Shoulders · Horizontal abduction
Rear Delt Machine
The rear delt machine, also called the reverse pec deck, is a guided shoulder exercise where you sit facing the pad and sweep two handles out and back in a wide arc. It isolates the rear deltoids and upper back with a fixed path, making it one of the easiest ways to train a muscle that most pressing leaves undertrained.
Also known as: Reverse pec deck, Rear delt fly machine, Reverse fly machine
- Muscle group
- Shoulders
- Movement pattern
- Horizontal abduction
- Type
- Isolation
- Equipment
- Pec deck / rear delt machine
- Difficulty
- Beginner
What muscles does the rear delt machine work?
Primary movers
- Rear deltoid
Assisting muscles
- Rhomboids
- Trapezius (middle)
- Infraspinatus
- Teres minor
The rear delts pull the upper arm backward and out to the side, which is horizontal abduction. The machine fixes the arc, so the delts do the work without much help from stabilising muscles.
The rhomboids and middle traps assist by pinching the shoulder blades together, and the rotator cuff muscles infraspinatus and teres minor help stabilise the joint.
Pressing movements load the front delts heavily, while the rear delts get less direct work. Training them balances the shoulder and supports posture.
Light weight and a slow tempo work best. Heavy loads let the traps and momentum take over.
How to do the rear delt machine
Setup
- 1
Adjust the seat so the handles are at shoulder height when you sit facing the pad.
- 2
Set the arm start position so you feel a light stretch at the front.
- 3
Hold the handles with a neutral or overhand grip, arms extended in front.
- 4
Keep a slight bend in your elbows.
Execution
- 1
Lead with your elbows and sweep the handles out and back in a wide arc.
- 2
Squeeze your rear delts at the end of the movement.
- 3
Hold for a second without shrugging.
- 4
Return slowly under control.
- 5
Keep your chest on the pad.
- 6
Do not let the stack touch down between reps.
Common rear delt machine mistakes
Turning it into a row
Bending the elbows and pulling back shifts the work to the lats.
The fix: Keep a fixed slight elbow bend and sweep the arms out in an arc.
Shrugging
Raising the shoulders moves the work to the traps.
The fix: Keep your shoulders down and lead with the elbows.
Swinging with momentum
Jerking the handles reduces tension.
The fix: Use a lighter weight and slow the return.
Wrong seat height
Handles too high or low change the muscles worked.
The fix: Set the handles at shoulder height.
How many sets and reps?
| Goal | Sets | Reps | Load | Rest |
|---|---|---|---|---|
| Hypertrophy | 3–4 | 12–15 | Light to moderate | 60 s |
| Endurance | 2–3 | 15–20 | Light | 45 s |
| Beginner | 2–3 | 12 | Light | 60 s |
Rear delts recover quickly and respond to frequency, so training them two or three times a week works well. Use controlled reps with a one-second squeeze. Add weight only when you can keep your shoulders down.
Running the rear delt machine in your next block? Hercules logs every set, shows last session's numbers before you lift, and suggests when to add weight.
Get it on Google PlayRear Delt Machine variations and alternatives
Seated Bent Over Rear Delt Raise
AlternativeA dumbbell version of the same movement.
Face Pull
AlternativeA cable exercise for the rear delts and external rotators.
Band Face Pulls
EasierA portable band version.
Lateral Raise
AlternativeTrains the side delts, which complement the rear delts.
Seated Row Machine
AlternativeA heavier horizontal pull with more lat involvement.
Frequently asked questions
What does the rear delt machine work?
The rear deltoids mainly, with the rhomboids, middle traps and rotator cuff helping.
Why are rear delts important?
They balance the front delts that pressing builds, support good posture and shoulder health, and add width to the back of the shoulder.
How heavy should I go?
Light enough that your traps stay quiet and you can control the return. Most people do best with 12 to 20 reps.
Reverse pec deck or face pulls?
Both work. The machine is easier to load and isolate, while face pulls add external rotation. Many programmes use both.
How do I set the machine?
Adjust the seat so the handles sit at shoulder height and the arms start slightly in front of you.
Hercules tracks every rear delt machine you log, shows you last session's numbers before you lift, and flags when your progress stalls.
Get it on Google Play