Muscle Strength Grading


Article Author:
Usker Naqvi


Article Editor:
Andrew Sherman


Editors In Chief:
Andrew Sherman
Richard Kaplan


Managing Editors:
Avais Raja
Orawan Chaigasame
Carrie Smith
Abdul Waheed
Khalid Alsayouri
Frank Smeeks
Kristina Soman-Faulkner
Radia Jamil
Patrick Le
Sobhan Daneshfar
Anoosh Zafar Gondal
Saad Nazir
William Gossman
Pritesh Sheth
Hassam Zulfiqar
Navid Mahabadi
Steve Bhimji
John Shell
Matthew Varacallo
Heba Mahdy
Ahmad Malik
Mark Pellegrini
James Hughes
Beata Beatty
Nazia Sadiq
Hajira Basit
Phillip Hynes
Tehmina Warsi


Updated:
7/1/2019 4:43:47 PM

Introduction

Muscle strength testing is an important component of the physical exam that can reveal information about neurologic deficits. It is used to evaluate weakness and can be effective in differentiating true weakness from imbalance or poor endurance. It may be referred to as motor testing, muscle strength grading, manual muscle testing, or many other synonyms. The muscle strength evaluation may be performed by nurses, physicians, physical therapists, occupational therapists, chiropractors, and other practitioners.

Function

The function of muscle strength testing is to evaluate the complaint of weakness, often when there is a suspected neurologic disease. It is an integral part of the neurologic exam, especially for patients with stroke, brain injury, spinal cord injury, neuropathy, amyotrophic lateral sclerosis, and a host of other neurologic problems.

The most commonly accepted method of evaluating muscle strength is the Medical Research Council Manual Muscle Testing scale. This method involves testing key muscles from the upper and lower extremities against the examiner’s resistance and grading the patient’s strength on a 0 to 5 scale accordingly:

  • 0 No muscle activation
  • 1 Trace muscle activation, such as a twitch, without achieving full range of motion
  • 2 Muscle activation with gravity eliminated, achieving full range of motion
  • 3 Muscle activation against gravity, full range of motion
  • 4 Muscle activation against some resistance, full range of motion
  • 5 Muscle activation against examiner’s full resistance, full range of motion

Commonly tested muscles include the shoulder abductors, elbow flexors, elbow extensors, wrist extensors, finger flexors, hand intrinsics, hip flexors, knee extensors, dorsiflexors, great toe extensor, and plantar flexors. These muscle groups are commonly chosen, so that important spinal nerve roots are assessed systematically; however, further muscles can be tested to evaluate individual peripheral nerves. For example, testing the strength of the elbow flexors, elbow extensors, wrist extensors, finger flexors, and hand intrinsics allow for a methodical evaluation of the C5 to T1 nerve roots. However, one could more specifically test the thumb abductors to evaluate the median nerve and the abductor digiti minimi to evaluate the ulnar nerve. [1][2][3]

Issues of Concern

Proper technique must be employed during testing to ensure valid results. Tight or restrictive clothing should be removed so that the examiner can visualize the muscles being tested and observe for muscle twitch. The examiner should also stabilize the joint and ensure that other muscles do not provide assistance. Muscles should first be tested with gravity eliminated by positioning the patient, so that muscle contraction is perpendicular to gravity, such as along an examining table or bed. If the patient is unable to engage the muscle with gravity eliminated, the examiner should place a hand on the muscle and ask the patient to contract his or her muscles again. This allows the examiner to feel for a muscle twitch, even if a twitch is not visible. This observation would differentiate a score of 0 from a score of 1. When the patient demonstrates the full range of motion with gravity eliminated, the test should be repeated against gravity for the full range of motion. If this is successful, the patient should be challenged by the addition of a small degree of resistance, then maximal resistance by the examiner. The unaffected or less affected side should be tested first to gauge contralateral strength for comparison; all four limbs should be tested for completeness and to help guide the differential diagnosis based on patterns of weakness, such as upper extremity only, lower extremity only, or proximal muscles rather than distal. [2]

The Medical Research Council Manual Muscle Testing method is very common, easy to perform, and does not require any specialized equipment. Despite these advantages, it also has its limitations. Scoring is subjective based on the examiner’s perception. There is variability between examiners for the maximal resistance they are able to apply, as some examiners are stronger than others. The test does not account for musculoskeletal conditions that may make testing painful or difficult to tolerate, such as tendinopathy or arthritis. The test is dependent on patient effort, which may be poor in some patients, owing to pain, proper comprehension of instructions, psychological causes, or secondary gain. Finally, the grading system classifies strength level but does not directly quantify strength. [4]

The Alternatives to the Medical Research Council Manual Muscle Testing system aims to quantify strength directly in terms of pounds, Newtons, or other units. This requires specialized equipment, most commonly dynamometers. Dynamometry provides a more precise measurement of the force that a muscle can exert and can allow for differences in strength to be tracked over time that an examiner may not subjectively notice when using the MRC scale. Hand-grip dynamometry is a popular example, in which the patient squeezes a handle that records the force being applied. Limitations of dynamometry include the need for costly or specialized equipment, limited muscle groups that can be tested, and limited availability of testing equipment to clinicians across specialties or settings. [5]

Another approach to muscle strength testing involves testing functional movements instead of quantifiable strength. Examples of functional tests include squatting or rising from a chair. Functional strength tests provide information about whether the patient is strong enough to perform essential daily activities, a limitation of both the Medical Research Council Manual Muscle Testing method and dynamometry. However, functional strength tests do not provide a grade or numeric quantity that can be tracked over time to gauge improvement. [5]

Clinical Significance

Muscle strength testing can help a practitioner diagnose neurologic problems in which weakness is a prominent deficit. The muscles targeted for testing should be methodically chosen based on suspected diagnoses and for complete characterization of the strength deficit in various limbs. Careful technique is important for ensuring valid and reproducible results. The Medical Research Council Manual Muscle Testing method is commonly accepted, performed across several disciplines, does not require special equipment, and demonstrates reasonable interrater reliability. More precise methods of measurement, such as hand-grip dynamometry, are less subjective and provide a quantifiable measurement that can be tracked over time. Functional assessment of strength focuses on how independently patients are able to perform their activities of daily living and whether strength is a limiting factor.

In patients with fictitious or hysterical weakness, the initial resistance to movement may appear normal, followed by a sudden giving away. Or the individual may not be using the adjacent or other supportive muscles in an appropriate fashion.

Other Issues

Limitations of the Grading Scale

  • Muscle being tested may have no clinical relevance
  • There may be individual variation in reporting
  • Only assesses muscles which are contracting in a concentric manner
  • The scale may not be applicable in all patients

Enhancing Healthcare Team Outcomes

Muscle strength testing is an important component of the physical exam that can reveal information about neurologic deficits. It is used to evaluate weakness and can be effective in differentiating true weakness from imbalance or poor endurance. It may be referred to as motor testing, muscle strength grading, manual muscle testing, or many other synonyms. The muscle strength evaluation may be performed by nurses, physicians, physical therapists, occupational therapists, chiropractors, and other practitioners.


Interested in Participating?

We are looking for contributors to author, edit, and peer review our vast library of review articles and multiple choice questions. In as little as 2-3 hours you can make a significant contribution to your specialty. In return for a small amount of your time, you will receive free access to all content and you will be published as an author or editor in eBooks, apps, online CME/CE activities, and an online Learning Management System for students, teachers, and program directors that allows access to review materials in over 500 specialties.

Improve Content - Become an Author or Editor

This is an academic project designed to provide inexpensive peer-reviewed Apps, eBooks, and very soon an online CME/CE system to help students identify weaknesses and improve knowledge. We would like you to consider being an author or editor. Please click here to learn more. Thank you for you for your interest, the StatPearls Publishing Editorial Team.

Muscle Strength Grading - Questions

Take a quiz of the questions on this article.

Take Quiz
What is the correct muscle strength grading in a patient with no muscle movement?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A patient is able to reach the top shelf in a kitchen but the heaviest item they can put on the shelf is a small can of soup. How would this level of strength be rated?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
During assessment of muscle strength a patient shows grade 1 out of 5 wrist extension. What would be the word equivalent of this measure?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
A patient's should strength is being evaluated. The patient is able to fully flex the shoulder when lying on her side but when standing is only able to flex to 135 degrees. What is the strength of the muscles that flex the shoulder?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
What is the purpose of manual muscle testing?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Which of the following is appropriate during manual muscle testing?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
Manual muscle testing of the knee is standardly done in the sitting patient. What position should be used in a patient who cannot go through full ROM while seated?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
What muscle grade is characterized by full range of motion against gravity and minimal resistance?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
What muscle grade is characterized by full range of motion against gravity?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
What muscle grade is characterized by full range of motion against full resistance?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up
What muscle grade is characterized by full range of motion against no gravity or resistance?



Click Your Answer Below


Would you like to access teaching points and more information on this topic?

Improve Content - Become an Author or Editor and get free access to the entire database, free eBooks, as well as free CME/CE as it becomes available. If interested, please click on "Sign Up" to register.

Purchase- Want immediate access to questions, answers, and teaching points? They can be purchased above at Apps and eBooks.


Sign Up

Muscle Strength Grading - References

References

Manual muscle testing, development and current use., WILLIAMS M,, The Physical therapy review, 1956 Dec     [PubMed]
Variations in current manual muscle testing., WINTZ MM,, The Physical therapy review, 1959 Jul     [PubMed]
Manual muscle testing: a method of measuring extremity muscle strength applied to critically ill patients., Ciesla N,Dinglas V,Fan E,Kho M,Kuramoto J,Needham D,, Journal of visualized experiments : JoVE, 2011 Apr 12     [PubMed]
Manual muscle strength testing: intraobserver and interobserver reliabilities for the intrinsic muscles of the hand., Brandsma JW,Schreuders TA,Birke JA,Piefer A,Oostendorp R,, Journal of hand therapy : official journal of the American Society of Hand Therapists, 1995 Jul-Sep     [PubMed]
Aids to the investigation of peripheral nerve injuries. Medical Research Council: Nerve Injuries Research Committee. His Majesty's Stationery Office: 1942; pp. 48 (iii) and 74 figures and 7 diagrams; with aids to the examination of the peripheral nervous system. By Michael O'Brien for the Guarantors of Brain. Saunders Elsevier: 2010; pp. [8] 64 and 94 Figures., Compston A,, Brain : a journal of neurology, 2010 Oct     [PubMed]

Disclaimer

The intent of StatPearls is to provide practice questions and explanations to assist you in identifying and resolving knowledge deficits. These questions and explanations are not intended to be a source of the knowledge base of all of medicine, nor is it intended to be a board or certification review of Physical Medicine. The authors or editors do not warrant the information is complete or accurate. The reader is encouraged to verify each answer and explanation in several references. All drug indications and dosages should be verified before administration.

StatPearls offers the most comprehensive database of free multiple-choice questions with explanations and short review chapters ever developed. This system helps physicians, medical students, dentists, nurses, pharmacists, and allied health professionals identify education deficits and learn new concepts. StatPearls is not a board or certification review system for Physical Medicine, it is a learning system that you can use to help improve your knowledge base of medicine for life-long learning. StatPearls will help you identify your weaknesses so that when you are ready to study for a board or certification exam in Physical Medicine, you will already be prepared.

Our content is updated continuously through a multi-step peer review process that will help you be prepared and review for a thorough knowledge of Physical Medicine. When it is time for the Physical Medicine board and certification exam, you will already be ready. Besides online study quizzes, we also publish our peer-reviewed content in eBooks and mobile Apps. We also offer inexpensive CME/CE, so our content can be used to attain education credits while you study Physical Medicine.