Musculoskeletal disorders, of which back pain accounts for more than half the number of cases, are the most common cause of chronic incapacity in industrialized countries. Approximately 10-20 percent of patients with low back pain develop chronic pain, defined as low back pain persisting more than 3 months. Low back pain represents a particularly costly sociomedical problem because of the expenditure associated with repeated treatment and the long-term absence from work and need for social support. These patients use more than 80% of health care resources for back problems, and treatment has a low success rate. Thus, the development of effective interventions aimed at management of the chronic problems is urgently required.