Torso Twist

Trains the internal and external obliques, the muscles on either side of your torso, which help you swing a bat, a golf club, or a racquet.

How to do it:
Lie on your back, with your knees bent at a 90-degree angle and your feet flat on the floor. Squeeze a light 2 to 5-pound medicine ball (at sporting goods stores) or a thick phone book tightly between your knees.

(A) Cup your hands lightly over your ears, then slowly raise your head, shoulders, and feet off the floor. This is your starting position.

(B) Slowly lower your knees to the right until you feel a comfortable stretch (about halfway to the floor). Hold this position for 5 seconds, then lift your knees back to the center.

(C) Lower your knees to the left for 5 seconds. Do six twists to each side.

Follow this exercise immediately with the Circular Crunch.