The shoulder press works the deltoid muscles. While performing the alternating dumbbell shoulder press on the ball, your abs and back will be contracted to keep your body steady.

Start in a seated position on the ball, feet flat on the floor. Raise the dumbbells to shoulder height. Keep your elbows bent, palms facing forward. Slowly raise one arm above your head, just short of locking your elbows. Return to the starting position. Perform the same movement on the opposite arm. Repeat the exercise in alternating fashion. Inhale as you lower each arm. Exhale as you extend.