Smart Workout Diary

Dumbbell One-Arm Posterior Fly on Stability Ball

The dumbbell one-arm posterior fly on a stability ball is a unilateral rear-shoulder exercise performed with the chest supported on the ball. It primarily trains the rear deltoid, with assistance from the upper back muscles, while the ball challenges controlled trunk positioning. It supports shoulder balance, upper-back strength, and muscular control.

Demonstration

Dumbbell One-Arm Posterior Fly on Stability Ball — demonstration 1
Dumbbell One-Arm Posterior Fly on Stability Ball — demonstration 2

Instructions

  1. Set up the ball: Place a stability ball on a non-slip surface and hold a light dumbbell in one hand.
  2. Take position: Lie face down with your chest supported on the ball, feet set wide on the floor, knees softly bent, and torso held still. Let the working arm hang beneath the shoulder with a neutral wrist and a slight bend in the elbow.
  3. Raise the dumbbell: Exhale and sweep the arm out to the side and slightly back until it is roughly level with your shoulder. Lead with the elbow and keep the shoulder away from the ear.
  4. Return with control: Inhale and lower the dumbbell slowly to the start without twisting your torso or swinging the weight. Complete the repetitions, then repeat on the other side.
Muscle Group
Rear Delts
Other Muscle Groups
Upper Back
Type
Strength
Mechanics
Isolation
Equipment
Dumbbell, Exercise Ball
Difficulty
Intermediate

Technique tips

  1. Use a light load: Rear deltoids respond best when you can lift without momentum or torso rotation.
  2. Keep the neck relaxed: Avoid shrugging; think of reaching the arm long as it moves away from the floor.
  3. Stabilize first: Widen your foot position or reduce the load if the ball causes excessive rocking.
Exercise library