STARTING POSITION:
You need to place a fitball behind your back. Place the dorsum of your right foot behind you on the fitball and the left foot in front of you. Contract your pelvic floor and core.
MOVEMENT:
Bending your knees, slowly lower your body down until you feel the stretch on your right thigh. Your right heel should be close to your butt. Make sure to keep your right shin perpendicular to the floor avoiding the rise of the heel. Maintain the stretch during the required time, return to the starting position and then switch sides and repeat with the other leg.
TIPS: You should feel the stretch of the muscles but not pain. Make sure your knee does not move toward the midline of your body.