Decline Single Arm Dumbbell Fly
In SetGrip: Dumbbell Fly (Decline, Single Arm)
- Secondary muscles
- Delts
- Body part
- Chest
- Position
- Lying
- Laterality
- Unilateral (one arm at a time)
- Category
- Strength
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Holding one dumbbell while lying head-down puts an offset load on your torso, so your obliques fight to keep you square on the bench while the working pec handles the fly. Reserve it for after you own the two-arm decline dumbbell fly, and start well lighter than half of what you would use for the pair.
How to do the Decline Single Arm Dumbbell Fly
- Lie down on a decline bench with a dumbbell in one hand, resting it on your thigh.
- Using your thigh to help raise the dumbbell, lift it up to shoulder width with your palm facing your torso.
- Rotate your wrist so that the palm of your hand is facing forward.
- As you breathe in, lower the dumbbell slowly to the side until you feel a stretch in your chest.
- Exhale and use your chest muscles to bring the dumbbell back up to the starting position.
- Repeat for the desired number of repetitions, then switch arms.
Tip: Imagine hugging a barrel rather than pushing a weight.
Muscles worked
Primary
Pectorals · Chest
On chest flies and cable crossovers the pecs pull the arms together in an arc and should feel a deep stretch at the bottom and a hard squeeze at the top.
Secondary
- Delts — Rear delt flies work the back of the shoulder as the arms swing wide, and the front delt assists on any chest fly.
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
Similar exercises
Frequently asked questions
What muscles does the Decline Single Arm Dumbbell Fly work?
The Decline Single Arm Dumbbell Fly primarily works the pectorals. It also involves the delts, which assist the movement and stabilise the joints.
Is the Decline Single Arm Dumbbell Fly good for beginners?
Not as a starting point. The Decline Single Arm Dumbbell 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.
What can I do instead of the Decline Single Arm Dumbbell Fly?
If you cannot do the Decline Single Arm Dumbbell Fly, try the Decline Dumbbell Fly, the Single Arm Dumbbell Fly or the Dumbbell Fly. Each of them trains the pectorals 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 Decline Single Arm Dumbbell 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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