What is the reverse pec deck?

The reverse pec deck (also called the rear delt fly machine) is a fixed-axis machine exercise designed to isolate the posterior deltoids and upper back via horizontal shoulder abduction.

What is the best grip for targeting the rear delts on the reverse pec deck?

A pronated (palms facing down / horizontal handle) grip with internally rotated shoulders provides the highest mechanical isolation for the posterior deltoid by minimizing lateral rotator contribution.

How high should the seat be adjusted?

Set the seat height so that your arms move parallel to the floor at exact shoulder level. If your hands are above your shoulders, lower the seat or raise your posture.

Should you pinch your shoulder blades on the reverse pec deck?

For maximum rear deltoid isolation, keep the scapulae relatively stable (slightly protracted) and lead the motion with your upper arms rather than squeezing your shoulder blades tightly together.

How does the reverse pec deck compare to dumbbell rear delt flyes?

The reverse pec deck provides a consistent resistance curve throughout the entire range of motion, whereas dumbbell flyes offer minimal tension at the bottom and peak tension only at the top.

Reverse Pec Deck: Form, Seat Height Setup Guide

Reverse Pec Deck

Master the reverse pec deck machine fly with seat height calibration, horizontal arm path, rear deltoid isolation, and scapular control cues.

Quick answer: Sit facing the pec deck machine with your chest against the pad, adjust seat height so handles are level with your shoulders, grasp the handles with a neutral or pronated grip, drive your arms outward in a horizontal arc, and control the return.

Pec deck / reverse fly machine beginner Rear Deltoids, Upper Back, Rhomboids

How to Do It

Adjust the machine's lever arms to the furthest rear setting so the handles sit directly in front of the chest pad.

Adjust the seat height so that when you sit facing the pad, the handles align horizontally with the height of your shoulders.

Sit facing inward with your chest pressed flat against the pad and feet planted firmly on the floor.

Grip the handles with either a neutral (vertical) or pronated (horizontal) grip, maintaining a slight, fixed bend in your elbows.

Drive your hands backward and outward in a wide horizontal arc, focusing on pulling with the backs of your shoulders.

Pause briefly at peak contraction without aggressively pinching your shoulder blades together, then return the handles under control.

Common Mistakes

Setting the seat too low, which forces the elbows up and shifts tension into the upper trapezius.

Bending and extending the elbows during the rep, turning the fly into a tricep extension.

Retracting the scapulae excessively early, allowing the rhomboids and mid-traps to overpower the rear delts.

Shrugging the shoulders toward the ears during the backward arc.

Letting the weight stack slam down at the start of each repetition.

The reverse pec deck is one of the most reliable exercises for developing the posterior deltoids and improving posture. Because the chest is anchored firmly against the support pad and the levers move along a fixed horizontal arc, it eliminates torso swaying and ensures constant mechanical tension throughout the entire repetition.

Setup & Handle Alignment Matrix

Adjustment Point	Ideal Configuration	Fault Indicator	Correction
Seat Height	Handles at exact mid-chest / shoulder level	Hands above eyes / neck	Raise seat until arms are horizontal
Chest Pad	Sternum flat against pad	Leaning back away from pad	Slide hips forward to maintain contact
Elbow Angle	Soft 10–15° bend, locked rigid	Elbows bending and straightening	Lock elbow angle before moving
Grip Style	Pronated (Palms down) or Neutral	Wrist bent backwards	Keep wrists straight and neutral

Execution Checkpoints

Lever Calibration: Pull the adjustment pins on both top cams and lock the handles in the closest setting directly in front of the pad.
The Seat Setup: Adjust the seat height. Sit facing inward with your chest pressed against the pad and feet flat on the floor.
The Grip: Grasp the horizontal handles (pronated) or vertical grips (neutral). Set a slight bend in your elbows and maintain that angle.[1][2]
The Horizontal Sweep: Inhale, brace, and push the handles outward in a wide sweeping arc toward the sides of the room. Focus on driving through the backs of your elbows.
Peak Contraction: Pause for 1 second when your arms reach the plane of your torso. Do not shrug your shoulders.
Smooth Return: Resist the weight stack smoothly over 2 seconds back to the starting point without letting the weight plates touch.

Programming & Volume Guidelines

Frequency: 2–3 times per week on pull days, shoulder days, or upper body sessions.
Volume: 3 to 4 sets of 12 to 15 reps, resting 60–75 seconds between sets.[1][2]

References

National Strength and Conditioning Association. Anaerobic and Muscle Endurance Development: Lifting Guidelines. National Strength and Conditioning Association (2017)Back to claim
Brad S Currier, Alysha C D'Souza, Maria A Fiatarone Singh, Caroline V Lowisz, Eric S Rawson, Brad J Schoenfeld, Abbie E Smith-Ryan, Jeremy P Steen, Gwendolyn A Thomas, N Travis Triplett, Tyrone A Washington, Timothy J Werner, Stuart M Phillips. American College of Sports Medicine Position Stand. Resistance Training Prescription for Muscle Function, Hypertrophy, and Physical Performance in Healthy Adults: An Overview of Reviews. Medicine & Science in Sports & Exercise (2026)Back to claim
Deborah Riebe, Barry A Franklin, Paul D Thompson, Carol E Garber, George P Whitfield, Melissa Magal, Linda S Pescatello. Updating ACSM's Recommendations for Exercise Preparticipation Health Screening. Medicine & Science in Sports & Exercise (2015)

See our exercise methodology for how this evidence is applied and its limits.

Frequently Asked Questions

What is the reverse pec deck?: The reverse pec deck (also called the rear delt fly machine) is a fixed-axis machine exercise designed to isolate the posterior deltoids and upper back via horizontal shoulder abduction.
What is the best grip for targeting the rear delts on the reverse pec deck?: A pronated (palms facing down / horizontal handle) grip with internally rotated shoulders provides the highest mechanical isolation for the posterior deltoid by minimizing lateral rotator contribution.
How high should the seat be adjusted?: Set the seat height so that your arms move parallel to the floor at exact shoulder level. If your hands are above your shoulders, lower the seat or raise your posture.
Should you pinch your shoulder blades on the reverse pec deck?: For maximum rear deltoid isolation, keep the scapulae relatively stable (slightly protracted) and lead the motion with your upper arms rather than squeezing your shoulder blades tightly together.
How does the reverse pec deck compare to dumbbell rear delt flyes?: The reverse pec deck provides a consistent resistance curve throughout the entire range of motion, whereas dumbbell flyes offer minimal tension at the bottom and peak tension only at the top.