Low back pain can be a complicated condition. Quite often in my practice I will see multiple muscles involved in causing lower back pain in my clients. For example trigger points in the hip flexors like the psoas muscle, along with trigger points in the back muscles themselves, such as the quadratus lumborum or the multifidus, can all be active and refer pain into the low back. When trigger points are active in multiple muscles at once this is called a chronic myofascial pain syndrome.