Manual Muscle Testing (MMT) Calculator
Grade upper and lower extremity muscle strength using the MRC 0–5 scale with myotome nerve level mapping, bilateral comparison, gravity-eliminated logic, and EMR-ready documentation.
Clinically reviewed by Dr. Nikhil Mahajan, PT, MPT · Jan 15, 2025Gravity Rule: If the patient cannot move the limb against gravity, the maximum possible score is 2/5. Test in the gravity-eliminated (horizontal) plane to distinguish between Grade 1 (trace only) and Grade 2 (full ROM, no gravity).
Upper Extremity Myotomes
8 muscle groups · C4 to T1 · Score Right (R) and Left (L) separately
Lower Extremity Myotomes
8 muscle groups · L1 to S2 · Score Right (R) and Left (L) separately
Clinical Modifiers
MRC Manual Muscle Testing Scale — Complete Reference
| Grade | Label | Definition | Testing Position | Clinical Significance |
|---|---|---|---|---|
| 0/5 | Zero | No visible or palpable muscle contraction | Any — no movement possible | Complete denervation or LMN lesion |
| 1/5 | Trace | Visible or palpable contraction — no joint movement | Gravity-eliminated plane | Nerve continuity present — prognostic value |
| 2/5 | Poor | Full ROM in gravity-eliminated position only | Horizontal plane (side-lying, supine) | Cannot function against gravity — significant impairment |
| 3/5 | Fair | Full ROM against gravity — no added resistance | Standard anatomical position | Functional minimum for ADLs in some joints |
| 4/5 | Good | Full ROM against gravity with moderate resistance | Standard position with manual resistance | Functional but weaker than normal — most PT discharge target |
| 5/5 | Normal | Full ROM against gravity with full resistance — normal strength | Standard position with full examiner resistance | Normal neuromuscular function — return to full activity |
What is Manual Muscle Testing (MMT)?
Manual Muscle Testing (MMT) is a standardized clinical technique for quantifying muscle strength using the MRC (Medical Research Council) 0–5 scale, originally developed by the Medical Research Council (1943) during World War II to assess peripheral nerve injuries in soldiers. It remains the universal language for documenting muscle strength in physical therapy, neurology, orthopedics, and rehabilitation medicine worldwide. MMT evaluates the ability of a muscle or muscle group to produce force against gravity and against manual resistance applied by the examiner, with results graded on a 6-point scale.
The MRC 0–5 Grading System Explained
- Grade 0 (Zero): Absolutely no visible or palpable muscle contraction. Indicates complete denervation or severe lower motor neuron (LMN) lesion. No prognostic value for voluntary recovery without nerve continuity.
- Grade 1 (Trace): A visible flicker of contraction or a palpable contraction under the examiner's fingers — but no actual joint movement. Confirms nerve continuity and provides favorable prognosis for recovery if innervation can be restored.
- Grade 2 (Poor): Muscle can move the limb through the complete range of motion when gravity is eliminated (tested in the horizontal plane). Maximum grade possible for a muscle that cannot function against gravity.
- Grade 3 (Fair): Muscle completes the full range of motion against gravity but cannot tolerate any additional manual resistance. The critical functional threshold — Grade 3 at the knee means the patient can extend the knee but not walk on stairs.
- Grade 4 (Good): Muscle completes full ROM against gravity and can withstand moderate manual resistance before the movement breaks down. Most physical therapy discharge criteria target Grade 4.
- Grade 5 (Normal): Full ROM against gravity with the examiner applying maximum resistance without breaking the movement. Normal neuromuscular function — cleared for return to full activity.
The Critical Gravity Rule
The most important concept in MMT is the gravity rule: if a muscle cannot move the limb against gravity at all, the maximum possible grade is 2/5. To distinguish between Grade 1 and Grade 2, place the limb in a gravity-eliminated position (horizontal plane) and ask for maximum effort. Common gravity-eliminated positions include:
- Hip abduction: Side-lying with tested hip uppermost
- Knee extension: Side-lying with limb supported
- Shoulder abduction: Supine with arm supported on table
- Elbow flexion: Supine with arm at side, tested horizontally
Plus/Minus Refinements (3+, 4–, 4+)
Clinicians frequently use plus and minus refinements to improve sensitivity between full grades:
- 3+/5: Completes ROM against gravity and holds against minimal resistance before breaking — better than 3 but not quite 4
- 4–/5: Takes resistance but breaks earlier than a true 4 — slight paresis with moderate function
- 4+/5: Takes more than moderate resistance — slightly below normal but very functional
These refinements improve clinical communication but are not part of the original MRC scale. Always document which convention is used.
MMT Myotome Mapping
Myotome-based MMT is essential for localizing nerve root lesions in cervical and lumbar radiculopathy:
- C5: Deltoid (shoulder abduction), Biceps (elbow flexion)
- C6: Wrist extensors (ECRL/ECRB), Biceps
- C7: Triceps (elbow extension), Wrist flexors
- C8: Finger flexors (FDP), Finger extensors
- T1: Finger intrinsics (interossei — finger abduction/adduction)
- L2–L3: Hip flexors (iliopsoas), Quadriceps
- L4: Ankle dorsiflexors (tibialis anterior), Quadriceps
- L5: Great toe extensors (EHL), Peronei
- S1: Ankle plantarflexors (gastrocnemius/soleus), Hamstrings
MMT vs Other Strength Measurements
- vs Dynamometry (HHD): Hand-held dynamometry provides objective force measurements in Newtons or kg — more precise than MMT for detecting subtle strength deficits. MMT is faster and requires no equipment.
- vs Modified Ashworth Scale: MAS measures spasticity (tone); MMT measures voluntary strength. Both are used together in upper motor neuron lesions — high spasticity can coexist with low voluntary strength.
- vs Fugl-Meyer Assessment: FMA measures overall motor recovery including synergy patterns in stroke; MMT measures discrete voluntary muscle strength. FMA is preferred for stroke research; MMT for peripheral nerve and radiculopathy assessment.