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Side-Lying External Rotation

Draftstrength92%beginner⬤ strong evidence
View FHIR resourceFHIR R4 ActivityDefinition — the interoperable form of this exercise

Positions & Range of Motion

Start
side-lying on the uninvolved side with a towel roll under the working elbow, elbow bent 90° and pinned to the side, forearm rotated down across the abdomen holding a light dumbbell
End
shoulder externally rotated so the dumbbell rotates up toward the ceiling and the knuckles aim at the far wall, towel still trapped under the elbow
Range of Motion
glenohumeral external rotation from internal/neutral up to end range, elbow fixed at 90°

How to Perform

Side-lying on uninvolved side with a towel roll under the working elbow. Elbow at 90°, externally rotate shoulder against light resistance.

Watch on YouTube↗

Opens a YouTube search for “Side-Lying External Rotation”

Equipment:dumbbell
Starting position: sidelying

Coaching Cues

  1. 1

    Quiet shoulder, packed scapula — back of cuff drives the rotation

    (verbal)
  2. 2

    Rotate the dumbbell upward toward the ceiling

    (verbal)
  3. 3

    Aim the knuckles at the far wall at end-range

    (verbal)
  4. 4

    Towel under the elbow stays trapped throughout

    (tactile)

Evidence-Based Dosing & EMG Data

Recommended Dosing

3×12–15, 3×/week × 6–12 weeks. 1–5 lb.

EMG Activation Data

Lower trap moderate; serratus anterior moderate; upper trap low. UT:SA 0.26, UT:LT 0.21 [Mendez-Rebolledo 2024; Cools 2007].

Muscles Involved (7)

Primary Movers

Infraspinatus
Teres Minor

Secondary Movers

Posterior Deltoid
Lower Trapezius— Moderate — good below 90° elevation

Stabilizers

Serratus Anterior
Upper Trapezius— Low — excellent UT:LT ratio

Lengthened / Stretched

Subscapularis— AUDIT: External rotation elongates the primary internal rotator subscapularis.

Easier Variations ↓

1

Light Load

1–2 lb dumbbell.

Harder Variations ↑

1

Standing Cable ER

Upright cable external rotation.

2

90° Abducted ER

Full can position at 90° abduction.

Target Movements (2)

Shoulder External RotationGlenohumeral Joint
Scapular DepressionScapulothoracic Articulation

Why This Exercise Matters

Everyday activities this exercise helps you do — essential means it directly trains the capacity the task needs:

Reaching OverheadSustained Overhead WorkThrowing & Overhead Sport

Goals This Helps With

Rehab, performance, prevention, and mobility goals this exercise supports — essential means it's a cornerstone:

Rotator Cuff TendinopathyrehabSubacromial Shoulder PainrehabShoulder Injury Preventionprevention