Stand facing partner throwing distance apart with left foot forward. First person holds medicine ball with right hand near side of head. Partner has arm up ready to receive ball.
First person throws medicine ball left of partner's head (partner's right side), forcefully extending arm forward. Partner catches ball with right hand, recoils ball to side of head, and immediately throws ball back to left of first person's head (first person's right side) in same manner. First person catches ball and repeats volley. Repeat by throwing ball back and forth. Continue using left hand to throw to opposite sides.
Start slow, gradually increasing speed throughout set. Perform prescribed repetitions or for time.