The Medical Research Council (MRC) scale describes muscle strength using six grades from 0 to 5. The finding is assessed relative to the expected normal strength of the muscle examined[^2].
MRC muscle strength grades 0–5
Grade | Description |
M0 | No muscle contraction is apparent. |
M1 | Muscle contraction is apparent without movement of the limb. |
M2 | Movement is possible when gravity is eliminated. |
M3 | Movement against gravity is possible through almost the full range. |
M4 | Movement against gravity and additional resistance is possible. |
M5 | Muscle strength corresponds to the expected normal strength. |
This table adapts the wording of the MRC scale. Used with the permission of the Medical Research Council. © Crown Copyright. The scale is available under the Open Government Licence 3.0[^2].
Assessment against gravity and resistance
Grades 2, 3 and 4 distinguish movement with gravity eliminated, against gravity, and against additional resistance[^3]. A standardized examination position supports comparison between assessments[^1].
Limitations of the scale
The scale is less precise for small differences in stronger muscles. A more finely graded scale may be more suitable for assessing grades 4 and 5[^2].
Difference from the MRC sum score
An individual grade from 0 to 5 differs from the MRC sum score. The sum score adds the grades of six muscle groups on both sides of the body and ranges from 0 to 60[^3].