Manual muscle testing grades

What is manual muscle testing?

Manual muscle testing (MMT) is a way to grade muscle strength with your hands and eyes, without equipment. You ask the patient to move. Then you look at the muscle and feel it with your fingers. When the patient can move against gravity, you add resistance with your hand. Paternostro-Sluga and colleagues (2008) trace the method to Lovett, as described by Wright in 1912, and describe it as a more qualitative method than measuring strength with a dynamometer.

A StatPearls review by Naqvi and colleagues lists the uses: finding neurological deficits, weakness in one area linked to musculoskeletal pain, and general weakness from deconditioning or aging. Clinicians, nurses, physical therapists, occupational therapists and chiropractors all use it.

The MRC muscle grading scale (0 to 5)

The Medical Research Council scale grades muscle power from 0 to 5 in relation to the maximum expected for that muscle. According to the MRC, it was first published in 1943 in "Aids to the Investigation of Peripheral Nerve Injuries" (War Memorandum No. 7). The 1976 edition, renamed "Aids to the Examination of the Peripheral Nervous System" (Memorandum No. 45), dates the pamphlet to 1941 with a revision in 1943.

The wording below is quoted from that 1976 edition. We checked it against a 1942 printing of War Memorandum No. 7, and the six grades are word for word the same.

The 1976 edition says: "It has long been customary to use a 0 to 5 scale for recording muscle power, but it is now generally recognised that subdivision of grade 4 may be helpful."

Plus and minus grades: 4-, 4 and 4+

The 1976 MRC edition adds one line under the scale: "Grades 4-, 4 and 4+, may be used to indicate movement against slight, moderate and strong resistance respectively." This is an option on top of the six-point scale, and it subdivides grade 4 only.

Other systems exist. Paternostro-Sluga and colleagues note that Kendall and McCreary grade with percentages, and Daniels and Worthingham with the words Normal, Good, Fair, Poor, Trace and Zero. We have not been able to check those textbooks directly, so this page does not convert between them. If your notes use a different system, name it, so the next person reads the grade the same way.

How is a muscle grade tested?

The MRC booklet sets the scene first. Test in a quiet room with a warm patient who knows what you are testing and why. Come back later if the patient or the examiner shows signs of tiring. Test one movement at a single joint where you can, and use the test positions shown in the booklet, because they avoid many "trick" movements.

As an example, this is the order Paternostro-Sluga and colleagues (2008) used to test wrist extension. The study wrote this order for its own modified scale; we show it here with the whole grades of the MRC scale.

1. Test against gravity first. The forearm was turned palm down, so lifting the hand works against gravity.
2. If the patient could not lift the hand against gravity, the forearm was turned halfway (thumb up) with the wrist straight. This was the gravity-eliminated position. The examiner felt the muscle: no contraction was grade 0, a contraction was grade 1, and a movement of more than 5 degrees was grade 2.
3. If the patient could lift the hand against gravity, that is at least grade 3. The examiner then added resistance with the forearm still palm down. Moving against resistance was grade 4, and matching the resistance of the other side was grade 5.
4. Each movement was tested 3 times and the best result was recorded.

The same study also tried a modified scale that adds in-between grades (2-3, 3-4 and 4-5), based mainly on how much of the range the patient can move. It is a research variant, not part of the MRC scale.

Build up your resistance over a few seconds rather than pushing suddenly. Ask the patient to keep breathing through the effort instead of holding their breath, especially if they have high blood pressure or heart disease. Do not resist a movement that is painful, or one near a recent fracture, an unstable joint, or a joint your surgeon has restricted after an operation. Leave it untested and write down why.

Where bone may be fragile, for example in severe osteoporosis or cancer that has spread to bone, use less resistance or leave the resisted part out. If pain stops the effort, record that next to the grade, because weakness from pain is not the same as weakness of the muscle.

Always look for the contraction and feel for it too. The MRC notes that how easily you can pick up a contraction depends on the patient's build.

MRC sum score calculator

The MRC sum score adds the grades of 6 muscle groups on both sides. Kleyweg and colleagues developed it in 1991 as a measure of overall muscle strength in Guillain-Barré syndrome. They reported almost perfect agreement between observers, and found it easy to assess and more sensitive than the functional score when patients were bedridden or on a ventilator.

The 6 movements are shoulder abduction, elbow flexion, wrist extension, hip flexion, knee extension and foot dorsiflexion, each graded 0 to 5 on the six-point MRC scale, as listed by Hough and colleagues (2011) and by Vanhoutte and colleagues (2012). Twelve scores of 0 to 5 give a total from 0 to 60.

The calculator is for clinicians recording their own examination. It adds up the grades you enter and does not diagnose any condition. The sum score uses the six-point scale, so if you recorded 4- or 4+, enter 4: the MRC defines both as steps within grade 4. The grades only mean something if the patient is awake and can follow what you ask. Hough and colleagues checked attention and understanding before every examination.

The sum score uses whole grades from 0 to 5 for each movement. If a movement cannot be tested, for example because of an injury or a medical device in the way, leave it as not tested. Hough and colleagues (2011) recorded such movements as missing, not as 0. To reach a total for their research, they then borrowed the grade of the same movement on the other side, or of a nearby muscle group on the same side. This calculator does not fill gaps: it shows a total only when all 12 movements are graded.

One published cutoff applies only to intensive care. In that research, intensive care unit-acquired weakness is defined as an MRC sum score below 48. Hough and colleagues explain this as average strength limited to movement against gravity and partial resistance. The cutoff was set for adults who became weak during critical illness. It is not a cutoff for other conditions or settings.

The same study shows how hard testing in the unit can be. Most eligible patients could not be tested at all because of coma, delirium or injury. In patients who could be tested, two observers' sum scores differed by 6 points or more in 23% of cases. Agreement on who had this weakness was only fair when patients were tested in the unit (kappa 0.38), compared with after they left it (kappa 1.0).

Limits of manual muscle testing

• It is subjective. The StatPearls review states that its reliability varies because judging resistance during testing is subjective.
• Grades 4 and 5 are harder to grade well. The MRC says its scale is more reliable and accurate in weak muscles (grades 0 to 3), while an analogue scale is more reliable and accurate for stronger muscles (grades 4 and 5). The MRC page does not name the comparison study.
• Grade 5 covers a wide range of strength. In the radial palsy study by Paternostro-Sluga and colleagues, 20 patients had grip rated grade 5, but on a dynamometer their affected hand had a median of 65% of the strength of the other hand. The authors warn that a wide range of strength levels is summarized under grade 5.
• Grade 4 is wide and its resistance is not defined. The same study notes that the MRC scale does not define how strong the resistance is or how much of the range the movement covers, and that slight, moderate and strong resistance depend heavily on the examiner. Vanhoutte and colleagues (2012) note that the scale has been criticized because grade 4 is too broad and grades 1 to 3 are too narrow. In their data from 1065 patients, physicians could not tell most MRC grades apart consistently.
• The grades in between are the hard ones. Agreement between examiners was substantial overall in the radial palsy study (weighted kappa 0.77 to 0.78 for the original MRC scale), but it fell when patients graded 0 or 5 were left out (0.26 to 0.62). Florence and colleagues (1992) studied boys with Duchenne muscular dystrophy, with the same physical therapist repeating the test on a modified MRC scale, and found that grades in the gravity-eliminated range were the most reliable.

Test the same way each time. Keep the position and instructions the same, and use the same examiner where you can. Paternostro-Sluga and colleagues advise training examiners together before comparing their grades.

If you notice sudden weakness yourself, especially in the face, arm or leg on one side, call your local emergency number. Weakness that spreads over hours or days also needs urgent medical care.

References

1. Medical Research Council. Aids to the examination of the peripheral nervous system. Memorandum No. 45 (superseding War Memorandum No. 7). London: Her Majesty's Stationery Office; 1976. ukri.org (PDF). MRC Muscle Scale used with the permission of the Medical Research Council, under the Open Government Licence 3.0, with plain language explanations added and the grade wording unchanged.
2. Medical Research Council, Nerve Injuries Committee. Aids to the investigation of peripheral nerve injuries. War Memorandum No. 7. London: His Majesty's Stationery Office; 1942 printing. Wellcome Library copy. archive.org
3. UK Research and Innovation. MRC Muscle Scale. ukri.org
4. Paternostro-Sluga T, Grim-Stieger M, Posch M, Schuhfried O, Vacariu G, Mittermaier C, Bittner C, Fialka-Moser V. Reliability and validity of the Medical Research Council (MRC) scale and a modified scale for testing muscle strength in patients with radial palsy. Journal of Rehabilitation Medicine. 2008;40(8):665-671. doi:10.2340/16501977-0235
5. Naqvi U, Margetis K, Sherman AL. Muscle strength grading. In: StatPearls. Treasure Island (FL): StatPearls Publishing; 2025. ncbi.nlm.nih.gov
6. Kleyweg RP, van der Meché FG, Schmitz PI. Interobserver agreement in the assessment of muscle strength and functional abilities in Guillain-Barré syndrome. Muscle and Nerve. 1991;14(11):1103-1109. doi:10.1002/mus.880141111
7. Hough CL, Lieu BK, Caldwell ES. Manual muscle strength testing of critically ill patients: feasibility and interobserver agreement. Critical Care. 2011;15(1):R43. doi:10.1186/cc10005
8. Vanhoutte EK, Faber CG, van Nes SI, et al. Modifying the Medical Research Council grading system through Rasch analyses. Brain. 2012;135(5):1639-1649. doi:10.1093/brain/awr318
9. Florence JM, Pandya S, King WM, Robison JD, Baty J, Miller JP, Schierbecker J, Signore LC. Intrarater reliability of manual muscle test (Medical Research Council scale) grades in Duchenne's muscular dystrophy. Physical Therapy. 1992;72(2):115-122. doi:10.1093/ptj/72.2.115

This page explains muscle strength grades for education. It is not a medical assessment.