Facing partner, sit on floor with knees bent. Hold medicine ball with both hands.
Lie back with ball over head and taps ball to floor. Immediately throw ball to partner from over head while sitting up. Partner catches ball slightly above and in front of head and repeats steps. Continue to volley ball back and forth.
Perform prescribed repetitions or for time. Feet may also be secured under weighted or anchored structure. If feet are not being supported by fixed object, legs may need to be extended somewhat to offer adequate counter balance to upper body. If upper back does not come completely down at end of movement, abdominal muscles may only be isometrically involved in exercise. See Spot Reduction Myth. Also see Medicine Ball Sit-up on Machine.