# How to Unf*#k Your Rear Delts (Backed by Science!)

Source: https://www.youtube.com/watch?v=y_bAiGtYd6M
Recap page: https://rapidrecap.app/video/y_bAiGtYd6M
Generated: 2025-11-10T17:35:45.813+00:00

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## Quick Overview

The absolute best way to train rear delts is by prioritizing exercises that involve shoulder extension, specifically ensuring that the scapulae retract (pull back) and the shoulders slightly protract (push forward) during the contraction phase to maximize mid-traps and rhomboid involvement while minimizing excessive upper trap/anterior deltoid involvement, contrasting common, less effective movements like high elbow rows or excessive internal rotation.

**Key Points:**
- The best exercises for rear delts are those that emphasize shoulder extension, such as incline dumbbell rear delt raises (6-8 reps) and cable rear delt fly variations (12-15 reps).
- Effective rear delt training requires the scapulae to retract (pull back) and the shoulders to slightly protract (push forward) during the peak contraction.
- Avoid exercises that primarily involve the lats or excessive internal rotation, as these shift focus away from the posterior deltoid.
- The single-arm cable crossover movement, performed by pushing forward and then pulling back into external rotation at the halfway point, is recommended for isolating the rear delt effectively.
- Incline dumbbell rear delt raises should keep the arm relatively straight to reduce mechanical advantage for the lats and promote external rotation, maximizing posterior delt focus.
- The presenter critiques common mistakes like high elbow raises or exercises that cause excessive shoulder retraction without protraction, which often over-involve the mid-traps and rhomboids.

![Screenshot at 00:24: Visual demonstration showing the correct execution of a rear delt movement, highlighting the necessary scapular retraction \(pulling back\) and slight protraction \(pushing forward\) via green angle indicators on the back musculature.](https://ss.rapidrecap.app/screens/y_bAiGtYd6M/00-00-24.png)

**Context:** The presenter, a bearded man in a gym environment featuring modern hexagonal lighting, provides a tutorial on the most effective methods for training the posterior (rear) deltoid muscles, referencing biomechanical principles and research studies to support his claims against common but suboptimal training techniques.

## Detailed Analysis

The video argues that the best approach for developing the rear deltoids involves exercises prioritizing shoulder extension, specifically mandating scapular retraction combined with slight protraction during the peak contraction to engage the mid-traps and rhomboids effectively without over-relying on the upper traps or anterior deltoids. The presenter critiques common advice like high elbow raises, stating that proper execution requires retracting the scapulae while slightly protracting the shoulders. Specific exercises recommended include incline dumbbell rear delt raises for 6-8 reps, emphasizing keeping the arm straight to maximize external rotation and posterior delt stress, and cable rear delt fly variations (12-15 reps) on a machine where the movement is horizontal abduction followed by external rotation. He also details a single-arm cable movement where the user pushes forward and then pulls back into external rotation, which he finds highly effective for isolation. The presenter notes that many common rear delt exercises, like the high/low cable fly or certain machine movements, can lead to excessive scapular retraction or poor form, causing unnecessary strain on the traps/rhomboids or failing to maximize posterior delt involvement.

### Rear Delt Training Principles

- Prioritize shoulder extension
- Require scapular retraction and slight protraction at peak contraction
- Avoid excessive upper trap/rhomboid involvement

### Best Unilateral Exercises

- Incline Dumbbell Rear Delt Raise (6-8 Reps)
- Single-Arm Cable Row (10-12 Reps) emphasizing horizontal abduction and external rotation

### Incline Dumbbell Raise Technique

- Keep arm relatively straight to reduce lat leverage
- Maximize external rotation at the top for peak rear delt tension

### Cable Machine Fly Technique

- Set up for horizontal abduction
- At the halfway point, transition to pulling back into external rotation while maintaining scapular depression and protraction

### Common Mistakes Critiqued

- High elbow rows and exercises causing excessive scapular retraction without protraction are poor choices
- Relying solely on movements that mimic the Jay Cutler high rear delt fly (which the speaker admits he made a short video about) without understanding the underlying mechanics.

### Scientific Backing

- References a study on 'Deltoid muscle contribution to shoulder flexion and abduction strength' which confirms that the posterior deltoid contributes significantly (up to 50%) to external rotation at 90 degrees of abduction.

![Screenshot at 00:02: Visual cue highlighting the target muscle area: 'GROW THIS!' pointing to the rear deltoid.](https://ss.rapidrecap.app/screens/y_bAiGtYd6M/00-00-02.png)
![Screenshot at 00:21: Demonstration of a seated row where the correct execution involves scapular retraction \(highlighted red area on back\).](https://ss.rapidrecap.app/screens/y_bAiGtYd6M/00-00-21.png)
![Screenshot at 00:44: Title card listing key movements: 'SHOULDER EXTENSION', 'HORIZONTAL SHOULDER ABDUCTION', and 'EXTERNAL ROTATION'.](https://ss.rapidrecap.app/screens/y_bAiGtYd6M/00-00-44.png)
![Screenshot at 01:52: Demonstration of the incline dumbbell raise emphasizing keeping the arm as straight as possible to reduce bicep/lat involvement.](https://ss.rapidrecap.app/screens/y_bAiGtYd6M/00-01-52.png)
![Screenshot at 02:31: Side-by-side comparison showing the INCORRECT \(scapular retraction only\) versus CORRECT \(scapular depression and protraction\) form during a rear delt movement.](https://ss.rapidrecap.app/screens/y_bAiGtYd6M/00-02-31.png)
![Screenshot at 03:40: Demonstration of the dual cable rear delt fly setup with recommended rep range \(12-15 Reps\).](https://ss.rapidrecap.app/screens/y_bAiGtYd6M/00-03-40.png)
![Screenshot at 04:21: Demonstration of the incline dumbbell rear delt raise with a recommended rep range of 6-8 Reps.](https://ss.rapidrecap.app/screens/y_bAiGtYd6M/00-04-21.png)
![Screenshot at 07:38: Presenter referencing a scientific paper titled 'Deltoid muscle contribution to shoulder flexion and abduction strength: an experimental approach' to support the technique advice.](https://ss.rapidrecap.app/screens/y_bAiGtYd6M/00-07-38.png)
![Screenshot at 09:50: Overhead view demonstrating the cable machine exercise with arms abducted to approximately 90 degrees, recommended range 15-20 Reps.](https://ss.rapidrecap.app/screens/y_bAiGtYd6M/00-09-50.png)