[Musculature as a source of back pain].

Lumbar muscle function is considered to be an important component of chronic low back pain (CLBP). Many studies have documented compromised muscle function in patients with CLBP. Although the mechanism associating muscle insufficiency to CLBP is not clearly understood, it is commonly held that the passive tissues of the spine are increasingly stressed with increasing functional muscle insuffiency. Functional instability of the spine plays a major role in the development of back pain. During the last few years, objective evaluation of the fatigue of back muscles by surface electromyography (EMG) with quantitative spectral techniques, evaluation of fibre type and size of the back muscles and quantifying of postural control of the lumbar spine during different tasks documented the failure of the spine in CLBP patients by a deficit of motor control more objectively. Besides this deficit, many patients show severe psychosocial problems and fear-avoidance beliefs. On this basis, treatment of CLBP with active rehabilitation, which includes educational, psychological, and social components along with the therapeutic exercises, has been increasingly advocated during recent years.