 Recruitment. Patients recruitment: The subjects are recruited from orthopedic hospitals departments in Utrecht the Netherlands. Participants will be asked if they want to refer NSP-CLBP patients for this research and by advertisement in an Dutch-language newspaper Appendix II. Also, NSP-CLBP patients who applied for physical therapy were asked if they wanted to participate in this research. A call form has been prepared for this purpose Appendix III. All subjects were asked if they would like to participate in this research. The subjects has been authorized to perform medical physiotherapeutic treatment. This has been done by signing a statement of agreement, as previously stated. Personal data will not be included in this research and are protected by researchers and the Committee of Medical Ethics University Hospital University of Brussels. 