Single Arm Dumbbell Fly
In SetGrip: Dumbbell Fly (Single Arm)
- Secondary muscles
- Delts
- Body part
- Chest
- Position
- Lying
- Laterality
- Unilateral (one arm at a time)
- Category
- Strength
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Working one arm at a time on the flat bench reveals exactly how much stronger one pec is than the other, and the off-center dumbbell makes your trunk brace against rolling for the whole set. Match total reps per side and lead with the weaker arm; it makes a useful periodic audit of your two-arm dumbbell fly.
How to do the Single Arm Dumbbell Fly
- Sit on a flat bench with a dumbbell in one hand, resting it on top of your thigh.
- Lie back on the bench, keeping the dumbbell pressed against your thigh.
- Using your free hand, help lift the dumbbell up to the starting position.
- Hold the dumbbell directly above your shoulder with your arm extended and palm facing inward.
- Lower the dumbbell out to the side in a wide arc, keeping a slight bend in your elbow.
- Pause when your arm is parallel to the ground, then reverse the movement and bring the dumbbell back to the starting position.
- Repeat for the desired number of repetitions, then switch arms and repeat.
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.
Where it fits in a workout
Flies are an isolation movement for after the pressing or rowing is done. Pair a chest fly with a rear delt fly for a balanced superset.
How many sets, how heavy and how hard: see what the ACSM position stands support.
Variations and alternatives
Similar exercises
When to talk to someone
- Chest discomfort, feeling faint or lightheaded, or trouble breathing during or after exercise can be signs of a heart attack. In the US, call 911 right away; elsewhere, call your local emergency number.
- Heart, metabolic or kidney disease, or symptoms like these when you are active: talk to your doctor before you start or step up training.
- Pregnant: ask your obstetric care provider which exercise suits you.
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More exercises
Sources
- ACSM position stand on exercise quantity and quality (Garber et al., 2011)
- ACSM preparticipation health screening (Riebe et al., 2015)
- ACOG Committee Opinion No. 804 on exercise in pregnancy (2020)
- CDC: About Heart Attack Symptoms, Risk, and Recovery (2024)
Sources checked on October 17, 2026. Full citations are in the exercise library.
Animation and exercise data: ExerciseDB, licensed to SetGrip. General information, not medical or coaching advice.