Single-Arm Cable Rear Delt Fly

What is the Single-Arm Cable Rear Delt Fly?

The single-arm cable rear delt fly trains one rear deltoid at a time against constant cable tension, sweeping a single handle across and back from the opposite low pulley. Working one side gives the rear delt a longer, cleaner arc and lets you match reps between sides, a precise way to build and even out the back of the shoulder.

Muscles worked

Primary: Shoulders

The rear (posterior) deltoid of the working arm pulls the arm back and out (horizontal abduction) against the cable, loaded through the whole arc.

Secondary: Traps

The traps and mid-back assist by retracting the shoulder blade as the arm sweeps back.

How to perform the Single-Arm Cable Rear Delt Fly

1. Set a single pulley to shoulder height and stand side-on, gripping the handle with the arm across the body.
2. Hold a soft elbow and keep the torso square so the working rear delt moves the load, not a twist of the trunk.
3. The single-cable line gives the rear delt smooth, constant horizontal tension through the whole arc.
4. Pull the handle out and back across the body, leading with the elbow toward the rear.
5. Squeeze the rear delt at the fully open position without letting the shoulder shrug up or the back arch.
6. Return under control across the front of the body, then finish the reps before switching sides.

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

Mechanics

A single-joint unilateral isolation on a cable: standing side-on and gripping the opposite-side low pulley, movement happens at the working shoulder as the arm sweeps from across the body out and back with a fixed soft elbow bend. Doing one side at a time gives a longer range and constant tension than a two-arm cable fly, with no chance for the stronger side to compensate.

Form cues

• •Stand side-on to the stack and hold the handle from the pulley on the far side so the cable crosses your body.
• •Sweep the arm out and back in a wide arc with a fixed soft elbow bend, leading with the pinky.
• •Squeeze the rear delt at the back without shrugging the trap up toward the ear.
• •Return under control against the cable, then finish the weaker side first and match on the other.

Common mistakes

• •Rotating the torso toward the pull instead of keeping it square to isolate the rear delt.
• •Bending the elbow into a row rather than holding a fixed soft-elbow fly.
• •Shrugging the shoulder up at the open position instead of squeezing the rear delt.
• •Letting the handle snap back across the body without controlling the return.

Variations & alternatives

• •Two-arm cable rear delt fly: both sides at once for more total volume per set.
• •Rear delt fly: the free-weight bent-over version with a fading tension curve.
• •Reverse pec deck: a machine that fixes the path and supports the torso.
• •Face pull: a rope pull to the face for the rear delts and upper back together.

Overhead Press

Shoulders · Barbell

Dumbbell Overhead Press

Shoulders · Dumbbell

Lateral Raise

Shoulders · Dumbbell

Cable Lateral Raise

Shoulders · Cable

Rear Delt Fly

Shoulders · Dumbbell

Programming: sets, reps & when to use it

Run the single-arm cable rear delt fly as a rear-delt accessory in the library’s higher 12–20 rep range, working each side for equal reps. Lead with the weaker rear delt to even out an imbalance, keep the weight light and the arc clean, and add plenty of weekly sets, because the rear delt lags for most lifters. Doing one side at a time doubles the sets, so plan your volume accordingly.

Frequently asked questions