The quadratus lumborum (QL) muscle is a muscle of the posterior abdominal wall lying deep inside the abdomen and dorsal to the iliopsoas. It makes up most of your middle and lower back. We have one each side of our backs. All fibres together give the muscle a rectangular appearance.
Insertion - inferior border of the 12th rib
The QL can be a common source of lower back pain as it connects to the pelvis as well as the vertebra. The cause of pain can be when the erector spinae back muscles are weak or inhibited, which can occur through poor posture for long periods of time such as in a seated position. The QL will take over supporting the spine if the erector spinae is not functioning properly. This overuse of the QL can cause restriction of the blood flow which can eventually cause muscle spasm and pain.
Continuous poor posture, especially in this seated position, can also cause kyphosis and will also put greater stress on the QL due to the weight being shifted forward and the spine and pelvis coming out of alignment. Promoting good posture and regular activity will help participants maintain a good posture and healthy muscles.
Here are some exercises/stretches for the QL: