Rear Delt Fly

What is the Rear Delt Fly?

The rear delt fly (bent-over reverse fly) is an isolation movement for the rear deltoids, the often-neglected back of the shoulder that balances all the front-delt work from pressing. Building the rear delts improves shoulder health and posture and rounds out a fuller, more three-dimensional shoulder.

Muscles worked

Primary: Shoulders

The rear (posterior) deltoid is the target, pulling the upper arms back and out to the sides (horizontal abduction) against the dumbbells.

Secondary: Traps

The traps and other mid-back muscles assist by retracting the shoulder blades as the arms travel back.

How to perform the Rear Delt Fly

1. Sit on the end of a bench and hinge your torso forward toward your thighs, or stand and bend to roughly 45 degrees at the hips.
2. Let the dumbbells hang under your chest with a neutral grip and a soft, fixed bend in each elbow.
3. Open the arms out to the sides in a wide arc, leading with the elbows and driving the pinkies up toward the ceiling.
4. Spread the shoulder blades apart at the bottom and pull them slightly toward each other as the arms rise, keeping the traps quiet.
5. Stop when the upper arms reach roughly torso height, squeezing the rear delts without swinging the torso up to help.
6. Lower the dumbbells under control back beneath the chest, resisting the pull rather than letting gravity drop them.

Suggested working range: 12–20 reps. Default progression: double progression.

Mechanics

A single-joint isolation performed bent over with dumbbells: movement happens almost entirely at the shoulder as the arms sweep out and back with a fixed slight elbow bend. Keeping the elbows soft and unchanging is what keeps the rear delt working rather than turning the movement into a row.

Form cues

• •Hinge at the hips so your torso is close to parallel with the floor and let the dumbbells hang beneath you.
• •Raise the arms out to the sides with a fixed soft elbow bend, leading with the pinkies.
• •Squeeze the rear delts and let the shoulder blades come together at the top without shrugging.
• •Stop when the arms reach roughly shoulder level and lower under control rather than dropping.

Common mistakes

• •Bending the elbows more during the rep so it becomes a row instead of a fly.
• •Swinging the torso up to throw the dumbbells out with momentum.
• •Letting the traps take over by shrugging the shoulders toward the ears at the top.
• •Using too much weight and cutting the range short so the rear delts never fully contract.

Variations & alternatives

• •Reverse pec deck: a machine that fixes the path and makes the rear-delt squeeze easy to feel.
• •Cable rear delt fly: constant tension across the whole arc from a pair of high pulleys.
• •Face pull: a cable pull to the face that trains the rear delts and upper back together.
• •Rear delt row: a higher-elbow row variation that biases the rear delts.

Overhead Press

Shoulders · Barbell

Dumbbell Overhead Press

Shoulders · Dumbbell

Lateral Raise

Shoulders · Dumbbell

Cable Lateral Raise

Shoulders · Cable

Smith Machine Overhead Press

Shoulders · Machine

Programming: sets, reps & when to use it

Program rear delt flies as an accessory in the library’s higher 12–20 rep range, where a clean squeeze matters more than load. The rear delt is small and responds to volume, so keep the weight light, avoid swinging the torso, and add plenty of weekly sets. Most lifters do far too little rear-delt work relative to their pressing.

Frequently asked questions