Single-Arm Cable Fly

What is the Single-Arm Cable Fly?

The single-arm cable fly works one side of the chest at a time against a constant cable pull, opening and closing the arm across the body through a wide arc. Training one arm alone lets you feel and fix a lagging side, adds a strong squeeze past the midline the two-arm version can’t reach, and brings the core into it to resist the sideways pull.

Muscles worked

Primary: Chest

The pectoralis major of the working side is the prime mover, contracting to bring the arm across the body (horizontal adduction) with the elbow held at a fixed angle. Because it works alone it can pull well past the midline for a harder peak contraction.

How to perform the Single-Arm Cable Fly

1. Set one pulley to shoulder height and stand side-on to the machine, taking the handle in the outside hand.
2. Step away to load the cable, stagger the feet for balance, and fix a soft bend in the working elbow.
3. Let the working arm open out until you feel a deep stretch across the chest, where the cable tension is highest.
4. Working one side at a time gives a longer effective arc and lets you brace the trunk against the rotation the cable creates.
5. Sweep the hand across the body toward the opposite hip in a hugging arc, squeezing the pec fully at the finish.
6. Return slowly to the stretched position under control, resisting the pull rather than letting it yank the shoulder back.

Suggested working range: 12–15 reps. Default progression: double progression.

Mechanics

A single-joint, unilateral isolation: movement happens almost entirely at the working shoulder while the elbow stays locked in a soft, unchanging bend so the triceps stay out of it. The cable keeps tension across the whole arc, and pressing one arm at a time adds an anti-rotation demand on the trunk that a two-arm fly doesn’t have.

Form cues

• •Set a fixed, soft bend in the working elbow and keep that exact angle the whole set: a changing angle turns it into a press.
• •Brace the core and stay square so the cable can’t twist your torso toward the stack.
• •Pull the handle across and slightly past the midline for a full squeeze the two-arm version can’t reach.
• •Keep the working shoulder blade set down and back so the pec, not the front delt, does the work.

Common mistakes

• •Letting the torso rotate toward the cable instead of bracing the trunk against the pull.
• •Straightening the working elbow so the fly becomes a one-arm press.
• •Snapping through the stretched position, where the shoulder is most exposed.
• •Using so much weight that the free arm or hip swings to help finish the rep.

Variations & alternatives

• •Cable fly: the two-arm version this movement is based on, for training both pecs together under constant tension.
• •Single-arm cable press: bend and extend the elbow instead of flying to bring the triceps in.
• •Dumbbell fly, a free-weight isolation with a deeper loaded stretch but drop-off at the top.
• •Pec-deck machine fly: a fixed-path two-arm alternative that’s easier to set up and control.

Barbell Bench Press

Chest · Barbell

Incline Barbell Bench Press

Chest · Barbell

Dumbbell Bench Press

Chest · Dumbbell

Incline Dumbbell Press

Chest · Dumbbell

Cable Fly

Chest · Cable

Programming: sets, reps & when to use it

Use the single-arm cable fly as a chest accessory or finisher in the library’s 12–15 rep range, where a clean stretch and a hard squeeze matter more than load. It’s especially useful when one pec lags: train the weaker side first and match its reps on the strong side.

Frequently asked questions