Medicine Ball Crunch and Twist
Lie down on the floor. Your knees should be bent at 90 degrees, your heels should be about 15 inches apart and resting on the floor. Hold the ball with your extended arms over your head.
Crunch your abs and lift your torso of the floor, rotate your torso to the left, and place the ball on the floor next to you.
Go back to the starting position and repeat the movement but this time rotate your torso to the right side.
Go back to the starting position and repeat the exercise according to the training plan alternating sides.