Aim: To compare the effects of Pilates with and without accessories on biochemical markers, pain intensity, functional disability and muscle strength in postmenopausal women with nonspecific chronic low back pain. Materials & methods: Twenty-two participants were randomized to a group of Pilates without (PG; n = 11) and with elastic resistance (PAG; n = 11) for 8 weeks, twice a week. We analyzed IGF-1, IGF-binding protein-3 (IGFBP-3), cortisol, creatine kinase, pain intensity, functional disability, abdominal and back strengths. Results: Both groups had lower pain intensity and functional disability and increased lumbar strength postinterventions. PAG exhibited an increase in IGF-1/IGFBP-3 ratio and reduction in creatine kinase compared with PG. Conclusion: Both interventions were effective in the treatment of low back pain. However, PAG presented better responses than PG. Clinical Trial Registration: Brazilian Clinical Trials Registry: ReBEC (RBR-9jwcykc), www.ensaiosclinicos.gov.br/rg/RBR-9jwcykc