Exercise guide
Dumbbell Single Arm Alternate Fly
- Intermediate
- Compound
- Rep-based
- Chest
- Shoulders
This isolation exercise targets the pectorals and anterior deltoids while challenging core stability by moving one arm at a time. The alternating pattern allows for intense focus on the mind-muscle connection and ensures balanced development across both sides of the chest.
Reviewed by the Crucible team · Updated June 2026
Muscles worked
Setup
- Lie flat on a bench with your feet planted firmly on the floor for stability.
- Hold a dumbbell in each hand directly over your chest with palms facing each other (neutral grip).
- Retract your shoulder blades into the bench and maintain a slight, fixed bend in your elbows.
How to do it
- Lower one dumbbell in a wide arc out to your side while keeping the opposite arm perfectly still in the starting position.
- Inhale as you lower the weight until your elbow is level with the bench and you feel a deep stretch in the chest.
- Exhale and use your pectoral muscle to pull the dumbbell back to the starting position in a controlled arc.
- Repeat the movement with the opposite arm, alternating sides for the duration of the set using a 2-0-2 tempo.
Form checklist
- Keep the non-moving arm locked vertically to maintain constant tension.
- Maintain a consistent slight bend in the elbows; do not turn the movement into a press.
- Ensure your lower back stays in contact with the bench and your core is engaged to prevent torso rotation.
- Avoid lowering the weights past the level of your torso to protect the shoulder joints.
Pro tips
- Imagine you are hugging a large barrel to maintain the correct circular path and maximize chest recruitment.
- Focus on 'pulling' with your inner chest rather than your hands to bring the weight back to center.
- Squeeze your glutes and core to resist the lateral pull of the weight, turning this into a total-body stability challenge.
Make it harder
- Add a 2-second isometric hold at the bottom of the movement where the stretch is greatest.
- Perform the exercise on an incline bench to increase the demand on the upper pectorals and anterior deltoids.
Frequently asked
- What muscles does the dumbbell single arm alternate fly work?
- The dumbbell single arm alternate fly primarily targets the pectorals, and also works the deltoids and serratus anterior as secondary muscles.
- What equipment do you need for the dumbbell single arm alternate fly?
- The dumbbell single arm alternate fly uses dumbbell.
- Is the dumbbell single arm alternate fly good for beginners?
- The dumbbell single arm alternate fly is rated intermediate. Build a base with simpler variations first, then progress to it with light load and strict form.