Inclusion Criteria:  patient age 18-60 years first spinal surgery in the areas L1-S1 signed informed consent for the participation in the study  Exclusion Criteria:  patients with a history of other back problems (compression fracture, spondylitis, tumour) patients after repeated spinal surgeries patients with a systemic disease affecting the muscles elite athletes patients who disagree to participate in the study women with a positive pregnancy test or women planning on becoming pregnant