Primary Muscle Group: Abdominal - Internal and External Obliques
Muscle Groups Worked in This Exercise: Side Abdominal - Internal and External Obliques, Deep Abdominal Muscles (transverse abdominis), and lower back (erector spinae)
Preparation: Lie on your side over the stability ball so your left hip is resting on the ball. Spread your legs for good solid balance.
Execution: Hold a medicine ball over your head and curl up towards the ceiling. Lay back down across the ball and repeat the movement. Repeat with the other side.