Weak Rotator Cuff - Muscles, Symptoms & Strengthening

Coronal section of the shoulder - Harrison's Principles of Internal Medicine 22E

The 4 Rotator Cuff Muscles (SITS)

"The subscapularis is the largest of the rotator cuff muscles... The supraspinatus superiorly, the infraspinatus posterosuperiorly, and the teres minor posteriorly [all insert on the greater tuberosity]." - Rockwood and Green's Fractures in Adults, 10th ed.

General Symptoms of a Weak/Injured Rotator Cuff

• Dull, aching pain deep in the shoulder, often in the deltoid region
• Night pain - woken by rolling onto the affected shoulder
• Weakness with overhead activities - lifting, reaching, throwing
• Painful arc - pain between 60-120° of active abduction
• Loss of active range of motion while passive range is often preserved (key sign)
• Difficulty with everyday tasks - combing hair, reaching behind the back, fastening a bra
• Muscle atrophy - wasting visible above/below the scapular spine (supraspinatus/infraspinatus) with chronic tears
• Acute onset - sudden pain and weakness after a fall on outstretched hand or heavy lift (traumatic tear)

Symptoms Specific to Each Muscle When Weak

1. Supraspinatus (most commonly injured)

• Inability to initiate shoulder abduction (arm lifting away from side)
• "Drop arm" - cannot sustain the arm at 90° against gravity or resistance
• Painful arc between 60-120°
• Weakness on the empty can test (arm at 30° forward, thumb pointing down - resistance applied)
• Most tears begin here, often in the "critical zone" of poor blood supply near the insertion

2. Infraspinatus

• Weakness of external rotation - difficulty rotating the forearm away from the body with elbow at 90°
• Trouble with overhead throwing motions (e.g., tennis serve, pitching)
• Hornblower's sign if combined with teres minor tear - cannot hold the hand to the mouth without abducting the elbow
• Visible atrophy in the infraspinous fossa below the spine of the scapula

3. Teres Minor

• Also weak external rotation, but isolated weakness is uncommon
• Contributes to the hornblower's sign alongside infraspinatus
• Usually affected alongside infraspinatus

4. Subscapularis (least commonly torn, but most powerful)

• Weakness of internal rotation - trouble tucking in shirt behind the back, reaching the spine
• Belly press test - cannot press the palm against the abdomen while keeping the elbow forward
• Lift-off test (Gerber) - cannot hold the hand away from the lower back against resistance
• Pain with reaching across the body

Strengthening Exercises - Individual Muscles

Supraspinatus

• Stand with arm at side. Raise arm to shoulder height at 30° forward of the coronal plane (the scapular plane), thumb pointing down (empty can) or up (full can - safer, less impingement).
• Start with no weight; progress to 1-3 lbs.
• 3 sets x 15 reps

• Lie on the unaffected side, raise the top arm to shoulder height in the plane of the scapula.
• Keep thumb pointing up.
• 3 sets x 15 reps

Infraspinatus + Teres Minor (both are external rotators - trained together)

• Lie on the unaffected side, affected arm on top, elbow bent 90°, forearm resting across abdomen.
• Slowly rotate forearm up toward the ceiling, keeping elbow pinned to the side.
• Hold 1-2 seconds at top, lower slowly (eccentric phase is key).
• 3 sets x 10-15 reps. Start with 1-2 lbs.

• Stand with elbow bent 90°, tucked against the side (place a folded towel between elbow and ribs to maintain position).
• Resistance band anchored at elbow height.
• Rotate forearm outward, hold, return slowly.
• 3 sets x 12-15 reps.

Subscapularis

• Stand with elbow at 90° tucked to your side.
• Band anchored behind you at elbow height.
• Rotate forearm in toward the abdomen against resistance, return slowly.
• 3 sets x 12-15 reps.

• Press palm against abdomen keeping the elbow forward (not dropping to the side).
• Progress to adding resistance by pressing into a wall with forearm.

Strengthening as a Group (Full Rotator Cuff Programs)

Phase 1 - Pain Control / Early Rehab

• Pendulum swings - lean forward, let arm hang, make small circles with gravity - unloads the joint, reduces spasm
• Passive range of motion - no muscle work, just restoring movement

Phase 2 - Range of Motion Restoration

• Posterior capsule stretch (cross-body stretch) - pull the affected arm across the chest with the other hand; holds the posterior capsule and infraspinatus
• Sleeper stretch - lie on affected side, push forearm down gently; stretches posterior capsule

Phase 3 - Strengthening (all four muscles + scapula)

• Lie face down on a table or elevated surface. Raise both arms:
  • Y shape (arms angled forward) = targets supraspinatus
  • T shape (arms straight out) = infraspinatus/teres minor
  • W shape (elbows bent, hands up) = subscapularis/external rotators

• Pull resistance band toward your chest keeping elbows close to the body.
• Trains the rotator cuff and the lower trapezius/rhomboids together - restores scapular rhythm.

• Push-up against a wall, add a "plus" at the top by protracting (pushing) the scapula forward.
• Activates serratus anterior to stabilize the scapula, allowing the rotator cuff to work from a stable base.

• Often guided by a physiotherapist; combines flexion-abduction-external rotation in one diagonal movement, training all cuff muscles in functional patterns similar to daily activities.

Key Training Principles