Surface Electromyography (SEMG)

Presented By:Presented By:

Joseph S. Ferezy, D.C.Joseph S. Ferezy, D.C.

Initially, Claims Made by the Manufacturers Were Frankly

Outrageous, and It Was Easy to Brush Paraspinal EMG off As

Useless.

More Recently, However, Literature Is Beginning to

Accumulate, and Manufacturers Appear to Have Upgraded the

Quality of the Equipment While Downgrading the Claims.

When the Doctor Looks for Answers, It Seems That Only the Manufacturers and Distributors

Are Supplying Them.

The Purpose of This Presentation Is to Sift Through the Claims,

and Examine the Facts Regarding Paraspinal EMG.

You Should Not Consider Buying a Device Which Measures Something If You Cannot Answer Three Questions:

What Am I Measuring, and What Is Known What Am I Measuring, and What Is Known About It? About It?

Is the Device Giving Me an Accurate Measure? Is the Device Giving Me an Accurate Measure? What Useful Clinical Information Can Be What Useful Clinical Information Can Be

Gleaned From This Measurement?Gleaned From This Measurement?

This Weekend, I Will Attempt to Present the Facts Necessary to

Think Through Each of the Above Questions. In Doing So,

Each of You Will Be Able to Make up His/her Own Mind, and Not Just Listen to My Opinions.

Without This Requisite Background, One Has No Chance at All of Critically

Examining the Utility of This Technology, in Regard to Their

Personal Clinical Needs.

There Are Numerous Problems Which Must Be Overcome Before One Can Say That They Can "Measure Spasm". What

Exactly Is a Spasm? There Is an Embarrassing Lack of Information

Related to Measuring Muscle Spasm, and the One Study of Interexaminer

Reliability Shows Lousy Reproducibility. Ironically, Our

Assessment of It Significantly Effect the Lives of Millions of People Each Year.

Surface Electrodes

"What Is Better, Surface Electrodes or "What Is Better, Surface Electrodes or Needle Electrodes?" Needle Electrodes?"

This Is Really an Apples and Oranges Question, or at Least a

Question Which Is Oversimplified And, Hence,

Unanswerable. For What Purpose Is the Electrode Is Being

Used? It Would Be Quite Painful to Look for Insertional

Activity With a Surface Electrode.

It Is Generally Accepted That a Surface Electrode Is Superior for

the Assessment of Global Myoelectric Activity. If You Are Looking for General Activity of

Muscle Tissue in a Particular Area, the Surface Electrode Is

Superior.

If You Are, However, Looking for Information Regarding a Specific Piece of a Specific

Muscle, Then a Needle or Wire Has an Obvious Advantage. In Fact, Even Tiny Movements (.1 Mm) Can Significantly Alter the Day to Day Reliability of Needle

Electrodes.

Most Equipment Manufacturers Will State That Surface Electrodes Are More Reliable, and Site Papers As Sources of Proven Reliability (Reproducibility). It Should Be Noted That Virtually All of

These Studies Regard Peripheral Musculature. Spector at New York Chiropractic College Did Do a Very

Good Study on Paraspinal Muscles and Attached Surface Electrodes, Reporting

Excellent Reliability Coefficients.

If the Readings From Attached Surface Electrodes Are Reliable, We Must Next Ask How Does the Procedure of "Scanning" Emg Compare to Attached

Surface Electrodes.

Thompson Et. Al. And the Mayo Clinic Study Are Often Sited As

Proof of Scanning Electrode Reliability As Compared to

Attached Surface Electrodes. Attached Surface Electrodes

Were Never Even Used in This Study.

Thompson Was Attempting to See If a 2 Second Average of

Integrated (MAP) Was Sufficient for a Reliable Reading. His

Conclusion Was That It Was Not. He States That Only 37% of the

Sites Sampled Fell Within an Acceptable Range With a Two

Second Scan.

One of His Conclusions Stated, "a Longer Integration Period Enhances

the Validity" and "A 10 Second Integration Period Would Improve the Quality of the Data Obtained..." This Raises a Significant Question As to the Reliability of Scanning Electrodes. A Properly Designed

Reliability Study for Scanning Electrodes Versus Attached Surface Electrodes Should Be Undertaken.

Once the Issue of Reliability Is Addressed, One Must Ask If the

Reading Is an Accurate Reflection of Myoelectric

Activity. To Determine This, Let Us First Consider Variables

Regarding Apparatus Detection and Recording of Signals.

Basmajian and Deluca

"It Is Important to Remember That the "It Is Important to Remember That the Characteristics of the Observed EMG Characteristics of the Observed EMG Signal Are a Function of the Apparatus Signal Are a Function of the Apparatus Used to Acquire the Signal As Well As the Used to Acquire the Signal As Well As the Electrical Current Which Is Generated by Electrical Current Which Is Generated by the Membrane of the Muscle Fibers". the Membrane of the Muscle Fibers".

If the Filter Is Narrow at the Point of Signal Acquisition, It Does Not Matter What Band Width Is Available From That

Point on. Like a Funnel Turned Upside Down.

Tissue Filtering The Amplitude of Action The Amplitude of Action

Potentials Decreases to Potentials Decreases to 25% Within 100 um.25% Within 100 um.

The Thickness of the The Thickness of the Fatty and Skin Tissues Fatty and Skin Tissues Must Also Be Must Also Be Considered. Considered.

The Tissue(s) Behaves The Tissue(s) Behaves As a Low-pass Filter As a Low-pass Filter Whose Bandwidth and Whose Bandwidth and Gain Decreases As the Gain Decreases As the Distance Increases.Distance Increases.

The Muscle Tissue Is Highly The Muscle Tissue Is Highly Anisotropic. Orientation of Anisotropic. Orientation of the Detection Surfaces of the the Detection Surfaces of the Electrode With Respect to Electrode With Respect to the Length of the Muscle the Length of the Muscle Fibers Is Critical. Fibers Is Critical.

Dirt, Oils, Etc. Must Be Dirt, Oils, Etc. Must Be Removed From the Skin, So Removed From the Skin, So That They Do Not Distort That They Do Not Distort the Signal. This Can Be the Signal. This Can Be Accomplished by Cleaning Accomplished by Cleaning the Skin With an Abrasive, the Skin With an Abrasive, Or, Minimally Wipe It With Or, Minimally Wipe It With Alcohol and Allowed to Dry Alcohol and Allowed to Dry Prior to Taking a Reading.Prior to Taking a Reading.

Electrode-electrolyte Interface

Behaves As a High-pass Filter. The Gain Behaves As a High-pass Filter. The Gain and Bandwidth Will Be a Function of the and Bandwidth Will Be a Function of the Area of the Detection Surfaces, Area of the Detection Surfaces, Electrolytic Treatment of the Surfaces, and Electrolytic Treatment of the Surfaces, and Any Chemical-electrical Alteration of the Any Chemical-electrical Alteration of the Junction.Junction.

The Detection Surfaces Should Always Be The Detection Surfaces Should Always Be Kept Clean.Kept Clean.

Bipolar Electrode Configuration This Property Ideally Behaves As a Band-pass Filter. This Property Ideally Behaves As a Band-pass Filter.

However, This Is Only True If the Inputs to the However, This Is Only True If the Inputs to the Amplifier Are Balanced and If the Filtering Aspects of Amplifier Are Balanced and If the Filtering Aspects of the Electrode-electrolyte Junctions Are Equivalent.the Electrode-electrolyte Junctions Are Equivalent.

A Larger Interdetection Surface Spacing Will Render a A Larger Interdetection Surface Spacing Will Render a Lower Band-width. This Aspect Is Particularly Lower Band-width. This Aspect Is Particularly Significant for Surface Electrodes.Significant for Surface Electrodes.

The Greater the Interdetection Surface Spacing, the The Greater the Interdetection Surface Spacing, the Greater the Susceptibility of the Electrode to Detecting Greater the Susceptibility of the Electrode to Detecting Measurable Amplitudes of Emg Signals From Adjacent Measurable Amplitudes of Emg Signals From Adjacent and Deep Muscles. and Deep Muscles.

Bipolar Electrode Configuration

A Rule of Thumb Is That the Electrodes Will A Rule of Thumb Is That the Electrodes Will Detect Measurable Signals From a Distance Detect Measurable Signals From a Distance Equal to the Interdetection Surfaces Spacing. Equal to the Interdetection Surfaces Spacing. However, the Anisotropy of the Tissues Beneath However, the Anisotropy of the Tissues Beneath the Electrode May Augment the Sensitivity of the Electrode May Augment the Sensitivity of the Electrodes Along the Surface of the Muscle the Electrodes Along the Surface of the Muscle Creating Cross-talk.Creating Cross-talk.

An Interdetection Surface Spacing of 1.0 Cm Is An Interdetection Surface Spacing of 1.0 Cm Is Recommended for Surface Electrodes.Recommended for Surface Electrodes.

Amplifier Characteristics

Values Should Minimally Distort the EMG Values Should Minimally Distort the EMG Signal Detected by the Electrodes.Signal Detected by the Electrodes.

Length of the Leads to the Preamp Should Length of the Leads to the Preamp Should Be As Short As Possible and Should Not Be As Short As Possible and Should Not Be Susceptible to Movement. The Be Susceptible to Movement. The Necessity of This Precaution Is Necessity of This Precaution Is Accentuated When Amplifiers With High Accentuated When Amplifiers With High Input Impedance Are Used.Input Impedance Are Used.

Typical Settings and Characteristics for the Amplifier Gain: Such That It Renders Gain: Such That It Renders

the Output With an the Output With an Amplitude of Approximately Amplitude of Approximately +- 1v.+- 1v.

Input Impedance > 10-12 Input Impedance > 10-12 Ohms Resistance in Parallel Ohms Resistance in Parallel With 5 Pf Capacitance.With 5 Pf Capacitance.

Common Mode Rejection Common Mode Rejection Ratio: > 100 db.Ratio: > 100 db.

Input Bias Current: As Low Input Bias Current: As Low As Possible (Typically Less As Possible (Typically Less Than 50 Pa).Than 50 Pa).

Noise < 5uv RMS.Noise < 5uv RMS. Bandwidth (3 Db Points Bandwidth (3 Db Points

for 12 Db/octave for 12 Db/octave Rolloff).Rolloff).

Surface Electrodes 20-Surface Electrodes 20-500 Hz.500 Hz.

Wire Electrodes 20-1000 Wire Electrodes 20-1000 Hz.Hz.

Monopolar and Bipolar Monopolar and Bipolar Needle Electrodes for Needle Electrodes for General Use - 20-1000 General Use - 20-1000 Hz.Hz.

The Bandwidth Filter of the Amplifier Is a Point of Contention Among

Manufacturers. Median Frequency of the Power Density Spectrum Appears to Provide an Appropriate Representation

of Biochemical Events Within the Muscle. It Is Well Documented That in

Sustained, Constant Force Isometric Contraction, a Shift Toward Lower Median Frequencies Occurs, As the

Muscle Fatigues.

Along With Decreasing Frequency Is an Increase in

Amplitude. These Phenomenon May Be Due to Recruitment of

Muscle Fibers, Motor Unit Synchronization, And/or

Conduction Velocity Changes of Muscle Fibers.

One Must Carefully Define the Term "Muscle Fatigue" Before

Determining How the Phenomena of Greater

Amplitude and Lower Frequency of Emg Signal During Active Voluntary Muscle Contraction Can Be Clinically Applied.

Physiologically, Muscle Fatigue Does Not Happen All at Once.

Histologically There Is No "Point of Fatigue", Just a

Continuum of Chemical Changes Leading to an Eventual Clinical Failure of the Patient to Perform

the Task.

The Emg Signal Under Voluntary Muscular Activity Has Been Extensively Studied. It Is Expressed As a Percent of (MVC). It Holds Excellent

Prospects for Clinical Application in Assessment of

Back Pain Patients.

Whether This Is the Same As "Spasm" Is Doubtful.

Methodology for Signal Acquisition Must Be

Meticulously Performed, "Placement Determination by

Bony Landmarks Is Unacceptable".

Roy and Deluca

Other Considerations

It Is Preferable to Have the Subject, the It Is Preferable to Have the Subject, the Electrode, and the Recording Equipment in an Electrode, and the Recording Equipment in an Electromagnetically Quiet Environment.Electromagnetically Quiet Environment.

However, If All the Procedures and Cautions However, If All the Procedures and Cautions Discussed Are Followed and Heeded, High Discussed Are Followed and Heeded, High Quality Recordings Will Be Obtained in the Quality Recordings Will Be Obtained in the Electromagnetic Environments Found in Most Electromagnetic Environments Found in Most Institutions, Including Hospitals.Institutions, Including Hospitals.

Where To Locate The Electrode

If One Is Measuring EMG Frequency If One Is Measuring EMG Frequency Parameters, It Is Essential to Avoid Parameters, It Is Essential to Avoid Placement of the Electrode Near the Motor Placement of the Electrode Near the Motor Point.Point.

Signal-to-noise Ratio.Signal-to-noise Ratio. Signal Stability (Reliability).Signal Stability (Reliability). Cross-talk From Adjacent Muscles. Cross-talk From Adjacent Muscles.

A Recent Article by Wolfe, Wolfe and Segal From Emory

University Reveals That "Extraneous Movements Such As Neck Flexion and Pelvic Rotation Can Elicit Profound Activity From Percutaneously Placed EMG Electrodes While

Little Change Is Seen at the Skin Surface."

So, Tissue Filtering, Electrode-electrolyte Interface (Skin Preparation),

Electrode Configuration, Amplifier Characteristics, Recording

Characteristics, Electrode Location and Other Considerations Will All Effect the Accuracy of the Signal Being Measured.

It Is Important to Check Into Manufacturers Specifications and

Approaches to Each of These Variables, and See If They Are Satisfactorily

Considered.

What Useful Information Can Be Obtained By Measuring Global

Myoelectric Activity?

This Is a Difficult Question to Answer. Much Available Literature Is Not Published in Peer Reviewed,

Referred Journals and Even the Referenced Literature Is Filled With

Questionable Methodologies, Contradictions and Hardware

Considerations. Let Us Begin With a Review What Is Known Regarding

Paraspinal Muscle Function.

Commonly They Comprise (From Superficial to Deep): the

Semispinales, the Multifidi, and the Rotatores Muscles.

Some Contend That Deep Rotator Muscle Paralysis Is the Cause of Idiopathic Scoliosis. It Has Been

Demonstrated That There Is Increased Muscular Activity on the Convex Side of the Scoliotic Curve.

As the Slowly Flexing Trunk Is Lowered, the Activity in Erector Spinae Increases Apace and Then Decreases to Quiescence When Full Flexion Is Reached. If an Attempt Is

Made Then to Force Flexion Further, Silence Continues to Prevail in the Erector. In Full Flexion, Then, the Weight of the Torso Is

Borne by the Posterior Ligaments and Fasciae-the Posterior Common Ligament, the

Ligamentum Flavum, the Interspinous Ligaments, and the Thick Dorsal

Aponeurosis.

With the Subject Standing, the Activity in Erector Spinae

Ceases Earlier During Forward Bending Than It Does When

Seated. In Some Patients They Find Complete Relaxation in the

Sitting but Not the Standing Posture.

In Standing Erect, Activity in the Erector Spinae Is Not Required, Except for Forced Extension. In the Initial Stages of Flexion of the Trunk in Bending Forward, the Movement Is Controlled by

the Intrinsic Muscles of the Back.

It Has Also Been Shown That the Position of Full Flexion While

Seated (Slouching) Is Maintained Comfortably for Long Periods and That During This Time the

Erector Spinae Remains Relaxed.

In Most Subjects Standing in a Relaxed Erect Posture Showed a "Low Level of Discharge" in the

Erector Spinae. Small Adjustments of the Position of the Head, Shoulders, or Hands Could Be Made Which Would

Abolish the Activity of the Muscle, I.E., An Equilibrium or

Balance Could Be Achieved.

From the Easy Upright Posture, It Has Been Found That

Extension (Hyperextension) of the Trunk Is Initiated, As a Rule,

by a Short Burst of Activity.

While Standing Upright

Flexion of the Trunk to One Side Is Accompanied Flexion of the Trunk to One Side Is Accompanied by Activity of the Erector Spinae of the Opposite by Activity of the Erector Spinae of the Opposite Side "Antagonist.“Side "Antagonist.“

If the Back Is Already Arched in Hyper-If the Back Is Already Arched in Hyper-extension, Not Even This Sort of Activity Occurs.extension, Not Even This Sort of Activity Occurs.

The Recording of Activity From Both Right and The Recording of Activity From Both Right and Left Erectores During Bending to Either Side Has Left Erectores During Bending to Either Side Has Also Been Shown, and There Is a Pattern of Also Been Shown, and There Is a Pattern of Cooperative Activity and Not a Simple Cooperative Activity and Not a Simple Simultaneous Antagonism. Simultaneous Antagonism.

Erectores Spinae Contract (Vigorously) During Coughing

and Straining. This Occurs Even in the Midst of Their Normal

Silence, Whether the Subject Is Erect or "Full-flexed." The

Clinical Implications of This Last Observation Should Be

Explored.

It Has Also Been Reported That the Erector Spinae Remained Relaxed

During the Initial Movement of Lifting Weights of up to 56 Lbs. It Is Movement at the Hip Joint That Accounts for the Earliest Phase of Apparent Extension of the Trunk.

However, the Ligaments of the Back Were Required to Carry the Added

Weight Without Help From the Adjacent Muscles.

During the Performance of Various Trunk Movements, Deep Muscles Showed Patterns of Activity That Clearly Showed Two Functions,

Sometimes They Initiate Movement, and at Other Times They Stabilize

the Trunk. Almost All the Movements Recruit All the Muscles of the Back in a Variety of Patterns,

Although the Predominance of Certain Muscles Is Also Obvious.

In Compound Movements, When Subjects Are Not Trying to Relax, There Is Constantly More Activity Than When the Movement Is

Carried Out Deliberately and With Conscious Effort to Avoid Unnecessary Activity of

Muscles. Complete Relaxation and Lower Levels of Contraction Are the "Ideal" Rather

Than the Rule for Normal Bending Movements. Muscles That Might Be

Expected to Return the Spine to the Vertical Position Often Remain Quiet; That Suggests That Such Factors As Ligaments and Passive

Muscle Elasticity Play an Important Role.

A Position of Complete Silence Is Easily Found for Iliocostalis in

the Erect Position, but With Slight Forward Swaying Activity Is Instantly Recruited. Forward

Flexion and Rotation in the Flexed Position Bring Out Its

Strongest Contractions, but It Is Also Fairly Active in Most Movements of the Spine.

Multifidus and Rotatores Have Rather Similar but Not Identical Activity. With Movements in the

Sagittal Plane, They Are Active As They Also Are in Contralateral

Rotary Movements. Yet, Like All the Other Muscles, These Too Relax

Almost Completely During Full Flexion, Leaving the Trunk Practically Hanging on Its

Ligaments.

In a Systematic Exploration of the Intrinsic Muscle of the Spinal

Column During Various Exercises Widely Advocated for Physical Fitness, It Was Found That the

Semispinalis Capitis and Cervicis Apparently Help to Support the

Head by Continuous Activity During Upright Posture. This Finding

Contradicts Other Studies.

In Almost All Vigorous Exercises Performed From the Orthograde

Position, It Has Been Found That the Most Active Muscle Is Spinalis; Next in Order Is Longissimus, and Least Active

Is the Iliocostalis Lumborum. Nevertheless All Three Muscles and the

Main Mass of Erector Spinae Act Powerfully During Strong Arching of the Back in the Prone Posture. During

Push-ups, There Is Considerable Individual Variation But, Typically, the Lower Back Muscles Remain Relaxed.

Simple Side-bending Exercises of the Trunk Do Not Recruit Erector Spinae As Long As There Is No

Concomitant Backward or Forward Bending. This Clearly Refutes

Earlier Opinions Whose Authors Had Ignored Movements in the

Ventrodorsal Plane That Do Involve Erector Spinae. Much of This Work

Has Been Confirmed, and the Technique Has Been Adopted for

Ergonomics by Tichauer.

Deep Muscles

Variations in the Pattern of Activity Variations in the Pattern of Activity During Forward Flexion, Extension, and During Forward Flexion, Extension, and Axial Rotation Suggest That the Axial Rotation Suggest That the Transversospinal Muscles Adjust the Transversospinal Muscles Adjust the Motion Between Individual Vertebrae.Motion Between Individual Vertebrae.

The Experimental Evidence Confirms the The Experimental Evidence Confirms the Anatomical Hypothesis That the Multifidi Anatomical Hypothesis That the Multifidi Are Stabilizers Rather Than Prime Movers Are Stabilizers Rather Than Prime Movers of the Whole Vertebral Columnof the Whole Vertebral Column

The Interpretation of Electrical Activity Presents Some Difficulties. Did a Muscle Showing Activity Produce the Movement,

Prevent the Movement, or Was It Contracting Isometrically? Therefore Emphasis Must Be

Placed on the Occurrence of Electrical Silence, Knowing That the Muscle Tested

Was Not Taking Part in the Movement Under Observation. Decreasing or Increasing

Activity During a Movement Also Seemed to Be Functionally More Important Than

Unchanging Activity.

One Study by Anderson Et. Al. Attempted to Relate Paravertebral Muscle Function to Disc

Pressures, and Found That the Amplitude of the EMG Signal and Pressure Increased Both With

Angles of Forward Flexion and With Increasingly Static Loads in Flexion. During Asymmetric

Loading, Pressure Values and Myoelectric Activity Increased, Being Greater on the Contralateral Side of the Lumbar Region and Ipsilateral Side of the

Thoracic Region. The Disc Pressure, Intraabdominal Pressure, and Semi-integrated

Rectified EMG Signal Were Higher Throughout When the Trunk Was Loaded in Rotation, Rather

Than in Lateral Flexion.

Changes in the Lumbar Curvatures During Sitting and Standing Lumbar Muscles Have Been Shown to Be Inactive Lumbar Muscles Have Been Shown to Be Inactive

During Relaxed Sitting but Showed Some Activity in During Relaxed Sitting but Showed Some Activity in Straight Sitting and in the Standing Posture.Straight Sitting and in the Standing Posture.

This Finding Is in Agreement With the Results of Most This Finding Is in Agreement With the Results of Most Other Workers. Other Workers.

Disc Pressure and Myoelectric Activity Change Disc Pressure and Myoelectric Activity Change Together. When the Back of a Seated Subject Is Together. When the Back of a Seated Subject Is Supported, Levels of Both Pressure and EMG Signal Supported, Levels of Both Pressure and EMG Signal Fall. In This Study It Was Confirmed That Fall. In This Study It Was Confirmed That Intramuscular Wire Electrodes Are Superior to Surface Intramuscular Wire Electrodes Are Superior to Surface Electrodes in the Study of Intrinsic Back Muscles Electrodes in the Study of Intrinsic Back Muscles (Anderson Et Al, 1974, 1977).(Anderson Et Al, 1974, 1977).

Forward Flexion in Sitting and Standing Positions Morris Et Al (1962) Found That Flexion-Morris Et Al (1962) Found That Flexion-

relaxation Can Occur, but They Felt That in relaxation Can Occur, but They Felt That in Normal Bending Movements the Back Muscles Normal Bending Movements the Back Muscles Remained Frequently Active.Remained Frequently Active.

Spontaneous Electrical Silence of the Lumbar Spontaneous Electrical Silence of the Lumbar Muscles in Extreme Flexion Has Also Been Muscles in Extreme Flexion Has Also Been Found in Subjects, but Only Half of Them Found in Subjects, but Only Half of Them Showed Spontaneous Inactivity of Their Showed Spontaneous Inactivity of Their Thoracic Muscles in Both Seated and Standing Thoracic Muscles in Both Seated and Standing Postures.Postures.

Flexion/Relaxation Phenomenon

This Flexion-relaxation Phenomena Has Been Validated by Numerous Studies, and Does

Appear to Be Absent in a Percentage of Low Back Pain

Patients.

During the Valsalva Maneuver With Increased Intrathoracic and

Abdominal Pressure While Holding a Sandbag of 11.25 Kg, All Thoracic and a Number of

Lumbar Muscles Showed Activity Instead of Electrical

Silence.

Extension From the Flexed to the Upright Posture While Inactivity of the Back Muscles During the While Inactivity of the Back Muscles During the

Last Stage of Flexion Can Be Explained in That Last Stage of Flexion Can Be Explained in That the Muscles Are No Longer Needed and the Muscles Are No Longer Needed and Ligaments Are Holding the Vertebral Column, Ligaments Are Holding the Vertebral Column, There Is No Explanation of Why These Muscles There Is No Explanation of Why These Muscles Do Not Always Become Active Immediately Do Not Always Become Active Immediately When Extension Is Begun. When Extension Is Begun.

Instead, There Frequently Are Short "Bursts" of Instead, There Frequently Are Short "Bursts" of Activity That Occur (Especially in the Lumbar Activity That Occur (Especially in the Lumbar Region) When the Movement of Extension Is Half Region) When the Movement of Extension Is Half Completed.Completed.

It Therefore Appears That in Most Persons the Lumbar

Transversospinal Muscles Do Not Initiate Extension From the

Fully Flexed Position.

Lifting Weights With Different Mechanical Advantages Seemed to

Indicate That in Most Instances More Energy Is Used in the Lumbar and Thoracic Back Muscles When

the Object Lifted Cannot Be Brought Close to the Line of Gravity of the

Subject. Investigators Also Noticed Increased Activity of the Back

Muscles When the Center of Gravity Was Shifted Forward.

Axial Trunk Rotation In One Study Less Than In One Study Less Than

Half of the Examined Half of the Examined Subjects Showed the Subjects Showed the Expected Activity of the Expected Activity of the Transversospinal Transversospinal Muscles of the Thoracic Muscles of the Thoracic Region, Whereas More Region, Whereas More Than Half of the Than Half of the Subjects Showed the Subjects Showed the Expected Activity in the Expected Activity in the Lumbar Region.Lumbar Region.

This Finding Is This Finding Is Somewhat Surprising Somewhat Surprising Considering That Most Considering That Most of the Actual Rotatory of the Actual Rotatory Movement Occurs in the Movement Occurs in the Thoracic Region. Thoracic Region.

Paradoxical Activity of the Paradoxical Activity of the Deep Muscles Was Found in Deep Muscles Was Found in Five Subjects at the Thoracic Five Subjects at the Thoracic and in Three Persons at the and in Three Persons at the Lumbar Level. Lumbar Level.

In the Lumbar Region the In the Lumbar Region the Muscular Activity Seemed Muscular Activity Seemed More Often to Support the More Often to Support the Theory of Rotatory Function. Theory of Rotatory Function. On the Other Hand, the On the Other Hand, the Position of Articular Facets Position of Articular Facets in Relation to the Direction in Relation to the Direction of Muscle Pull Casts Doubt of Muscle Pull Casts Doubt on the Anatomical on the Anatomical Feasibility of Such a Feasibility of Such a Function.Function.

Perhaps the Designation of Specific Function Is Almost Impossible in the

Back, Where We Have a Complex Arrangement of Muscle Bundles Acting on a Multitude of Equally

Complex Joints. Those Who Insist on Finding Prime Movers,

Antagonists, and Synergists in the Genuine Musculature of the Back Will Be Always Disappointed.

In a Wire Electrode Study of Intrinsic Muscles, a Tokyo

Orthopedics Team Was Unable to Provide Validation for Reeducation Exercises Widely Advocated and

Used in France. Rather Than Abandon the Exercises, They

Suggested That the Transversospinal Muscles Are Stabilizers and That

This Function Is Important.

Standing

Continuous Activity of the Back Muscles in the Continuous Activity of the Back Muscles in the Lower Thoracic Region During Standing Has Been Lower Thoracic Region During Standing Has Been Reported. The Activity of These Muscles Appears Reported. The Activity of These Muscles Appears to Depended on Their Relation to the Line of to Depended on Their Relation to the Line of Gravity. The Segments of the Vertebral Column Gravity. The Segments of the Vertebral Column Located Further Posterior to the Line of Gravity Located Further Posterior to the Line of Gravity Had the Tendency to Fall Forward, a Movement Had the Tendency to Fall Forward, a Movement That Was Counteracted by the Back Muscles. The That Was Counteracted by the Back Muscles. The Thoracic Muscles Showed a Greater Tendency to Thoracic Muscles Showed a Greater Tendency to Remain Active, While the Lumbar Muscles Acted Remain Active, While the Lumbar Muscles Acted With "Bursts" of Electrical Potentials.With "Bursts" of Electrical Potentials.

Some Muscles Apparently Contract Unnecessarily. These Contractions Were More Often Seen in Women and Untrained Men. Further Confounding Any Attempt to Seek What Is Normal

for All.

Asymmetry

There Are Some Differences in Activity of There Are Some Differences in Activity of the Transversospinal Muscles at the Same the Transversospinal Muscles at the Same Levels. Levels.

This Asymmetrical Activity Occurred This Asymmetrical Activity Occurred During Quiet Sitting and Standing but Was During Quiet Sitting and Standing but Was Also Noted With Movements in the Also Noted With Movements in the Sagittal Plane. Sagittal Plane.

Wolf and Basmajian (1980) and Wolf Et Al. (1979) Assembled and Analyzed

Quantified Data Correlating Normal Back Movements With the EMG Activity in 121 Adult Subjects Who Reported No

History of Low Back Discomfort. EMG Records Were Obtained From Vertical

Pairs of Surface Electrodes Placed Bilaterally 3 Cm From the Midline at the L3-4 and L4-5 Levels. Recordings Were Made of a Range of Possible Movements

While Standing and Sitting (With the Pelvis Stabilized).

Differences in Left- and Right-sided Mobility Are Minimal And,

As Expected, Men Showed a Significantly Greater Excursion in Vertebral Separation During

Complete Trunk Flexion

Significantly Greater Activity Occurred During Extension From the Flexed

Trunk Position Than Vice Versa for Each Electrode Pairing. For Rotational

Movements in the Standing or Sitting Postures, Greater Activity Was Seen During Rotation Contralateral to the

Location of a Unilaterally Placed Electrode Pair. The Magnitude of This Activity Level Was Not Significantly Greater for Male or Female Subjects.

During Stooping or Squatting Movements, Males

Demonstrated Significantly Greater Activity Than Females for Recordings at All Electrode Placements, Except the Lower

Bilateral Pair.

All Results in Relation to the Mechanical Advantage, Center and Line of Gravity, and the Possible Axis of Movement Confirm the Idea That the Transversospinal Muscles Act As Dynamic Ligaments. These Adjust Small Movements Between Individual Vertebrae, While Movements of the Vertebral Column Probably Are Performed by Muscles With

Better Leverage and Mechanical Advantage (for Details, See Donisch and Basmajian,

1972).

Normative Data Cram and Also Matheson Cram and Also Matheson

Have Accumulated Have Accumulated Normative Data for Non-Normative Data for Non-pain Patients but One Must pain Patients but One Must Be Extremely Careful Be Extremely Careful Relying on This Data.Relying on This Data.

Both Studies Used the Both Studies Used the Narrow Band Equipment. Narrow Band Equipment. Wider Frequency Filters Will Wider Frequency Filters Will Detect More EMG Signal, Detect More EMG Signal, and Therefore Readings Will and Therefore Readings Will Vary.Vary.

The "Normal Range" Is Very The "Normal Range" Is Very Broad.Broad.

Cram's Data Has Come Cram's Data Has Come Under Scrutiny for Statistical Under Scrutiny for Statistical Error.Error.

Finally Meeker and Others Finally Meeker and Others Have Been Unable to Detect Have Been Unable to Detect Differences Between Pain Differences Between Pain and Non-pain Controls Using and Non-pain Controls Using This Data. This Data.

Most Manufacturers and Most Manufacturers and Distributors Readily Admit Distributors Readily Admit to the Problem With to the Problem With Normative Data, but Speak Normative Data, but Speak of Side to Side Asymmetries.of Side to Side Asymmetries.

As Noted Above, Not As Noted Above, Not Enough Is Known About Enough Is Known About Complex Acting Intrinsic Complex Acting Intrinsic Back Muscles to Know What Back Muscles to Know What Degree of Asymmetry Is Degree of Asymmetry Is Normal.Normal.

Recently, Some Very Impressive Studies, Specifically Sihvonen and Coworkers

From Finland, and Arena and Co-workers in Augusta Georgia, Have Had Success in Differentiating Back Pain Patients From Non-pain Controls. Arena States That Disk Patients Had the Most Significant

Findings, and Urges for Diagnostic Categorization of Patients for Future

Studies. It Is Proposed That the Lack of Diagnostic Criteria Is Responsible for the

Contradictory Findings of Earlier Investigators.

Conclusions

"Electromyography Has a Great Deal of "Electromyography Has a Great Deal of Practical Value in This Area And, Aside Practical Value in This Area And, Aside From Some General-but Important From Some General-but Important Observations Recorded Above, Much Observations Recorded Above, Much Remains to Be Learned by This Technique, Remains to Be Learned by This Technique, Especially About the Fine Functioning of Especially About the Fine Functioning of Various Areas and Depths of the Intrinsic Various Areas and Depths of the Intrinsic Muscles of the Back". Muscles of the Back".

Basmajian and Deluca Basmajian and Deluca