Lie supine on the stability ball with the ball supporting your mid-to-upper back. Plant your feet shoulder-width apart on the floor, bend your knees 90 degrees, and place hands lightly behind your head.

1. Brace your core and initiate the movement by crunching up and twisting your torso.
2. Bring your right elbow toward your left knee, aiming to lift your right shoulder blade off the ball.
3. Pause briefly at the peak of the contraction, squeezing the oblique muscles.
4. Slowly return to the starting position, maintaining tension on the core.
5. Alternate sides, twisting the left elbow toward the right knee for the next repetition.