Manual Muscle Testing: Introduction

Introduction to Manual Muscle Testing for an Active Population

by Brent Brookbush DPT, PT, COMT, MS, PES, CES, CSCS, ACSM H/FS

Definition:

Manual Muscle Testing - A test performed via the application of external resistance by the practitioner, in an attempt to stress a specific muscle(s) to determine whether that muscle is sufficiently active/strong enough to meet the demands of daily activity (including sport). A solid foundation of knowledge in musculoskeletal anatomy is a prerequisite, as testing positions, range of motion (ROM), resistance and identifying compensations will be dependent on the size, function and actions of the muscle being tested, the muscles crossing proximal joint structures, and the structure of those joints (1, 2).
Active Population - A population of individuals who are functionally independent, and are most often active for recreation, exercise for reasons of health and fitness, or those individuals who play in sports either for recreation or profession.

Why Manual Muscle Testing (MMT)?

In orthopedic rehabilitation, fitness and performance enhancement facilities, manual muscle testing (MMT) is most often used to refine exercise/intervention selection. Most often, reliable and relevant MMTs highlight weakness/inhibition, implying which activation and integration exercises may be appropriate. In essence, manual muscle testing will assist the human movement professional in building a more refined activation protocol or integrated/movement prep warm-up. MMT's may also highlight compensation or synergistic dominance implying a need for mobility techniques (3-6).

Manual Muscle Testing (MMT) of the Tibial Internal Rotators

What's in a name?

manual (adj.) c. 1400, from Latin manualis "of or belonging to the hand; that can be thrown by hand," from manus "hand, strength, power over; armed force; handwriting," from PIE *man- (2) "hand" (source also of Old Norse mund "hand," Old English mund "hand, protection, guardian," German Vormund "guardian," Greek mane "hand"). (Etymology online )

"Manual" - An important term for every human movement professional to understand! In a clinical, fitness or performance setting, the word "manual" implies that the practitioner is going to use their hands (or bodies) to perform or resist an action by the patient/client, i.e. "manual stretching," "manual release" or "manual resistance." The ability of a practitioner to use "manual" techniques is commonly used to define the boundaries of the scope of practice of a human movement professional. For example, a personal trainer cannot legally perform manual release techniques, just as a licensed massage therapist cannot legally perform manual joint mobilizations (in most states). Be careful to mind the laws regarding scope of practice in the state that you currently work.

muscle (n.) late 14c., from Middle French muscle "muscle, sinew" (14c.) and directly from Latin musculus "a muscle," literally "little mouse," diminutive of mus "mouse" (see mouse (n.)). So called because the shape and movement of some muscles (notably biceps) were thought to resemble mice. The analogy was made in Greek, too, where mys is both "mouse" and "muscle," and its comb. form gives the medical prefix myo- . Compare also Old Church Slavonic mysi "mouse," mysica "arm;" German Maus "mouse; muscle," Arabic 'adalah "muscle," 'adal "field mouse." In Middle English, lacerte, from the Latin word for "lizard," also was used as a word for a muscle. (Etymology Online )

The use of the word muscle implies these tests are specific to the muscular system; although other systems may affect results. For example, these tests would not be reliable for the assessment of joint impairment, and/or fascial impairment, and although gross weakness may imply neural involvement, further testing would be needed to confirm a diagnosis.

test (v.) 1748, "to examine the correctness of," from test (n.), on the notion of "put to the proof." Earlier "assay gold or silver" in a test (c. 1600). Meaning "to administer a test" is from 1939; sense of "undergo a test" is from 1934. Related: Tested; testing. (Etymology Online )

The use of the word test implies that this is a means of determining the "correct" amount of muscle strength. An assessment should be reliable, specific, sensitive and relevant to the practice of rehabilitation, fitness or sports performance.

A lecture by Dr. Brent Brookbush for Rowan University, "Introduction to Functional Anatomy"

Prerequisite Knowledge:

A solid foundation of knowledge in musculoskeletal anatomy is a prerequisite, as testing positions, range of motion (ROM), resistance and identifying compensations will be dependent on the size, function and actions of the muscle being tested, the muscles crossing proximal joint structures, and the structure of those joints.
Understanding the basics of postural dysfunction , human movement science and what muscles are likely to exhibit under-activity is essential for selecting the appropriate muscle tests for a given dysfunction. Below is a list of commonly under-active muscles (also displayed in the template above):
It is the recommendation of the Brookbush Institute that a gross dynamic movement assessment, such as the Overhead Squat Assessment , is used to highlight which body segment should be assessed further using Manual Muscle Testing. This will increase efficiency and relevancy of the assessment results.
Some experience with corrective/therapeutic exercise (and the Overhead Squat Assessment ) is also recommended prior to adding Manual Muscle Testing to your assessment/evaluation process. This ensures that the practitioner has some practical suggestions for the client/patient based on assessment findings.

This is a "must have" text for any human movement professional. Not only for descriptions of the tests themselves, but as a detailed reference for muscular anatomy, function, and common musculoskeletal complaints.

Kendal's Basic Rules of Procedure that Apply to Muscle Strength Testing (quoted from Kendall et. al (1))

Place the subject in a position that offers the best fixation of the body as a whole (usually supine, prone, or side-lying).
Stabilize the part proximal to the tested part or, as in the case of the hand, adjacent to the tested part. Stabilization is necessary for specificity in testing.
Place the part to be tested in precise anti-gravity test position, whenever appropriate, to help elicit the desired muscle action and aid in grading.
Use test movements in the horizontal plane when testing muscles that are too weak to function against gravity. Use test movements in antigravity positions for most trunk muscle test in which body weight offers sufficient resistance.
Apply pressure directly opposite the line of pull of the muscle or the muscle segment being tested. Like that anti-gravity position, the direction of pressure helps to elicit the desired muscle action.
Apply pressure gradually but not too slowly, allowing the subject to "get set and hold." Apply uniform pressure; avoid localized pressure that can cause discomfort.
Use a long lever whenever possible, unless contraindicated. The length of the lever is determined by the location of the pressure along the lever arm. Better discrimination of strength for purposes of grading is obtained through use of a long lever.
Use a short lever if the intervening muscles do not provide sufficient fixation for use of a long lever."

Brookbush Institute modifications of Manual Muscle Testing (MMT) for an Active Population

Mobility techniques may precede MMTs to ensure testing occurs through previously lost ROM.
Additional cuing to reciprocally inhibit commonly over-active synergists may be used to make testing more provocative.
Any additional joint actions performed by the patient/client will be noted as potential compensation.
Additional resistance may be used to approximate forces of sporting activity.
Side-to-side comparison may be beneficial for those patients/clients who present with asymmetrical dysfunction (e.g. unilateral shoulder pain, unilateral knee pain, asymmetrical weight shift, etc.), but test "strong without compensation" during initial testing.
Anti-gravity positions are not discussed in these articles, due to the patient/client population seen by "human movement professionals" - that is, focus is placed on orthopedic outpatient, otherwise healthy, and often either recreationally active or athletic individuals (patients/clients). (We do advocate learning anti-gravity positions for any professional interested in treating neurologic dysfunction, geriatric populations, and/or working in an inpatient settings)
The Kendal et al. scale is replaced with simpler more reliable scale for this patient population.

Kendal et al., Muscle Testing and Function Scale:

Brookbush Institute Scale:

Strong - The patient/client can resist considerable force in the testing position, without signs of compensation.
Weak - The patient/client cannot resist even moderate force in the testing position, and "gives way."
With Compensation - The patient/client attempts to alter the testing position as a means of matching resistance (for example, adopting a hip flexed and abducted position during gluteus medius manual muscle testing )
With Pain - The testing position, and/or resistance in the testing position causes pain.
- This result implies that referral to a medical professional (physical therapist, chiropractor, athletic trainer, physician, etc) is likely necessary. Mind your scope!

Note: The muscles listed on the template match the muscles that are commonly addressed with Activation and Integration Techniques

What are we testing?

Length/Tension relationships, Under-activity and Weakness

Manual Muscle Testing for an Active Population should likely be used to assess under-active muscles, refine the selection of activation and integration techniques , and as a means of re-assessing the effectiveness of the techniques selected.

Under-active - When used to refer to skeletal muscle, this term refers to diminished tone; diminished resistance to passive stretching, diminished muscle activity either statically or dynamically, and/or latent or delayed firing/recruitment. Synonymous with the terms hypotonic, inhibited and phasic, and may be related to altered reciprocal inhibition, arthrokinematic inhibition and/or increased resting length.
Length/Tension Relationship - The relationship between the amount of tension a muscle fiber may produce, and the length of the muscle relative to resting length. The relationship could be described as a slightly left skewed inverted-U, where maximal force output is noted closed to mid-range, and less force can be produced as a muscle fiber becomes shortened or lengthened toward end range.

Length Tension Relationship - Note that maximal force is produced close to middle of range and that the amount of tension produced decreases as a muscle is lengthened or shortened.

The Problem with Assessing "Weak" Muscles:

The term "weak" relative to human movement science, assessment and intervention is a "poor choice" of terminology, because it implies a need for activation and/or strengthening. The quandary is that length/tension relationships dictate that both short and long muscles (over-active and under-active) muscles may test "weak", despite the propensity of short muscles to become over-active. Applying activation techniques to "weak" over-active muscles, may further exacerbate dysfunction rather than correct the "weakness" noted. For example, it is common to note "weakness" in the short hip flexors in those with an anterior pelvic tilt , despite the decrease in length. Does that imply they should be activated/strengthened? You may find it surprising, or counter-intuitive, but this muscle group will often test "strong" when release and lengthening techniques return normal extensibility and tone.

The Brookbush Institute recommends MMTs are applied to muscles that have been hypothesized as long/under-active based on gross movement assessment/dynamic postural assessment (overhead squat assessment ). For example, an individual exhibiting an anterior pelvic tilt, exhibits increased length and a decrease in activity of those muscles that would prevent excessive hip flexion. The gluteus maximus MMT could be used to confirm that hypothesis and reassess post intervention.

Altered Length/Tension Relationships Lecture:

Commonly Under-active Muscles:

Fortunate for the practitioner, certain muscles have a propensity toward under-activity. Various texts have discussed this tendency, most commonly referring to these muscles as “phasic” (long/underactive) (2 -5). It is for the list of commonly under-active (phasic) muscles that "Manual Muscle Tests for an Active Population" will be described in the following articles, with a result of "weak" or "with compensation" implying a set of activation exercises for the same muscles.

How much external Resistance?

"A Moderate Amount?" - This is where knowledge, experience and the "art of practice" meet. The term "moderate force" implies that a force is applied to the muscle that is sufficient to approximate the normal amount of stress the muscle may encounter during functional tasks. The amount of force applied is going to depend on the size of the muscle, it's function, testing position, and the size and conditioning of the individual. Learning the appropriate amount of force to apply in each test is dependent on your comparison of many individuals with and without dysfunction. Practice, experience, and when possible, a good mentor, are essential to performing these assessments well.

Serratus Anterior Manual Muscle Test

The Difference Between a Good Test and a Bad Test:

Good tests, assessments and evaluations are both reliable and relevant -

Reliability - the overall consistency of a measure.
- Reliability refers to the ability of a test or assessment to produce consistently accurate results, time-after-time, regardless of who is performing the assessment. If an assessment cannot produce consistent results, than a professional cannot determine the accuracy of a measurement, compare that measurement to normative data, or reassess and compare measurements taken on two separate dates. Although the psychometrics and statistics used to determine whether a test is truly reliable are a bit complex, the concept behind reliability is fairly simple and falls into to two broad categories.
  - Inter-tester reliability - assesses the agreement (or lack of) between two or more testers in their assessment.
  - Intra-tester reliability assesses the agreement (or lack of) between test scores from one test administration to the next (administered by a single tester).
Relevance - closely connected or appropriate to the matter at hand.
- Will the test you are using enhance the service you are offering? In my humble opinion, the actual impact an assessment has on application is not given enough credit. If the results of an assessment do not impact how you will proceed, that assessment is not relevant, and it should be discarded. Each test, assessment and evaluation used by the human movement professional should be chosen because the data from that assessment has a direct impact on practice.

Deep Cervical Flexor Isolated Activation

Why Assess?

Why should the human movement professional place so much weight on assessments?

Assessment - is the act of assessing, i.e. determining the importance, size, or value of - (Dictionary ).

In most cases, the results of an assessment are compared to "normative data." If the individual exhibits values that are within normal parameters than it may be assumed that the aspect of health or motion assessed is not contributing to the patient's complaint or movement impairment. If the results fall outside of normal parameters, it may indicate that the aspect of health or motion assessed is contributing to, or being affected by the patient's complaint or movement impairment. In some cases, the results of an assessment are compared to an "ideal model." In this case, deviations from the ideal are noted as potential issues. For example, deviations noted in the Overhead Squat Assessment are compared to an "ideal model" of posture and movement.

Assessments used by human movement professionals could be divided into three broad categories:

"Clear" the Patient/Client for Intervention - Test, assessments and evaluations used to determine if a patient/client's issue may improve given the assessing professionals scope, skills, abilities and willingness to treat that individual.
- For example: many of the special tests used in orthopedic medicine assist in determining the level of pathology at a joint, or imply the likelihood of a particular diagnosis. Certain issues and diagnoses are beyond the scope of the human movement professional, and are better treated by diagnostic professionals in the medical community (physicians, podiatrists, surgeons, etc.). A Calf Squeeze (Thompson) Test is one example, in which a positive sign may indicate a rupture of the achilles tendon and the need for surgical intervention.
Highlight Contraindications - Tests, assessments and evaluations used to stratify risk or preclude a professional from addressing certain tissues, motions or using a particular technique.
- For example, the Vertebral Artery Test (VBI) is often used to determine if high velocity thrust mobilizations (manipulations) are safe for a patient with cervical dysfunction. A PAR-Q is another example of this type of assessment that may imply that high intensity exercise is not safe or recommended for an individual with comorbidities.
Refine Exercise/Intervention Selection: Tests, assessments and evaluations used to assist the professional in determining which techniques, modalities and exercises will best address a patient/client's complaints or desired goals.
- Most movement assessments fall into this category. For example, a positive Ely Test may indicate a need to release and/or lengthen the rectus femoris .

Note: An assessment, or a particular set of signs on an assessment, may fall into more than one category. For example, although goniometry is an assessment most often used to Refine Exercise/Intervention selection, if a particular range of motion is significantly altered, with an abnormal end-feel, and/or causes the patient or client/pain, the individual may need to be referred to a physician for diagnosis. Further, that same patient may return to the human movement professional with physician prescribed limitations on activity. - "When in doubt, refer out!"

External Rotator Manual Muscle Test

How to use Manual Muscle Testing:

Now that you have read the definitions and descriptions, the above the paragraph titled "Why Manual Muscle Testing?" should make more sense:

In orthopedic rehabilitation, fitness and performance enhancement facilities, manual muscle testing (MMT) is most often used to refine exercise/intervention selection. Most often, reliable and relevant MMTs highlight weakness/inhibition, implying which activation and integration exercises may be appropriate. In essence, manual muscle testing will assist the human movement professional in building a more refined activation protocol or integrated/movement prep warm-up. MMT's may also highlight compensation or synergistic dominance implying a need for mobility techniques .

Once a gross movement assessment is administered (e.g. Overhead Squat Assessment ) to determine the segments that exhibit dysfunction and the compensatory motion, MMTs may be used to determine which under-active muscles may be contributing to that dysfunction. While a gross movement assessment can only imply that all structures at a joint have adopted compensatory changes in length, extensibility and activity - MMTs may implicate specific muscles. Although this may seem to imply that manual muscle testing is superior to gross movement assessment, the results of MMT's have to be considered relative to how the individual compensates during functional movement patterns. Generally, comparing MMTs to gross movement assessment results in one of 3 types of changes to a corrective exercise/intervention plan.

Reduces Potential Structures - Example, an individual exhibits "knees bow in " during an overhead squat assessment , "strong" during gluteus maximus MMT and "with compensation" during gluteus medius MMT . This may be additional evidence that the individual needs to release their tensor fasciae latae (TFL) and activate their gluteus medius , but it is unlikely that gluteus maximus activation is necessary.
Highlights Additional Structures - Example, an individual exhibits "arms fall " during the overhead squat assessment , 170° of shoulder flexion , but also tests "weak" during serratus anterior MMT . Despite this individual presenting with shoulder joint signs, it is likely that the addition of serratus anterior activation would be beneficial. Note: the relationship between scapula, thoracic and shoulder joint motion is intimately tied; the example above is a very common scenario, and is noted in several research studies - see Regional Interdependence.
Confirms Findings of Gross Movement Assessment - Example, an individual exhibits "knees bow out " during an overhead squat assessment , also exhibits "weak" or "with compensation" on tibialis anterior and tibialis posterior MMTs. Although this does not add or reduce the potential limiting structures, it does add an objective measure to the compensation noted.

Enjoy this preview from our upcoming Manual Muscle Testing articles:

Additional Articles on Manual Muscle Testing for an Active Population:

Bibliography:

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Questions, comments and critiques are welcome and encouraged.