hypertonicity of ipsilateral quadratus lumborum. Chronic hypertonicity of quadratus lumborum tends to cause low back pain due to its ability to create compressive stress on lumbar segment. Treatment While stretching and strengthening the quadratus lumborum are indicated for unilateral lower back pain, heat or ice applications as well as massage should be considered as part of any comprehensive rehabilitation regimen. Current studies show that application of heat or ice, massage, and estim will not leave long-term benefits. Careful assessment of muscular imbalances and movement impairments by a therapist is recommended in order to address the underlying issues mentioned. References External links - "Posterior Abdominal Wall, Dissection, Anterior View" Muscles of the torso