Table 4.

MRC Grade Degree of Strength

5.	Normal strength.
5−	Barely detectable weakness.
4S	Same as 4 but stronger than reference muscle.
4	Muscle is weak but moves the joint against a combination of gravity and some resistance.
4W	Same as 4, but weaker than reference muscle.
3+	The muscle is capable of transient resistance but collapses abruptly. This degree of weakness is difficult to put into words, but it is a muscle that is able to move the joint against gravity and an additional small amount of resistance. It is not to be used for muscles capable of sustained resistance throughout their whole range of movement.
3	Muscle cannot move against resistance but moves the joint fully against gravity. With the exception of knee extensors, the joint must be moved through its full mechanical range against gravity. If a patient has contractures that limit movement of the joint, the mechanical range obviously will be to the point at which the contractures cause a significant resistance to the movement.
3−	Muscle moves the joint against gravity but not through the full extent of the mechanical range of the joint.
2	Muscle moves the joint when gravity is eliminated.
1	A flicker of movement is seen or felt in the muscle.
0	No movement.