The following is an exclusive excerpt from the book Developing the Core, published by Human Kinetics.All text and images provided by Human Kinetics.

Lie on your back with your arms out to the sides and palms flat on the floor. Keeping your legs straight and feet together, raise your thighs so that they are perpendicular with the ground. Keeping your upper back pressed to the floor, slowly lower your legs directly to the right. Raise your legs back to the start position, and repeat the process on your left. Alternate from side to side for the desired number of repetitions.

Variation

Reverse Pendulum Medicine Ball Twister: Bend your knees and perform the reverse pendulum movement as described. If the movement becomes easy, place a medicine ball between your knees or thighs.

The National Strength and Conditioning Association (NSCA), the world’s leading sport conditioning organization, offers its unrivaled expertise in a book perfect for any athlete seeking to strengthen the core and improve athletic performance. Featuring 11 ready-to-use sport-specific programs, Developing the Core provides more than 50 of the most effective exercises along with science-based assessments to help athletes understand their individual needs. The book is available in bookstores everywhere, as well as online at the NSCA Store.