Manual Muscle Testing Grading (MMT Grades) Overview

Manual muscle testing grading system (MMT Testing) is the most common method used by clinicians to evaluate muscles strength.
MMT utilizes a standardized grading system that is determined by the ability of the tested muscle act against gravity or against resistance applied by the examiner.
Manual Muscle Testing Grades
In 1916, Lovett and Martin first described the method of manual muscle testing in newborns with infantile paralysis. Since then, abundant research has been conducted regarding its various applications, including modifications of the original grading scale used to describe muscular strength.
Despite these modifications, the scale that is most widely accepted is very similar to the original proposal by Lovett and Martin and was devised by the Medical Research Council (MRC) in 1943.
The MMT Grades has six levels (Grades 0 to 5):
- Grade 0: No visible or palpable contraction.
- Grade 1: Visible or palpable contraction without motion.
- Grade 2: Full range of motion, gravity eliminated.
- Grade 3: Full range of motion against gravity.
- Grade 4: Full range of motion against gravity, moderate resistance.
- Grade 5: Full range of motion against gravity, maximal resistance.
Although the MMT grades is still widely used in clinical practice due to its low cost and rapidity, there are several limitations that must be noted:
- The first limitation is that the MMT scale is subjective in nature and the score depends on the clinician’s judgment.
- The second limitation of MMT is the inability of the scale to detect small, between-level differences in strength. This is largely due to the stepwise design of the scale and has spurred the development of other scales that have more diagnostic levels.
- Third, the MMT grades scale has been criticized for not being capable of detecting clinically relevant differences in muscle strength.
MMT Grades was originally developed to measure strength improvements in patients treated with paralytic disorders and muscular dystrophies. Thus, the application of MMT grades to a variety of clinical settings is probably due to tradition rather than sound scientific rationale. As a result of the subjectivity and reported inaccuracy of MMT, many clinicians (and insurers) prefer to measure strength with more objective means that are more sensitive, such as with handheld dynamometers.
See Also: Hip Muscles Anatomy

MMT Grades Testing Reiability
The inter- and intra-observer reliabilities of MMT grades in the evaluation of various pathologies resulting in muscle weakness range from 0.82 to 0.97 and 0.96 to 0.98, respectively, according to reports dating back to 1954. However, only a few studies have specifically examined the reliability of manual muscle testing for the evaluation of patients with various shoulder pathologies.
References
- Lovett RW, Martin EG. Certain aspects of infantile paralysis with a description of a method of muscle testing. JAMA. 1916;66:729–33.
- Naqvi U, Sherman Al. Muscle Strength Grading. [Updated 2021 Sep 2]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK436008/
- Barr AE, Diamond BE, Wade CK, Harashima T, Pecorella WA, Potts CC, Rosenthal H, Fleiss JL, McMahon DJ. Reliability of testing measures in Duchenne or Becker muscular dystrophy. Arch Phys Med Rehabil. 1991 Apr;72(5):315-9. PMID: 2009048.
- Wadsworth CT, Krishnan R, Sear M, Harrold J, Nielsen DH. Intrarater reliability of manual muscle testing and hand-held dynametric muscle testing. Phys Ther. 1987;67(9):1342–7.
- Cibulka MT, Weissenborn D, Donham M, Rammacher H, Cuppy P, Ross AS. A new manual muscle test for assessing the entire trapezius muscle. Physiother Theory Pract. 2013;29(3):242–8.
- Aitkens S, Lord J, Bernauer E, Fowler Jr WM, Lieberman JS, Berck P. Relationship of manual muscle testing to objective strength measurements. Muscle Nerve. 1989;12(3):173–7.
- Li RC, Jasiewicz JM, Middleton J, Condie P, Barriskill A, Hebnes H, Purcell B. The development, validity, and reliability of a manual muscle testing device with integrated limb position sensors. Arch Phys Med Rehabil. 2006;87(3):411–7.
- Toonstra J, Mattacola CG. Test-retest reliability and validity of isometric knee-fl exion and -extension measurement using 3 methods of assessing muscle strength. J Sport Rehabil 2013;Technical Notes(7). pii: 2012–0017.
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