing based on information they received about the influences of the righting reflex on test outcomes. They believed the seated test would negate this muscular activity and would, therefore, be more accurate.

I asked them if they had ever tried performing standing tests. They admitted they hadn’t, and that they were relying on information received through other sources. One doctor admitted to trying standing tests, but his brand of EMG equipment made it difficult to perform.

I asked the doctors if these were valid reasons to choose seated testing, and they all agreed the logic was questionable. I then inquired if it would be valuable to have SEMG testing more closely correlate with X-ray methods, and they all concurred. The group was in agreement that seated testing could not offer this benefit, nor provide the potential integration of findings that standing testing could.

The information overload many doctors experience today encourages reliance on readily available protocols, and equipment usage recommendations often fall into this category. They follow the information they receive from their manufacturer’s representative, which was to perform the tests seated. Published research has shown that the standing test is more valuable than the seated test.1,2

Case Study
To demonstrate the differences between standing and seated testing, I recruited a volunteer from the group for SEMG evaluation. To ensure the integrity of the test, the doctor was instructed to withhold any comment about his area of symptomatology. We began by performing a seated neutral test, as shown in Scan 1. Immediately following that examination, we performed the standing neutral test, which is illustrated in Scan 2. When both tests were complete, the "patient" was asked to reveal his areas of complaint, which were described as the left upper thoracic and right lower lumbar regions.

Several observations were evident upon evaluation of the testing methods and their results:
The seated neutral test showed:

The test results were not very informative. A slight increase in muscular activity was noted in the cervical and mid-thoracic regions.
The readings appeared relatively balanced when comparing left and right sides.
The readings did not correlate well with the patient’s complaints.
The standing neutral test showed:
Significantly more muscle activity was noted compared with the seated test.
Test results correlated very well with the patient’s complaints. Muscle tension was noticeably higher in the upper thoracic and lower lumbar regions. Lumbar muscular activity was higher on the left, not unexpectedly, due to compensation patterns that had developed in response to dysfunction. Muscle firing often occurs on the side opposite the patient’s perceived area of pain, due to compensatory patterns.
There was no noticeable influence of the "righting reflex" on the test results.

A proprietary Autoscanning feature, unique to the MyoVision instrument used for the tests, provided additional assurance that potential variations in readings due to slight motion would be minimized.

The Autoscan software prevents the recording of data before muscle activity has stabilized, diminishing input associated with either the righting reflex or extraneous patient motion.

The overall value of the standing SEMG test for both doctor and patient was quite clear. The standing neutral exam readily demonstrated dysfunctional areas and produced more credible correlation to patient symptomatology. These features enhance the benefits of SEMG use in clinical practice and improve the effectiveness of SEMG findings for patient education.

After this demonstration, everyone agreed that the standing neutral SEMG exam was the optimal test for both clinical and patient education applications.

Comparison Of Methods
To summarize the differences between seated and standing SEMG testing, here is a comparison that reviews both methods in common clinical and patient education situations:

Factors	Standing	Seated
Correlates with X-Ray?	YES	NO
Functional by reproducing mechanical stresses?	YES	NO
Demonstrates dysfunction?	YES: Patient does not rely upon chair to provide stability. Accentuates muscular compensation for subluxation.	NO: Readings are diminished because pelvis is artificially stabilized by chair.
Screening Benefits?	YES: Standing increases visibility and reduces "fear of commitment." Generates more traffic at your booth and more people will allow you to test them.	NO: Seated testing reduces visibility. Fear of commitment is increased by requirement to be seated. Results in fewer tests.
Affected by Righting Reflex?	NO. Extraneous muscular activity readings are further reduced by the Autoscan feature.	NO: Seated posture reduces overall muscular activity, functional and extraneous.

Demonstrates Short Leg Phenomenon?	YES	NO. Not reproducible when seated.
Demonstrates Antalgic Posture?	YES	NO. Not reproducible or poorly demonstrated when seated.

Note that there are times when a seated neutral test may be appropriate. If a patient’s symptomatology is demonstrated more in a seated posture than when standing, or if a patient cannot perform the standing test, a seated SEMG exam may be indicated. Understanding SEMG testing and outcomes will help when clinical decisions about its use are required.

In summary, if you are interested in a higher level of clinical correlation between findings and symptomatology, standing SEMG testing will help you achieve it. And for patient education, the standing test has numerous benefits. In your office or at a public event, standing SEMG testing is a valuable method for detecting and illustrating spinal dysfunction, and for educating patients about the vertebral subluxation.

References

1. Cram and Engstrom, as reported in Introduction to Surface Electromyography, 1998, Aspen Publishers.

2. Kessler, Cram, and Traue, as reported in Introduction to Surface Electromyography, 1998, Aspen Publishers.

About the authors: David Marcarian, who has served as a consultant to corporations and educational organizations, is founder of Precision Biometrics, a supplier of instruments, including the Myovision surface electromyography and Thermoglide systems. With degrees in physics and psychology, he has served as an instructor for Canadian Memorial Chiropractic College and has trained over 6,000 chiropractors in proper SEMG utilization. The National Institutes of Health awarded him a $450,000 grant to design SEMG and related monitoring equipment, and he conducted SEMG-documented research studies at NASA on ergonomic factors of muscle fatigue in helicopter pilots. For more information, call (800) 969-6961, ext. 9.

return to top