Study aim: The purpose of the present study is to compare two isometric and isotonic stability training methods on pain and performance of people with non-specific chronic back pain. Design: In this research, patients in two training groups will receive therapeutic exercises for 8 weeks, and the control group will not receive any intervention. For the randomization process, each patient will choose a number in a closed envelope. For the convenience of calculation, the website program "Research Randomize" will be used. The groups included isometric stability training, isotonic stability training and control. G*Power 3.1 was used to calculate the sample size with an alpha of 0.05, a power (90%) and an effect size (0.5). A total of 36 patients (12 in each group) were required for the study. For this reason, in order to avoid the possible drop rate of participants, the number of 15 people (45 people in total) will be allocated in the groups. Settings and conduct: These people will be identified by an orthopedic doctor and referred to the sports science laboratory of Shahid Beheshti University to perform exercises (subject courses and evaluators). Participants/Inclusion and exclusion criteria: Research entry criteria: the subjects of this study include people with chronic back pain. The subjects of this study will not participate in any other sports activities or therapeutic interventions during the research. Exclusion criteria from the research: having symptoms such as: fever, cough, weakness, and in general suspected people with the corona virus; bone diseases; mental disorders; neurological and muscular disorders; congenital abnormalities; any trauma; history of spinal surgery and In general; having any other disease except non-specific chronic back pain. Intervention groups: 1- Exercise therapy group, 2- Exercise therapy group, 3- Control group. Main outcome variables: Pain and disability