Across Bench Single Arm Dumbbell Rear Delt Fly
In SetGrip: Dumbbell Rear Delt Fly (Across Bench, Single Arm)
- Secondary muscles
- Traps, Rhomboids
- Body part
- Shoulders
- Position
- Lying
- Laterality
- Unilateral (one arm at a time)
- Category
- Strength
Track this exercise in SetGrip — no account needed
Lying chest-down across a flat bench with a single dumbbell parks your torso on the pad, so the low back holds nothing while one rear delt does all the work. Because you drape sideways across the bench, the free hand can grip the frame for stability, and each shoulder gets its own strict set to close left-right gaps.
How to do the Across Bench Single Arm Dumbbell Rear Delt Fly
- Lie face down on a flat bench with a dumbbell in one hand, palm facing inwards.
- Extend your arm straight down towards the floor, keeping it close to your body.
- Raise your arm up and back, squeezing your shoulder blade towards your spine.
- Pause for a moment at the top, then slowly lower your arm back down to the starting position.
- Repeat for the desired number of repetitions, then switch arms.
Tip: Lead with the elbows and think of reaching wide rather than lifting up.
Muscles worked
Primary
Delts · Shoulders
Front raises hit the front delt, lateral raises the side, and Y or rear raises the back head; whichever you pick, the burn should build across the top of the shoulder by the last few reps.
Secondary
- Traps — The upper traps will take over if you shrug, so a slight downward pull of the shoulders keeps them out of it.
- Rhomboids
Common mistakes
- Swinging from the hips — a small bounce at the bottom is the sign of a weight that is too heavy; lighten it and lift from a dead stop.
- Shrugging as you raise — the traps take over when the shoulders rise toward the ears; keep them down and lead with the elbows.
- Raising far above shoulder height — on lateral and front raises the upper traps take over past parallel, so stop around shoulder level unless the variation is built to go overhead.
- Locked elbows — keep a soft bend in the elbow throughout so the load stays on the shoulder rather than the joint.
Sets, reps and where it fits
| Goal | Sets × reps | Rest |
|---|---|---|
| Muscle growth | 3–4 × 10–15 per side | 60–90 s |
| Endurance / finisher | 2–3 × 15–20 per side | 45 s |
| Strength | Not ideal — pick a compound lift for the same muscle | — |
Raises are accessory work and belong after the presses in a shoulder or push session. Superset lateral raises with a rear delt fly using the same dumbbells for a complete shoulder finisher.
Variations and alternatives
Similar exercises
Without dumbbell
Frequently asked questions
What muscles does the Across Bench Single Arm Dumbbell Rear Delt Fly work?
The Across Bench Single Arm Dumbbell Rear Delt Fly primarily works the delts. It also involves the traps and rhomboids, which assist the movement and stabilise the joints.
Is the Across Bench Single Arm Dumbbell Rear Delt Fly good for beginners?
Yes. The Across Bench Single Arm Dumbbell Rear Delt Fly is rated beginner: it uses a dumbbell and the movement is simple to learn. Start light, focus on the full range of motion and add load once every rep looks the same.
What can I do instead of the Across Bench Single Arm Dumbbell Rear Delt Fly?
If you cannot do the Across Bench Single Arm Dumbbell Rear Delt Fly, try the Side Lying on Floor Single Arm Dumbbell Rear Delt Fly, the Wide Grip Dumbbell Upright Row or the Side Lying Single Arm Dumbbell Lateral Raise. Each of them trains the delts through a similar movement, so you can swap them in without changing the rest of the workout.
How many sets and reps should I do?
It depends on your goal. For the Across Bench Single Arm Dumbbell Rear Delt Fly, a sensible starting point is muscle growth: 3–4 × 10–15 per side with 60–90 s rest; endurance / finisher: 2–3 × 15–20 per side with 45 s rest. Do it after your compound lifts. It is a finishing movement, not the main event.
Track the Across Bench Single Arm Dumbbell Rear Delt Fly in SetGrip
All 1,100+ exercises with animations are in the app. No account, no sign-up — your data stays on your iPhone. Works with Apple Watch.
More exercises
Exercise data and animations are licensed ExerciseDB content used in SetGrip. This page is for general information and is not medical or coaching advice.