Smart Workout Diary

Dumbbell Alternating Posterior Fly on Stability Ball

The dumbbell alternating posterior fly on a stability ball is a supported rear-shoulder isolation exercise performed one arm at a time. It primarily targets the rear deltoids, with the upper back assisting to control the shoulder blades. It can help develop shoulder balance, upper-body posture, and controlled pulling strength.

Demonstration

Dumbbell Alternating Posterior Fly on Stability Ball — demonstration 1
Dumbbell Alternating Posterior Fly on Stability Ball — demonstration 2

Instructions

  1. Set up securely: Hold a light dumbbell in each hand and lie face down over the stability ball, with your chest and abdomen supported. Plant your feet wide on the floor and keep your neck neutral.
  2. Start position: Let both arms hang toward the floor with a soft bend in the elbows and palms facing inward. Brace your abdomen so the ball does not roll.
  3. Raise one arm: Keeping the torso still, lift one dumbbell out to the side in a wide arc until the upper arm is roughly in line with the torso. Lead with the elbow and gently draw the shoulder blade back.
  4. Lower with control: Pause briefly, then lower that dumbbell slowly to the start without shrugging the shoulder or twisting the body.
  5. Alternate sides: Repeat with the other arm, maintaining a stable position on the ball. Continue for the planned number of repetitions per side.
  6. Finish safely: Use a light load that allows smooth control; stop if you cannot keep the ball stable or feel sharp shoulder discomfort.
Muscle Group
Rear Delts
Type
Strength
Mechanics
Isolation
Equipment
Dumbbell, Exercise Ball
Difficulty
Intermediate

Technique tips

  1. Prioritize stability: Keep the feet wide and the abdomen braced; body movement should not create momentum for the dumbbell.
  2. Use a light load: Rear deltoids respond well to controlled repetitions, so avoid weights that force you to swing or shrug.
  3. Keep the shoulder down: Think of reaching long through the arm while gently moving the shoulder blade back, rather than lifting toward the ear.
  4. Breathe steadily: Exhale as you lift and inhale as you lower, maintaining a slow, even tempo.
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