Background and objectives: In the last few years, several studies have focused on short-term treatment effects of exercise therapy. However, there is a lack of knowledge concerning the long-term treatment effects recorded after several years. Hence, this study was performed to investigate the short- and long-term effects of supervised physical training on functional ability, self-rated pain and disability in secondary prevention of low back pain. Methods: One hundred and eighty-three hospital employees with chronic low back pain were randomly assigned either to back school (comparison group), or three-months supervised physical training including a back school (exercise group). Various measurements of functional ability were performed and subjects completed questionnaires on self-rated pain, disability, and general well-being before treatment, immediately after intervention, and at six-months follow-up. At one-year and at ten-years follow-up participants evaluated treatment effectiveness. Results: Out of 183 employees, 148 completed the program. Participation at follow-ups ranged from 66 to 96%. Supervised physical training significantly improved muscular endurance and isokinetic strength during a six-months follow-up, and effectively decreased self-rated pain and disability during a one-year follow-up. At ten-years follow-up the subjects' assessment of the effectiveness of treatment was significantly better in the exercise group. Conclusions: Supervised physical training effectively improved functional capacity and decreased LBP and disability up to one-year follow-up. The subjects' positive evaluation of the treatment effect at ten-years follow-up suggests a long-term benefit of trainin
