IRCT20190527043730N1 IRCT 2019-07-16 Shiraz University of Medical Sciences Effect of lumbar stabilization exercise performed on stable versus unstable surfaces in chronic low back pain patient Comparison of the effect of exercise on stable surface versus unstable surface on cross section area of lumbar stabilizer muscle, pain, disability index, static and dynamic balance in patients with chronic low back pain 2019-04-21 anticipated 40 Complete https://irct.ir/trial/40038 interventional Randomization: Randomized, Blinding: Single blinded, Placebo: Not used, Assignment: Parallel, Purpose: Treatment, Randomization description: Individuals with block randomization and sealed opaque envelopes concealment take place in two groups, Blinding description: in this study evaluations and intervention are performed by two different physiotherapists. N/A Chronic low back pain. Intervention 1: Intervention group 1: This group will receive the common physical therapy treatment and exercise on unstable surface for 18 session during a period of 6 weeks. lumbar stabilization exercise program progressively increase during the 6-week exercise program. The subjects will ask to perform three sets of 10 repetitions during the first and second week, progress to three sets of 15 repetitions during each session in the third and fourth weeks, and three sets of 20 repetitions during the fifth and sixth weeks. Intervention 2: Intervention group 2: This group will receive the common physical therapy treatment and exercise on stable surface for 18 session during a period of 6 weeks. lumbar stabilization exercise program progressively increase during the 6-week exercise program. The subjects will ask to perform three sets of 10 repetitions during the first and second week, progress to three sets of 15 repetitions during each session in the third and fourth weeks, and three sets of 20 repetitions during the fifth and sixth weeks. Undecided - It is not yet known if there will be a plan to make this available Justification or reason for indecision in sharing IPD is without plane