conceptshoulder-exercises
Shoulder external-rotation exercise
Notes
Shoulder external-rotation exercise
One-line summary: Sidelying ER ranked highest for infraspinatus/teres minor EMG; prone horizontal abduction at 100° with full ER ranked highest for supraspinatus and deltoid — activation, not a measured 1RM ranking.
This page is research synthesis, not medical advice. It is not a rehab protocol.
The insight
Among seven common external-rotation drills in healthy adults, sidelying ER produced the greatest infraspinatus and teres minor EMG; prone horizontal abduction at 100° with full ER produced the greatest supraspinatus and deltoid EMG. A separate small isokinetic study reported eccentric ER training raised eccentric strength and supraspinatus fascicle length. From 2026-08-22-academic-research-effective-shoulder-exercises-strength.
Evidence
- From 2026-08-22-academic-research-effective-shoulder-exercises-strength: Reinold et al. 2004 (n=10 healthy adults, intramuscular EMG) — sidelying ER at 0° abduction: infraspinatus 62% MVIC, teres minor 67% MVIC. Prone horizontal abduction at 100° with full ER: supraspinatus 82% MVIC, middle deltoid 87% MVIC, posterior deltoid 88% MVIC.
- From 2026-08-22-academic-research-effective-shoulder-exercises-strength: “EMG is activation, not a measured strength gain.” The Reinold abstract frames the work as information “to develop rehabilitation programs” and for future studies — not a treatment prescription.
- From 2026-08-22-academic-research-effective-shoulder-exercises-strength: Vetter et al. 2023 (preliminary, 16 physically active men, twice-weekly eccentric isokinetic ER, ~6 weeks) — +24% eccentric strength (p=.008), +16% supraspinatus fascicle length (p=.003), +19% fascicle volume (p=.002), and a 4% decrease in passive ROM on a stretch test.
Contradictions / tensions
- Activation ≠ adaptation. Reinold reports %MVIC; Vetter reports dynamometer eccentric training. Different outcomes and populations.
- Does not fill the missing gym-lift ranking on progressive-resistance-training.
Open questions
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