Smart Workout Diary

Dumbbell One-Arm Fly

The dumbbell one-arm fly is a unilateral chest isolation exercise usually performed lying on a flat bench. It primarily trains the pectoral muscles through a controlled horizontal arc, while the shoulder helps stabilize the weight. It can help develop chest-focused strength, muscle control, and left-to-right balance.

Demonstration

Dumbbell One-Arm Fly — demonstration 1
Dumbbell One-Arm Fly — demonstration 2

Instructions

  1. Set up on a flat bench: Lie on your back with both feet firmly on the floor. Hold one dumbbell above the working-side chest with a neutral wrist and a slight bend in the elbow.
  2. Brace your position: Keep your head, upper back, and hips in contact with the bench. Keep the non-working arm on the bench or holding its edge for stability.
  3. Lower under control: Inhale and lower the dumbbell out to the side in a wide arc. Maintain the same soft elbow bend and keep the shoulder blade gently set against the bench.
  4. Use a comfortable range: Stop when you feel a chest stretch without shoulder discomfort; do not force the arm far below the level of your torso.
  5. Return smoothly: Exhale and bring the dumbbell back above your chest by squeezing the chest, following the same arc. Complete the desired repetitions, then repeat on the other side.
Muscle Group
Chest
Type
Strength
Mechanics
Isolation
Equipment
Dumbbell, Bench
Difficulty
Beginner

Technique tips

  1. Keep a soft elbow bend: Do not straighten and bend the elbow repeatedly; the movement should come mainly from the shoulder.
  2. Choose a modest load: Fly variations place the shoulder in a long lever position, so prioritize control over heavy weight.
  3. Keep the wrist stacked: Maintain a neutral wrist directly behind the dumbbell rather than letting it bend back.
  4. Avoid momentum: Use a slow, even lowering phase and do not bounce out of the bottom position.
Exercise library