Reverse Machine Flyes
Reverse machine flyes are performed seated, facing into a pec deck style machine set to its reverse position, pressing the handles outward and backward instead of the usual inward chest fly motion. Because the machine supports your torso and guides the arc of the movement, this is one of the more beginner-friendly ways to train the rear deltoids, the back-facing part of the shoulder muscle that most pressing exercises leave undertrained. It suits anyone new to rear delt training or anyone who finds the balance and hinge required by the dumbbell version distracting from the muscle they're actually trying to work.
Why it works
The rear deltoid pulls the arm backward and outward, a direction the chest and front shoulder muscles trained by most pushing exercises never touch, which is why this small muscle group so often lags behind. A reverse machine fly isolates that exact motion: the seat and chest pad hold your torso still, so none of the effort goes toward balancing your body the way it does in a bent-over dumbbell version, and the machine's arm guides your hands through a consistent, fixed path. That combination lets a beginner focus entirely on feeling the rear delts contract, without needing the hip hinge and core stability the free-weight version demands at the same time.
Set up
- Raise or lower the seat until the handles sit roughly level with your shoulders once you're seated.
- Sit facing into the machine with your chest against the pad, if one is present, and grip a handle in each hand with your arms extended forward.
- Set the machine's arms to the reverse fly position, if adjustable, before loading the weight.
- Keep a slight bend in your elbows and your shoulders down and away from your ears before starting.
How to do it
- Press the handles outward and back in a wide arc, leading with your elbows rather than pulling with your hands.
- Continue until your arms are roughly in line with your torso, squeezing your shoulder blades together at the end of the range.
- Pause briefly at the back of the movement, feeling the contraction across your rear shoulders and upper back.
- Return the handles forward slowly along the same arc, resisting the machine's resistance rather than letting it snap you back.
- Keep your chest against the pad throughout, without twisting or leaning to move more weight.
Form cues
- Chest stays against the pad.
- Lead with the elbows, not the hands.
- Squeeze the shoulder blades at the back.
- Slow, controlled return every rep.
Breathing: Exhale as you press the handles outward and back, inhale as you return them forward.
Common mistakes
Setting the weight so heavy that the reps turn into short, jerky pulses.
Fix: Drop the weight until you can complete each rep with a full, controlled arc; a shortened, jerky range trains momentum more than it trains the rear delts.
Letting the torso rotate or lean to help move the handles.
Fix: Keep your chest pressed against the pad and your torso still. Any twisting means the weight has exceeded what your rear delts alone can handle.
Stopping the handles well short of shoulder blade squeeze at the back of the movement.
Fix: Continue the arc until your shoulder blades draw together, since that squeeze is where much of the rear delt contraction happens.
Letting the weight stack slam on the return instead of controlling it.
Fix: Guide the handles back forward under control the entire way, rather than letting the machine's resistance snap them back quickly.
How to program it
- Three sets of 12 to 20 reps at a light to moderate weight is typical, since the rear delts respond well to higher rep ranges.
- This works well early in a session for beginners still learning to feel the rear delts fire, since the machine removes most of the technical demands other rear delt exercises carry.
- Most lifters can train this two to three times a week, since the load stays light and the joints involved recover quickly.
- As shoulder training experience grows, pair it with or replace it with a free-weight rear delt exercise for more variety in the loading pattern.
Safety notes
- Avoid loading the machine so heavy that your torso needs to twist or lean to move the handles; that's a sign to reduce the weight.
- Stop the set if you feel the movement working your traps or upper back more than your rear shoulders; adjust the seat height or handle position before continuing.
Exercise profile
- Force
- Pull
- Mechanics
- Isolation
- Category
- Strength
Frequently asked questions
What muscles do reverse machine flyes work?
Mainly the rear deltoids, the back-facing part of the shoulder muscle, along with some assistance from the upper back muscles that pull the shoulder blades together.
Are reverse machine flyes good for beginners?
Yes, since the seat and pad support your torso and the machine guides the arc, removing the balance and hip hinge demands of the dumbbell version while you learn to feel the rear delts working.
Reverse machine flyes vs dumbbell reverse flyes: what's the difference?
The machine version supports your torso and fixes the arc of motion, while the dumbbell version requires a forward hip hinge and more stabilization, making it a step up in difficulty once the machine version feels easy.
How much weight should I use on reverse machine flyes?
Start light. Most people need less weight than they expect, since the rear deltoid is a small muscle group and a heavier load usually shortens the range of motion instead of building more strength.