1. Muscle Strength Testing
University of the Philippines Manila
COLLEGE OF ALLIED MEDICAL PROFESSIONS
PT 142 Assessment in Physical Therapy
Mitch B. Encabo, MPA, PTRP
Edited for instruction by:
Aila Nica J. Bandong, PTRP

2. LEARNING OBJECTIVES
At the end of the session the students should be able to:
Define muscle strength and their functional implications
Discuss basic considerations in performing muscle strength testing
Differentiate methods of doing muscle strength testing
Discuss Daniels and Worthingham’s manual muscle testing
Discuss modified tests used in assessing muscle strength
Instrumental muscle strength testing
Functional muscle strength testing
Discuss probable conditions that require modifications of the standard technique

3. MUSCLE STRENGTH TESTING
Refers to the determination of the strength of a muscle or muscle group
Does not reflect muscle function
Test based on the
Effective performance of movement
Manual resistance
Gravity

4. MUSCLE STRENGTH TESTING
Purpose
Diagnostic
Examine the improvement or deterioration of a patient’s status over time
Predictive or prognostic tool
Determine the extent of strength loss
Outcome measures in clinical research
Determine the need for compensatory measures or assistive devices
Helps in the formulation of the treatment plan
Evaluates the effectiveness of treatment

5. MUSCLE STRENGTH vs ENDURANCE
Force production
Voluntary exertion in one maximal effect
Results in isotonic or isometric contractions
Gross indicator of functional ability
Muscle Endurance
Repeated contractions
Maintenance of isometric contraction

6. MUSCLE WEAKNESS
Any reduction of the normal ability of the muscle to generate force
Causes:
Muscle strain
Pain, reflex inhibition
PNI, Nerve root lesion, UMNL
Tendon pathology, avulsion, rupture
Prolonged disuse/immobilization
Psychological overlay

7. Evaluation of muscle strength
Test performance
Evaluation of muscle strength
TEST COMPONENTS

8. Test Performance Muscle origin, insertion and action
Function of participating muscles
Patterns of substitution
Ability to detect contractile activity
Ability to palpate muscle or tendon
Ability to detect atrophy
Recognize abnormal position or movement

9. Test Performance
Awareness of deviation from normal ROM , laxity or deformities
Identify muscles with the same innervation
Relationship of diagnosis to sequence and extent of test
Ability to modify test procedures as necessary
Effect of fatigue
Effect of sensory loss and movement

10. Evaluation of Muscle Strength
Detect substitution whenever weakness exist
Accurate grading of muscle strength

11. BASIC CONSIDERATIONS Observation Palpation Positioning Stabilization
Resistance
Validity and reliability

12. Observation and Palpation
Observe the size and contour of muscles
Palpate contractile tissues

13. Positioning Patient comfort Depends partly on the effect of gravity
Use position that offers the best fixation of the body as a whole
Use antigravity positions as applicable
Two jointed muscles

14. Stabilization Proximal attachment of muscles
Used to isolate the desired action to a specific joint
Stabilize the part proximal to the part being tested
Stabilization of the proximal attachment of the muscle through:
Muscle tension
Gravitational pull
External pressure from
manual stabilization

15. Resistance Force that acts in opposition to a contracting muscle
Applied in the direction opposite the line of pull
Must never be sudden or jerky
Applied gradually, but not to slowly, to allow the patient to “get set and hold”
Applied uniformly
Long lever arm vs Short lever arm
Break test vs Active resistance test

16. Active Resistance Test
Break Test
Resistance applied at the end range
Patient is asked to hold the part at a point and examiner “breaks it”
Active Resistance Test
Application of manual resistance against actively contracting muscles
Examiner gradually increases resistance until maximum tolerance

17. Validity and Reliability
Inherent limitation
Types of muscle contractions
Rate of tension development
Affected by
Difference in testing methods
Magnitude of resistance
Force application, point of application, speed
Factors
Patient factors
Therapist factors
Environmental factors
Others

18. Validity and Reliability
Patient Factors
Age
Gender
Pain
Fatigue
Lower motor
neuron disease
Spasticity
Therapist factors
Experience
Manner and content
of instructions
Interaction
Environmental factors
Temperature
Distractions
Other factors
Muscle factors
Psychological factors
Methodological factors

19. Muscle Strength Testing
METHODS
Muscle Strength Testing
Instrumental
Manual
Functional

20. Daniels and Worthingham
METHODS OF MMT
Daniels and Worthingham
Motion
* Gradually increasing
* Maximum at end-range
Concentric to isometric
Numerical or qualitative scores
Kendall
Individual muscles
Maximum at midrange
Isometric
Percentages
What is being tested?
Resistance
Type of Contraction
Method of Grading

21. Daniels and Worthingham MMT
Criteria used in assigning a muscle grade
Factors considered include the following:
Subjective Factors
Examiner’s impression of the amount of resistance to give before the actual examination
Amount of resistance that the patient tolerates during the actual test
Objective Factors
Ability of the patient to move the body part against gravity
Ability of the patient to complete full range of motion
Ability of the patient to hold the position once at the end of the range of motion
Other Factors
Amount of manual resistance applied
Ability of the muscle to move the part through the full ROM
Effect of gravity
Evidence of contraction

22. Daniels and Worthingham MMT: GRADING
Normal ( N or 5 )
Full range against maximum resistance and gravity
Good ( G or 4 )
Full range against moderate resistance and gravity
“Gives” or “yields” at the end of the range given maximum resistance
Functional threshold for the lower extremity
Fair Plus ( F+ or 3 )
Full range against mild resistance and gravity
“Gives” or “yields” to some extent at the end of its range given moderate or maximum resistance
For users of orthosis
Fair ( F or 3 )
Full range against gravity
“Gives” at the end of the range against mild resistance
Functional threshold for the upper extremities

23. Daniels and Worthingham MMT: GRADING
Poor ( P or 2 )
Full range, gravity eliminated
Poor Minus ( P- OR 2 - )
Partial range gravity eliminated
Trace ( T or 1 )
Visible or palpable contraction
No movement of the body part
Zero (0)
No visible or palpable contraction

24. How to Document???
All muscles of the trunk and extremities are grossly graded 5/5 EXCEPT: ® Shoulder abductors – 3/5 ® Knee flexors – 3/5 Significance: Muscle weakness 2 to deconditioning

25. How to Document??? All the muscles of the wrist and hand are grossly
BREAK TEST
All the muscles of the wrist and hand are grossly
graded 5/5 EXCEPT:
® wrist flexors – 4/5
® radial deviators – 4/5 ( 10 deg )
Significance: Muscle weakness 2 to pain brought about by reflex inhibition

26. How to Document???
RANGE TEST
All of the muscles of the lower limb are grossly graded as 5/5 EXCEPT for
® hip extensors = 4/5 (0-90 degrees)
® hip adductors = 4/5 (0-20 degrees)
Significance: Muscle weakness due to prolonged immobilization, range test was used 2 to contractures of the hip flexors and adductors

27. Daniels and Worthingham MMT: LIMITATIONS
Presence of UMNL/ Spasticity
Presence of joint instability due to chronic flaccidity
Presence of severe contractures

28. Daniels and Worthingham MMT: AREAS/CONDITIONS THAT REQUIRE MODIFICATIONS
Hands and toes
Face
Neck
Weight bearing muscles
Children

29. Hands and Toes
Weight is minimal so effect of gravity is unimportant and need not be considered
Tested in either gravity eliminated or gravity-assisted position
Grading:
5 Full range with max resistance
4 Full range with mod resistance
3 Full ROM (whether gravity eliminated or assisted)
2 Partial ROM (whether gravity eliminated or assisted)
1 Palpable or observable flicker of muscle contraction

30. Face
Not always practical or possible to palpate muscle, apply resistance, or position the patient
Grading:
N/F (N)or light impairment
Completes test movement with ease and control
WF Moderate impairment that affects the degree of active motion
Performs test with difficulty
NF Severe impairment
Minimal muscle contraction
0 Absent

31. Weight Bearing Muscles
Neck
Using gravity eliminated position when testing for neck flexion and extension is impractical
A muscle grade of 2 is assigned when the patient can complete partial ROM while in a gravity resisted position
Weight Bearing Muscles
To be resisted maximally, some muscles require the assistance of body weight
For gastrocnemius and soleus only

32. Children May not cooperate with standard MMT procedures
2-5 y/o can initiate test position, but they cannot sustain it because they don’t understand the concept of exerting counterforce vs examiners resistance
Needs to be modified for 4-6 y/o

33. Daniels and Worthingham: MODIFIED TESTS
Combined tests for the extremities
Quickie tests
Squatting
Walking on heels and toes
Break test
Movement cannot be totally prevented but can be minimized by telling the patient “don’t let me move you”
Evaluation of functional activities
Donning and doffing
Gripping the examiners hand

34. Daniels and Worthingham: CONSIDERATIONS
Always start the test at grade 3
In case a movement needs to be tested in the non-standard position , indicate the position used
When in doubt about the grade assigned to a muscle group place a (?) beside the grade
Note special cases ( MMT of fingers or toes, UMNL )
Freedom from discomfort or pain
Quiet non-distracting well ventilated environment
Adequately firm and wide plinth with adjustable height
Minimal position changes
Presence of all materials needed for the test

35. Instrumented Muscle Testing
Advantage: increases the level of accuracy and reliability of strength testing
Instruments/ devices
Cable tensiometer
Strain gauge
Hand-held dynamometer
Modified sphygmomanometer
Grip strength dynamometer
Pinch meter

36. Cable Tensiometer

37. Strain Gauge

38. Hand-held Dynamometer

39. Modified Sphygmomanometer

40. Pinch Meter

41. Instrumented Muscle Testing: LIMITATIONS
Measures isometric strength only
Not useful for testing trunk strength
Instrumented Muscle Testing: CONSIDERATIONS
Reliability is reasonable
Important to standardize strength
Instruments are not interchangeable

42. Dynamic Muscle Testing
Makes more sense since muscles function dynamically
Machine use: Isokinetic machines

43. Isokinetic Testing Machine: LIMITATIONS
Validity has not yet been established
Movement occurring at constant speed is artificial
Positions and movement constraints are not realistic

44. Functional Muscle Testing
Utilized in cases when muscle strength cannot be tested by MMT:
Presence of spasticity and flaccidity
Patients with poor comprehension
Patients who are unable to follow instructions
Observations and description of certain movements or activities of the patient

45. REFERENCES
Clarkson & Gilewich(1989), Musculoskeletal Assessment. Joint Range of Motion and Manual Muscle Strength: Williams & Wilkins. Erickson and McPhee(1993) Clinical Evaluation. In Delisa: Rehabilitation Principles and Practice (2nd ed). Philadelphia: JB Lippincott Company. Harms - Ringdahl(1993)International Perspectives in Physical Therapy.Muscle Strength. New York: Churchill Livingstone. Hislop and Montgomery(2002): Daniels and Worthingham’s Muscle Testing: Techniques of Manual Examination(7th ed) Philadelphia:WB Saunders Company. Kendall,McCreary, Provance: Muscle Testing and Function (4th ed)Baltimore: Williams and Wilkins, Magee(1997) Orthopedic Physical Assessment(3rd ed) Philadelphia: WB Saunders Company. Tobis and Hong (1990) Muscle Testing in Kottke and Lehmann: Krusen’s Handbook of Physical Medicine and Rehabilitation (4th Ed) Philadelphia:WB Saunders Company