Side Abdominal Muscles (internal and external obliques)
Additional Muscles:
Deep Abdominal Muscles (transverse abdominis)
To make the Ball Pass harder, you can use weights or circular weights which will work your upper body as well as the abs.
Ball pass should ideally be done with a partner closer to your height to avoid bending.
Ball pass is a fun way to do the Twist exercise with a partner. Ball Pass helps shape your side abdominal muscles, but also works your deep abdominal muscles and your lower back.
Stand with a partner with your backs touching. Pass a ball (basket ball or a football) from one side to your partner. The partner receives the ball and passes the ball back from the other side.
Do not pass the ball merely by moving the hands. The whole top body must turn to make the pass or receive the pass.
Keep your back straight, do not lean front or back.