Use of the medical research council muscle strength grading system in the upper extremity

The Medical Research Council of Great Britain (MRC) system is known and most commonly used muscle strength grading system for manual muscle testing (MMT) worldwide. The MRC system was intended to be used to grade recovery from paralysis attributable to nerve repair. Surgeons using early techniques of nerve repair were gratified to achieve grade 3 strength in a previously paralyzed muscle. Modern techniques may achieve better results and engender higher expectations of a measurement system. A new system of grading for MMT should retain the advantages of the MRC. Useful potential modifications of the MRC include a grade for a muscle that achieves strength against resistance but not against gravity and a standardized subdivision of grade 4. The MRC will continue to be used unless handheld dynamometer (HHD) is widely adopted or until a better grading system is developed and well validated.