Reverse Fly: Targeting Rear Deltoids for Shoulder Health and Aesthetics

How do you target rear delts on a reverse fly?

To effectively target the rear deltoids during a reverse fly, prioritize precise form over heavy weight, focusing on horizontal abduction of the humerus with a fixed elbow angle and minimized scapular retraction to isolate the posterior shoulder musculature.

Understanding the Rear Deltoid

The deltoid muscle, a powerful and complex muscle of the shoulder, is composed of three distinct heads: anterior (front), medial (side), and posterior (rear). The posterior deltoid originates from the inferior lip of the spine of the scapula and inserts into the deltoid tuberosity of the humerus. Its primary actions include horizontal abduction (transverse extension) and external rotation of the humerus.

Why Target Them? While often underdeveloped compared to the anterior and medial heads, a strong and well-developed posterior deltoid is crucial for:

• Shoulder Health and Stability: It helps balance the forces around the shoulder joint, reducing the risk of impingement and other injuries.
• Posture: Strong rear delts contribute to better posture by counteracting the internal rotation often associated with modern lifestyles and excessive chest/anterior delt training.
• Aesthetics: A well-rounded shoulder appearance is incomplete without developed rear deltoids, contributing to a broader, more three-dimensional look.

The Reverse Fly: A Core Movement

The reverse fly (also known as the rear delt fly or bent-over raise) is an isolation exercise specifically designed to target the posterior deltoid. It involves moving the arms in an arc away from the body in the horizontal plane, against resistance.

Key Principles for Rear Deltoid Isolation

Achieving optimal rear deltoid activation during a reverse fly hinges on understanding and applying specific biomechanical principles:

• Minimizing Scapular Retraction: While the rhomboids and middle trapezius also perform scapular retraction, excessive squeezing of the shoulder blades together will shift the emphasis away from the rear deltoids and onto these larger back muscles. The goal is to move the humerus (upper arm bone), not primarily the scapula. Think of the shoulder blade as a stable base from which the humerus moves.
• Fixed Elbow Angle: Maintain a slight, consistent bend in the elbows (typically 10-30 degrees) throughout the movement. This converts the force into leverage against the rear deltoid and prevents the biceps or triceps from assisting too much. Avoid locking out the elbows or letting them straighten excessively during the eccentric phase.
• Humeral Plane of Motion: The primary action for the rear deltoid is horizontal abduction (moving the arm away from the midline in the transverse plane). The movement should occur largely in line with the rear deltoid fibers, which means the arms should move outwards and slightly upwards, forming a "T" shape with the body, rather than straight up or down.
• Mind-Muscle Connection: Consciously focus on contracting the rear deltoids. A helpful cue is to imagine "pulling with your elbows" rather than your hands, which helps to keep the emphasis on the shoulder joint and away from the forearms or biceps.

Executing the Reverse Fly for Optimal Rear Delt Engagement

The reverse fly can be performed with dumbbells, on a reverse fly machine, or using cables. Each variation offers slight advantages.

General Execution Cues:

1. Setup: Regardless of the variation, ensure your starting position allows for proper shoulder mechanics.
   • Machine Reverse Fly: Adjust the seat height and chest pad so your shoulders are aligned with the machine's pivot point. Handles should be within comfortable reach without excessive stretching.
   • Dumbbell Bent-Over Reverse Fly: Hinge at your hips, keeping a neutral spine and a slight bend in your knees. Your torso should be roughly parallel to the floor (or slightly higher, depending on comfort and hamstring flexibility). Let the dumbbells hang directly below your shoulders, palms facing each other (neutral grip).
   • Incline Bench Dumbbell Reverse Fly: Lie chest-down on an incline bench set at a low to moderate angle (e.g., 30-45 degrees). This provides support for your torso and reduces spinal stress. Let the dumbbells hang straight down.
2. Initiate the Movement: With your fixed slight elbow bend, initiate the movement by "pulling" the weights outwards and slightly upwards. Imagine you are trying to push your elbows out to the sides, away from your body.
3. Path of Motion: The weights should move in a wide arc, leading with the elbows. Avoid simply lifting the weights straight up.
4. Peak Contraction: Squeeze your rear deltoids at the top of the movement. The range of motion will be limited by the point where your elbows are in line with your torso, or slightly behind it. Do not allow your shoulder blades to excessively retract and pinch together; the focus remains on the movement of the humerus.
5. Controlled Eccentric: Slowly and deliberately lower the weights back to the starting position, maintaining control throughout the entire range of motion. Resist the urge to let gravity drop the weights.

Common Mistakes to Avoid:

• Using Too Much Weight: This is the most common error. Heavy weight leads to momentum, compromises form, and recruits larger muscle groups like the traps and rhomboids, negating rear delt isolation. Light to moderate weight is key.
• Excessive Scapular Retraction: Squeezing the shoulder blades together at the top shifts tension from the rear delts to the middle back. Keep the scapulae relatively stable; the movement is primarily at the glenohumeral joint.
• Leading with the Hands/Straight Arms: If you lead with your hands or straighten your arms, you'll engage the biceps (if you pull with bent arms) or triceps (if you lock out the arms), and reduce the leverage on the rear deltoid.
• Lack of Control: Flinging the weight up and letting it drop down reduces time under tension and increases injury risk. Focus on a slow, controlled eccentric phase.
• Shrugging: Elevating the shoulders towards the ears engages the upper trapezius, again taking focus away from the rear delts. Keep the shoulders depressed and away from the ears.

Programming Considerations

For optimal rear deltoid development, aim for:

• Rep Ranges: Moderate to high repetitions (e.g., 10-20 reps) are often most effective, as the rear delts respond well to higher volume and time under tension, especially given the need for strict form.
• Workout Placement: Incorporate reverse flies as an accessory exercise, typically after compound movements for the back or shoulders, or as part of a dedicated "pull" or "shoulder" day.
• Complementary Exercises: Pair reverse flies with other exercises that promote good posture and shoulder health, such as face pulls, external rotations, and rotator cuff strengthening exercises.

Conclusion

Targeting the rear deltoids on a reverse fly requires a deliberate approach centered on precise form, controlled movement, and a deep understanding of the muscle's function. By prioritizing lighter weights, maintaining a fixed elbow angle, minimizing scapular retraction, and focusing on the humerus's horizontal abduction, you can effectively isolate and develop this crucial component of shoulder health, stability, and aesthetics. Consistent application of these principles will yield significant improvements in your posterior shoulder development.