There is evidence for altered muscle activity patterns in individuals with non-specific chronic back pain (NSCBP). It is unknown why these alterations in activation pattern occur and how they may be linked to pain experience and to the development of CNSBP. The main objective of this study is to investigate the spatial aspects of muscle activation in relation to fatigue/endurance and CNSBP. A novel approach, utilizing a new multi-channel surface-EMG (MCsEMG) technique will be applied in this project to get insight in fundamental mechanisms related to motor control and fatigue/endurance. In this project data from healthy persons and from patients with NSCBP will be collected and analyzed. NSCBP patients will be compared to healthy persons. To minimize heterogeneity between groups the subject's age range will be from 30 - 50 years. The investigators main hypothesis is that motor control mechanisms of the lumbar muscles are disturbed in NSCBP patients compared to normals, explaining the reduced tolerance for static postures. There has been little investigation of the lumbar musculature with MCsEMG recordings. The lumbar musculature has a complex organization; many, relatively small muscles, in a restricted area. Utilizing two HDsEMG grids with 252 Ag/AgCl contacts will be the superior non-invasive method to investigate motor control mechanisms in this region, and further the investigators understanding of neuromuscular adaptations related to NSCBP. The project may demonstrate changes that will lead us to new insight and new strategies for the treatment of back pain.