📖 Static demo — read-only snapshot
You’re browsing a static build of the Body IQ knowledge graph, so everything loads with no backend. A few things that need the live server are turned off here:
- Global search (sidebar) is disabled — it queries the API.
- The JSON API and the API “Try it” playgroundaren’t included.
- The data is a snapshot — it refreshes only when the demo is rebuilt, not live from the database.
Everything else — the body map, progression ladders, coverage heatmap, exercise finder, and all anatomy/exercise/source pages — works fully. The full app (live search + API + database) runs from the source on GitHub.
Prone Horizontal Abduction with External Rotation (Prone Y/T)
Positions & Range of Motion
- Start
- Prone, forehead down, arms hanging off the sides in a Y or T with thumbs pointing up (shoulders externally rotated)
- End
- Arms lifted toward the ceiling, thumbs up, scapulae retracted and depressed with mid/lower trap engaged and upper trap quiet
- Range of Motion
- Arms lift a few inches off the floor; glenohumeral horizontal abduction with scapular retraction to end range
How to Perform
Lying face down, lift arms in a Y or T position with thumbs pointing up (external rotation). Demonstrates optimal scapular neuromuscular control with excellent UT/MT ratio (0.43) and UT/LT ratio (0.30). Activates middle and lower trapezius at >50% MVIC while keeping upper trapezius <20%.
Opens a YouTube search for “Prone Horizontal Abduction with External Rotation (Prone Y/T)”
Coaching Cues
- 1
Long neck, lifted breastbone — pull from below the shoulder blade
(verbal) - 2
Lift the thumbs toward the ceiling
(verbal) - 3
Reach the hands wide toward the far walls
(verbal) - 4
Pinch a coin between the lower shoulder blades
(tactile)
Evidence-Based Dosing & EMG Data
3×8-15 reps, 3 days/week
MT and LT >50% MVIC; optimal UT/MT ratio 0.43, UT/LT ratio 0.30 [Mendez-Rebolledo 2024]
Muscles Involved (7)
Primary Movers
Secondary Movers
Lengthened / Stretched
Synergists & Assistors
Easier Variations ↓
Prone I Raise
Lift arms straight overhead (I position). Simpler movement pattern before progressing to Y and T.
Standing Band Y/T
Perform the Y/T pattern standing with a light resistance band. Gravity-reduced position.
Harder Variations ↑
Prone Y/T with Light Weight
Add 1-3 lb dumbbells to increase resistance in the elevated position.
Prone W Raise
Add the W position (elbows bent, squeeze shoulder blades) to create a Y/T/W circuit targeting all scapular stabilizers.
Target Movements (4)
Why This Exercise Matters
Everyday activities this exercise helps you do — essential means it directly trains the capacity the task needs:
Goals This Helps With
Rehab, performance, prevention, and mobility goals this exercise supports — essential means it's a cornerstone:
Research Notes
EMG data at 100° abduction: supraspinatus 82% MVIC, middle deltoid 87% MVIC, posterior deltoid 88% MVIC, MT >50% MVIC, LT >50% MVIC [Reinold 2004, Mendez-Rebolledo 2024]. Optimal UT/MT (0.43) and UT/LT (0.30) ratios. Early scapular stabilizer activation (-474.7 to 89.9 ms relative to UT) [Mendez-Rebolledo 2024]. Dosing: 3×8-15 reps, 3 days/week [Mulroy 2020]. AUDIT[medium]: The emgNotes/notes report supraspinatus 82% MVIC, middle deltoid 87% MVIC, and posterior deltoid 88% MVIC 'at 100° abduction' citing Reinold 2004 — but those exact values are Reinold's data for Prone External Rotation at 90° abduction (a different exercise, reproduced verbatim in prone-er-90-abduction). This transplants another exercise's EMG onto the prone Y/T. → Remove the supraspinatus/middle-deltoid/posterior-deltoid MVIC figures here or re-attribute them; keep only the trapezius ratio data (Mendez-Rebolledo 2024) that actually describes the prone Y/T.
Evidence Sources (6)
- 📄Therapeutic Exercise: Foundations and Techniques— Kisner C, Colby LA, Borstad J
Therapeutic exercise foundations for Prone Horizontal Abduction with External Rotation (Prone Y/T)
- 📄ACSM's Guidelines for Exercise Testing and Prescription— American College of Sports Medicine
ACSM exercise prescription guidelines for Prone Horizontal Abduction with External Rotation (Prone Y/T)
- 📄Comparative Electromyographic Study of Scapular Stabilizing Muscles During Five Main Rehabilitation Exercises— Mendez-Rebolledo G, Araya-Quintanilla F, Guzmán-Muñoz E, et al.
Comparative Electromyographic Study of Scapular Stabilizing Muscles During Five Main Rehabilitation Exercises — evidence for Prone Horizontal Abduction with External Rotation (Prone Y/T)
- 📄Scapular Muscle Activity From Selected Strengthening Exercises Performed at Low and High Intensities— Andersen CH, Zebis MK, Saervoll C, et al.
Scapular Muscle Activity From Selected Strengthening Exercises Performed at Low and High Intensities — evidence for Prone Horizontal Abduction with External Rotation (Prone Y/T)
- 📄Electromyographic Analysis of the Rotator Cuff and Deltoid Musculature During Common Shoulder External Rotation Exercises— Reinold MM, Wilk KE, Fleisig GS, et al.
Electromyographic Analysis of the Rotator Cuff and Deltoid Musculature During Common Shoulder External Rotation Exercises — evidence for Prone Horizontal Abduction with External Rotation (Prone Y/T)
- 📄Rehabilitation Exercises for Dysfunction of the Scapula: Exploration of Muscle Activity Using Fine-Wire EMG— Berckmans KR, Castelein B, Borms D, Parlevliet T, Cools A
Rehabilitation Exercises for Dysfunction of the Scapula: Exploration of Muscle Activity Using Fine-Wire EMG — evidence for Prone Horizontal Abduction with External Rotation (Prone Y/T)