Sit on a stability ball with both feet flat on the floor, holding a medicine ball with both hands.
Lie back on the stability ball, bringing your arms overhead until they are parallel with the floor.
Sit up and throw the ball to a partner standing in front of you.
Perform a sit up with out the medicine ball.
When you sit back up your partner will throw the ball to you.
Perform another sit up with the ball, again bringing your arms overhead until they are parallel with the floor.
Repeat this pattern for the required number of repetitions.
