STARTING POSITION:
Lie on the floor facing down and place a fitball between your heels with your legs extended. Place your hands under your forehead for a more comfortable position. Contract your pelvic floor and core while keep your body straight.
MOVEMENT:
Maintaining the fitball between your heels, fully bend your knees. Return to the starting position and repeat the movement.
TIPS: The exercise key is quality over quantity. The trick is to perform the exercise using proper form.