Chronic low back pain is a public health issue affecting over 20% of the Spanish population, causing disability, reduced quality of life, and work absenteeism. Over the past decades, the benefits of physical exercise for improving symptoms in patients with chronic low back pain have been studied. Exercise has also been shown to improve quality of life, general health, self-efficacy, and fear of pain, regardless of pathology. Research on the effect of physical exercise in chronic low back pain patients has shown promising results. Therefore, the therapeutic exercise program proposed in this study may help participants adopt healthy habits that positively impact their quality of life.

This will be a clinical trial in patients with chronic low back pain. The main purpose of the study is to evaluate the efficacy of a self-selected resistance training program versus physiotherapist-prescribed exercises in improving pain intensity and disability in adults with chronic low back pain. Secondary objectives include evaluating differences between the two groups after 12 weeks in treatment satisfaction, degree of compliance, kinesiophobia, self-efficacy, muscle endurance, and lumbar electromyographic activity.

If you agree to participate, a member of the research team experienced in exercise programs for chronic low back pain will instruct you on how to perform the program. The follow-up study will include 34 participants randomly assigned to two groups: one group performing self-selected resistance exercises, and one group performing physiotherapist-prescribed exercises. The study will last 12 weeks, assessing your condition at the start and end of the study. You will complete questionnaires on pain intensity (Numerical Pain Rating Scale, NPRS), disability (Oswestry Disability Index, ODI), treatment satisfaction (CRES-4), adherence to treatment, kinesiophobia (TSK-11), self-efficacy (Pain Self-Efficacy Questionnaire, PSEQ), muscle endurance (Biering-Sørensen test), and surface electromyographic activity of the erector spinae (longissimus) muscle (sEMG-ESL) using the mDurance® device.

POTENTIAL BENEFITS AND RISKS OF PARTICIPATION Expected direct benefits of participation may include improvements in pain intensity, disability, treatment satisfaction, adherence to therapeutic exercise, kinesiophobia, self-efficacy, muscle endurance, and electromyographic activity.

However, it is possible that you may not experience any personal benefit. The information obtained will contribute to scientific knowledge about CLBP and may help others in the future.

ALTERNATIVE TREATMENTS Chronic low back pain is a pathological entity with extensive study, which can present different conservative therapeutic options, such as psychological therapy, regular physical exercise and the adoption of healthy habits.

COMPENSATION Participation in this study will not incur any costs for you. OTHER RELEVANT INFORMATION Any new information discovered during your participation that may affect your willingness to participate in the study will be communicated to you by your doctor as soon as possible.

If you decide to withdraw your consent to participate in this study, no new data will be added to the database, and if samples have already been collected, you may request the destruction of all previously obtained, identifiable samples to avoid further analysis.

You should also be aware that you may be excluded from the study if the sponsor or researchers deem it necessary, either for safety reasons or because they believe you are not complying with the established procedures.

In either case, you will receive a clear explanation of the reason for your withdrawal from the study. The sponsor may suspend the study for any of the reasons stipulated in current legislation.

By signing the attached consent form, you agree to comply with the study procedures explained to you. When your participation is over, you will receive the best available treatment that your doctor considers most appropriate for your condition.