WORKS: Complete ab region, with emphasis on obliques and serratus
• Place your lower back on a stability ball at a 45-degree angle with your feet shoulder-width apart on the floor and your knees at a 90-degree angle.
• Hold the medicine ball in front of your body with elbows slightly bent (A).
• Twist ball to the outside of your left hip (B), then around to outside of right hip.
• Follow the ball with your eyes, maintaining core tension.
• Switch sides and repeat for 10 reps per side for three sets.
Tip No. 4: Keep your back straight and your shoulders off the ball to keep the tension in your core.
SEE ALSO: 8 Weeks to Six-Pack Abs with This Diet