The quadratus lumborum muscle resides deep in your lower back. It stabilizes your pelvis and lower back, and assists in sideways flexion of your spine and lower back rotation, according to ExRX.net. Stretching your quadratus lumborum is not too difficult, and often you'll also get the benefit of stretching other muscles in the vicinity, such as your glutes and those in your hips. The only real trick is to know that the muscle runs parallel to the lumbar spine on each side of your lower back, so if you are not feeling a stretch there, you are unlikely to be stretching your quadratus lumborum.
Lie on your back, either on the floor or a bed, to perform the hooklying stretch. Bend your knees with your feet still touching the bed. Rest your hands on your stomach. Place a pillow under your neck if you wish; this will not interfere with the stretch.
Cross your right leg over your left. Lower your knees slowly to the right until you feel a stretch in your right lower back and hips. Keep your shoulders on the floor or bed. Hold for five seconds.
Bring your legs back to center where they started. Switch legs and drop your knees slowly to the left. Hold for five seconds and bring your legs back to center. Repeat the stretch multiple times if so instructed by a physician.
Kneel in front of a stool, chair or table to perform the kneeling quadratus lumborum stretch for your lower back, hips and the sides of the torso. Use a sturdy object that won't topple over easily.
Put your hands on the floor with your arms straight in an all-fours position. Reach with your left arm to the leg of the stool on your right and grab the leg about shoulder height with your palms facing to the left. This causes your body to twist slightly to the right.
Shift back diagonally toward your left so that your left side curves slightly from your arm to hip. Keep your right hand firmly on the floor. Hold for five seconds.
Shift your body forward again to the starting position, and put your left hand on the floor. Reach to the left with your right hand, and repeat the stretch on the right side. Do not expect each side to stretch the same amount. Go slowly and do not force anything.