The aim is to compare the effectiveness and cost-effectiveness of a Pilates program versus home-based exercises in individuals with chronic non-specific low back pain. This is a randomized controlled trial with economic evaluation. Participants will be sequentially enrolled and randomly allocated into two groups: 1) Pilates: Mat Pilates sessions, supervised by a physiotherapist (2x/week for 6 weeks); 2) Home-Based Exercise: face-to-face familiarization (two sessions), supervised by another physiotherapist. After familiarization, the exercises will be prescribed using a booklet containing descriptions of sets/repetitions, as well as guidelines and precautions, to be performed during 6 weeks (2x/week) and monitored in a diary. Participants will be supervised by the physiotherapist (telephone/text messaging). Participants will be evaluated in three different moments: 1) Baseline (pre-intervention); 2) At the end of the intervention (post-intervention, 6 weeks); and 3) After six months follow-up (from post-intervention). Primary outcomes: pain intensity and disability. Secondary outcomes: perception of recovery, postural balance, and quality of life. Concurrently, a cost-effectiveness study will be conducted comparing the Pilates vs Home-Based Exercise, from the perspectives of public healthcare and society. In the first perspective, only costs incurred by the public healthcare system will be included (direct costs related to consultations, medications, tests, hospitalizations, and professional fees). In the second perspective, private health care expenses, costs incurred by patients (transportation and support by caregivers, when applicable), as well as indirect costs (missed workdays and loss of productivity) will be included. The incremental cost-effectiveness ratios for the primary outcomes and cost-utility ratios will be calculated for both perspectives. The cost-utility ratio will express the incremental costs per quality-adjusted life year (QALY). In addition, the absolute and incremental net monetary benefit will be calculated. Sensitivity analyses will be conducted. Data normality assumptions will be evaluated using the Shapiro Wilk test. If confirmed, a mixed model will be used, for the comparisons between groups and moments. It is hypothesized that the Pilates will be more cost-effective compared to the home-based exercise program.

Inclusion Criteria:

• Presence of chronic non-specific back pain for more than 12 consecutive weeks;
• Not having attended Pilates or physiotherapy sessions for at least 6 months prior to enrollment.

Exclusion Criteria:

• History of trauma or fractures in the spine;;
• Diagnosis of osteoarthritis, disc herniation or spondylolisthesis;
• Referred pain (visceral, abdominoplasty, appendicitis, abdominal and pelvic surgeries);
• Previous surgery on the spine;
• Presence of root symptoms;
• Pregnancy.

The outcome assessor won't have any knowledge about the study purposes and will be unaware of the group allocation. The statistical analysis will also be performed blinded for group allocation.