Side Lying on Floor Single Arm Dumbbell Rear Delt Fly
In SetGrip: Dumbbell Rear Delt Fly (Side Lying on Floor, Single Arm)
- Secondary muscles
- Traps, Rhomboids
- Body part
- Shoulders
- Position
- Lying
- Laterality
- Bilateral (both sides together)
- Category
- Strength
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No bench required: lying on the floor on your side, you sweep one dumbbell from in front of your body up and back until the rear delt fully contracts. The floor caps the stretch position, so the emphasis lands on the squeeze at the end of the arc; light weight and a deliberate hold suit it well.
How to do the Side Lying on Floor Single Arm Dumbbell Rear Delt Fly
- Lie face down on the floor with a dumbbell in each hand, palms facing each other.
- Extend your arms straight out in front of you, keeping a slight bend in your elbows.
- Engaging your shoulder muscles, lift your arms up and out to the sides, squeezing your shoulder blades together.
- Pause for a moment at the top, then slowly lower your arms back down to the starting position.
- Repeat for the desired number of repetitions.
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 | 60–90 s |
| Endurance / finisher | 2–3 × 15–20 | 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 Side Lying on Floor Single Arm Dumbbell Rear Delt Fly work?
The Side Lying on Floor 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 Side Lying on Floor Single Arm Dumbbell Rear Delt Fly good for beginners?
Yes. The Side Lying on Floor 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 Side Lying on Floor Single Arm Dumbbell Rear Delt Fly?
If you cannot do the Side Lying on Floor Single Arm Dumbbell Rear Delt Fly, try the Wide Grip Dumbbell Upright Row, the Across Bench Single Arm Dumbbell Rear Delt Fly 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 Side Lying on Floor Single Arm Dumbbell Rear Delt Fly, a sensible starting point is muscle growth: 3–4 × 10–15 with 60–90 s rest; endurance / finisher: 2–3 × 15–20 with 45 s rest. Do it after your compound lifts. It is a finishing movement, not the main event.
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