How is muscle power (strength) graded using the Medical Research Council (MRC) scale?

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Medical Research Council (MRC) muscle power grading scale

The MRC scale grades muscle power from 0 (no visible contraction) to 5 (normal) relative to the maximum expected for the tested muscle. [1]

Grade 5 corresponds to normal muscle power. [2]

Grade 4 corresponds to movement against gravity and resistance. [2]

Grade 3 corresponds to movement against gravity over (almost) the full range. [2]

Grade 2 corresponds to movement of the limb but not against gravity. [2]

Grade 1 corresponds to visible contraction without movement of the limb. [2]

Grade 0 corresponds to no visible contraction. [2]