Which statement corresponds to a muscle score of 5?

• A. 4 muscle score - active movement against gravity, and some resistance
• B. 3 muscle score - active movement against gravity
• C. 5 muscle score - active movement against full resistance w/o evident fatigue ('normal strength')
• D. 2 muscle score - active movement without gravity

Answer: (C)

Muscle strength is graded on a 0–5 scale during manual muscle testing. A score of 5 means normal strength: the muscle can actively move through its full range against maximal resistance with no evident fatigue. This is the highest grade, indicating the muscle can surmount full examiner resistance and still perform the movement smoothly. The other descriptions correspond to lower grades—4 is movement against gravity with some resistance, 3 is movement against gravity, and 2 is movement with gravity eliminated—so they don’t match normal strength.