Position feet under support with knees bent. With two medicine balls at bottom of chute, grasp closest medicine ball with both hands.
With ball in both hands, lie down onto back support while lowering medicine ball to chest. Raise torso from back support by bending waist and hips while pushing ball away from chest. Immediately throw ball into target and grasp other medicine ball at bottom of chute. Repeat movement.
Intensity can be increased by using heavier medicine ball, by performing movement faster, using overhead throwing motion. If upper back does not come completely down at end of movement, abdominal muscles may only be isometrically involved in exercise. See similar plyometric movement: Medicine Ball Situp (with partner). See Spot Reduction Myth and Dangerous Exercise Essay.