Muscle strength grading scale (0 to 5): what each grade means and how nurses chart it

Each grade and the bedside check that separates it from the next

The scale most nursing texts use is the Medical Research Council grading, which runs from 0 to 5. Every grade is defined by two questions: can the limb beat gravity, and can it hold against the examiner's hand? Working through those two questions in order gives a repeatable answer.

The jump from 2 to 3 is the one students mix up. Moving the arm across the sheet is grade 2, because the bed is carrying the weight. Lifting it off the sheet and holding it there, even briefly, is grade 3.

What 4/5 strength means and why it is easy to misread

A grade of 4/5 means the muscle beats gravity and holds against some resistance, but not the full push a healthy muscle would resist. MSD Manuals points out that the gap between grade 4 and grade 5 covers a large range of strength, so two clients charted at 4/5 can be quite different. If your unit uses plus or minus marks inside grade 4, follow local policy and use them the same way every time.

Because grade 4 is so wide, subtle weakness hides in it. MSD Manuals lists pronator drift of an outstretched arm as a sign of mild weakness, and suggests functional checks: rising from a squat or a chair tests the proximal leg muscles, while walking on heels and toes tests the distal ones. A client who scores 5/5 on a seated push test but cannot stand from a chair without using the arms has weakness the grade did not catch.

Charting strength so the next nurse can compare

Open RN Nursing Skills teaches the test as a side-by-side comparison: hand grasps together, then arms pulling and pushing against resistance, then legs. Strength is expected to be equal on both sides, although the dominant side is usually slightly stronger. Write the grade for each limb or muscle group, for example right grip 5/5 and left grip 4/5, rather than a single word such as weak.

A normal entry can be as short as the Open RN sample: upper and lower extremity strength rated 5 out of 5. In Open RN's table of expected versus unexpected musculoskeletal findings, strength of 3/5 or less is listed as unexpected, and a new unexpected finding is documented and reported to the provider. What makes a finding urgent is change, so compare against the last recorded grade, not only against normal.

Hypothetical practice case: grading a sudden one-sided change

Hypothetical scenario for practice, not a real exam item: a 72-year-old client admitted for pneumonia had 5/5 strength in all limbs on admission. Six hours later the nurse finds the left arm lifts off the bed but drops when lightly pushed, and the left leg slides along the sheet but cannot be raised. The right side holds against full resistance.

The weak answer here is to chart the grades and recheck at the next scheduled assessment. A new one-sided loss of strength is a neurological change, so the nurse checks the rest of the neuro picture, such as speech, facial symmetry and level of consciousness, and escalates under the facility's rapid response or stroke protocol.

When the 0 to 5 grade misleads

The scale measures the effort the client can give, so anything that limits effort lowers the grade without true weakness. Pain is the common one: Open RN advises never to examine to the point of pain, and a client guarding a painful shoulder may score 3/5 with normal muscle. Older adults may also have limited mobility and range of motion from joint changes, which the nurse should note beside the grade.

The grade also assumes the client understands the instruction. A drowsy or confused client may not push on command, so a low grade then says more about cognition than about the muscle. In that case, describe what you saw, such as spontaneous movement of all four limbs, and use a tool built for altered consciousness instead.

Sources and further reading

MSD Manual Professional Version: How To Assess Muscle Strength. MRC 0 to 5 grade definitions, the large range between grades 4 and 5, pronator drift as a subtle weakness sign, rising from a squat or chair for proximal and heel and toe walking for distal strength, comparing sides.

Open RN Nursing Skills 2e: 13.4 Musculoskeletal Assessment. Muscle strength scale used in nursing assessment, strength expected equal bilaterally, not examining to the point of pain, older adult mobility limits, 3/5 or less listed as unexpected with new findings documented and reported.

Open RN Nursing Skills 2e: 6.7 Assessing Motor Strength. Bilateral hand grasp, upper and lower extremity resistance testing, unequal strength suggesting neurological disease, dominant side usually slightly stronger.

Open RN Nursing Skills 2e: 13.5 Sample Documentation. Sample documentation of normal strength as rated 5 out of 5 in upper and lower extremities.