Background and aimsClinical lumbar instability causes pain and socioeconomic suffering; however, an appropriate treatment for this condition is unknown. This article examines the effect of a 10 week core stabilization exercise (CSE) program and 3 month follow-up on pain-related outcomes in patients with clinical lumbar instability.MethodsForty-two participants with clinical lumbar instability of at least 3 months in duration were randomly allocated either to 10 weekly treatments with CSE or to a conventional group (CG) receiving trunk stretching exercises and hot pack. Pain-related outcomes including pain intensity during instability catch sign, functional disability, patient satisfaction, and health-related quality of life were measured at 10 weeks of intervention and 1 and 3 months after the last intervention session (follow-up); trunk muscle activation patterns measured by surface electromyography were measured at 10 weeks.ResultsCSE showed significantly greater reductions in all pain-related outcomes after 10 weeks and over the course of 3 month follow-up periods than those seen in the CG (P<0.01). Furthermore, CSE enhanced deep abdominal muscle activation better than in the CG (P<0.001), whereas the CG had deterioration of deep back muscle activation compared with the CSE group (P<0.01). For within-group comparison, CSE provided significant improvements in all pain-related outcomes over follow-up (P<0.01), whereas the CG demonstrated reduction in pain intensity during instability catch sign only at 10 weeks (P<0.01). In addition, CSE showed an improvement in deep abdominal muscle activation (P<0.01), whereas the CG revealed the deterioration of deep abdominal and back muscle activations (P<0.05).ConclusionTen week CSE provides greater training and retention effects on pain-related outcomes and induced activation of deep abdominal muscles in patients with clinical lumbar instability compared with conventional treatment.