Step by step instructions
Lie faceup with your legs extended on the ground in front of you and hold a weighted ball or dumbbell over your chest, elbows bent out to your sides. (Beginners, skip the weight and place your hands behind your head.) Lift legs, head, and shoulders as you bend your right knee and rotate your left shoulder toward it.
Extend your right leg as you bend your left knee toward your chest and rotate your shoulder toward it. That's one rep. Focus on rotating your shoulder (not your elbow) toward your knee.