Side Plank Dumbbell Rear Delt Fly
In SetGrip: Dumbbell Rear Delt Fly (Side Plank)
- Primary muscleUpper Back
- EquipmentDumbbell
- DifficultyAdvanced
- TypeIsolation · Push
Holding a side plank while the top arm performs a rear delt fly makes the obliques and shoulder share every rep, because the fly's arc actively tries to tip the plank over. Choose the dumbbell by what the plank can tolerate rather than what your rear delt can lift, which usually means the lightest pair on the rack.
How to do the Side Plank Dumbbell Rear Delt Fly
- Start by lying on your side with your legs extended and stacked on top of each other.
- Place your forearm on the ground directly below your shoulder, keeping your elbow bent at a 90-degree angle.
- Hold a dumbbell in your top hand, with your arm extended straight down towards the ground.
- Engage your core and lift your hips off the ground, creating a straight line from your head to your heels.
- While maintaining the side plank position, lift the dumbbell up towards the ceiling, squeezing your shoulder blades together.
- Lower the dumbbell back down to the starting position.
- Repeat for the desired number of repetitions, then switch sides.
Tip: Imagine hugging a barrel rather than pushing a weight.
Muscles worked
Primary
Upper Back · Back
On reverse flies the rhomboids and mid traps squeeze the shoulder blades together at the end of each rep.
Common mistakes
- Elbows bending as you tire — this turns a fly into a press; set the elbow angle at the start and keep it constant for the whole set.
- Going too heavy — flies are a stretch and squeeze movement, not a strength lift; you should be able to pause at the bottom without the shoulders rolling forward.
- Stopping short of the stretch — let the arms open until you feel the chest or rear delts lengthen, then bring them back under control.
- Not squeezing at the finish — the last few inches are where the muscle shortens most, so hold the contraction for a count before opening again.
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 | — |
Flies are an isolation movement for after the pressing or rowing is done. Pair a cable crossover with a cable rear delt fly on the same station, or dumbbell chest flies with dumbbell rear delt flies on the same bench.
Variations and alternatives
Frequently asked questions
What muscles does the Side Plank Dumbbell Rear Delt Fly work?
The Side Plank Dumbbell Rear Delt Fly primarily works the upper back. It also involves the delts and abs, which assist the movement and stabilise the joints.
Is the Side Plank Dumbbell Rear Delt Fly good for beginners?
Not as a starting point. The Side Plank Dumbbell Rear Delt Fly is rated advanced because it demands strength, mobility or coordination that takes time to build. Beginners should work up to it through the easier variations listed on this page.
How many sets and reps should I do?
It depends on your goal. For the Side Plank 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.
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