Begin by selecting a medicine ball (beginners 6 lbs.; advanced 10lbs). Assume a seated position on the floor with the knees bent and feet placed flat on the floor (as if doing a sit-up exercise). The feet may or may not be anchored during this movement. If a high speed is desired then the feet can be anchored on a sit-up board.

Place the medicine ball directly in front of the trunk and maintain constant tension in the abdominals; remember to maintain a normal breathing pattern. Slowly begin to rotate, allowing the trunk and knees to naturally move in opposite directions.

For greater difficultly increase the speed of rotation or perform the movement on an incline sit-up board.