With a partner, sit on the floor or sit straddled on separate benches. Sit side by side facing opposite directions approximately 2 meters apart. Hold a medicine ball with both hands.
Rotate your torso away from your partner and tap the ball on the floor just behind your hip. Rotate your torso to the opposite direction and throw the ball to your partner. Your partner catches the ball and executes the same sequence. Continue to exchange the ball. When finished, face opposite direction and repeat.
Start slow, gradually increasing your speed throughout the set.